TC170 Datasheet, PDF (5/8 Pages) TelCom Semiconductor, Inc – CMOS CURRENT MODE PWM CONTROLLER

CMOS CURRENT MODE
PWM CONTROLLER
1
TC170
SWITCH
CURRENT
× 3.15 CURRENT-SENSE
AMPLIFIER
4
+
3
RS
–
–+
0.75V
PWM COMPARATOR
+
–
7
VDD
ERROR
AMPLIFIER
100 µA
FROM
UNDERVOLTAGE
LOCKOUT
Q4
5
+
6
–
V1
LIMIT
BUFFER
AMPLIFIER
Q3
350mV
TC170
LOCK-UP
AMPLIFIER
–
Q1
Q2
+ _POSITIVE
FEEDBACK
IL
3.5k
10
2
R
SQ
"A" = 1
OUTPUT
OFF (LOW)
S
PWM LATCH
VREF
5.1V
3
2
R1
1
V1
SHUTDOWN
COMPARATOR
R2
4
16
6k
350mV
5
Figure 1. R1 and R2 Set Maximum Peak Output Current
× 3.15 CURRENT-
SENSE
AMPLIFIER
TC170
I
4
R*
C
RS
3
*OPTIONAL RC FILTER
(A) Ground Reference
I
RS
× 3.15 CURRENT-
SENSE AMPLIFIER
4
3
TC170
(B) Above-Ground Resistive Sensing
Figure 2. Resistive Sensing
TELCOM SEMICONDUCTOR, INC.
6
VOUT
7
8
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