RS199

Bidirectional, Zero-Drift, High or Low Side,
Voltage Output, Current Shunt Monitor
1 FEATURES

Wide Common-Mode Range: 0V to 26 V

Input Offset Voltage: ±100μV (TYP)

Accuracy: (TYP)– Gain Error:– ±0.4% (A Version)– ±2μV/°C Offset Drift– 10ppm/°C Gain Drift

Choice of Gains:– RS199A: 50 V/V– RS199B: 100 V/V– RS199C: 200 V/V

Quiescent Current: 72μA (TYP)Supply Range: +2.7V to +26V

Operating Temperature Range: -40°C to+125°C

Micro SIZE PACKAGES: SC70-6

3 DESCRIPTIONSThe RS199 series of voltage-output, current-shuntmonitors (also called current-sense amplifiers) arecommonly used for overcurrent protection, precision
current measurement for system optimization, or inclosed-loop feedback circuits. This series of devices
can sense drops across shunt resistors at common
mode voltages from 0 V to 26 V, independent of the
supply voltage. Three fixed gains are available: 50
V/V, 100 V/V, and 200 V/V. The low offset of the zerodrift architecture enables current sensing withmaximum drops across the shunt as low as 10mV fullscale.
These devices operate from a single 2.7V to 26V
power supply, drawing 72μA of supply current. The
RS199 families of operational amplifiers are specified
at the full temperature range of -40°C to 125°C, andoffered in SC70-6 packages.

2 APPLICATIONSNotebook ComputersCell Phones



Qi-Compliant Wireless Charging
Transmitters

Telecom Equipment

Battery Chargers

Power Management

REV A.1.1

Device Information(1)PART
NUMBER
RS199

PACKAGEBODY SIZE (NOM)

SC70-62.10mm×1.25mm(1) For all available packages, see the orderable addendum atthe end of the data sheet.

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RS1994 Simplified Schematic

2.7 V to 26 V

RSHUNT

Sup ply

Reference
Voltage

REF

OUT

GND

IN-

V+

IN+

Loa d

OutputCBYPASS
0.01μF to 0 .1μF

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RS199
Table of Contents
1 FEATURES .......................................................................................................................................................1
2 APPLICATIONS ................................................................................................................................................1
3 DESCRIPTIONS ................................................................................................................................................1
4 Simplified Schematic ......................................................................................................................................2
5 Revision History ..............................................................................................................................................4
6 PACKAGE/ORDERING INFORMATION (1) ......................................................................................................5
7 Pin Configuration and Functions ...................................................................................................................6
7.1 Pin Description ............................................................................................................................................6
7.2 Device Comparison Table ...........................................................................................................................6
8 SPECIFICATIONS ............................................................................................................................................7
8.1 Absolute Maximum Ratings ........................................................................................................................7
8.2 ESD Ratings................................................................................................................................................7
8.3 Recommended Operating Conditions .........................................................................................................7
8.4 ELECTRICAL CHARACTERISTICS ...........................................................................................................8
8.5 TYPICAL CHARACTERISTICS ..................................................................................................................9
9 Detailed Description ......................................................................................................................................10
9.1 Overview .................................................................................................................................................. 11
9.2 Functional Block Diagram ........................................................................................................................ 11
9.3 Feature Description .................................................................................................................................. 129.3.1 Basic Connections ............................................................................................................................. 129.3.2 Selecting RSHUNT ................................................................................................................................ 12
9.4 Device Functional Modes......................................................................................................................... 129.4.1 Input Filtering ..................................................................................................................................... 129.4.2 Shutting Down the RS199 Series ...................................................................................................... 14
9.4.3 REF Input Impedance Effects ........................................................................................................... 15
9.4.4 Using the RS199 With Common-Mode Transients Above 26V ........................................................ 15
9.4.5 Improving Transient Robustness ...................................................................................................... 1710 Application and Implementation ................................................................................................................18
10.1 Application Information .......................................................................................................................... 18
10.2 Typical Applications ............................................................................................................................... 18
10.2.1 Unidirectional Operation .................................................................................................................. 18
10.2.2 Design Requirements ...................................................................................................................... 18
10.2.3 Detailed Design Procedure ............................................................................................................. 18
10.2.4 Bidirectional Operation .................................................................................................................... 19
10.2.5 Design Requirements ...................................................................................................................... 19
10.2.6 Detailed Design Procedure ............................................................................................................. 19
11 Power Supply Recommendations .............................................................................................................20
12 PACKAGE OUTLINE DIMENSIONS ............................................................................................................21
13 TAPE AND REEL INFORMATION ...............................................................................................................22

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RS1995 Revision History
Note: Page numbers for previous revisions may different from page numbers in the current version.
VersionChange Date

Change Item

A.0

2022/11/22

Preliminary version completed

A.1

2023/04/19

Initial version completed

A.1.1

2024/02/29

Modify packaging naming

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RS1996 PACKAGE/ORDERING INFORMATION (1)PRODUCTRS199

ORDERING
NUMBER
RS199AXC6TEMPERATURE
RANGE-40°C ~125°C

PACKAGE LEAD
SC70-6 (3)PACKAGEMARKING (2)199A

PACKAGE OPTION
Tape and Reel,3000

NOTE:(1) This information is the most current data available for the designated devices. This data is subject to change without notice and revisionof this document. For browser-based versions of this data sheet, refer to the right-hand navigation.
(2) There may be additional marking, which relates to the lot trace code information (data code and vendor code), the logo or theenvironmental category on the device.
(3) Equivalent to SOT363.

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RS1997 Pin Configuration and Functions
TOP VIEW

REF

1

6

OUT

GND

2

5

IN-

4

IN+

+
3

V+

SC70-6

7.1 Pin Description
PIN

I/O (1)NAME

DESCRIPTION

SC70-6REF

1

I

Reference voltage, 0 V to V+

GND

2

-

GroundV+

3-

Power supply, 2.7 V to 26 V

IN+

4

I

Connect to supply side of shunt resistor.

IN-

5

I

Connect to load side of shunt resistor.

OUT

6

O

Output voltage

NC (2)--

Not internally connected. Leave floating or connect to ground.

(1) I = Input, O = Output.
(2) NC denotes no internal connection. These pins can be left floating or connected to any voltage between GND and V+.

7.2 Device Comparison Table
Product

Gain

R1 & R2

R3 & R4

RS199A

50

1MΩ

20KΩ

RS199B

100

1MΩ

10KΩ

RS199C

200

1MΩ

5KΩ

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RS1998 SPECIFICATIONS
8.1 Absolute Maximum Ratings
Over operating free-air temperature range (unless otherwise noted) (1)
MIN

MAX

Supply Voltage
Analog inputs,
VIN+, VIN– (2)Voltage26
Differential (VIN+) - (VIN-)

-26

26

Common-mode (3)026

REF input

GND-0.3(V+)+0.3

Output (3)GND-0.3(V+)+0.3

Current

Input current Into all pins (3)θJA

Package thermal impedance (4)Temperature

UNIT

SC70-6

V

V

5

mA

265

°C/W

Operating range, TA

-40

125

Junction, TJ (5)

-40

150

Storage, Tstg

-55

150

°C

(1) Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may
degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond
those specified is not implied.
(2) VIN+ and VIN– are the voltages at the IN+ and IN– pins, respectively.
(3) Input voltage at any pin can exceed the voltage shown if the current at that pin is limited to 5 mA.
(4) The package thermal impedance is calculated in accordance with JESD-51.
(5) The maximum power dissipation is a function of TJ(MAX), RθJA, and TA. The maximum allowable power dissipation at any ambient
temperature is PD = (T J(MAX) - TA) / RθJA. All numbers apply for packages soldered directly onto a PCB.

8.2 ESD Ratings
The following ESD information is provided for handling of ESD-sensitive devices in an ESD protected area only.
VALUE
V(ESD)

Electrostatic discharge

Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)±3000

Charged-device model (CDM), per ANSI/ESDA/JEDEC JS-002(2)±1500

Machine Model (MM)

±300

UNIT
V

(1) JEDEC document JEP155 states that 500 V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250 V CDM allows safe manufacturing with a standard ESD control process.

ESD SENSITIVITY CAUTION
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric changes could cause the device not to meet its publishedspecifications.

8.3 Recommended Operating Conditions
Over operating free-air temperature range (unless otherwise noted)
MIN

NOM

MAX

UNIT

VCM

Common-mode input voltage

12

V

VS

Operating supply voltage (applied to V+)

5

V

TA

Operating free-air temperature-40

7 / 23125°C

www.run-ic.com

RS1998.4 ELECTRICAL CHARACTERISTICS(At TA = +25C, VS=5V, VIN+=12V, VSENSE= VIN+ - VIN-, VREF = VS/2, Full (8) =-40C ~+125C, unless otherwise noted.) (1)
PARAMETERSYMBOL

CONDITIONSTEMPMIN(2)FULL

2.7

TYP(3)

MAX(2)

UNIT

26

V

POWER SUPPLY
Operating Voltage Range

VS

Quiescent Current

IQ

VSENSE= 0mVVOS

VSENSE= 0mV

72

25C
FULL

100
130

μA

INPUT CHARACTERISTICS
Input Offset Voltage, RTI (4)Input Offset Voltage Average
Drift

VOS TC

Input Bias Current (5) (6)IB

VS=2.7V to 18V,
VIN+=18V,VREF=2V,
VSENSE= 0mV
VSENSE= 0mV

Input Offset Current (5)Common-Mode Voltage
Range
Common-Mode Rejection
Ratio
NOISE, RTI (4)IOS

VSENSE= 0mVPower-Supply Rejection
Ratio

PSRR

VCM

25C

-350

±100

350

μV

FULL

±2

μV/C

25C

±0.2

μV/V

25C

±26

μA

25C

±0.02

μA

FULL

0
85

CMRR

VIN+=0V to 26V
VSENSE= 0mV

25C

Input Voltage Noiseenp-pf= 0.1Hz to 10Hz

Input Voltage Noise Densityenf = 1KHz

26

V

95

dB

25C

2.7

μVPP

25C

100

nV/√HZDYNAMIC PERFORMANCE
Slew Rate (7)Bandwidth

SR
BW

OUTPUT CHARACTERISTICS
Swing to V+ Power-Supply
Rail
Swing to GND
Gain

GGain Error

25C

0.12

V/μs

CLOAD =10pF,
A Version

25C

25

kHz

RL = 10 kΩ to GND

25C(V+)-0.06(V+)-0.08

RL = 10 kΩ to GND

25C(V-)+0.04(V-)+0.06

A Version

25C

50

A Version

Gain Error vs Temperature
Nonlinearity Error
Maximum Capacitive LoadCLOAD

VSENSE=-5 mV to 5 mV
No sustained
oscillation

V
V/V

25C

±0.4

FULL

10

±1.5

ppm/°C

%

25C

±0.01

%

25C

1

nF

TEMPERATURE RANGE
Specified Range

-40

125

°C

Operating Range

-40

125

°C

NOTE:
(1) Electrical table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very
limited self-heating of the device.
(2) Limits are 100% production tested at 25°C. Limits over the operating temperature range are ensured through correlations using statisticalquality control (SQC) method.
(3) Typical values represent the most likely parametric norm as determined at the time of characterization. Actual typical values may varyover time and will also depend on the application and configuration.
(4) RTI = Referred-to-input.
(5) This parameter is ensured by design and/or characterization and is not tested in production.
(6) Positive current corresponds to current flowing into the device.
(7) Number specified is the slower of positive and negative slew rates.
(8) Specified by characterization only.

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RS199
8.5 TYPICAL CHARACTERISTICS
NOTE: The graphs and tables provided following this note are a statistical summary based on a limited number of samples
and are provided for informational purposes only.
At TA = +25C, VS=5V, VIN+=12V, VREF = VS/2, unless otherwise noted.
71

100

70.5

Quiescent Current(uA)

Quiescent Current(uA)

120

80
60
40
20
0

70
69.5
69
68.5

-20
-40

68
2

6

10
14
18
Supply Voltage(V)2226-40 -25 -10 5 20 35 50 65 80 95 110 125
Temperature (℃)

Figure 1. Quiescent Current vs Supply Voltage

Figure 2. Quiescent Current vs Temperature

400

60
40

200
100

CMRR(uV/V)

Input Offset Voltage(uV)

300

0
-100
-200
-300
-400

-500
-600

#1
#2
#3
#4
#5
#6

20
0

-40
-60

-40 -25 -10 5 20 35 50 65 80 95 110 125
Temperature(℃)-40 -25 -10 5 20 35 50 65 80 95 110 125
Temperature (℃)

Figure 3. Input Offset Voltage vs Temperature

Figure 4. Common-Mode Rejection Ratio vsTemperature30

45

Input Bias Current (uA)

Input Bias Current (uA)

40
25
20
15
10
5
0

#1
#2
#3
#4
#5
#6

-20

#1
#2
#3
#4
#5
#6

30
25
20
15

VREF=2.5V

10
5
0
-5

-40 -25 -10 5 20 35 50 65 80 95 110 125
Temperature(℃)

Figure 5. Input Bias Current vs Temperature

VREF=0V35

0 2 4 6 8 10 12 14 16 18 20 22 24 26
Common-Mode Voltage(V)Figure 6. Input Bias Current vs Common-Mode
Voltage

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RS199TYPICAL CHARACTERISTICS

0.5uV/div

500mV/div

NOTE: The graphs and tables provided following this note are a statistical summary based on a limited number of samples
and are provided for informational purposes only.
At TA = +25C, VS=5V, VIN+=12V, VREF = VS/2, unless otherwise noted.

VOUT

10mV/div

VIN

VS=±2.5V
VREF=01s/div

100us/div

Figure 7. 0.1Hz to 10Hz Input Voltage Noise

Figure 8. Step Response (20mVPP Input Step)

Inverting Input Overload

2V/div

2V/div

Noninverting Input Overload

0V

0V
VOUT

VS=±2.5V
VREF=0
RL=10K

VS=5V,
VCM=12V,
VREF=2.5V

VOUT
VS=5V,
VCM=12V,
VREF=2.5V

100us/div

100us/div

Figure 9. Inverting Differential Input Overload

Figure 10. Noninverting Differential Input
Overload

VS=5V,1kHz
Step with
VDIFF=0V,
VREF=2.5V

VIN

1V/div

1V/div

VIN

VOUT
0V

VS=5V,1kHz
Step with
VDIFF=0V,
VREF=2.5V

VOUT
0V

100us/div

100us/div

Figure 11. Start-Up Response

Figure 12. Brownout Recovery

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RS1999 Detailed Description
9.1 Overview
The RS199 is a 26V common mode, zero-drift topology, current-sensing amplifier that can be used in both lowside and high-side configurations. The device is a specially-designed, current-sensing amplifier that is able toaccurately measure voltages developed across a current-sensing resistor on common-mode voltages that far
exceed the supply voltage powering the device. Current can be measured on input voltage rails as high as 26V
and the device can be powered from supply voltages as low as 2.7V.
The zero-drift topology enables high-precision measurements with maximum input offset voltages as low as
350μV with a maximum temperature contribution of 2μV/°C over the full temperature range of -40°C to +125°C.

9.2 Functional Block Diagram
V+

IN-

OUT

IN+

+

REF

GND

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RS1999.3 Feature Description
9.3.1 Basic Connections
Figure 13 shows the basic connections for the RS199. The input pins, IN+ and IN-, must be connected as close
as possible to the shunt resistor to minimize any resistance in series with the shunt resistor.
RSHUNTPower Supply

Load
5V Supply
CBYPASS
0.1µF

V+

IN-

-

OUT

+
IN+

ADC
Microcontroller

REF
GND

Figure 13. Typical Application
Power-supply bypass capacitors are required for stability. Applications with noisy or high-impedance power
supplies may require additional decoupling capacitors to reject power-supply noise. Connect bypass capacitors
close to the device pins.

9.3.2 Selecting RSHUNTThe zero-drift offset performance of the RS199 offers several benefits. Most often, the primary advantage of the
low offset characteristic enables lower full-scale drops across the shunt. For example, non-zero-drift current
shunt monitors typically require a full-scale range of 100mV.
The RS199 series gives equivalent accuracy at a full-scale range on the order of 10mV. This accuracy reduces
shunt dissipation by an order of magnitude with many additional benefits.
Alternatively, there are applications that must measure current over a wide dynamic range that can takeadvantage of the low offset on the low end of the measurement. Most often, these applications can use thelower gain of 50 or 100 to accommodate larger shunt drops on the upper end of the scale.

9.4 Device Functional Modes
9.4.1 Input Filtering
An obvious and straightforward filtering location is at the device output. However, this location negates theadvantage of the low output impedance of the internal buffer. The only other filtering option is at the device input
pins. This location, though, does require consideration of the ±30% tolerance of the internal resistances. Figure
14 shows a filter placed at the inputs pins.

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RS199RSHUNTBus Supply

LoadPower Supply

CBYPASS
0.1µF

V+
RINT

INRS < 10Ω

Bias

CF

Output

OUT

+
RINT

IN+

RS < 10ΩREF
GND

Figure 14. Filter at Input Pins
The addition of external series resistance, however, creates an additional error in the measurement so the valueof these series resistors must be kept to 10Ω (or less if possible) to reduce any affect to accuracy. The internalbias network shown in Figure 14 present at the input pins creates a mismatch in input bias currents when adifferential voltage is applied between the input pins. If additional external series filter resistors are added to thecircuit, the mismatch in bias currents results in a mismatch of voltage drops across the filter resistors. Thismismatch creates a differential error voltage that subtracts from the voltage developed at the shunt resistor.
This error results in a voltage at the device input pins that is different than the voltage developed across theshunt resistor. Without the additional series resistance, the mismatch in input bias currents has little effect on
device operation. The amount of error these external filter resistors add to the measurement can be calculatedusing Equation 2 where the gain error factor is calculated using Equation 1. The amount of variance in the
differential voltage present at the device input relative to the voltage developed at the shunt resistor is based
both on the external series resistance value as well as the internal input resistors, R3 and R4 (or R INT as shownin Figure 14). The reduction of the shunt voltage reaching the device input pins appears as a gain error whencomparing the output voltage relative to the voltage across the shunt resistor. A factor can be calculated todetermine the amount of gain error that is introduced by the addition of external series resistance. The equation
used to calculate the expected deviation from the shunt voltage to what is seen at the device input pins is given
in Equation 1:(1250×RINT)
Gain Error Factor =(1250×RS) + (1250×RINT) + (RS×RINT)(1)
where:• RINT is the internal input resistor (R3 and R4).
• RS is the external series resistance.
With the adjustment factor equation including the device internal input resistance, this factor varies with eachgain version, as listed in Table 1. Each individual device gain error factor is listed in Table 2.

Table 1. Input Resistance
PRODUCTGAIN

RINT(KΩ)

RS199A

50

20

RS199B

100

10

RS199C200

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RS199
Table 2. Device Gain Error Factor
PRODUCTSIMPLIFIED GAIN ERROR FACTOR
20000(17 × R S ) + 20000
10000(9 × R S ) + 10000
1000
R S + 1000

RS199A
RS199B
RS199CThe gain error that can be expected from the addition of the external series resistors can then be calculated
based on Equation 2:
Gain Error(%)=100-(100×Gain Error Factor)(2)
For example, using an RS199B and the corresponding gain error equation from Table 2, a series resistance of10Ω results in a gain error factor of 0.991. The corresponding gain error is then calculated using Equation 2,
resulting in a gain error of approximately 0.89% solely because of the external 10Ω series resistors. Using an
RS199A with the same 10Ω series resistor results in a gain error factor of 0.991 and a gain error of 0.84% again
solely because of these external resistors.

9.4.2 Shutting Down the RS199 Series
Although the RS199 series does not have a shutdown pin, the low power consumption of the device allows theoutput of a logic gate or transistor switch to power the RS199. This gate or switch turns on and turns off theRS199 power-supply quiescent current.
However, in current shunt monitoring applications, there is also a concern for how much current is drained fromthe shunt circuit in shutdown conditions. Evaluating this current drain involves considering the simplified
schematic of the RS199 in shutdown mode shown in Figure 15.

Shu tdo wn
Control

RSHUNT

Sup ply

Reference
Voltage

REF

OUT

GND

IN-

V+

IN+

CBYPASSLoa d

OutputPRODUCT

R3 AND R4

RS199A
RS199B
RS199C

20 kΩ
10 kΩ
5 kΩ

NOTE: 1 MΩ paths from shunt inputs to reference and the RS199 outputs.

Figure 15. Basic Circuit for Shutting Down the RS199 With a Grounded Reference
There is typically slightly more than 1MΩ impedance (from the combination of 1MΩ feedback and 5kΩ input
resistors) from each input of the RS199 to the OUT pin and to the REF pin. The amount of current flowing
through these pins depends on the respective ultimate connection. For example, if the REF pin is grounded, thecalculation of the effect of the 1MΩ impedance from the shunt to ground is straightforward. However, if thereference or operational amplifier is powered when the RS199 is shut down, the calculation is direct; instead ofassuming 1MΩ to ground, however, assume 1MΩ to the reference voltage. If the reference or operational
amplifier is also shut down, some knowledge of the reference or operational amplifier output impedance under
shutdown conditions is required. For instance, if the reference source functions as an open circuit when not
powered, little or no current flows through the 1MΩ path.
Regarding the 1MΩ path to the output pin, the output stage of a disabled RS199 does constitute a good path to
14 / 23www.run-ic.com

RS199ground. Consequently, this current is directly proportional to a shunt common-mode voltage impressed acrossa 1MΩ resistor.
NOTE: When the device is powered up, there is an additional, nearly constant, and well-matched 25μA thatflows in each of the inputs as long as the shunt common-mode voltage is 3V or higher. Below 2V commonmode, the only current effects are the result of the 1MΩ resistors.

9.4.3 REF Input Impedance Effects
As with any difference amplifier, the RS199 series common-mode rejection ratio is affected by any impedance
present at the REF input. This concern is not a problem when the REF pin is connected directly to mostreferences or power supplies. When using resistive dividers from the power supply or a reference voltage, theREF pin must be buffered by an operational amplifier.
In systems where the RS199 output can be sensed differentially, such as by a differential input analog-to-digitalconverter (ADC) or by using two separate ADC inputs, the effects of external impedance on the REF input canbe cancelled. Figure 16 depicts a method of taking the output from the RS199 by using the REF pin as areference.
Loa d

Sup plyADC

2.7 V to 26 V

REF

OUT

GND

IN

V+

IN+

OutputCBYPASS
0.01μF to 0 .1μF

Figure 16. Sensing the RS199 to Cancel Effects of Impedance on the REF Input

9.4.4 Using the RS199 With Common-Mode Transients Above 26VWith a small amount of additional circuitry, the RS199 series can be used in circuits subject to transients higher
than 26V, such as automotive applications. Use only Zener diode or Zener-type transient absorbers (sometimes
referred to as transzorbs); any other type of transient absorber has an unacceptable time delay. Start by adding
a pair of resistors (see Figure 17) as a working impedance for the Zener. Keeping these resistors as small as
possible is preferable, most often approximately 10Ω. Larger values can be used with an effect on gain as
discussed in the Input Filtering section. Because this circuit limits only short-term transients, many applications
are satisfied with a 10Ω resistor along with conventional Zener diodes of the lowest power rating that can befound. This combination uses the least amount of board space.

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RS199RSHUNT

Sup ply

Loa dReference
Voltage

Shu tdo wn
Control

REF

OUT

GND

IN-

V+

IN+

OutputCBYPASS

Figure 17. RS199 Transient Protection Using Dual Zener Diodes
In the event that low-power zeners do not have sufficient transient absorption capability and a higher powertranszorb must be used, the most package-efficient solution then involves using a single transzorb and backto-back diodes between the device inputs. This method is shown in Figure 18.
RSHUNT

Sup ply

Loa dReference
Voltage

Shu tdo wn
Control

REF

OUT

GND

IN-

V+

IN+

OutputCBYPASS

Figure 18. RS199 Transient Protection Using a Single Transzorb and Input Clamps

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RS1999.4.5 Improving Transient Robustness
Applications involving large input transients with excessive dV/dt above 2kV per microsecond present at thedevice input pins can cause damage to the internal ESD structures on version A devices. This potential damage
is a result of the internal latching of the ESD structure to ground when this transient occurs at the input. Withsignificant current available in most current-sensing applications, the large current flowing through the input
transient-triggered, ground-shorted ESD structure quickly results in damage to the silicon. External filtering canbe used to attenuate the transient signal prior to reaching the inputs to avoid the latching condition. Take careto ensure that external series input resistance does not significantly affect gain error accuracy. For accuracy
purposes, keep the resistance under 10Ω if possible. Ferrite beads are recommended for this filter because of
their inherently low dc ohmic value. Ferrite beads with less than 10Ω of resistance at dc and over 600Ω ofresistance at 100MHz to 200MHz are recommended. The recommended capacitor values for this filter are
between 0.01μF and 0.1μF to ensure adequate attenuation in the high-frequency region. This protection scheme
is shown in Figure 19.
Shu ntReference
Load

Voltage
DeviceREF

OUT

SupplyOutputIN-

GND
MMZ16 08B60 1C
2.7 V to 26 V

IN+

V+

0.01μFto 0 .1μF

0.01μF to 0 .1μF

Figure 19. Transient Protection
To minimize the cost of adding these external components to protect the device in applications where largetransient signals may be present, version B and C devices are now available with new ESD structures that are
not susceptible to this latching condition. Version B and C devices are incapable of sustaining these damages
causing latched conditions so these devices do not have the same sensitivity to the transients that the version
A devices have, thus making the version B and C devices a better fit for these applications.

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RS19910 Application and Implementation
Information in the following applications sections is not part of the RUNIC component specification, and RUNIC
does not warrant its accuracy or completeness. RUNIC’s customers are responsible for determining suitabilityof components for their purposes. Customers should validate and test their design implementation to confirm
system functionality.

10.1 Application Information
The RS199 measures the voltage developed across a current-sensing resistor when current passes through it.
The ability to drive the reference pin to adjust the functionality of the output signal offers multiple configurations,as discussed throughout this section.

10.2 Typical Applications
10.2.1 Unidirectional Operation
Bus Supply

LoadPower Supply

CBYPASS
0.1µF

V+

IN-

OUT

Output

+
IN+

REF
GND

Figure 20. Unidirectional Application Schematic

10.2.2 Design Requirements
The device can be configured to monitor current flowing in one direction (unidirectional) or in both directions(bidirectional) depending on how the REF pin is configured. The most common case is unidirectional where theoutput is set to ground when no current is flowing by connecting the REF pin to ground, as shown in Figure 20.
When the input signal increases, the output voltage at the OUT pin increases.

10.2.3 Detailed Design Procedure
The linear range of the output stage is limited in how close the output voltage can approach ground under zero
input conditions. In unidirectional applications where measuring very low input currents is desirable, bias the
REF pin to a convenient value above 50mV to get the output into the linear range of the device. To limit commonmode rejection errors, RUNIC recommends buffering the reference voltage connected to the REF pin.
A less frequently-used output biasing method is to connect the REF pin to the supply voltage, V+. This method
results in the output voltage saturating at 200mV below the supply voltage when no differential input signal ispresent. This method is similar to the output saturated low condition with no input signal when the REF pin isconnected to ground. The output voltage in this configuration only responds to negative currents that develop
negative differential input voltage relative to the device IN- pin. Under these conditions, when the differential
input signal increases negatively, the output voltage moves downward from the saturated supply voltage. The
voltage applied to the REF pin must not exceed the device supply voltage.

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RS19910.2.4 Bidirectional Operation
Bus Supply

LoadPower Supply
CBYPASS0.1 µF

V+

IN-

Reference
Voltage-

OUT

Output

+
REF

+

IN+

-

GND

Figure 21. Bidirectional Application Schematic

10.2.5 Design Requirements
The device is a bidirectional, current-sense amplifier capable of measuring currents through a resistive shunt in
two directions. This bidirectional monitoring is common in applications that include charging and discharging
operations where the current flow-through resistor can change directions.

10.2.6 Detailed Design Procedure
The ability to measure this current flowing in both directions is enabled by applying a voltage to the REF pin;see Figure 21. The voltage applied to REF (VREF) sets the output state that corresponds to the zero-input levelstate. The output then responds by increasing above VREF for positive differential signals (relative to the IN- pin)and responds by decreasing below VREF for negative differential signals. This reference voltage applied to the
REF pin can be set anywhere between 0 V to V+. For bidirectional applications, V REF is typically set at mid-scalefor equal signal range in both current directions. In some cases, however, V REF is set at a voltage other than
mid-scale when the bidirectional current and corresponding output signal do not need to be symmetrical.

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RS19911 Power Supply Recommendations
The input circuitry of the RS199 can accurately measure beyond its power-supply voltage, V+. For example,
the V+ power supply can be 5V, whereas the load power-supply voltage can be as high as 26V. However, theoutput voltage range of the OUT pin is limited by the voltages on the power-supply pin. Also, the RS199 canwithstand the full input signal range up to 26V range in the input pins, regardless of whether the device has
power applied or not.

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RS19912 PACKAGE OUTLINE DIMENSIONS
SC70-6
D

1.30
b

1.9

E

E1
0.75

Pin1
Index Area

0.65

0.4

e
e1

RECOMMENDED LAND PATTERN (Unit: mm)

0.2

A A2

c

θ
L

A1

Dimensions In Millimeters

L1

Dimensions In Inches

Symbol
Min

Max

Min

Max

A

0.900

1.100

0.035

0.043

A1

0.000

0.100

0.000

0.004

A2

0.900

1.000

0.035

0.039

b

0.150

0.350

0.006

0.014

c

0.080

0.150

0.003

0.006

D

2.000

2.200

0.079

0.087

E

1.150

1.350

0.045

0.053

E1

2.150

2.450

0.085

0.096

e

0.650 (BSC)

0.026 (BSC)

e11.300 (BSC)

0.051 (BSC)

L

0.260

L1
θ

0.460

0.010

0.525
0°

0.018
0.021

8°

0°

8°

NOTE:
A. All linear dimension is in millimeters.
B. This drawing is subject to change without notice.
C. Body dimensions do not include mold flash or protrusion. Mold flash and protrusion shall not exceed 0.15 per side.
D. BSC: Basic Dimension. Theoretically exact value shown without tolerances.

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RS19913 TAPE AND REEL INFORMATIONREEL DIMENSIONSTAPE DIMENSION

Reel
DiameterReel Width(W1)

DIRECTION OF FEEDNOTE: The picture is only for reference. Please make the object as the standard.

KEY PARAMETER LIST OF TAPE AND REEL
Package Type
SC70-6

Reel
Diameter7’’

Reel
Width(mm)
9.5

A0
(mm)
2.40

B0
(mm)
2.50

K0
(mm)
1.20

P0
(mm)
4.0

P1
(mm)
4.0

P2
(mm)
2.0

W
(mm)
8.0

Pin1
Quadrant
Q3

NOTE:
1. All dimensions are nominal.
2. Plastic or metal protrusions of 0.15mm maximum per side are not included.

22 / 23www.run-ic.com

RS199IMPORTANT NOTICE AND DISCLAIMER
Jiangsu RUNIC Technology Co., Ltd. will accurately and reliably provide technical and reliability data (including
data sheets), design resources (including reference designs), application or other design advice, WEB tools,
safety information and other resources, without warranty of any defect, and will not make any express or implied
warranty, including but not limited to the warranty of merchantability Implied warranty that it is suitable for a
specific purpose or does not infringe the intellectual property rights of any third party.
These resources are intended for skilled developers designing with RUNIC products You will be solely
responsible for: (1) Selecting the appropriate products for your application; (2) Designing, validating and testing
your application; (3) Ensuring your application meets applicable standards and any other safety, security orother requirements; (4) RUNIC and the RUNIC logo are registered trademarks of RUNIC INCORPORATED. All
trademarks are the property of their respective owners; (5) For change details, review the revision history
included in any revised document. The resources are subject to change without notice. Our company will not
be liable for the use of this product and the infringement of patents or third-party intellectual property rights due
to its use.

23 / 23www.run-ic.com