CS3972 Datasheet, PDF (3/6 Pages) Cherry Semiconductor Corporation – 1.25A High Efficiency Switching Regulator

PACKAGE PIN #
16L
5L
SO Wide TO-220
8L
PDIP
16
3
1
2
1
2
3
2
3
1,4,5,6,7,8,
4
10,12,15
9
5
5
11
6
13
4
7
14
8
Package Pin Description
PIN SYMBOL
FUNCTION
Gnd
Logic and power ground on TO-220. Logic ground only on 8L
PDIP.
V_C
Control voltage can be used for frequency compensation, cur-
rent limit threshold, frequency synchronization, and soft start.
V_FB
Feedback voltage is the negative input to the error amplifier.
NC
No connection.
V_IN
Supply input voltage with a range of 3V to 60V.
E₁
Emitter One is a power ground which should always be con-
nected to logic ground since it is used as the negative input to
the current sense amp.
V_SW
Collector of internal 75V NPN power switch.
E₂
Emitter Two is a power ground which can be left disconnected
to reduce the switch rating to 625mA.
Typical Performance Characteristics
Reference Voltage vs. Temperature
1.274
1.264
1.254
1.244
1.234
1.224
1.214
-50 -25
-0 25 50 75 100 125 150
Temperature (°C)
Switching Frequency vs. Temperature
47
45
43
41
39
37
35
33
-50 -25
-0 25 50 75 100 125 150
Temperature (°C)
Driver Current vs. Switch Current
100
90
80
70
60
50
40
30
20
10
0
0
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0
Switch Current (A)
Maximum Duty Cycle
97
96
95
93
92
91
90
-50 -25
-0 25 50 75 100 125 150
Junction Temperature (°C)
Switch Saturation Voltage
1.6
Tj=25°C
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.0
Switch Current (A)
3