Page 1
FA7611CP(E)
1
■ Description
The FA7611CP(E) is a bipolar IC containing basic circuit
necessary for PWM-type switching power supply control.
■ Features
• Low-voltage operation (VCC = 3.6 to 22V)
• Predrivers: Totem-pole output or open-collector for CH1 and
open-collector output for CH2
• Latch-mode short-circuit protection function (no malfunction
due to electrical noise)
• soft-start function
• Undervoltage lock-out function
•
One capacitor shared for short circuit protection and for soft start
to minimize the number of external discrete components
■ Applications
• Battery power supply for portable equipment
■ Dimensions, mm
Á SSOP-16
1
8
9
16
0.6
0~10˚
0.65
7.9
±0.3
5.3
6.2
0.1
±0.1
0.2
+0.1
–0.05
0.3
2.1max
Á DIP-16
Bipolar IC
For Switching Power Supply Control
■ Block diagram
FA7611CP(E)
Pin Pin Description
No. symbol
1 CT Oscillator timing capacitor
2 CS Capacitor for soft-start, short-
circuit protection and delay
3 DT2 Dead time adjustment
4 IN2 (+) Non-inverting input to error
amplifier
5 IN2 (–) Inverting input to error amplifier
6 FB2 Error amplifier output
7 GND Ground
8 OUT2 CH. 2 Output
9 VCC Power supply
10 OUT1R CH. 1 Current limiting resistor
11 OUT1 CH. 1 Output
12 FB1 Error amplifier output
13 IN1 (–) Inverting input to error amplifier
14 IN1 (+) Non-inverting input to error
amplifier
Reference voltage (0.5V)
15 DT1 Dead time adjustment
16 REF Reference voltage output (2.5V)
1
16
9
8
19.4
6.5
7.6
3.4
4.3max
1.5
0.81
3.1min
0.2min
0~15˚
0~15˚
0.5
±0.1
2.54
±0.25
0.3
+0.1
–0.05
Page 2
FA7611CP(E)
2
■ Electrical characteristics (Ta = 25°C, VCC = 6V, RT = 33kΩ, CT = 1000pF)
Reference voltage section
Item Symbol Test condition Min. Typ. Max. Unit
Output voltage VREF IOR = 1mA 2.425 2.475 2.525 V
Line regulation LINE VCC = 3.6 to 20V, IOR =1mA 4 12 mV
Load regulation LOAD IOR = 0.1 to 1mA 1 6 mV
Output voltage variation due to temperature change VTC1 Ta = –20 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 = 1000pF, RT = 33kΩ 95 115 135 kHz
Frequency variation 1 (due to supply voltage change) fdV VCC = 3.6 to 20V 1 %
Frequency variation 2 (due to temperature change) fdT Ta = –20 to +85°C5%
Error amplifier section
Item Symbol Test condition Min. Typ. Max. Unit
Reference voltage VB 0.484 0.494 0.504 V
Input bias current IB 5 100 nA
Open-loop voltage gain AV 70 dB
Unity-gain bandwidth GB 0.6 MHz
Maximum output voltage (Pin 6 and Pin 12) VOM+ RNF = 100kΩ
V
REF
–0.2
V
VOM– RNF = 100kΩ 200 mV
Output source current (Pin 6 and Pin 12) IOM+ VOM = 1V 40 85 200
µ
A
PWM comparator section
Item Symbol Test condition Min. Typ. Max. Unit
Input threshold voltage (Pin 6 and Pin 12) VTH0 Duty cycle = 0% 0.85 0.95 V
Input threshold voltage (Pin 6 and Pin 12) VTH50 Duty cycle = 50% 1.1 V
■ Absolute maximum ratings
Item Symbol Rating Unit
Supply voltage VCC 22 V
Reference voltage output current
IOR 5mA
Output current IO ±50 mA
Total power dissipation Pd 400 mW
Operating temperature Topr –20 to +85 °C
Storage temperature Tstg –40 to +150 °C
■ Recommended operating conditions
Item Symbol Min. Max. Unit
Supply voltage VCC 3.6 20 V
Feedback resistance RNF 100 kΩ
Oscillator timing capacitor CT 220 22,000 pF
Oscillator timing resistance RT 10 100 kΩ
Oscillation frequency fOSC 5 200 kHz
Page 3
FA7611CP(E)
3
Dead time adjustment circuit section
Item Symbol Test condition Min. Typ. Max. Unit
Input bias current (Pin 3 and Pin 15) IBDT 80 300 nA
Input threshold voltage (Pin 3 and Pin 15) VTH DT0 Duty cycle = 0% 0.22 0.32 V
Input threshold voltage (Pin 3 and Pin 15) VTH DT50 Duty cycle = 50% 0.46 V
Short-circuit protection circuit section
Item Symbol Test condition Min. Typ. Max. Unit
Input threshold voltage (Pin 6 and Pin 12) VTH PC 1.20 1.50 1.80 V
Charge current (Pin 2) ICHG
Pin 2 = 0V, Pin 6, Pin 12 = 2V
10 30 50
µ
A
Latch-mode threshold voltage (Pin 2) VTH LA 1.20 1.50 1.80 V
Undervoltage lockout circuit section
Item Symbol Test condition Min. Typ. Max. Unit
OFF-to-ON threshold voltage VTH ON 2.65 V
ON-to-OFF threshold voltage VTH OFF 2.60 V
Voltage hysteresis VHYS 50 mV
Output section
Item Symbol Test condition Min. Typ. Max. Unit
CH. 1 H-level output voltage (Pin 11) V01H RL = 10kΩ 3.5 4.0 V
CH. 1 L-level output voltage (Pin 11) V01L Output sink current = 20mA 0.25 0.65 V
CH. 1 Output source current (Pin11) ISOURCE1 ROUT1 = 470Ω 811 mA
(Pin 11) = 0V
CH. 2 L-level output voltage (Pin 8) V02L Output sink current = 20mA 1.0 1.5 V
Overall device
Item Symbol Test condition Min. Typ. Max. Unit
Supply current ICC LA Latch mode 2.0 3.0 mA
Operating-state supply current ICC AV RL = ∞ Duty cycle = 50% 3.5 6.0 mA
Page 4
FA7611CP(E)
4
■ Characteristic curves (Ta = 25°C)
Oscillation frequency (fOSC) vs. Output duty cycle vs. CS terminal voltage (VCS)
timing capacitor capacitance (C
T)
Output duty cycle vs. DT terminal voltage (VDT) Output duty cycle vs. FB terminal voltage (VFB)
CH-1 output source current (ISOURCE1) vs. L-level output voltage (VO1L) vs.
supply voltage (V
CC) CH. 1 output sink current (ISINK1)
Page 5
FA7611CP(E)
5
L-level output voltage (VO2L) Supply current (ICC) vs. supply voltage(VCC)
vs. CH. 2 output sink current (I
SINK2)
Operating-state supply current (ICCAV) vs.
oscillation frequency (f
OSC)
Error amplifie frequency (f) vs. valtage gain (AV) / phase (θ)
Phase θ [deg]
Page 6
FA7611CP(E)
6
■ Application circuit
Á Flyback-transformer type and chopper type buck converter circuit
Á Chopper type buck converter and inverting converter 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.
Please connect a capacitor, which the value is about 0.01µF to 0.1µF,
between VCC and REF terminals in order to prevent from irregular
output pulse at start-up.
3.3k 30.1k
1k
0.01µ
VCC
22000p
16
REF DT1 IN1(+) IN1(–) FB1
FA7611CP(E)
OUT1 OUT1R VCC
CT CS DT2 IN2(+) IN2(–) FB2 GND OUT2
1
15
2
14
3
13
4
12
5
11
6
10
7
9
8
Q
1
L
1
R
11
Buck
5V
VCC
Inverting
–5V
+
–
C
1
+
–
C
10
D
10
+
–
+
–
5.02k
100k 22k
4.7µ
330k
1000p
2.2k
820k
56k
1k
47000p
C
2
+
–
C
20
D
20
R
20
R
21
Q
2
L
2
R
out1
3.3k 63.5k
1k
100k
VCC
22000p
22k
0.01µ
1M
VCC
16 15 14 13 12 11 10 9
+
–
TR
REF DT1 IN1(+) IN1(–) FB1
FA7611CP(E)
OUT1
OUT1R
VCC
CT CS DT2 IN2(+)IN2(–) FB2 GND OUT2
12345678
C
1
Q
1
+
–
Flyback
24V
10V
–10V
Buck
5V
C
11
+
–
C
12
+
–
C
13
+
–
20.07k
0.01µ
4.7µ
1M
330k
1000p
2.2k
820k
56k
1k
C
20
+
–
C
2
R
out1
D
20
Q
2
R
21
R
20
L
2
D
10
D
11
D
12
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