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STMicroelectronics Electronic Components Datasheet

L4990A Datasheet

PRIMARY CONTROLLER

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L4990A pdf
L4990
® L4990A
PRIMARY CONTROLLER
CURRENT-MODE CONTROL PWM
SWITCHING FREQUENCY UP TO 1MHz
LOW START-UP CURRENT < 0.45mA
HIGH-CURRENT OUTPUT DRIVE SUITABLE
FOR POWER MOSFET (1A)
FULLY LATCHED PWM LOGIC WITH DOU-
BLE PULSE SUPPRESSION
PROGRAMMABLE DUTY CYCLE
100% AND 50% MAXIMUM DUTY CYCLE
LIMIT
PROGRAMMABLE SOFT START
PRIMARY OVERCURRENT FAULT DETEC-
TION WITH RE-START DELAY
PWM UVLO WITH HYSTERESIS
IN/OUT SYNCHRONIZATION
DISABLE LATCHED
INTERNAL 100ns LEADING EDGE BLANK-
ING OF CURRENT SENSE
PACKAGE: DIP16 AND SO16W
DESCRIPTION
This primary controller I.C., developed in BCD60II
technology, has been designed to implement off
BLOCK DIAGRAM
MULTIPOWER BCD TECHNOLOGY
DIP16
SO16W
ORDERING NUMBERS: L4990/L4990A(DIP16)
L4990D/L4990AD (SO16W)
line or DC-DC power supply applications using a
fixed frequency current mode control.
Based on a standard current mode PWM control-
ler this device includes some features as pro-
grammable soft start, IN/OUT synchronization,
disable (to be used for over voltage protection
and for power management), precise maximum
Duty Cycle Control, 100ns (typ) leading edge
blanking on current sense, pulse by pulse current
limit and overcurrent protection with soft start in-
tervention.
2
RCT
3
DC
+
-
14
DIS
-
+
2.5V
DIS
ISEN
SS
OVER CURRENT
13
+
-
1.2V
7
1V
SYNC
1
TIMING
T
DC-LIM
15
VCC
8
25V
16V/10V
+
-
Vref
PWM UVLO
VREF
4
9
VC
BLANKING
PWM
FAULT
SOFT-START
2R
R
12
SGND
SQ
R
VREF OK
CLK
DIS
6
COMP
13V 10
OUT
2.5V
+
E/A
-
11
PGND
5
VFB
D98IN1002
July 1999
1/24


STMicroelectronics Electronic Components Datasheet

L4990A Datasheet

PRIMARY CONTROLLER

No Preview Available !

L4990A pdf
L4990 - L4990A
ABSOLUTE MAXIMUM RATINGS
Symbol
VCC
IOUT
Ptot
Tj
Tstg
Parameter
Supply Voltage (ICC < 50mA) (*)
Output Peak Pulse Current
Analog Inputs & Outputs (6,7)
Analog Inputs & Outputs (1,2,3,4,5,15,14 13)
Power Dissipation @ Tamb = 70°C
Junction Temperature, Operating Range
Storage Temperature, Operating Range
(*) maximum package power dissipation limits must be observed
Value
selflimit
1.5
-0.3 to 8
-0.3 to 6
1
-25 to 125
-55 to 150
Unit
V
A
V
V
W
°C
°C
PIN CONNECTION
SYNC
RCT
DC
VREF
VFB
COMP
SS
VCC
1 16
2 15
3 14
4 13
5 12
6 11
7 10
89
D95IN197
THERMAL DATA
Symbol
Rth j-amb
Rth j-amb
Parameter
Thermal Resistance Junction to Ambient
Thermal Resistance Junction to Ambient
N.C.
DC-LIM
DIS
ISEN
SGND
PGND
OUT
VC
DIP16
SO16
Value
80
120
Unit
°C/W
°C/W
PIN FUNCTIONS
N. Name
1 SYNC
2 RCT
3 DC
4 VREF
5 VFB
6 COMP
7 SS
8 VCC
9 VC
10 OUT
11 PGND
12 SGND
13 ISEN
14 DIS
15 DC-LIM
16 NC
Fun ction
Synchronization. A synchronization pulse terminates the PWM cycle and discharges Ct
Oscillator pin for external Ct, Rt components
Duty Cycle control
5.0V +/-1.5% reference voltage
Error Amplifier Inverting input
Error Amplifier Output
Soft start pin for external capacitor Css
Supply for internal ”Signal” circuitry
Supply for Power section
High current totem pole output
Power ground
Signal ground
Current sense
Disable. It must never be left floating. Tie to SGND if not used.
Connecting this pin to Vref, DC is limited to 50%. If it is left floating or grounded no limitation is
imposed
Not connected
2/24


Part Number L4990A
Description PRIMARY CONTROLLER
Maker STMicroelectronics
Total Page 24 Pages
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