November 2007 Rev 10 1/23
23
MC34063AB - MC34063AC
MC34063EB - MC34063EC
DC/DC converter control circuits
Features
■Output switch current in excess of 1.5 A
■2 % reference accuracy
■Low quiescent current: 2.5 mA (typ.)
■Operating from 3 V to 40 V
■Frequency operation to 100 kHz
■Active current limiting
Description
The MC34063A/E series is a monolithic control
circuit delivering the main functions for DC/DC
voltage converting.
The device contains an internal temperature
compensated reference, comparator, duty cycle
controlled oscillator with an active current limit
circuit, driver and high current output switch.
Output voltage is adjustable through two external
resistors with a 2 % reference accuracy.
Employing a minimum number of external
components the MC34063A/E devices series is
designed for step-down, step-up and voltage-
inverting applications.
SO-8
DIP-8
Table 1. Device summary
Order codes
DIP-8 SO-8
MC34063ABN (1) MC34063ABD-TR
MC34063ACN (1) MC34063ACD-TR
MC34063EBN MC34063EBD-TR
MC34063ECN MC34063ECD-TR
1. The "A" version is not recommended for new designs.
www.st.com
Contents MC34063AB - MC34063AC - MC34063EB - MC34063EC
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Contents
1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2 Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
6 Typical application circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
7 Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
MC34063AB - MC34063AC - MC34063EB - MC34063EC Diagram
3/23
1 Diagram
Figure 1. Block diagram
Pin configuration MC34063AB - MC34063AC - MC34063EB - MC34063EC
4/23
2 Pin configuration
Figure 2. Pin connections
Table 2. Pin description
Pin n° Symbol Name and function
1 SWC Switch collector
2 SWE Switch emitter
3 TC Timing capacitor
4 GND Ground
5 CII Comparator inverting input
6V
CC Voltage supply
7I
PK IPK sense
8 DRC Voltage driver collector
MC34063AB - MC34063AC - MC34063EB - MC34063EC Maximum ratings
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3 Maximum ratings
Note: Absolute maximum ratings are those values beyond which damage to the device may occur.
Functional operation under these condition is not implied.
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
VCC Power supply voltage 50 V
VIR Comparator input voltage range -0.3 to 40 V
VSWC Switch collector voltage 40 V
VSWE Switch emitter voltage (VSWC = 40V) 40 V
VCE Switch collector to emitter voltage 40 V
VDC Driver collector voltage 40 V
IDC Driver collector current 100 mA
ISW Switch current 1.5 A
PTOT Power dissipation at TA = 25°C for DIP-8 1.25 W
for SO-8 0.625
TJOperating junction temperature 150 °C
TSTG Storage temperature range -40 to 150 °C
TOP Operating ambient temperature range
for AC and EC series 0 to 70
°Cfor AB series -40 to 85
for EB series -40 to 125
Table 4. Thermal data
Symbol Parameter DIP-8 SO-8 Unit
RthJA Thermal resistance junction-ambient (1) 100 160 °C/W
RthJC Thermal resistance junction-case 42 20 °C/W
1. This value depends from thermal design of PCB on which the device is mounted.
Electrical characteristics MC34063AB - MC34063AC - MC34063EB - MC34063EC
6/23
4 Electrical characteristics
(Refer to the test circuits, VCC = 5 V, TA = TLOW to THIGH, unless otherwise specified, see
Note 2)
Table 5. Oscillator
Symbol Parameter Test conditions Min. Typ. Max. Unit
fOSC Frequency VPIN5 = 0V, CT = 1 nF, TA = 25°C 24 33 42 kHz
ICHG Charge current VCC = 5 to 40V, TA = 25°C 24 33 42 µA
IDISCHG Discharge current VCC = 5 to 40V, TA = 25°C 140 200 260 µA
IDISCHG/ICHG
Discharge to charge
current ratio PIN 7 = VCC, TA = 25°C 5.2 6.2 7.5 µA
VIPK(sense) Current limit sense voltage ICHG = IDISCHG, TA = 25°C 250 300 350 mV
Table 6. Output switch
Symbol Parameter Test conditions Min. Typ. Max. Unit
VCE(sat)
Saturation voltage, darlington
connection ISW = 1 A, PIN 7, 8 connected 1 1.3 V
VCE(sat) Saturation voltage ISW = 1 A, RPIN8 = 82 Ω to VCC
Forced β ~ 20 0.45 0.7 V
hFE DC current gain ISW = 1 A,VCE = 5 V, TA = 25°C 50 120
IC(off) Collector off-state current VCE = 40 V 0.01 100 µA
Table 7. Comparator
Symbol Parameter Test conditions Min. Typ. Max. Unit
VTH Threshold voltage TA = 25°C 1.225 1.25 1.275 V
TA = TLOW to THIGH 1.21 1.29
Regline
Threshold voltage line
regulation VCC = 3 to 40 V 1 5 mV
IIB Input bias current VIN = 0 V -5 -400 nA
MC34063AB - MC34063AC - MC34063EB - MC34063EC Electrical characteristics
7/23
Note: 1 Maximum package power dissipation limit must be observed.
2T
LOW = 0 °C, THIGH = 70 °C (AC and EC series); TLOW = -40 °C, THIGH = 85 °C (AB series);
TLOW = -40 °C, THIGH = 125 °C (EB series).
3 If darlington configuration is not used, care must be taken to avoid deep saturation of output
switch. The resulting switch-off time may be adversely affected. In a darlington configuration
the following output driver condition is suggested:
Forced β of output current switch = ICOUTPUT/(ICDRIVER - 1 mA(a))
≥
10
4 Start-up voltage is the minimum power supply voltage at which the internal oscillator begins
to work.
Table 8. Total device
Symbol Parameter Test conditions Min. Typ. Max. Unit
ICC Supply current
VCC = 5 to 40 V
CT = 1 nF
PIN 7 = VCC
VPIN5 >VTH
PIN 2 = GND
Remaining pins
open
for MC34063A 2.5 4
mA
1.5 4for MC34063E
VSTART-UP Start-up voltage (Note 4)TA = 25°C
CT = 1 µF, PIN 5 = 0
for MC34063A 2.1 V
for MC34063E 1.5
a. Current less due to a built in 1 kΩ anti leakage resistor.
Typical performance characteristics MC34063AB - MC34063AC - MC34063EB - MC34063EC
8/23
5 Typical performance characteristics
Figure 3. Emitter follower configuration
output saturation voltage vs emitter
current
Figure 4. Output switch ON-OFF time vs
oscillator timing capacitor
Figure 5. Common emitter configuration
output switch saturation voltage vs
collector current
Figure 6. Darlington configuration collector
emitter saturation voltage (VCEsat)
vs temperature
MC34063AB - MC34063AC - MC34063EB - MC34063EC Typical performance characteristics
9/23
Figure 7. Power collector emitter saturation
voltage (VCEsat) vs temperature
Figure 8. Current limit sense voltage (VIPK)
vs temperature
Figure 9. Reference voltage vs temperature Figure 10. Bias current vs temperature
Figure 11. Supply current vs temperature Figure 12. Supply current vs input voltage
Typical application circuit MC34063AB - MC34063AC - MC34063EB - MC34063EC
10/23
6 Typical application circuit
Figure 13. Step-up converter
Figure 14. Printed evaluation board
PIN 1 = VOUT
PIN 2 = GND
PIN 3 = GND
PIN 4 = VIN
Table 9. Test condition (VOUT = 28 V)
Test Conditions Value (Typ.) Unit
Line Regulation VIN = 8 to 16 V, IO = 175 mA 30 mV
Load Regulation VIN = 12 V, IO = 75 to 175 mA 10 mV
Output Ripple VIN = 12 V, IO = 175 mA 300 mV
Efficiency VIN = 12 V, IO = 175 mA 89 %
MC34063AB - MC34063AC - MC34063EB - MC34063EC Typical application circuit
11/23
Figure 15. Step-down converter
Figure 16. Printed evaluation board
PIN 1 = VOUT
PIN 2 = GND
PIN 3 = GND
PIN 4 = VIN
Table 10. Test condition (VOUT = 5 V)
Test Conditions Value (typ.) Unit
Line regulation VIN = 15 to 25 V, IO = 500 mA 5 mV
Load regulation VIN = 25 V, IO = 50 to 500 mA 30 mV
Output ripple VIN = 25 V, IO = 500 mA 100 mV
Efficiency VIN = 25 V, IO = 500 mA 80 %
ISC VIN = 25 V, RLOAD = 0.1 Ω1.2 A
Typical application circuit MC34063AB - MC34063AC - MC34063EB - MC34063EC
12/23
Figure 17. Voltage inverting converter
Figure 18. Printed evaluation board
PIN 1 = VOUT
PIN 2 = GND
PIN 3 = GND
PIN 4 = VIN
Table 11. Test condition (VOUT = 12 V)
Test Conditions Value (typ.) Unit
Line regulation VIN = 4.5 to 6 V, IO = 100 mA 15 mV
Load regulation VIN = 5 V, IO = 10 to 100 mA 20 mV
Output ripple VIN = 5 V, IO = 100 mA 230 mV
Efficiency VIN = 5 V, IO = 100 mA 58 %
ISC VIN = 5 V, RLOAD = 0.1 Ω0.9 A
MC34063AB - MC34063AC - MC34063EB - MC34063EC Typical application circuit
13/23
Note: VSAT = Saturation voltage of the output switch
VF = Forward voltage drop of the output rectifier
The following power supply characteristics must be chosen:
VIN = Nominal input voltage
VOUT = Desired output voltage, |VOUT| = 1.25 (1 + R2/R1)
IOUT = Desired output current
fMIN = Minimum desired output switching frequency at the selected values of VIN and IO
VRIPPLE = Desired peak to peak output ripple voltage. In practice, the calculated capacitor
value will and to be increased due to its equivalent series resistance and board layout. The
ripple voltage should be kept to a low value since it will directly affect the line and load
regulation.
Table 12. Calculation
Parameter Step-Up
(Discontinuous mode)
Step-Down
(Continuous mode)
Voltage Inverting
(Discontinuous mode)
ton/toff
(ton + toff) max 1/fmin 1/fmin 1/fmin
CT4.5x10-5ton 4.5x10-5ton 4.5x10-5ton
IPK(switch) 2Iout(max)[(ton/toff)+1] 2Iout(max) 2Iout(max)[(ton/toff)+1]
RSC 0.3/IPK(switch) 0.3/IPK(switch) 0.3/IPK(switch)
CO
L(min)
OUT
V
F
V
IN m
i
(
–+
VIN min()
Vsat
–
-
---------------------------------------------
--
V
OUT
V
F
+
Nmin()
Vsat
–VO
U
–
-
------------------------------------------------
--
V
OUT
V
F
+
VIN Vsat
–
-------------------------------
I
out
t
on
Vripple p p–()
-------------------------------
I
PK switch()
t
on
t
off
+
()
8Vripple p p–()
------------------------------------------------------
I
out
t
on
Vripple p p–()
-------------------------------
V
IN min()
V
sat
–
IPK switch()
-
---------------------------------- ton m
i
(
×
N
min()
V
sat
–
V
out
–
IPK switch()
--
-----------------------------------------------ton(
×
V
IN min()
V
sat
–
IPK switch()
-
---------------------------------- ton m
i
(
×
Typical application circuit MC34063AB - MC34063AC - MC34063EB - MC34063EC
14/23
Figure 19. Step-up with external NPN switch
Figure 20. Step-down with external NPN switch
MC34063AB - MC34063AC - MC34063EB - MC34063EC Typical application circuit
15/23
Figure 21. Step-down with external PNP switch
Figure 22. Voltage inverting with external NPN switch
Typical application circuit MC34063AB - MC34063AC - MC34063EB - MC34063EC
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Figure 23. Voltage inverting with external PNP saturated switch
Figure 24. Dual output voltage
MC34063AB - MC34063AC - MC34063EB - MC34063EC Typical application circuit
17/23
Figure 25. Higher output power, higher input voltage
Package mechanical data MC34063AB - MC34063AC - MC34063EB - MC34063EC
18/23
7 Package mechanical data
In order to meet environmental requirements, ST offers these devices in ECOPACK®
packages. These packages have a lead-free second level interconnect. The category of
second level interconnect is marked on the package and on the inner box label, in
compliance with JEDEC Standard JESD97. The maximum ratings related to soldering
conditions are also marked on the inner box label. ECOPACK is an ST trademark.
ECOPACK specifications are available at: www.st.com
MC34063AB - MC34063AC - MC34063EB - MC34063EC Package mechanical data
19/23
Dim.
mm. inch.
Min. Typ. Max. Min. Typ. Max.
A3.30.130
a1 0.7 0.028
B1.39 1.65 0.055 0.065
B1 0.91 1.04 0.036 0.041
b0.5 0.020
b1 0.38 0.5 0.015 0.020
D9.80.386
E8.80.346
e 2.54 0.100
e37.62 0.300
e4 7.62 0.300
F 7.1 0.280
I4.80.189
L3.30.130
Z 0.44 1.6 0.017 0.063
Plastic DIP-8 mechanical data
P001F
Package mechanical data MC34063AB - MC34063AC - MC34063EB - MC34063EC
20/23
Dim. mm. inch.
Min. Typ. Max. Min. Typ. Max.
A1.35 1.75 0.0530.069
A1 0.10 0.25 0.04 0.010
A2 1.10 1.65 0.0430.065
B0.33 0.51 0.0130.020
C0.190.25 0.007 0.010
D4.80 5.00 0.189 0.197
E3.80 4.00 0.150 0.157
e 1.27 0.050
H5.80 6.20 0.2280.244
h 0.25 0.50 0.010 0.020
L 0.40 1.27 0.016 0.050
k8° (max.)
ddd 0.1 0.04
SO-8 mechanical data
0016023/C
MC34063AB - MC34063AC - MC34063EB - MC34063EC Package mechanical data
21/23
Dim.
mm. inch.
Min. Typ. Max. Min. Typ. Max.
A330 12.992
C 12.813.2 0.504 0.519
D 20.2 0.795
N60 2.362
T 22.4 0.882
Ao 8.1 8.5 0.3190.335
Bo 5.5 5.90.216 0.232
Ko 2.1 2.30.082 0.090
Po 3.94.1 0.1530.161
P7.98.1 0.311 0.319
Tape & reel SO-8 mechanical data
MC34063AB - MC34063AC - MC34063EB - MC34063EC
23/23
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