Replacement of
MC34063A
MIK34063A
DC-to-DC Converter
Control Circuits
October 1997 revised November 1999
Description
The MIK34063A Series is a monolithic control circuit containing the primary functions required for DC-to-DC converters. These devices
consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit,
driver and high current output switch. This series was specifically designed to be incorporated in Step-Down and Step-Up and Voltage-
Inverting applications with a minimum number of external components.
Features
Operation from 3.0 V to 40 V Input
Low Standby Current
Current Limiting
Output Switch Current to 1.5 A
Output Voltage Adjustable
Frequency Operation to 100 kHz
Precision 2% Reference
Pin connections
Schematic Diagram
Switch
Collector
Switch
Emitter
Timing
Capacitor
Gnd
Driver
Collector
I
Sense
pk
I
Oscillator
pk
V
CC
Comparator
Inverting
Input
Comparator
+
-
R
S
100
Q1
Q2
6
7
8
1
2
3
4
5
Q
C
T
1.25 V
Reference
Absolute Maximum Ratings
Symbol Parameter Maximum
Units
V
CC
Power Supply Voltage
40
Vdc
V
IR
Comparator Input Voltage Range
-0.3 to +40
Vdc
V
C(switch)
Switch Collector Voltage
40
Vdc
V
E(switch)
Switch Emitter Voltage (V
PIN1
= 40 V)
40
Vdc
V
CE(switch)
Switch Collector to Emitter Voltage
40
Vdc
V
C(driver)
Driver Collector Voltage
40
Vdc
I
C(driver)
Driver Collector Current (Note 1)
100
mA
I
SW
Switch
Current
1.5 A
T
J
Operating Junction Temperature
+150
C
T
A
Operating Ambient Temperature Range
0 to +70
C
Tstg
Storage Temperature Range
-65 to +150
C
Page 1 of 8
Replacement of
MC34063A
MIK34063A
DC-to-DC Converter
Control Circuits
October 1997 revised November 1999
Electrical characteristics
(Vcc = 5.0 V, T
A
= T
low
to T
high
, unless otherwise specified.)
Characteristics
Symbol Min Typ Max Units
OSCILLATOR
Frequency (V
pin5
= 0V, C
T
= 1.0 nF, T
A
= 25
C)
f
OSC
24
33
42
kHz
Charge Current(V
CC
= 5.0V to 40V, T
A
= 25
C)
I
chg
24
35
42
A
Discharge Current (V
CC
= 5.0V to 40V, T
A
= 25
C)
I
dischg
140
220
260 A
Discharge to Charge Current Ratio (Pin 7 to V
CC
, T
A
= 25
C)
I
dischg
/
I
chg
5.2 6.5 7.5
Current Limit Sense Voltage (I
chg
= I
dischg
, T
A
= 25
C)
V
ipk(sence)
250 300 350 mV
OUTPUT SWITCH (NOTE 2)
Saturation Voltage, Darlington Connection (I
SW
= 1.0 A, Pins 1, 8 connected)
V
CE(sat)
1.0
1.3 V
Saturation Voltage, Darlington Connection (I
SW
= 1.0 A, R
pin 8
= 82
to V
CC
, Forced
20)
V
CE(sat)
0.45
0.7 V
DC Current Gain (I
SW
= 1.0 A, V
CE
= 5.0 V, T
A
= 25
C)
h
FE
50
75
Collector Off-State Current (V
CE
= 40 V)
I
C(off)
40
100
A
COMPARATOR
Threshold Voltage
(T
A
=25C)
(T
A
=T
low
to T
high
)
Vth
1.225
1.21
1.25
1.275
1.29
V
Threshold Voltage Line Regulation
(Vcc=3.0 V to 40 V)
Reg
line
1.4
5.0 mV
Input Bias Current
(Vin=0 V)
I
IB
-20
-400
nA
TOTAL DEVICE
Supply Current (Vcc
= 5.0 V to 40 V, C
T
= 1.0 nF, Pin 7 = V
CC
, Vpin 5 > Vth, Pin 2 = Gnd,
remaining pins open)
I
CC
4.0
mA
Note1: Maximum package power dissipation limits must be observed.
Note2: Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient temperature as
possible.
Page 2 of 8
Replacement of
MC34063A
MIK34063A
DC-to-DC Converter
Control Circuits
October 1997 revised November 1999
Page 3 of 8
Typical Performance Characteristics
0.01
0.1
0.02
0.05
0.2
0.5
1.0
2.0
5.0
10.0
C OSCILLATOR TIMING CAPACITOR (nF)
T ,
f
on
f
off
V
= 5.0 V
Pin 7 = V
Pin 5 = Gnd
T = 25 C
CC
CC
A
O
10 s/DIV
V
(
V
)
OS
C
,
OS
C
I
L
L
A
T
OR
V
O
L
T
AG
E
Pins 1, 5,8
Open
C
1.0
nF
=
=
T
1.0
2.0
10
20
50
100
200
5.0
t (
o
n
-
o
ff ,
OU
T
P
U
T
S
W
I
T
CH
O
N
-
O
F
F
T
I
M
E
V
5.0V
Pin 7 V
Pin 2 Gnd
CC
CC
=
=
=
T
25 C
A
=
O
500
1000
Figure 1.
.
Output Switch On-Off Time versus
Oscillator Timing Capacitor
Figure 2.
.
Timing Capacitor Waveform
Figure 3.
.
Emitter Follower Configuration Output
Saturation Voltage versus Emitter Current
Figure 4.
.
Common Emitter Configuration Output Switch
Saturation Voltage versus Collector Current
Figure 5.
.
Current Limit Sense Voltage versus
Temperature
Figure 6.
.
Standby Supply Current versus
Supply Voltage
s
)
Replacement of
MC34063A
MIK34063A
DC-to-DC Converter
Control Circuits
October 1997 revised November 1999
Application Information
Figure 1.
.
Step-Up Converter
Figure 2a.
External NPN Switch.
Note: R to 0 for constant V
in
Figure 2.
.
External Current Boost Connections for I Peak Greater than 1.5 A
C
Figure 2b.
External NPN Saturated Switch.
Page 4 of 8
Replacement of
MC34063A
MIK34063A
DC-to-DC Converter
Control Circuits
October 1997 revised November 1999
Figure 3.
.
Step-Down Converter
Figure 4b.
External PNP Suturated Switch.
Figure 4.
.
External Current Boost Connections for I Peak Greater than 1.5 A
C
Figure 4a.
External NPN Switch.
Page 5 of 8
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