AIC29722A, 75V, 200kHz Step-Down Converter

 FEATURES DESCRIPTION

Wide 4.5V to 75V Operating Input Range

Output Adjustable from 0.8V to 40VStandby Current 400µA

Power Save Mode at Light Load

Programmable Maximum Peak Current130mΩ Internal Power MOSFET Switch



91.8% Efficiency at VIN=72V, VOUT=12V@1.2A



81.4% Efficiency at VIN=72V, VOUT=5V@0.8A



Fixed 200kHz Frequency

Thermal ShutdownCycle-by-Cycle Over Current Protection

Available in SOP-8 Exposed Pad Package

The AIC2972 is a monolithic step-down switch
mode converter. It achieves 2A continuous output current over a wide input supply range withexcellent load and line regulation.
The maximum peak current can be programmedby sensing current through an accurate sense
resistor.
Fault condition protection includes cycle-by-cycle
current limiting and thermal shutdown.
The AIC2972 requires a minimum number ofreadily available standard external components.
The AIC2972 is available in SOP-8 exposed padpackage.

 APPLICATIONS

Balance Bike

Ebike

USB Power Supplies APPLICATIONS CIRCUIT

Typical Application Circuit

Analog Integrations Corporation

Si-Soft Research Center
1A1, 1 Li-Hsin 1st Rd., Science Park, Hsinchu 300, Taiwan, R.O.C.
TEL: 886-3-5772500

FAX: 886-3-5772510

DS-2972G-03 20210528
www.analog.com.tw

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AIC2972

 ORDERING INFORMATIONAIC2972XXXX XXPIN CONFIGURATIONPACKING TYPE
TR: TAPE & REEL
TB: TUBEPACKAGE TYPE
S8E: SOP-8 Exposed Pad

SOP-8 Exposed Pad
TOP VIEW
SW

1ILIM 2VIN3GND 48 BS
9( ILIM)

7 POK6 EN
5 FB

G: Green PackageExample: AIC2972GS8ETR Green SOP-8 Exposed Pad Package
and Tape & Reel Packing Type ABSOLUTE MAXIMUM RATINGS
VIN Pin and ILIM Pin Voltage ……………………………………………………………………………. 76V
SW Pin Voltage …………………………………………………………….…….………. -0.3V to VIN + 0.3V
BS Pin Voltage ………………………………………………………………….…………………. VSW + 6.0V
POK Pin Voltage ……………………………………………………………………………………. 0V to 45V
All Other Pins Voltage ………………………………………………………………………....-0.3V to +6.5VJunction Temperature…………………………………………………….……………...……………... 150°C
Lead Temperature …………………………………………………………….………..………………. 260°C
Storage Temperature Range ………...........................................……………….............. - 65°C ~ 150°C
Operating Ambient Temperature Range ………...............................…….….................... - 40°C ~ 85°C
Thermal Resistance Junction to Case

SOP-8 Exposed Pad* ........................................... 15°C/W

Thermal Resistance Junction to Ambient

SOP-8 Exposed Pad* ........................................... 45°C/W(Assume no Ambient Airflow)
Absolute Maximum Ratings are those values beyond which the life of a device may be impaired.
* Measured on approximately 42x45mm^2 of 1 oz copper.

2AIC2972

 ELECTRICAL CHARACTERISTICS(VIN=12V, TA=25°C, unless otherwise specified.) (Note1)
PARAMETERSYMBOL

CONDITIONS

MIN

TYP

MAX UNITS

Supply Voltage

VIN

4.5

75

V

Output Voltage

VOUT

0.8

40

V

Feedback Voltage

VFB

4.5V ≤ VIN ≤ 80V

0.785 0.805 0.825

VFeedback Bias Current

IBIAS(FB)

VFB = 0.8V

10nA

Switch On ResistanceRDS(ON)130mΩ

Current Limit(Note 2)
Oscillator Frequency

fSW

Fold-Back Frequency
Boot-Strap Voltage
Minimum On Time(Note 3)

VFB = 0.6V

1.2

1.35

1.5

A

160200240kHz

VFB = 0V
VBST - VSWTONVFB = 1V

Under Voltage Lockout Threshold Rising

3.0

Under Voltage Lockout Threshold Hysteresis

200

Supply Current (Quiescent)
Thermal Shutdown(Note 3)

VEN = 2V, VFB = 1V

70kHz

6V

100

ns

3.3

3.6

VmV

400
160700μA°C

Note 1: Specifications are production tested at TA=25°C. Specifications over the -40°C to 85°C operating
temperature range are assured by design, characterization and correlation with Statistical Quality
Controls (SQC).
Note 2: Sense resistor defined.
Note 3: Guaranteed by design.

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AIC2972

 TYPICAL PERFORMANCE CHARACTERISTICS
100

100

90

90

VIN=36V80

VIN=36V

70

Efficiency (%)

Efficiency (%)

80

VIN=12V

70
60
50
40

6050

VIN=60V30

VIN=60V30

VIN=75V20

VIN=75V

40

20
10100
11010011000

10100Fig. 1 Efficiency vs. Output Current (VOUT=5V)

Fig. 2 Efficiency vs. Output Current (VOUT=12V)

100

5.30

90

5.28

Output Voltage (V)

VIN=36V

80

Efficiency (%)

7060

VIN=75V50

VIN=60V

40

5.22
5.20
5.18

20

5.14

10

5.12

10100

VIN=60V

5.24

5.16

1

VIN=75V

5.26

300

VIN=36V
VIN=12V

5.10

1000

1

10100

1000

Output Current (mA)

Output Current (mA)

Fig. 3 Efficiency vs. Output Current (VOUT=24V)

Fig. 4 Output Voltage vs. Output Current (VOUT=5V)

12.06

24.60

12.04

24.57

VIN=75V

12.02

Output Voltage (V)Output Voltage (V)1000

Output Current (mA)

Output Current (mA)

12.0011.98
11.96
11.94

24.51
24.48

VIN=36V
24.45

VIN=36V

11.92

VIN=75V
24.54

VIN=60V

24.42
11.90

VIN=60V

11.88
11.86

24.39
24.36

1

10100

1000

Output Current (mA)

Fig. 5 Output Voltage vs. Output Current (VOUT=12V)

1

10100

1000

Output Current (mA)

Fig. 6 Output Voltage vs. Output Current (VOUT=24V)

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AIC2972

 TYPICAL PERFORMANCE CHARACTERISTICS (Continued)(CH1: VSW, CH3: VOUT(ac), CH4: IL)(CH1: VSW, CH3: VOUT(ac), CH4: IL)

Fig. 7 Output Ripple (VIN=36V, VOUT=5V, IOUT=1mA)

Fig. 8 Output Ripple (VIN=36V, VOUT=5V, IOUT=2A)(CH1: VIN, CH2: VSW, CH3: VOUT, CH4: IL)(CH1: VIN, CH2: VSW, CH3: VOUT, CH4: IL)

Fig. 9 VIN Power On (VIN=36V, VOUT=5V, IOUT=0A)

Fig. 10 VIN Power On (VIN=36V, VOUT=5V, IOUT=2A)(CH1: VEN, CH2: VPOK, CH3: VOUT, CH4: IL)(CH1: VEN, CH2: VPOK, CH3: VOUT, CH4: IL)

Fig. 11 Enable On (VIN=36V, VOUT=12V, IOUT=0A)

Fig. 12 Enable On (VIN=36V, VOUT=12V, IOUT=2A)

5AIC2972 TYPICAL PERFORMANCE CHARACTERISTICS (Continued)(CH3: VOUT(ac), CH4: IOUT)(CH3: VOUT(ac), CH4: IOUT)

Fig. 13 Load Transient (VIN=24V, VOUT=5V, IO=0.2-1.8A)

Fig. 14 Load Transient (VIN=24V, VOUT=12V, IO=0.2-1.8A)

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AIC2972

 PIN DESCRIPTIONSPin No.

Pin Name

1SW2, 9ILIM

3VIN

4GND

5FB

6EN

7

POK8BS

Pin Function
Switch Output. Connect this pin to the switching end of the inductor.
Programmable maximum peak current pin by sensing current through an
accurate sense resistor between this pin and VIN pin.
Supply Voltage. The AIC2972 operates from a +4.5V to +75V unregulated input. CIN is needed to prevent large voltage spikes from appearing at the input.
Put CIN as close to the IC as possible. It is the drain of the internal power device and power supply for the whole chip.
Ground. This pin is the voltage reference for the regulated output voltage. For
this reason care must be taken in its layout. This node should be placed outside of the D1 to CIN ground path to prevent switching current spikes from inducing voltage noise into the part.
Feedback. An external resistor divider from the output to GND, tapped to theFB pin sets the output voltage. To prevent current limit run away during a shortcircuit fault condition the frequency-fold-back comparator lowers the oscillator
frequency when the FB voltage is below 250mV.
Enable pin. Connect to low off the chip, floating is enable.
Power good signal. When FB is less than 90% of 0.8V, PGOOD is low. It is an
open-drain output. Use a high value pull-up resistor externally to pull it up tosystem power supply or its output as next chip enable signal. Connected toGND or floating when don’t use this function.
Bootstrap. This pin acts as the positive rail for the high-side switch’s gate driver. Connect a 100nF ceramic capacitor and 10ohm resistor between this pin
and SW.

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AIC2972

 APPLICATION INFORMATION
Main Control Loop

Choose R1 to be around 300kΩ for optimal transient

The AIC2972 is a current mode buck regulator. Thatresponse. R2 is then given by:is, the error amplifier (EA) output voltage isR2 =proportional to the peak inductor current. At thebeginning of a cycle, the integrated high side powerswitch M1 is off; the EA output voltage is higher thanR1
VOUT
−10.805
Table 1 Resistor Selection for Common

the current sense amplifier output; and the current
comparator’s output is low. The rising edge of theVOUT(V)R1(kΩ)

R2(kΩ)

3.3300(1%)

96(1%)

200kHz clock signal sets the RS Flip-Flop. Its output

5300(1%)57.1(1%)turns on M1 thus connecting the SW pin and inductor

12300(1%)

21.4(1%)to the input supply.

15300(1%)

16.9(1%)

The increasing inductor current is sensed and24300(1%)

10.2(1%)

amplified by the Current Sense Amplifier. Ramp

32300(1%)

7.6(1%)

compensation is added to Current Sense Amplifier

Selecting the Inductor

output and compared to the Error Amplifier output by
the PWM Comparator. When the Current Sense
Amplifier plus Slope Compensation signal exceeds
the EA output voltage, the RS Flip-Flop is reset andthe AIC2972 reverts to its initial M1 off state. If theCurrent Sense Amplifier plus Slope Compensation
signal does not exceed the COMP voltage, then thefalling edge of the CLK resets the Flip-Flop. The
output of the Error Amplifier integrates the voltage

33µH to 100µH inductor with a DC current rating of atleast 30% percent higher than the maximum load
current is recommended for most applications. For
highest efficiency, the inductor DC resistance shouldbe less than 50mΩ. For most designs, the inductancevalue can be derived from the following equation.
L=VOUT × (VIN − VOUT )VIN × ∆I L × fSW

theWhere ΔIL is the inductor ripple current. Choose

0.8V bandgap reference. The polarity is such that ainductor current ripple to be approximately 30%~40%

FB pin voltage, which is lower than 0.8V, increasesof the maximum load current. The maximum inductor

the EA output voltage. Since the EA output voltage ispeak current is:difference

betweenthefeedbackandproportional to the peak inductor current, an increase
in its voltage increases current delivered to the output.

I L ( MAX ) = IOUT ( MAX ) +∆I L
2An external Schottky Diode (D1) carries the inductor

Under light load conditions below 100mA, larger

current when internal power MOS is off.

inductance is recommended for improved efficiency.

Setting the Output Voltage

Selecting the Input Capacitor

The external resistor divider is used to set the output

The input capacitor reduces the surge current drawn

voltage (see the schematic on front page). The

from the input and also the switching noise from thefeedback resistor R1 also sets the feedback loop

device. The input capacitor impedance at thebandwidth with the internal compensation capacitor.

switching frequency should be less than the input

8AIC2972
sourceimpedance

toprevent

highfrequency

diode and the convertor, for the cost issues, theswitching current from pass to the input. For mostnormal selection of PCB is 1oz thickness, the thickapplications, a 47µF to 100µF

solder tin is benefit on heat dissipation.

electrolytic capacitor

is sufficient.

(2) ILIM is internal connected the power MOS, theSelecting the Output Capacitor

heat dissipation should be considered for this pin.

The output capacitor keeps output voltage ripple(3) The large current path (ILIM, SW) should be put

small and ensures regulation loop stability. Thecloser the converter as possible, use short, straight,

output capacitor impedance should be low at thewide copper foil connect.

switching frequency. A 220µF electrolytic capacitor is(4) Input capacitor should be put as close as possible

recommended.

to VIN pin and GND.

ILIM sense resistor(5) The loop of input capacitor, internal power MOS

Power current flows into the chip via the external
accuracy sense resistor which defined the maximumpeak current. In guarantee under the normal start up
with full load, the sense resistor is recommended use
the larger value to ensure less surge current andoutput short power dissipation. The sense resistor

and schottky diode is the highest di/dt radiation
region, reduce this region as possible. A 0.1µF
ceramic capacitor can be used to form a small loopwith internal power MOS and schottky diode, which
can reduce the switch ringing caused by PCB
parasitic inductor.

value should be reduced when used it at low(6) The outside feedback resistor should be placed

temperature situation to ensure enough startup

nearby the FB pin and keep away from SW node.

energy.

(7) A 220pF ceramic capacitor between VIN and SW
Table 2 Sense Resistor Selection

pin can be used to reduce the switch negative
overshoot and improve EMI performance whenMax. output current （A）

Rsense（mΩ）

0.850

1.040

2.030

needed.
Figures 3 to 5 show the layout diagrams of AIC2972.

Loop compensation
A 12pF to 82pF ceramic capacitor connected
between FB and OUT can optimize the loop stability
for both bandwidth and phase margin, recommended
a 22 pF to 47pF ceramic capacitor in most case.
PCB Layout(1) Under the large output current and high input
voltage case, the schottky diode and the converter isthe main heat source, don’t put them too close, thePCB layout should keep enough area for heatdissipation. Recommended ratio is 6:4 for schottky

9

AIC2972

Fig. 15 Top Layer

Fig. 16 Bottom Layer

Fig. 17 Top Component Placement10

AIC2972

 APPLICATION EXAMPLES

Fig. 18 AIC2972 Application Circuit for 5V/2A Output Application
Table 3 BOM List for 5V/2A Output Application
Ref
C1A
C1B
C2C3C4D1L1R1R2R3R4U1Value
100µF
0.1µF
220µF
100nF
47pF
3A
33µH
300kΩ
57.1kΩ
10Ω30mΩDescription
Electrolytic,100V
Ceramic capacitor,100V
Electrolytic,16V
Ceramic capacitor, 100V, X7R
Ceramic, capacitor 25V, X7R
Schottky Diode, SMD, 100V, 3A
Inductor CDRH104, 2.4A
Film Res., 1%
Film Res., 1%
Film Res., 1%
Film Res., 1%
DC-DC convertor

Package
ELC SMD0603
ELC SMD
0603
0603
SMB
CDRH104
0603
0603
0603
1206
SOP-8E

Manufacturer
jiang haimuRatajiang haimuRatamuRataPanasonic
Panasonic
Panasonic
AIC2972

Qty
11111111111
1

Manufacturer P/N
VTD-100V100
GRM188R71C104K
VTD-100V220
GRM188R71C104K
GRM32DR71E470K
SS310
ERJ-3EKF3003V
ERJ-3EKF5712V
ERJ-3EKF0011V

Note: recommended to use a low VF schottky diode for efficiency promotion.

11

AIC2972

Fig. 19 AIC2972 Application Circuit for 12V/2A Output Application
Table 4 BOM List for 12V/2A Output Application
RefC1A
C1B
C2C3C4D1L1R1R2R3R4U1Value
100µF
0.1µF
220µF
100nF
47pF
3A
47µH
300KΩ
21.5KΩ
10Ω30mΩDescription
Electrolytic,100V
Ceramic capacitor,100V
Electrolytic,25V
Ceramic capacitor, 100V, X7R
Ceramic, capacitor 25V, X7R
Schottky Diode, SMD, 100V, 3A
Inductor CDRH127, 2.5A
Film Res., 1%
Film Res., 1%
Film Res., 1%
Film Res., 1%
DC-DC convertor

Package
ELC SMD
0603
ELC SMD
0603
0603
SMB
CDRH127
0603
0603
0603
1206
SOP-8E

Manufacturer
jiang haimuRatajiang haimuRata
muRataPanasonic
Panasonic
Panasonic
AIC2972

Qty
111111111111

Manufacturer P/N
VTD-100V100
GRM188R71C104K
VTD-100V220
GRM188R71C104K
GRM32DR71E470K
SS310
ERJ-3EKF3003V
ERJ-3EKF2152V
ERJ-3EKF0011V

Note: recommended to use a low VF schottky diode for efficiency promotion.

12AIC2972

 PHYSICAL DIMENSIONS SOP-8 Exposed PadD

h X 45°A

SEE VIEW B

B
WITH PLATING

0.25

CA1AeAH

E1E

D1EXPOSED THERMAL PAD(Heat Sink)(BOTTOM CENTER OF PACKAGE)GAUGE PLANESEATING PLANE

θL
VIEW B

BASE METALSECTION A-A

Note : 1. Refer to JEDEC MS-012E.
2. Dimension "D" does not include mold flash, protrusions
or gate burrs. Mold flash, protrusion or gate burrs shall not
exceed 6 mil per side .
3. Dimension "E" does not include inter-lead flash or protrusions.
4. Controlling dimension is millimeter, converted inch
dimensions are not necessarily exact.

SOP-8 Exposed PadSYM
BO
L

MIN.

MAX.

A

1.35

1.75

MILLIMETERS

A1

0.00

0.15

B

0.31

0.51

C0.170.25

D

4.80

5.00

D1

1.50

3.50

E

3.80

4.00

E1

1.0

e

2.55
1.27 BSC

H

5.80

6.20

h0.25

0.50

L0.40

1.27

θ

0°

8°

Note:
Information provided by AIC is believed to be accurate and reliable. However, we cannot assume responsibility for use of any circuitry other thancircuitry entirely embodied in an AIC product; nor for any infringement of patents or other rights of third parties that may result from its use. We
reserve the right to change the circuitry and specifications without notice.
Life Support Policy: AIC does not authorize any AIC product for use in life support devices and/or systems. Life support devices or systems aredevices or systems which, (I) are intended for surgical implant into the body or (ii) support or sustain life, and whose failure to perform, whenproperly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to theuser.

13