Datasheet FA7622CP, FA7622CE Datasheet (CALLM)

FA7622CP(E)

1

FA7622CP(E)

■ Dimensions, mm
Á SSOP-20

1

7.2

10

11

20

5.3

0.6

0~10˚

0.65

7.9

±0.3

0.1

±0.1

0.3

0.2

+

0

.1

–0

.05

2.1max

Á DIP-20

1

20

11

10

24.4

6.4

7.62

3.6

5.1max

1.52

0.77

2.54min

0.51min

0~15˚

0~15˚

0.46

±0.1

2.54

±0.25

0.25

+0.1

–0.05

Bipolar IC

For Switching Power Supply Control

■ Description

The FA7622CP(E) is a DC-DC converter IC that can directly
drive a power MOSFET. This IC has all the necessary
protection functions for a power MOSFET. It is optimum for a
portable equipment power supply which uses low-voltage input
to output comparably large power.

■ Features

• Drive circuit for connecting a power MOSFET
(Io = ±600mA)

• Built-in voltage step-up circuit to drive a power MOSFET
gate: A converter circuit requires only an N-channel power
MOSFET.

• Dual control circuit

• Overcurrent limiting circuit

• Overload cutoff circuit with timer and latch circuit

• ON/OFF control pin

• Wide operating range: 3.6 to 28V

• High-frequency operation: up to 1MHz

• 20-pin package (DIP/SSOP)

■ Applications

• Battery power supply for portable equipment

+

-

+

-

+

-

+

-

FB1

ON/OFF

19

17

IN1+

3

CP

IN2+

4

REF

DT1 CT RT VCC1 SW

20

16 1 2 14

13

BIAS

OSC

UVLO

Duty

limit

OCP

12

VCC2

15

OCL1

11

OUT1

­PWM1

ER, AMP1

VB

ER, AMP2

PWM2

Duty

limit

OCP

10

OUT2

OCL2

8

GND

DT2

7

6

5

IN2-

FB2

-

Timer

&

latch

18

9

SW

Pin Pin Description
No. symbol

1 CT Oscillator timing capacitor
2 RT Oscillator timing resistor
3 CP Timer and latch circuit
4 IN2+ Non-inverting input to error

amplifier

5 IN2- Inverting input to error amplifier
6 FB2 Error amplifier output
7 DT2 Dead time adjustment
8 OCL2 Overcurrent limiting circuit 2
9 GND Ground
10 OUT2 CH.2 output
11 OUT1 CH.1 output
12 VCC2 Power supply 2
13 SW Switch for boost circuit
14 VCC1 Power supply 1
15 OCL1 Overcurrent limiting circuit 1
16 DT1 Dead time adjustment
17 FB1 Error amplifier output
18 IN1+ Non-inverting input to error

amplifier

19 ON/OFF Output ON/OFF control
20 REF Reference voltage output

■ Block diagram

FA7622CP(E)

2

■ Electrical characteristics (Ta = 25°C, VCC = 6V, RT = 36kΩ, CT = 180pF)
Reference voltage section

Item Symbol Test condition Min. Typ. Max. Unit
Output voltage VREF IOR = 1mA 2.400 2.475 2.550 V
Line regulation LINE

V

CC

= 3.6 to 26V, IOR = 1mA

515mV

Load regulation LOAD IOR = 0.1 to 1mA 2 mV
Output voltage variation due to temperature change VTC1 Ta = –30 to +25°C–1 1%

VTC2 Ta = +25 to +85°C–1 1%

Oscillator section

Item Symbol Test condition Min. Typ. Max. Unit

Oscillation frequency fOSC CT = 180pF, RT = 36kΩ 100 110 120 kHz
Frequency variation 1 (due to supply voltage change) fdV VCC = 3.6 to 26V 1 %
Frequency variation 2 (due to temperature change) fdT Ta = –30 to +25°C5%

Error amplifier section (ch. 1)

Item Symbol Test condition Min. Typ. Max. Unit

Reference voltage VB 0.832 0.858 0.884 V
Input bias current IB 5 100 nA
Open-loop voltage gain AVO 40 dB
Unity-gain bandwidth fT 1.0 MHz
Maximum output voltage VOH No load 1.8 V

VOL No load 300 mV

Output source current IOH VOH = 0V 30 60 90

µ

A

Error amplifier section (ch. 2)

Item Symbol Test condition Min. Typ. Max. Unit

Input offset voltage VIO 210mV
Input bias current IB 5 100 nA
Common-mode input voltage VCOM 0 1.0 V
Open-loop voltage gain AVO 70 dB
Unity-gain bandwidth fT 1.0 MHz
Maximum output voltage VOH No load 1.8 V

VOL No load 300 mV

Output source current IOH VOH = 0V 40 80 120

µ

A

■ Absolute maximum ratings

Item Symbol Rating Unit

Supply VCC1 28 V
voltage

VCC1 20 V

Supply voltage VCC2 28 V
ON/OFF pin voltage VON/OFF –0.3 to +7 V
Out pin output current IOUT ±600 mA
Total power dissipation Pd 650 mW
Junction temperature Tj 125 °C
Operating temperature Topr –30 to +85 °C
Storage temperature Tstg –40 to +150 °C

Voltage boost
circuit not used

Voltage boost
circuit used

■ Recommended operating conditions

Item Symbol Min. Max. Unit

VCC1 3.6 26 V
VCC1 3.6 18 V
RNF 100 kΩ

CT 50 2200 pF
RT 24 100 kΩ
fOSC 50 1000 kHz

Supply
voltage

Feedback resistance
Timing capacitance
Timing resistance
Oscillation frequency

Voltage boost
circuit not used

Voltage boost
circuit used

FA7622CP(E)

3

Pulse width modulation circuit section ( FB1, FB2 pin )

Item Symbol Test condition Min. Typ. Max. Unit

Input threshold voltage VTHO Duty cycle = 0% 1.6 1.8 V
Input threshold voltage VTHI Duty cycle = 100% 0.8 1.0 V

Dead time adjustment circuit section ( DT1, DT2 pin )

Item Symbol Test condition Min. Typ. Max. Unit

Input threshold voltage VTH0 Duty cycle = 0% 1.6 1.8 V
Input threshold voltage VTH1 Duty cycle = 100% 0.8 1.0 V
Standby voltage VSTR DT1, DT2 pin open 1.8 V

Overcurrent limiting circuit section

Item Symbol Test condition Min. Typ. Max. Unit

Input threshold voltage VTHOC 180 210 240 mV
Hysteresis voltage VHYOC 40 mV
Input bias current IOC 50 100

µ

A

Delay in OCL tdoc Overdriving: 50mV 120 ns

Timer and latch circuit section

Item Symbol Test condition Min. Typ. Max. Unit

Latch-mode threshold voltage VTHCP 1.00 1.25 1.50 V
Input bias current IINCP VCP = 1.5V, VFB = 0.3V 1

µ

A

CP pin voltage / LOW VSATC ICP = 20 µA, VFB = 1.0V 300 mV

Output ON/OFF control circuit section

Item Symbol Test condition Min. Typ. Max. Unit

OFF-to-ON threshold voltage VTHON 3.0 V
ON-to-OFF threshold voltage VTH OFF 0.60 V
Input bias current IIN VIN = 3V 180

µ

A

Undervoltage lock-out circuit section

Item Symbol Test condition Min. Typ. Max. Unit

OFF-to-ON threshold voltage VCCON 2.80 3.00 3.20 V
ON-to-OFF threshold voltage VCCOF 2.90 V
Voltage hysteresis VHYS 0.10 V

Output section

Item Symbol Test condition Min. Typ. Max. Unit

Saturation voltage (H level) VSAT+ IO = –50mA 1.50 2.00 V
Saturation voltage (L level) VSAT–

I

O

= 50mA

1.70 2.20 V

Voltage step-up circuit section

Item Symbol Test condition Min. Typ. Max. Unit

Output voltage VOUP L=330µH, C=1µF, No load 10.5 12.5 14.0 V

Overall device

Item Symbol Test condition Min. Typ. Max. Unit

Stand-by supply current ICCST Out pin open 0.1 10

µ

A

Operating VCC1 current ICC1 Normal operation 3.8 5.5 mA
Operating VCC2 current ICC2 Normal operation VCC2=12V 1.5 2.2 mA

OUT1, OUT2 open
Duty cycle=50%

FA7622CP(E)

4

1. Oscillator section

This section charges and discharges an external capacitor C

T.

The charge current is determined by the external resistor R

T

connected to the IC. By charging and discharging the
capacitor, this section provides a 1.0 to 1.6V triangle wave at
the CT pin. The oscillation frequency can be set between
50kHz to 1MHz. The frequency can be

calculated approximately as follows:

f

OSC ( kHz ) ⫽

7.1 • 10

5

RT ( kΩ ) • CT ( pF )

(1)

...................…

2. Error amplifier section
Error amplifier

➀

As Fig. 3 shows, the inverting input of the error amplifier is
connected to the V

B reference voltage (0.858V typ.). The non-

inverting input IN1+ and output FB1 connect to external
terminals.
During ordinary operation, the IN1+ terminal voltage is almost
equal to V

B. The power-supply output VOUTA can be

determined as follows:

V

OUTA ⫽

R1 + R2

R2

(2)

.................................…

•V

B

The DC gain of the error amplifier is 40dB (typ.), regardless of
external parts connected to the IC. Correct the phase by
connecting capacitor C

1 between the VOUTA and FB1 pins.

Error amplifier

➁

• Voltage step-up or step-down chopper circuit

As Fig. 4 shows, the non-inverting input IN2+, inverting input
IN2–, and output FB2 of the error amplifier are connected to
external terminals.
The feedback voltage V

OUTB to the IN2+ pin can be

determined as follows:

V

OUTB ⫽

( R3 + R4 ) • R6
R4 • ( R5 + R6 )

(3)

..................……

• V

REF

The DC gain AV from the VOUTB to FB2 pin is 70dB (min),
when R

7 is not connected.

When R

7 is connected, the AV can be determined as follows:

AV ⫽

R

4

R3 + R4

(4)

...........

• 1 +

R

7 • (R5 + R6)

R

5 • R6

Fig. 3

To correct the phase, connect the resistor R8 and capacitor C2
in series between the IN2– and FB2 pins.

Fig. 4

Fig. 1 Oscillator

1

2

RTCT

C

T

V =1.0 (V)

RT

I = 앐

CT

1.0 (V)

R

T

R

T

1.0V

1.6V

CT pin voltage waveform

O S C

1

REF

CT

C

T

20

9

GND

I
V : 1.0
→ 1.6V

CT
CT

I
V : 1.6
→ 1.0V

CT

CT

Fig. 2

10

20

⫹

⫺

6

R3

VOUTB

FB2

ER.AMP2

C2

R4

R6

R5

IN2
IN2

REF

Q2

R8

R7

5

4

+

-

(Controlled by Q2)

OUT2

R1

18

17

11

⫹

⫺

VOUTA

R2

FB1

IN1

ER.AMP1

Q1

C1

+

(Controlled by Q1)

V

B

36kΩ

OUT1

■ Description of each circuit

FA7622CP(E)

5

• Inverting chopper circuit

According to the circuit shown in Fig. 5, the power output
voltage V

OUTB can be determined as follows:

V

OUTB = –

R

11

R10

(5)

..............................

• V

REF

The AV between the VOUTB and FB2 pins can be determined
as follows:

A

V ⫹

–R11

R12

(6)

.................................................

To correct the phase, connect the resistor R

13 and capacitor

C

3 in series between the IN2– and FB2 pins.

By using this circuit, invert the output polarity of OUT2 with an
external transistor to drive a P-channel MOSFET (or PNP
transistor).

3. PWM comparator section

As Fig. 6 shows, a PWM comparator has three input
terminals. PWM comparator 1 determines the duty cycle of
the output from the OUT1 pin. This comparator compares the
C

T oscillator Voltage (Pin 1) with the FB1 voltage (Pin 17) or

the DT1 voltage (Pin 16), whichever is greater. When the
highest of these voltages is lower than the C

T voltage, the

PWM output is high. When it is higher than C

T, the PWM

output is low.
PWM comparator 2 determines the duty cycle of the output
from the OUT2 pin. To determine the PWM output, this
comparator compares the C

T oscillator voltage (Pin 1) with the

FB2 voltage (Pin 6) or the DT2 voltage (Pin 7) whichever is
higher.
During ordinary operation, the OUT1 and OUT2 pin voltages
have the same polarity as the output from each comparator.
When the power supply is turned on, the pulse width
gradually increases. The time constant for soft-start is
determined by the external resistor and capacitor across pins
16 and 7. In Figures 7 and 8, the time ts required for the pulse
width (duty-cycle) to reach about 30% after start-up can be
determined as follows:
(Units: µF for Cs and kΩ for Rs, Rs1, and Rs2)

Fig. 5

Fig. 8

Fig. 6

⫹

⫺

C3

Q3

FB2

R10

R9

REF

R11

R12

R13

IN2

IN2

ER.AMP2

V

CC1

+

-

VOUTB(Controlled by Q3

)

10

20

6

5

4

OUT2

⫹

⫺

PWM output

FB1(FB2)

DT1(DT2)

Time

CT

PWM output

PWM1
(PWM2)

DT1(DT2)
FB1(FB2)

CT

⫺

Fig. 7

DT1(DT2)

20

⫹

⫺

1

FB1(FB2)

CS

CT

RS

REF

PWM output

PWM1
(PWM2)

⫺

20

⫹

⫺

1

⫺

DT1(DT2)

FB1(FB2)

C

S

CT

R

S2

REF

PWM output

PWM1
(PWM2)

R

S1

Fig.8:
t

S (mS) = CS • ln

R

S1

0.417RS1 – 0.583 RS2

(7)

.................................

Fig.7:
t

S (mS) = 0.54CS • RS

Where, RS1 / RS2 > 0.716

(8)

……

R

S1 • RS2

RS1 ⫹ RS2

Please connect enough large capacitance between REF and
GND pins in order to prevent irregular output pulse caused by
minus voltage at DT1 or DT2 pin when IC is shut down.

FA7622CP(E)

6

4. Timer and latch circuit for overload protection

Figure 9 shows the timer and latch circuit for overload
protection and Fig. 10 shows its timing during an overload.
If the power supply output decreases due to an overload, the
error amplifier output decreases. If the voltage decreases to
less than 0.3V, the switch that clamps the CP pin voltage to
the ground disconnects. This charges capacitor Cp from the
REF pin through the resistor Rcp and the CP pin voltage
increases. When the voltage reaches 1.25V, OUT1 (OUT2)
voltage is clamped to ground.
The N-channel MOSFET (or NPN transistor) connected to the
OUT1 (or OUT2) is turned OFF and cuts off the power supply.
The time t

L from when the circuit is overloaded until the power

supply is cut off can be determined as follows:

(9)

.................

t

L (mS) = 0.67CP (µF) • RCP (kΩ)

5. Overcurrent limiting circuit

This is a pulse-by-pulse overcurrent limiting circuit which
detects and limits the peak of each drain current pulse from the
main switching transistor (MOSFET).
Figure 11 shows the overcurrent limiting circuit and Fig. 12
shows its timing.
This circuit detects a drain current with a voltage sampling
resistor Rs. If a voltage lower than the VCC1 pin voltage by
210mV or more is input to OCL1 (OCL2), the OUT1 (OUT2) is
clamped to ground. At the same time, DT1 (DT2) is raised to
the reference voltage V

REF. (This reduces the duty-cycle to

0%)
This circuit has hysteresis to prevent noise from causing
malfunction.
The R

S voltage which is propotional to drain current is limited

to 210mV (typ.) and released at 170mV (typ).

Fig. 9

Fig. 10

Fig. 11

Fig. 12

⫺

OUT1
(OUT2)

OCL1
(OCL2)

VCC1

-0.21V

REF

DT1
(DT2) VCC1

D

I

⫹

Rs

OUT1
(OUT2)

Time

VCC1

VCC1

-0.2V

OCL1
(OCL2)

(Similar to ID)

Voltage waveforms

PWM output

FB1(FB2)
DT1(DT2)

Time

CP

CT

1.25V
(Threshold voltage
of CP pin)

Voltage waveforms

20

⫹

⫺

⫹

⫺

1.25V

CP

S1

REF

OUT1
(OUT2)

RCP

FB1
(FB2)

0.3V

CP

FA7622CP(E)

7

6. IC ON/OFF control circuit

This control circuit turns the entire IC ON or OFF by an
external signal using an ON/OFF control pin to limit the IC’s
current consumption to 10µA or less.
Figure 13 shows the IC ON/OFF control circuit and Fig. 14
shows its timing.
To turn the IC OFF, this circuit clamps OUT1 (OUT2) to
ground when the ON/OFF pin voltage is controlled to less than

0.60V. The internal bias current is cut off to turn off the
switching transistor.
To turn the IC ON, raise the ON/OFF pin voltage immediately
to 3.0V or more to charge the soft-start capacitor gradually.

7. Voltage boost circuit

By using the circuit shown in Fig. 15, this IC generates a
voltage 6.5V (typ.) higher than the VCC1 input voltage at the
VCC2 pin. This circuit allows the IC to drive MOSFET gates
directly. With this circuit, the IC can drive a low-level side
N-channel MOSFET at 3.6 to 18V as VCC1 (not possible with
conventional ICs). In addition, an N-channel MOSFET can be
used on the high-level side of a buck chopper. In Fig. 15, the
inductor (L) is about 100µH or more and the capacitor (Cup)
should be greater than about 0.1µF.
If voltage boost is not necessary, connect the VCC1 and VCC2
pins directly, and SW pin must be opened.

8. Undervoltage lock-out circuit

This circuit prevents a malfunction at a low supply voltage.
When the supply voltage VCC1 rises and reaches 3.0V, this
circuit is activated. When VCC1 drops below 2.9V, this circuit
clamps OUT1 (OUT2) to ground. The CP pin voltage is reset

to low by means of cutting off a power supply input.

9. Output circuit

As Fig. 17 shows, OUT1 and OUT2 with a totempole
structure can drive a MOSFET.
Since both the maximum output source and sink currents are

600mA, a MOSFET can be switched at high speed.

Fig. 14 Control of output

Fig. 16

ON/OFF

3.0V

⫹

⫺

0.6V

OUT1
(OUT2)

ID

Fig. 13

OUT1
(OUT2)

Time

0V

ON/OFF

3.0V

Voltage waveforms

14 13 12

VCC1 VCC2SW

LD

CUP

R E G U L A T O R

Fig. 15

GND

OUT1
(OUT2)

VCC2

FA7622CP(E)

8

■ Application circuit

Parts tolerances characteristics are not defined in the circuit design
sample shown above. When designing an actual circuit for a product,
you must determine parts tolerances and characteristics for safe and

economical operation.

+

+

+

+

20

19

18

17

16 15

14

13 12 11

10987

6

5432

1

REF

ON/OFF

IN1+ FB1

DT1

OCL1

VCC1 SW

OUT1

VCC2

OUT2GNDOCL2

DT2FB2

IN2-

IN2+CP

RTCT

FA7622P(M)

2.2k

10.6k

470k

683

683

684

330

472

330µ

683

1µ

10

0.33

47k

100µ

33µ

VIN

5.5~9V

5V

47µ

12V

100µ

33µ

0.33

47k

10

330

472

120k

470k

3.3k

102

360k

510k

683

180p

3.3K

100k

ON/OFF

1µ

64k

36k