RS6651

Efficient Synchronous Step-Up Converter with a 2.7A
Switch
1 FEATURES

3 DESCRIPTIONS•

Input Voltage Range: 2.2V to 5.5V•

Up to 90% Efficiency at Typical Operating

The RS6651 is an internally compensated, 1.1MHz
switching frequency, current mode, synchronous step-up
switching regulator, which can generate 5V output at 1A
load current from a 3.3V rail.

Conditions•

Quiescent Current: 20μA (TYP)•

Less than 1μA Shutdown Current•

Adjustable Output Voltage Up to 5.5V•

Power-Save Mode for Improved

This device turns into power-saving mode to maintain highefficiency by lowering switching frequency. With its antiringing circuitry damping the charge in parasitic capacitor, it
reduces EMI interference significantly. Its output isdisconnected by the rectifier circuit during shutdown, withno input to output leakage.

Efficiency at Low Output Power•

Low Reverse Leakage Current when
VOUT > VIN•

Load Disconnect During Shutdown•

Output Short Circuit Protection•

Thermal Shutdown Protection•

Internal 1.5ms Soft Start Time•Operating Temperature Range: -40°C to+85°C
Micro SIZE PACKAGE: TSOT23-6•

RS6651-ADJ is output voltage programmable with an
external resistor divider. When the RS6651 is in shutdown
mode, the isolation switch disconnects the output from
input to minimize the leakage current. The RS6651 also
implements output short circuit protection, output
overvoltage protection, and thermal shutdown.
The RS6651 is available in Green TSOT23-6 package. It
operates over an ambient temperature range of -40°C to+85°C.

2 APPLICATIONS

Device Information (1)•Portable Audio Players•

Single-Cell Li-Ion Powered Products•

Cellular Phones•

Personal Medical Products

PART NUMBER

PACKAGEBODY SIZE(NOM)

RS6651

TSOT23-6

2.92mm×1.60mm(1)

For all available packages, see the orderable addendum at the end of
the data sheet.

4 TYPICAL APPLICATION
Power
SupplyL
2.2µ H

C1

VCC
GND

SW

RS6651

Output voltage
can be adjusted

VOUT

EN

R1

C2

FB

R2

REV A.4

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RS6651
Table of Contents
1 FEATURES ............................................................................................................................................................................... 1
2 APPLICATIONS ...................................................................................................................................................................... 1
3 DESCRIPTIONS ...................................................................................................................................................................... 1
4 TYPICAL APPLICATION ...................................................................................................................................................... 1
5 Revision History ..................................................................................................................................................................... 3
6 PACKAGE/ORDERING INFORMATION (1) ..................................................................................................................... 4
7 Pin Configuration and Functions ........................................................................................................................................ 5
8 SPECIFICATIONS ................................................................................................................................................................... 6
8.1 Absolute Maximum Ratings .......................................................................................................................................... 6
8.2 ESD Ratings ...................................................................................................................................................................... 6
8.3 Recommended Operating Conditions ......................................................................................................................... 6
8.4 ELECTRICAL CHARACTERISTICS ............................................................................................................................... 7
8.5 TYPICAL CHARACTERISTICS ...................................................................................................................................... 8
9 Detailed Description ...........................................................................................................................................................10
9.1 Overview .........................................................................................................................................................................10
9.2 Functional Block Diagram............................................................................................................................................10
10 TYPICAL APPLICATION CIRCUITS ..............................................................................................................................11
11 Application and Implementation ...................................................................................................................................12
11.1 APPLICATION INFORMATION ...............................................................................................................................1211.2 Adjustable Output Voltage Version ........................................................................................................................1211.3 Inductor Selection .......................................................................................................................................................1211.4 Selecting the Input Capacitor ...................................................................................................................................1211.5 Selecting the Output Capacitors .............................................................................................................................12
11.6 Layout Guidelines .......................................................................................................................................................13
12 PACKAGE OUTLINE DIMENSIONS .............................................................................................................................14
13 TAPE AND REEL INFORMATION .................................................................................................................................15

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RS6651
5 Revision History
Note: Page numbers for previous revisions may different from page numbers in the current version.
VERSION

Change Date

Change Item

A.0

2021/11/02

A.1

2022/04/01

A.2

2022/04/18

A.3

2024/04/09

A.4

2024/05/29

Initial version completed
1. Update Package Qty on Page 4@RevA.0
2. IST parameter(TYP) change to 550mA
Add the maximum and minimum values of ELECTRICAL CHARACTERISTICS
1. Add MSL on Page 4@RevA.2
2. Update PACKAGE note
Update Input Voltage Range: 2.2V to 5.5V

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RS6651
6 PACKAGE/ORDERING INFORMATION (1)PRODUCT
RS6651ORDERING
NUMBER
RS6651YTHTEMPERATURE
RANGE-40°C ~+85°C

PACKAGELEAD
TSOT23-6

PACKAGEMARKING (2)6651

MSL (3)

PACKAGE OPTIONMSL3Tape 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) MSL, The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications.

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RS6651
7 Pin Configuration and Functions
TOP VIEW
SW

1

6

VCC

GND

2

5

VOUT

EN

3

4

FB

TSOT23-6

PIN DESCRIPTION
NAME

PIN
TSOT23-6

I/O (1)

FUNCTION

SW

1

I

Boost Switch Node. Connect this node to one terminal of power inductor.

GND

2

—

EN

3

I

FB

4

I

Ground.
Enable input. Logic high voltage enables the device. Logic low voltage disables thedevice and turns it into shutdown mode.
Voltage feedback of adjustable output voltage.

VOUT

5

O

Boost Converter Output. Place a storage capacitor close to this pin.

VCC

6

I

Supply voltage.

(1) I = Input, O = Output.

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RS6651
8 SPECIFICATIONS
8.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)(2)(3)
MIN

MAX

UNIT

-0.3

6

V

190

°C/W

VIN

Input voltage on VCC, VOUT, SW, FB, ENθJA

Package thermal impedance (4)TJ

Operating Junction temperature (5)

-40

150

°C

Tstg

Storage temperature range

-60

150

°C

260

°C

TSOT23-6

Lead Temperature (Soldering, 10s)
(1)
(2)
(3)
(4)
(5)

Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating
Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
All voltages are with respect to the GND pin.
Internal thermal shutdown circuitry protects the device from permanent damage. The actual chip output current is subject to the inputoutput voltage difference, ambient temperature and PCB heat dissipation design.
The package thermal impedance is calculated in accordance with JESD-51.
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)±4000

Charged-Device Model (CDM), per ANSI/ESDA/JEDEC JS-002(2)

±1200

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

MAX

UNIT

5.5

V

VCC

Input supply voltage on VCC

2.2

VIN

Input supply voltage on SW, OUT, FB, EN

-0.3

5.5

V

TA

Operating temperature

-40

+85

°C

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RS6651
8.4 ELECTRICAL CHARACTERISTICS(VIN = 3.6V, Full = -40°C to +85°C, typical values are at TA = +25°C, unless otherwise noted.) (1)
PARAMETERSYMBOL

CONDITIONSTEMPMIN (2)TYP (3)

MAX (2) UNITS

DC/DC STAGE
Output Voltage Range

VOUT

Full

3.0

5.5

V

Input Voltage Range

VIN

+25°C

2.2

5.5

V

Feedback Voltage

VFB

Full

480

495

510

mV

Switching Frequency

Freq

Full

930

1100

1200

kHz

Switch Current Limit

IL

+25°C

2.15

2.7

3.25

A

Start-Up Current Limit

IST

VOUT<VIN+25°C

Boost Switch On-ResistanceRds-low

VOUT = 5V

Rectifying Switch On-ResistanceRds-high

VOUT = 5V
VCC = 2.2V to VOUT - 0.5V

Line Regulation

VIN < 0.9*VOUT

Load Regulation
Quiescent Current

IQ

Shutdown Current

ISD

VEN = VCC = 3.6V,
not switching
VEN = 0V, VCC = 3.6V

550

mA

+25°C

60

mΩ

+25°C

120

mΩ

+25°C

0.5

%

+25°C

0.5

%

+25°C

20

30

μA

+25°C

1

μA

Full

0.4

V

10

μA

CONTROL STAGE
EN Input Low Voltage

VIL

EN Input High Voltage

VIH

EN Input Current

IEN

Full
Clamped on GND or VCC

1.4

V

Full

Over-Temperature Protection

150

°C

Over-Temperature Hysteresis

20

°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.

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RS6651
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.
5.1

5.07

VIN=3.6V,VOUT=5V

5.08

Output Voltage(V)5.06

Output Voltage(V)

VIN=3.6V,VOUT=5V

5.06

5.04
5.02
5
4.98
4.96

4.94

5.05
5.04
5.03
5.02
5.01
5
4.99

4.92
4.9

4.98
0

100 200 300 400 500 600 700 800 900 1000

-55

-35

30

25

25

20
15
10
VIN=2.2V
VIN=3.6V
VIN=4.5V

0
-55

-35

-15

5

25

Temperature(℃)

45

5

25

45

65

85

Figure 2. Output Voltage vs Temperature30

65

Quiescent Current(μA)

Quiescent Current(μA)

Figure 1. Output Voltage vs Output Current

5-15

Temperature(℃)

Output Current(mA)

20
15
10
85℃
25℃
-40℃

5
0
2.2

85

2.6

3.0

3.4

3.8

4.2

4.6

Input Voltage(V)Figure 3. Quiescent Current vs Temperature

Figure 4. Quiescent Current vs Input Voltage

100

100

90
90

70
60
50
40

VIN=2.7V
VIN=3V
VIN=3.6V
VIN=4.2V
VIN=4.5V

30
20
10

VOUT=5V00

Efficiency(%)

Efficiency(%)

80

80
70
IOUT=10mA
IOUT=50mA
IOUT=100mA
IOUT=500mA

60
VOUT=5V50

100 200 300 400 500 600 700 800 900 1000

2.2

2.6

3

3.4

3.8

4.2

4.6

Input Voltage(V)Output Current(mA)

Figure 5. Output Current vs Efficiency

Figure 6. Input Voltage vs Efficiency

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RS6651
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.

Maximum Output Current(A)2.5

VOUT=5V

2.0
1.5

VOUT

1.0

IOUT

0.5
0.0
2.2

2.6

3.0

3.4

3.8

Input Voltage(V)

4.2

4.6

VIN=3.6V, IOUT=200mA~800mA

Figure 8. Load Transient Response

Figure 7. Maximum Output Current vs Input
Voltage

EN
SW

VIN
VOUT

VOUT
IL

VIN=3.6V, VOUT=5V

VIN=3V~3.6V, RL=25Ω

Figure 10. Start - Up after Enable

Figure 9. Line Transient Response

VOUT

VOUT

IL

IL

VIN=3.6V, RL=2.5KΩ

Figure 11. Output Voltage in Power-Save Mode

VIN=3.6V, RL=10Ω

Figure 12. Output Voltage in Continuous Mode

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RS6651
9 Detailed Description
9.1 Overview
The RS6651 is a high performance, highly efficient boost converter. To achieve high efficiency the power stage
is realized as a synchronous boost topology. For the power switching two actively controlled low RDS(ON) power
MOSFETs are implemented.

9.2 Functional Block Diagram

VCC

Start Up

VREF
FB

EN

VOUT

VREF

D1

OVP
Q2

Logic
Control

VREF

Gate
Driver

FB

SW
Q1

GND
OSC
Current
Sense

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RS6651
10 TYPICAL APPLICATION CIRCUITS

Figure 13. Typical Single-Cell Li-Ion Input or Dual Dry Cell Input Boost

Figure 14. Supply with an Auxiliary Positive Output

Figure 15. Supply with an Auxiliary Negative Output

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RS6651
11 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 suitability ofcomponents for their purposes. Customers should validate and test their design implementation to confirm
system functionality.

11.1 APPLICATION INFORMATIONThe RS6651 is a synchronous boost converter operating in 2.2V to 5.5V supply range, for generating a regulated
output voltage which can be set to as low as 10% above the supply voltage. An inductor, an output storage
capacitor and an input decoupling capacitor should be selected to ensure proper performance desired in a
specific application circuit.

11.2 Adjustable Output Voltage Version
An external resistor divider is used to adjust the output voltage. The resistor divider needs to be connected
between VOUT, FB and GND as shown in Figure 13. When the output voltage is regulated properly, the typicalvoltage value at the FB pin is 500mV. The maximum recommended value for the output voltage is 5.5 V. The
value of the resistor connected between VOUT and FB, R1, depending on the needed output voltage (VOUT), canbe calculated using Equation 1:VV
R1 = R 2 × ( OUT − 1) = R 2 × ( OUT − 1)
(1)
VFB

500mV

As an example, if an output voltage of 5.05 V is needed, a 910KΩ resistor is calculated for R1 when for R2 a
100kΩ has been selected.

11.3 Inductor Selection
The device has been optimized to operate with inductance values between 1μH and 4.7μH. Nevertheless,operation with higher inductance values may be possible. Both average current and peak current should be
evaluated in inductor selection. The maximum average inductor current is estimated using Equation 2:
VI
L = OUT× OUT(2)
VIN ×𝜂

Where,ηis the efficiency of the device, which can be set to 0.8 for estimation.
Choosing a proper inductance for a given current ripple value is readily done in design practice. A smaller ripple
reduces the magnetic hysteresis losses in the inductor, as well as output voltage ripple and EMI. Though
regulation settle time may rise when load changes. The minimum inductance value for the inductor at given
condition is estimated by using Equation 3:
V ×(V
−V )
L = IN OUT IN(3)
ΔIL ×f×VOUT

Where f is the switching frequency and ΔIL is the ripple current in the inductor, which normally is 20% of theaverage inductor current or is a design specified value. In typical applications, a 2.2μH inductance isrecommended. After choosing an inductor, peak current at maximum loading and lowest input voltage issuggested to be evaluated, which should be lower than the switch current limit of this device as well as theinductor saturation current.

11.4 Selecting the Input Capacitor
Multilayer ceramic capacitors are an excellent choice for the input decoupling of the step-up converter as they
have extremely low ESR and are available in small footprints. Input capacitors should be located as close as
possible to the device. While a at least 10μF input capacitor is recommended to improve transient behavior of
the regulator and EMI behavior. A ceramic capacitor or a tantalum capacitor with a 100nF ceramic capacitor inparallel, placed close to the IC, is recommended.

11.5 Selecting the Output Capacitors
The output ripple voltage is related to the equivalent series resistance (ESR) of the capacitor and its capacitance.
Assuming a capacitor with zero ESR, the minimum capacitance needed for a given ripple can be calculated by:
I
×(V
−V )
CMIN = OUT OUT IN(4)Where，

f×ΔV×VOUT

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RS6651
COUT is the output capacitor; IOUT is the output current; VOUT is the output voltage; VIN is the input voltage; ΔV isthe output voltage ripple required; ƒSW is the switching frequency
The additional output ripple component caused by ESR is calculated by:
Where
ΔVESR = IOUT × R ESR(5)
Where,ΔVESR is the output voltage ripple caused by ESR; RESR is the resistor in series with the output capacitor;
For the ceramic capacitor, the ESR ripple can be neglected. However, for the tantalum or electrolytic capacitors,
it must be considered if used.
The total ripple is the sum of the ripple caused by the capacitance and the ripple caused by the ESR of thecapacitor. Additional voltage change may be caused by load transients; the output capacitor has to completely
supply the load during the charging phase of the inductor.
The value of the output capacitance depends on the speed of the load transients and the load current during theload change. With the calculated minimum value of 10μF and load transient considerations, the recommended
output capacitance value is in the range of 10μF to 47μF.
Care must be taken when evaluating a ceramic capacitor’s derating under the DC bias. Ceramic capacitors canderate by as much as 90% of its capacitance at its rated voltage. Therefore, enough margins on the voltage rating
should be considered to ensure adequate capacitance at the required output voltage. And instead of using one
22μF capacitor, we more recommend two 10μF capacitors in parallel.

11.6 Layout Guidelines
As for all switching power supplies, especially those high frequency and high current ones, layout is an importantdesign step. Careful layout is always important to ensure good performance and stable operation to any kind of
switching regulators.
Minimize the high current path including the switch FET, rectifier FET, and the output capacitor;
Minimize the length and area of all traces connected to the SW pin;
Use the GND pin of the device as the center of star-connection to other grounds. Keep the common path to the
GND pin, which returns the small signal components and the high current components as short as possible to
avoid ground noise.
Place the FB being far away from the SW trace, as the FB node is sensitive and easily picks up noise;
Place the input and the output capacitors as close to the IC as possible;

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RS6651
12 PACKAGE OUTLINE DIMENSIONSTSOT23-6 (3)
D

1.90

b

2.59

E

E1
0.99

Pin1
Index Area

0.95

0.69
e
e1

RECOMMENDED LAND PATTERN (Unit: mm)

0.2

A A2

c

θ
L

A1

Dimensions In Millimeters

Dimensions In Inches

Min

Max

Min

Max

A (1)

-----

1.100

-----

0.043

A1

0.000

0.100

0.000

0.004

A2

0.700

1.000

0.028

0.039

b

0.300

0.500

0.012

0.020

c

0.080

0.200

0.003

0.008

D (1)

2.850

2.950

0.112

0.116

E (1)

1.550

1.650

0.061

0.065

E1

2.650

2.950

0.104

Symbol0.950(BSC) (2)

e

0.116
0.037(BSC) (2)

e1

1.800

2.000

0.071

0.079

L

0.300

0.600

0.012

0.024

θ

0°

8°

0°

8°

NOTE:
1. Plastic or metal protrusions of 0.15mm maximum per side are not included.
2. BSC (Basic Spacing between Centers), "Basic" spacing is nominal.
3. This drawing is subject to change without notice.

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RS6651
13 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 TypeTSOT23-6

Reel
Diameter
7’’

Reel Width
(mm)
9.5

A0
(mm)
3.17

B0
(mm)
3.10

K0
(mm)
1.10

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.

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RS6651
IMPORTANT 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 or otherrequirements; (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 beliable for the use of this product and the infringement of patents or third-party intellectual property rights due
to its use.

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