FA13844P Fujitsu, FA13844P Datasheet

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FA13844P

Manufacturer Part Number
FA13844P
Description
Manufacturer
Fujitsu
Datasheet
FA13842,13843,13844,13845
The FA1384X series are CMOS current mode control ICs for
off-line and DC-to-DC converters.
These ICs can reduce start-up circuit loss and are optimum for
high efficiency power supplies because of the low power
dissipation achieved through changes in the CMOS fabrication
process.
These ICs can drive a power MOSFET directly.
The high-performance, compact power supply can be
designed with minimal external components .
• CMOS process
• Low-power dissipation
• Standby current 2 A (max.), start-up current 30 A (max.)
• Pulse-by-pulse current limiting
• 5V bandgap reference
• UVLO (Undervoltage lockout) with hysteresis
• Maximum duty cycle
• Pin-for-pin compatible with UC384X
Type
FA13842P 16.5V 1V
FA13842N
FA13843P
FA13843N
FA13844P 16.5V 1V
FA13844N
FA13845P
FA13845N
Note: Pins are fully compatible, but characteristics are not.
Description
Features
Types of FA1384X series
When our ICs are applied to a power supply circuit
designed for other manufactures' 384X series, the
characteristics and safety features of the power supply
must be checked.
UVLO
Start threshold Stop threshold cycle
9.6V 1V
9.6V 1V
9V 1V
9V 1V
9V 1V
9V 1V
FA13842, 13843: 96%
FA13844, 13845: 48%
Maximum duty Package
96%
96%
48%
48%
DIP
SOP
DIP
SOP
DIP
SOP
DIP
SOP
SOP-8
DIP-8
Dimensions, mm
2.54
8
1
0.4
8
1
For Switching Power Supply Control
0.25
0.1
9.3
4.9
1.5
1.27
0.46
4
FA13842, 13843, 13844, 13845
5
4
5
0.2
0.1
7.62
CMOS IC
1

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FA13844P Summary of contents

Page 1

... Types of FA1384X series Type UVLO Start threshold Stop threshold cycle FA13842P 16. FA13842N FA13843P 9. FA13843N FA13844P 16. FA13844N FA13845P 9. FA13845N Dimensions, mm SOP-8 0.4 DIP Maximum duty Package ...

Page 2

FA13842, 13843, 13844, 13845 Block diagram FA13842, 13843 VCC 7 UVLO VCC 5V REF 30V ENB 2.5V UVLO RT/CT OSC 4 ER AMP COMP ISNS 3 5V Controlled block FA13844, 13845 VCC ...

Page 3

Recommended operating conditions Item Symbol Supply voltage V CC Oscillation timing capacitor C T Oscillation timing resistor R T Oscillation frequency f OSC Electrical characteristics (Vcc=15V, R Reference voltage section Item Symbol Reference voltage V REF Line regulation L INE ...

Page 4

FA13842, 13843, 13844, 13845 Output section Item Symbol High-level output V OH Low-level output V OL Rise time tr Fall time tf Under-voltage lockout section Item Symbol Start threshold Min. operating voltage V TH OFF Hysteresis V ...

Page 5

Characteristic curves (Ta=25˚C) Timing resistance vs. oscillation frequency FA13842, FA13843 100 2.2nF 470pF C =10nF 15V CC Ta= 25˚ Oscillation frequency (kHz) Timing resistance vs. oscillation frequency FA13844, FA13845 100 470pF 2.2nF C ...

Page 6

FA13842, 13843, 13844, 13845 ISNS threshold voltage vs. COMP voltage 1200 V = 15V CC FB= 0V 1000 OUT= off 800 600 400 200 COMP voltage (V) COMP to ISNS offset voltage vs. temperature 2.5 ...

Page 7

VCC supply current vs. VCC supply voltage 10k 3.3nF 7 T OUT= No load VCC voltage (V) Output waveform Vcc=15V, OUT CL=1nF, Ta=25˚C V ...

Page 8

FA13842, 13843, 13844, 13845 Description of each circuit 1. Oscillator The oscillation frequency is determined by timing resistance R and timing capacitor C , which are connected to RT/CT T terminal charged to about 3V through R T ...

Page 9

Output stage An output stage of CMOS inverter composition is incorporated, thereby making it possible to fully swing the gate voltage of a power MOSFET to the The output stage provides a source current of 400mA ...

Page 10

FA13842, 13843, 13844, 13845 Latched shutdown 3. A typical circuit for latched shutdown is shown in Fig. 8. The voltage of the OUT terminal is kept low if the voltage of the COMP terminal is low. The voltage of the ...

Page 11

The method of detecting an overvoltage (detection on primary side) A typical latched shutdown circuit to protect against overvoltages detected on the primary side is shown in Fig. 11. When the secondary voltage increases in the flyback circuit, the ...

Page 12

FA13842, 13843, 13844, 13845 4. Soft start A soft-start circuit is shown in Fig. 15. An aproximate soft-start time is determined with the following calculation. This soft-start time is defined as the time the ISNS terminal threshold voltage increases from ...

Page 13

Feedback circuit 7-1 A method that does not use an internal ER AMP A method that does not use an internal ER AMP is shown in Fig. 18. Connect the FB terminal to GND and connect an optocoupler to ...

Page 14

FA13842, 13843, 13844, 13845 Fig. 22 illustrates a case when the inductor current variation i ’ smaller than i at t0. In this case, inductor current L L variations gradually converges and the inductor current becomes stable. ...

Page 15

Application circuit AC80~264V ~ R1 560k FA13842 R VCC T 7 8.2k UVLO 30V UVLO COMP 1 RT/ C11 1000pF 2200pF 2 1R PC2 R19 ISNS 1k 3 R18 C10 1k 100pF ...

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