DC-DC Converter Control Circuits
PIN CONFIGURATION
1
2
3
4
8
7
6
5
1
2
3
4
8
7
6
5
MC34063A/B
SOP-8
DIP-8
PIN DESCRIPTION
Pin No.
Name
1
2
3
4
5
6
7
8
Switch Collector
Switch Emitter
Timing Capacitor
GND
Comparator Inverting Input
V
CC
I
PK
Sense
Driver Collector
SOP-8 / DIP-8 PKG
Function
Internal switch transistor collector
Internal switch transistor emitter
Timing Capacitor to control the switching frequency
Ground pin for all internal circuits
Inverting input pin for internal comparator
Voltage supply
Peak Current Sense Input by monitoring the voltage drop across an
external I sense resistor to limit the peak current through the switch
Voltage driver collector
BLOCK DIAGRAM
Driver
Collector
8
S
R
Q
1
Q1
Switch
Collector
Q2
2
I
PK
Sense
7
I
PK
Oscillator
Switch
Emitter
Timing
Capacitor
3
V
CC
6
Comparator
Comparator
Inverting
Input
+
-
5
1.25V
Reference
Regulator
4
GND
Jan. 2011 - Rev. 1.0
-
3
-
HTC
HTC [ HTC KOREA TAEJIN TECHNOLOGY CO. ]
