TC18C46-1 Datasheet, PDF (1/10 Pages) TelCom Semiconductor, Inc – CMOS CURRENT MODE PWM CONTROLLER

1 _TC18C46
TC28C46
TC38C46
CMOS CURRENT MODE PWM CONTROLLER
FEATURES
GENERAL DESCRIPTION
s Isolated Output Drive
s Low Power CMOS Construction
s Low Supply Current ................................. 2mA Typ.
s Wide Supply Voltage Operation .............. 8V to 18V
s Latch-Up Immunity ................... 500mA on Outputs
s Above and Below Rail Input Protection ............. 6V
s High Output Drive ................................ 500mA Peak
s Current Mode Control
s Fast Rise/Fall Time ..................... 50nsec @ 1000pF
s High Frequency Operation .......................... 500kHz
s UV Hysteresis Guaranteed
s Programmable Current Limit
s Shutdown Pin Available
s Double Ended
s Soft Start
s Low Prop Delay Current Amp
to Output ......................................... < 350nsec Typ.
s Low Prop Delay Shutdown
to Output ......................................... < 400nsec Typ.
s TC38C46Pin Compatible with Unitrode UC3846
s ESD Protected ................................................. ±2 kV
FUNCTIONAL BLOCK DIAGRAM
The TC38C46 is a current mode CMOS PWM control
IC. It draws only 2 mA supply current, so it can be driven
without a costly 50-60 Hz transformer. The output drive
stage is capable of high drive currents, 300mA typical.
The TC38C46 is pin compatible with earlier bipolar
products so that designers can easily update older designs.
A number of improvements have been added.
This second generation part has been designed with an
isolated drive stage. Unlike its cousin, the TC170, the output
stage of the TC38C46 can be run from a separate power
supply such as a secondary winding on an output trans-
former. This allows for bootstrap start-up of the power
supply.
ORDERING INFORMATION
Part No.
TC18C46MJE
TC28C46EOE
TC28C46EPE
TC38C46COE
TC38C46CPE
Configuration
Pkg./Temperature
Non-Inverting
Non-Inverting
Non-Inverting
Non-Inverting
Non-Inverting
16-Pin CerDIP
– 55°C to +125°C
16-Pin SOIC (Wide)
– 40 °C to +85°C
16-Pin Plastic DIP (Narrow)
– 40°C to +85°C
16-Pin SOIC (Wide)
0°C to +70°C
16-Pin Plastic DIP (Narrow)
0°C to +70°C
VREF
2
VIN ¹⁵
RT ⁹
CT ⁸
SYNC ¹⁰
– CURRENT ₃
SENSE INPUT
4
+ CURRENT
SENSE INPUT
COMPENSATION ⁷
+ ERROR ₅
AMP INPUT
6
– ERROR
AMP INPUT
5.1 VOLT
REFERENCE
OSCILLATOR
UNDER VOLTAGE
LOCKOUT
DQ
CURRENT SENSE
AMPLIFIER
PWM
–
.65V COMPARATOR
x3
+
–+ ⁺
–
R
Q
S
S
PWM LATCH
CQ
+VS+
+ ^100µA
LIMIT BUFFER
AMPLIFIER
+
Q4
–
–
ERROR
AMPLIFIER
Q3
Q1
350mV _–
+
LOCK-UP
AMPLIFIER
POSITIVE
FEEDBACK
Q2
SHUTDOWN
COMPARATOR
+
– 350mV
6kΩ
TC18C46
TC28C46
TC38C46
3.5kΩ
13 _VDD
11 ^{OUTPUT A}
14 _{OUTPUT B}
12 ^GROUND
1 _{CURRENT LIMIT}
SOFT START ADJUST
16 _SHUTDOWN
TC38C46 OUTPUTS
LOW IN OFF STATE
2
3
4
5
6
7
8
TELCOM SEMICONDUCTOR, INC.
TC18/28/28/C46-8 9/23/96
4-101