MC34063A DC-TO-DC Converter Control Circuits

DESCRIPTION PIN CONFIGURATION

The MC34063A is a monolithic control circuit containing
Switch Diver
the primary functions required for DC-to-DC converters. Collector 1 8 Collector
The device consists of an internal temperature compen- Switch
2 7 IPK Sense
Emitter
sated reference, comparator, controlled duty cycle oscill-
Timing 3 6 VCC
ator with an active current limit circuit, driver and high Capacitor
Comparator
current output switch. MC34063A is specifically designed GND 4 5 Inverting
Input
to be incorporated in Step-Down, Step-Up and Voltage-
(Top View)
Inverting applications with a minimum number of extern-
al components.

FEATURES
Operation from -0.3V to 40V Input
Low Standby Current
Current Limiting
Output Switch Current to 1.5A
Output Voltage Adjustable
Frequency Operation to 42kHz
Precision 2% Reference

APPLICATION
DC-DC Converter

ORDERING INFORMATION
Orderable
Temperature Range Package Package Qty
Device
SOP8L MC34063ADG 75Units/Tube
0°C to +70°C SOP8L Pb-Free MC34063ADRG 2500Units/Tape
DIP8L MC34063APG 50Units/Tube

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MC34063A DC-TO-DC Converter Control Circuits
SCHEMATIC DIAGRAM
8 1
Drive Switch
Collector Collector

S Q Q2

R Q1

7 100
Ipk 2
Sense
Switch
Emitter
Ipk
Oscillator GT

6 3
VCC Timing
Capacitor
+
1,25V
Comparator Reference
_ Regulator

5 4
Comparator GND
Inverting
Input

(Bottom View)
Figure 1. Representative Schematic Diagram

ABSOLUTE MAXIMUM RATINGS

Parameter Symbol Value Unit
Power Supply Voltage VCC 40 V
Comparator Input Voltage Range VIR −0.3 to +40 V
Switch Collector Voltage VC(switch) 40 V
Switch Emitter Voltage (VPin1 = 40 V) VE(switch) 40 V
Switch Collector to Emitter Voltage VCE(switch) 40 V
Driver Collector Voltage VC(driver) 40 V
Driver Collector Current (Note 1) IC(driver) 100 mA
Switch Current ISW 1.5 A
D Package 625 mW
Power Dissipation, TA = 25°C PD
P Package 1.25 W
D Package 160
Thermal Resistance, TA = 25°C RθJA °C/W
P Package 100
Operating Junction Temperature TJ +150 °C
Operating Ambient Temperature Range TA 0 to +70 °C
Storage Temperature Range Tstg −65 to +150 °C

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MC34063A DC-TO-DC Converter Control Circuits
ELECTRICAL CHARACTERISTICS
(Vcc = 5.0V, TA=0 to +70°C, unless otherwise specified)
Parameter Symbol Test Conditions Min Typ Max Unit
OSCILLATOR
Frequency fosc V Pin5 =0V,C T =1.0nF,T A = 25°C 24 33 42 kHz
Charge Current Ichg V CC = 5.0V to 40V, T A = 25°C 24 33 42 μA
Discharge Current I dischg V CC = 5.0V to 40V, T A = 25°C 140 200 260 μA
Discharge to Charge
Idischg/Ichg Pin7 to V CC , T A =25°C 5.2 6.2 7.5
Current Ratio
Current Limit Vlpk(sense) I chg = I dischg , T A = 25°C 250 300 350 mV
Sense Voltage
OUTPUT SWITCH (Note 3)
Saturation Voltage, I SW = 1.0A,
VCE(sat) 1.0 1.3 V
Darlington Connection Pins 1, 8 connected
ISW = 1.0A, Forced β = 20
Saturation Voltage, VCE(sat) 0.45 0.7 V
Darlinton Connection RPin 8 = 82Ω to VCC
I SW = 1.0A, V CE =5.0V,
DC Current Gain hFE 50 75
T A = 25°C
Collector Off-State
IC(off) V CE = 40V 40 100 μA
Current
COMPARATOR
T A = 25°C 1.225 1.25 1.275
Threshold Voltage V th V
T A = T low to T high 1.21 1.29
Threshold Voltage
Reg line V CC = 3.0V to 40V 1.4 5.0 mV
Line Regulation
Input Bias Current IIB V in = 0V -20 -400 nA
TOTAL DEVICE
V CC = 5.0V to 40V,
Supply Current ICC C T = 10nF, V pin7 = V CC , 2.5 4.0 mA
V Pin5 > V th , Pin 2 = GND,
Remaining pins open

NOTE 1: Maximum package power dissipation limits must be observed

NOTE 2: Low duty cycle pulse techniques are used during test to maintain juction temperature as
close to ambient temperature as possible

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MC34063A DC-TO-DC Converter Control Circuits

Assembly Information:

CHIP APPEARANCE CHIP SIZE 1,18 × 1,27 mm

CHIP THICKNESS 460 ± 20 μm
8 1a SWITCH 90 × 90 μm
1 7 1b COLLECTOR
2a SWITCH 90 × 90 μm
2b EMITTER
TIMING 90 × 90 μm
3 CAPACITOR
BONDING PAD 4 GROUND 90 × 90 μm
DIMENSION COMPARATOR
90 × 90 μm
5 INVERTING
2 3 4 5 6 INPUT
6 Vcc 90 × 90 μm
7 Ipk SENCE 90 × 90 μm
DRIVER 90 × 90 μm
8 COLLECTOR
SCRIBE LINE WIDTH 96 μm
TOP METAL Al
BACK METAL –
WAFER SIZE 100 mm

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 MC34063A DC-TO-DC Converter Control Circuits
TYPICAL PERFORMANCE CHARACTERISTICS
ton-off.OUTPUT SWITCH ON-OFF TIME(μS)

1000

VOSC,OSOCILLATOR VOLTAGE(V)
500 V CC =5.0V
200 Pin7=V CC
Pin5=GND
100 T A =25°C

200 mV / DIV
50
t on
20
10

5.0
t off VCC=5.0V Pins1,5,8=Open
2.0 Pin7=VCC CT=1.0μF
1.0 Pin2=GND TA=25°C
0.01 0.02 0.05 0.1 0.2 0.5 1.0 2.0 5.0 10 10μS / DIV
CT,OSCILLATOR TIMING CAPACITOR(nF)
Figure 2. Output Switch On−Off Time vs. Figure 3. Timing Capacitor Waveform
Oscillator Timing Capacitor

1.8
VCE(sat),SATURATION VOTAGE(V) 1.1
1.0
VCE(sat),SATURATION VOTAGE(V)

1.7
0.9
Darlington Connection
1.6 0.8
0.7
1.5
0.6 VCC=5.0V
1.4 0.5 Pin7=Vcc
VCC=5.0V Pins 2,3,5=GND
Pins1,7,8=Vcc 0.4 TA = 25ºC
1.3 Pins3,5=GND Forcedβ = 20
TA = 25ºC 0.3
1.2
0.2
1.1 0.1
0
1.0
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6

IE, EMITTER CURRENT(A) IC, COLLECTOR CURRENT(A)

Figure 4. Emitter Follower Configuration Output Figure 5. Common Emitter Configuration Output Switch
Saturation Voltage vs. Emitter Current  Saturation Voltage vs. Collector Current

3.6
400
380 3.2
VIPK(sense),CURRENT LIMIT

ICC,SUPPLY CURRENT(mA)

Vcc=5.0V
360 Ichg=Idischg 2.8
340 2.4
SENSE VOLTAGE(V)

320 2.0
300
1.6
280
1.2 CT=1.0nF
260
0.8 Pin7=Vcc
240 Pin2=GND
220 0.4

200 0
-55 -25 0 25 50 75 100 125 0 5.0 10 15 20 25 30 35 40

TA,AMBIENT TEMPERATURE(°C) VCC,S UPPLY VOLTAGE(V)

Figure 6. Current Limit Sense Voltage vs. Figure 7. Standby Supply Current vs. Supply Voltage
Temperature 

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MC34063A DC-TO-DC Converter Control Circuits
TYPICAL APPLICATION

L1

170μH

R3 8 1
DRC SWC
180Ω

7 2
Ipk SWE D1
BYV10-40

RSG 6 3
VCC TC
0.22Ω
VIN 5 4
CII GND VOUT
12V
+
C2 C3
100μF 1.5nF

R1 R2

2.2kΩ 47kΩ
+
C3
330μF

Figure 8. Step−Up Converter

For VOUT=28V
Parameter Test Conditions Result(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 %

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MC34063A DC-TO-DC Converter Control Circuits
TYPICAL APPLICATION(CONTINUED)

8 1
DRC SWC

BYV10-40
7 2
Ipk SWE
RSC
0.33Ω D1
6 3
VCC TC

5 4
Vin CII GND L1
220μH
+
C2 C3
100μF 470pF

R2 R1

1.2kΩ 3.6kΩ
+
C1
470μF

Figure 9. Step−Down Converter

For VOUT = 5V
Parameter Test Conditions Result(Typ) Unit
Line Regulation VIN = 15 to 25 V, IO = 500 mA 5 mV
Load Regulation VIN = 25 V, IO = 50 to 500mA 30 mV
Output Ripple VIN = 25 V, IO = 500 mA 100 mV
Efficiency VIN = 25 V, IO = 500mA 80 %
ISC VIN = 25 V, Rload = 0.1 Ω 1.2 A

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MC34063A DC-TO-DC Converter Control Circuits
TYPICAL APPLICATION(CONTINUED)

8 1
DRC SWC

L1
7 2
Ipk SWE
RSC 90μH
0.22Ω
6 3
VCC TC

VIN 5 4
4.5 to 6V CII GND
D1
+ BYV10-40
C2 C3
100μF 1.5nF

R2 R1
VOUT
-12V / 100mA
8.2kΩ 953kΩ
C1
1000μF
+

Figure 10. Voltage Inverting Converter

For VOUT = -12V

Patameter Test Conditions Result(Typ) Unit
Line Regulation VIN = 4.5 to 6 V, IO = 100 mA 15 mV
Load Regulation VIN = 5 V, IO = 10 to 100mA 20 mV
Output Ripple VIN = 5 V, IO = 100 mA 230 mV
Efficiency VIN = 5 V, IO = 100mA 58 %
ISC VIN = 5 V, Rload = 0.1 Ω 0.9 A

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MC34063A DC-TO-DC Converter Control Circuits
TYPICAL APPLICATION(CONTINUED)

1 VOUT
S Q Q2
+
R Q1

7
Ipk
RSC
Oscillator
3

VIN 6 1.25V
+ Reference
Comparator Regulator
4
_

Figure 11. Step-up with External NPN Switch

1
S Q Q2

R Q1

7
Ipk
RSC
Oscillator
3
VOUT
VIN 6 1.25V
+ Reference +
Regulator
Comparator 4
_

Figure 12. Step-down with External NPN Switch

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MC34063A DC-TO-DC Converter Control Circuits
TYPICAL APPLICATION(CONTINUED)

1
S Q Q2

R Q1

VOUT
2
+
7

RSC Ipk
Oscillator 3

VIN 6 1.25V
+ Reference
Regulator
Comparator 4
_

Figure 13. Step-down with External PNP Switch

1
S Q Q2

R Q1

RSC Ipk
Oscillator 3
VOUT
VIN 6 1.25V
+ Reference
Regulator
Comparator 4 +
_

Figure 14. Voltage Inverting with External NPN Switch

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MC34063A DC-TO-DC Converter Control Circuits
TYPICAL APPLICATION(CONTINUED)

1
S Q Q2

R Q1 VOUT

2 +
7
Ipk
RSC Oscillator 3

VIN
6 1.25V
+ Reference
Comparator Regulator
4
_

Figure 15. Voltage Inverting with External PNP Saturated Switch

+12V

GND
+
8

1
Q2 -12V
S Q

R Q1

RSC Ipk
Oscillator 3

VIN 6 1.25V
+ Reference
Comparator Regulator
4
_

Figure 16. Dual Output Voltage

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 MC34063A DC-TO-DC Converter Control Circuits

TYPICAL APPLICATION(CONTINUED)

+ +VOUT

Isolated from input

-VOUT

+
8

1
S Q Q2

R Q1

VIN 7

RSC Ipk 3
Oscillator

6 1.25V
+ Reference
Comparator Regulator
4
_

Figure 17. Higher Output Power, Higher Input Voltage

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MC34063A DC-TO-DC Converter Control Circuits
CALCULATION
Table 1 Design Formula Table

Calculation Step-Up Step-Down Voltage-Inverting

Vout + VF - Vin(min) Vout + VF |Vout | + VF

ton/toff
Vin(min) - Vsat Vin(min) - Vsat - Vout Vin - Vsat
1 1 1
(ton+toff)max f f f
ton + toff ton + toff ton + toff
toff
ton/toff + 1 ton/toff + 1 ton/toff + 1

ton (ton + toff) - toff (ton + toff) - toff (ton + toff) - toff
CT 4.0×10 -5 ton 4.0×10 -5 ton 4.0×10 -5 ton
ton ton
Ipk(switch) (
2Iout(max) toff + 1 ) 2Iout(max) (
2Iout(max) toff + 1 )
0.3 0.3 0.3
RSC I PK(switch) IPK(switch) IPK(switch)
(Vin(min) - Vsat) (Vin(min) - Vsat - Vout) (Vin(min) - Vsat)
L(min) ton(max) ton(max) ton(max)
Ipk(switch) Ipk(switch) Ipk(switch)
Ioutton Ipk(switch)(ton + toff) Ioutton
CO ≈ ≈
Vripple(p-p) 8Vripple(p-p) Vripple(p-p)

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(pp)=Desired peak-to-peak output ripple voltage.In prictice,the calculated capacitor value
will need to be increased due to its equivalent series resistance and board layout.
The ripple should be kept to a low value since it will directiy affect the line and load
regulation.

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MC34063A DC-TO-DC Converter Control Circuits
PHYSICAL DIMENSIONS
SOP8L

A3 A1 A2

4
B1

R2

3
A

R1

B2
C1

C
C2

C4
C3

D1

Dimension(mm) Dimension(mm)
Symbol Symbol
Min Max Min Max
A 4.95 5.15 C3 0.05 0.20
A1 0.37 0.47 C4 0.20(TYP)
A2 1.27(TYP) D 1.05(TYP)
A3 0.41(TYP) D1 0.40 0.60
B 5.80 6.20 R1 0.07(TYP)
B1 3.80 4.00 R2 0.07(TYP)
B2 5.0(TYP) 1 17 (TYP)
C 1.30 1.50 2 13 (TYP)
C1 0.55 0.65 3 4 (TYP)
C2 0.55 0.65 4 12 (TYP)

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MC34063A DC-TO-DC Converter Control Circuits

DIP8L
A D2
1

2
B

D1
D

C4
C1
C

C2
C3

A5
A3 A4
A1
A2

Dimension(mm) Dimension(mm)
Symbol Symbol
Min Max Min Max
A 9.30 9.50 C2 0.5(TYP)
A1 1.524(TYP) C3 3.3(TYP)
A2 0.39 0.53 C4 1.57(TYP)
A3 2.54(TYP) D 8.20 8.80
A4 0.66(TYP) D1 0.20 0.35
A5 0.99(TYP) D2 7.62 7.87

B 6.3 6.5 1 8 (TYP)

C 7.20(TYP) 2 8 (TYP)
C1 3.30 3.50 3 5 (TYP)

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