Document
www.DataSheet4U.com
www.fairchildsemi.com
KA3511DS
Intelligent Voltage Mode PWM IC
Features
• • • • • • • • • • • • • • Complete PWM control and house keeping circuitry Few external components Precision voltage reference trimmed to 2% Dual output for push-pull operation Each output TR for 200mA sink current Variable duty cycle by dead time control Soft start capability by using dead time control Double pulse suppression logic Over voltage protection for 3.3V / 5V / 12V Under voltage protection for 3.3V / 5V / 12V One more external input for various protection (PT) Remote on/off control function (PS-ON) Latch function controlled by remote and protection input Power good signal generator with hysteresis
Description
The KA3511DS is a fixed frequency improved performance pulse width modulation control circuit with complete housekeeping circuitry for use in the secondary side of SMPS (Switched mode power supply). It contains various functions, which are precision voltage reference, over voltage protection, under voltage protection, remote on/off control, power good signal generator and etc.
OVP (Over voltage protection) section
It has OVP functions for +3.3V,+5V,+12V and PT outputs. The circuit is made up of a comparator with four detecting inputs and without hysteresis voltage. Especially, PT (Pin18) is prepared for an extra OVP input or another protection signal.
UVP (Under voltage protection) section Precision reference section
The reference voltage trimmed to ± 2% (4.9V ≤ Vref ≤ 5.1V) It also has UVP functions for +3.3V, +5V, +12V outputs. The block is made up of a comparator with three detecting inputs DataSheet4U.com and without hysteresis voltage.
DataShee
PG (Power good signal generator) section
Power good signal generator is to monitor the voltage level of power supply for safe operation of a microprocessor. KA3511DS requires few external components to accomplish a complete housekeeping circuits for SMPS.
Remote on/off section
Remote on/off section is used to control SMPS externally. If a high signal is supplied to the remote on/off input, PWM signal becomes a high state and all secondary outputs are grounded. The remote on/off signal is transferred with some on-delay and off-delay time of 8ms, 24ms respectively.
24-SDIP
1
DataSheet4U.com
©2001 Fairchild Semiconductor Corporation
Rev. 1.0.0
DataSheet 4 U .com
www.DataSheet4U.com
KA3511DS
Internal Block Diagram
24
C1
RT 7 CT
8
OSCILLATOR
PWM CONTROL
D
Q
CK
Q
22
C2 E TREM
COMP E/A(-) E/A(+)
2 23 DEAD TIME CONTROLER R Q S
1.4V 0.1V
3 4
1.25V
Delay Controller
5 6
REM (PS-ON)
DEAD TIME CONTROL 21 INTERNAL BIAS
11 OVP COMP Vref Start Up Ichag 18 17 V5 PG GENERATOR
1.25V
PG PT V12 V5 V3.3
VREF
14
Vref
Vref 16 15
Vcc
1 V5
COMP3
1.8V!"0.6V
DET
9 COMP2
1.8V!"0.6V
et4U.com
UVP COMP
1.25V
DataShee
DataSheet4U.com 10
TPG
19
20
TUVP
GND
ADSolute Maximum Ratings
Parameter Supply voltage Collector output voltage Collector output current Power dissipation(KA3511DS) Operating temperature Storage temperature Symbol VCC VC1, VC2 IC1, IC2 PD TOPR TSTG Value 40 40 200 1.5 −25 to 85 −65 to 150 Unit V V mA W °C °C
Temperature Characteristics
Parameter Temperature coefficient of Vref (-25°C≤Ta≤85°C) Symbol ∆Vref/∆T Min. Typ. 0.01 Max. Unit %/°C
DataSheet4U.com
2
DataSheet 4 U .com
www.DataSheet4U.com
KA3511DS
Pin Definition : KA3511DS
C1
E
C2
DTC
GND
TUVP
PT
V12
V5
V3.3
Vref
NC
#24
#13
AS DS KA3511D
#1
Vcc COMP E/A(-) EA(+) TREM REM RT CT DET TPG PG NC
#12
et4U.com
Pin Number 1 2 3 4 5 6 7 8 9 10 11 12
Pin Name VCC COMP E/A(-) E/A(+) TREM REM RT CT DET TPG PG NC
I/O I O I I I I O -
Pin Function Supply voltage E/A output E/A (-) input E/A (+) input Remote on/off delay Remote on/off input Oscillation freq. setting R Oscillation freq. setting C Detect input PG delay Power good signal output NC
Pin Number 13
Pin Name NC Vref V3.3 V5 V12 PT TUVP GND DTC C2 E C1
I/O O I I I I I O O
Pin Function Descrition NC Precision reference VTG OVP, UVP input for 3.3V OVP, UVP input for 5V OVP, UVP input for 12V Extra protection input UVP delay Signal ground Deadtime control input Output 2 Power ground Output 1
DataShee
14 DataSheet4U.com 15 16 17 18 19 20 21 22 23 24
DataSheet4U.com
3
DataSheet 4 U .com
www.DataSheet4U.com
KA3511DS
Pin Number Pin Name 1 2 3 4 5 VCC COMP E/A(-) E/A(+) TREM
Pin Function Descrition Supply voltage. Operating range is 10V~30V. VCC=20V, Ta=25°C at test. Error amplifier output. It is connected to non-inverting input of pulse width modulator comparator. Error amplifier inverting input. Its reference voltage is always 1.25V. Error amplifier non-inverting input feedback voltage.This pin may be used to sense power supply output voltage. Remote on/off delay. Ton/Toff=8ms/24ms (Typ.) with C=0.1uF. Its high/low threshold voltage is 1.8V/0.6V. Remote on/off input. It is TTL operation and its threshold voltage is 1.4V. Voltage at this pin can reach normal 4.6V, with aDSolutely maxim.