BM34063
DC-DC CONVERTER
Features
3V to 40V Input Voltage Operation
Internal 1.6A Peak Current Switch
Internal ±1.8% Reference
Low Quiescent Current at 1.6mA
Frequency Operation from 100Hz~100KHz
Output Voltage Adjustable
Active Current Limiting
Step-Up, Step-Down or Inverting Switching
Regulators
Description
The BM34063 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.
Pin Assignment
DIP/SOP-8
1
2
3
4
SW
C
SW
E
TC
GND
DRC
Ipk
VCC
FB
8
Pin1: Switch Collector (SWC)
Pin2: Switch Emitter (SWE)
7
6
5
Pin5: Comparator Inverting Input (FB)
Pin6: Voltage Supply (Vcc)
Pin7: Ipk Sense (Ipk)
Pin3: Timing Capacitor (TC)
Pin4: Ground (GND)
Pin8: Voltage Driver Collector (DRC)
Ordering Information
Part Number
BM34063HP
BM34063HS
Package
DIP-8
SOP-8
2004/06/15
1
BM34063
DC-DC CONVERTER
Absolute Maximum Ratings
(Ta=25°C, Unles Otherwise Specified)
Parameter
Power Supply Voltage
Comparator Input Voltage Range
Switch Collector Voltage
Switch Emitter Voltage
Switch Emitter to Collector Voltage
Driver Collector Voltage
Switch Current
Power Dissipation at Ta=25
o
C
Operating Ambient Temperature Range
Storage Temperature Range
Operating Junction Temperature
Thermal Resistance Junction-ambient
Symbol
V
CC
V
ir
V
C(SW)
V
SWE
V
CE
V
C(DR)
I
SW
P
D
T
opr
T
stg
T
opj
θJA
DIP-8
SO-8
0~+70
-65~+150
120
125
o
Value
40
-0.3~+40
40
40
40
40
1.5
1
0.625
Unit
V
V
V
V
V
V
A
W
o
o
o
C
C
C
C/W
Block Diagram
SC
Pin1: 1.6A Switch Collector
Q2
Q1
80Ω
Q
S
R
DRI
Pin8: Driver Collector
IPK
CT
Oscillator
IPK
Pin7: Highside Current Sense
Input, VCC-VIPK=300mV
SE
Pin2: Darlington Switch Emitter
TC
Pin3: Oscilletor Timing Capacitor
1.25V
Reference Voltage
VCC
Comparator
Pin6: Power Supply Input
+
-
FB
Pin5: Feedback Comparator
Inverting Input
GND
Pin4: Power GND
2004/06/15
2
BM34063
DC-DC CONVERTER
Electrical Characteristics
(V
CC
=5V,Ta=0~70°C, unless otherwise specified)
Parameter
Oscillator
Charging Current
Discharge Current
Frequency
Discharge to Charge Current Ratio
Current Limit Sense Voltage
Output Switch
Saturation Voltage,
Darlington Connection
Saturation Voltage
DC Current Gain
Collector Off-State Current
Comparator
Threshold Voltage
Threshold Voltage Line Regulation
Input Bias Current
Total Device
Supply Current
I
CC
V
CC
=5~40V, V
PIN7
=V
CC
, V
Pin5
>V
FB
,
C
T
=0.001uF, Pin7=GND,
Remaining pins open
-
1.6
3
mA
V
FB
∆V
FB
I
IB
V
CC
=5~40V
V
IN
=0V
1.23
-
-
1.25
1.5
40
1.27
6
400
V
mV
nA
V
CE(sat)
1
V
CE(sat)
2
h
FE
I
CC(off)
I
SW
=1A, V
C(SW)
=V
C(DR)
I
SW
=1A, I
C(DR)
=50mA
I
SW
=1A, V
CE
=5V
V
CE
=40V, Ta=25
o
C
-
-
35
-
1
0.4
120
10
1.3
0.7
-
100
uA
V
V
I
chg
I
dischg
f
OSC
I
dischg
/I
chg
V
IPK
V
CC
=5~40V, Ta=25
o
C
V
CC
=5~40V, Ta=25
o
C
V
PIN5
=0, C
T
=1nF, Ta=25 C
V
PIN7
=V
CC
, Ta=25
o
C
I
dischg
=I
chg
, Ta=25 C
o
o
Symbol
Test Condition
Min.
10
140
28
5.2
250
Typ.
25
190
33
6
300
Max.
40
240
40
7.5
350
Unit
uA
uA
KHz
mV
Application Information
Design Formula Table
Calculation
t
on
/t
off
(t
on
+t
off
) max
C
T
I
C(sw)
R
S
L
(min)
C
O
Step-Down
(V
out
+V
F
)/(V
in(min)
-V
sat
-V
out
)
1/F
min
4*10
-5
t
on
2*I
out(max)
0.3/I
C(sw)
(V
in(min)
-V
sat
/I
pk(sw)
)*t
on(max)
(I
pk(sw)
*(t
on
+t
off
))/(8*V
ripple(P-P)
)
Step-Up
(V
out
+V
F
-V
in(min)
)/(V
in(min)
-V
sat
)
1/F
min
4*10
-5
t
on
2*I
out(max)
(t
on
+t
off
/t
off
)
0.3/I
C(sw)
(V
in(min)
-V
sat
/I
pk(sw)
)*t
on(max)
I
out
*t
on
/V
ripple(P-P)
Voltage-Inverting
(|V
out
|+V
F
)/(V
in(max)
-V
sat
)
1/F
min
4*10
-5
t
on
2*I
out(max)
(t
on
+t
off
/t
off
)
0.3/I
C(sw)
(V
in(min)
-V
sat
/I
pk(sw)
)*t
on(max)
I
out
*t
on
/V
ripple(P-P)
V
sat
: Saturation voltage of the output switch.
V
F
: Forward voltage drop of the ringback rectifier.
The following power supply characteristics must be chosen:
V
in
: Nominal input voltage.
V
out
: Desired output voltage. |Vout|=1.25*(1+RB/RA)
I
out
: Desired output current
F
min
: Minimum desired output switching frequency at the selected values for Vin and Iout.
V
ripple(P-P)
: Desired peak to peak output ripple voltage in practice, the calculated value will need to be increased due to
the capacitor equivalent series resistance and board layout. The ripple voltage should be kept to a low value since it
will directly effect the line and load regulation.
2004/06/15
3
BM34063
DC-DC CONVERTER
Application Information
(Continued)
L1
R1
150Ω
200uH
D1
1N5819
V
out
28V / 200mA
C
out
220uF
BM34063
8
7
6
1
2
3
4
RSC
0.22
V
in
C1
100uF
5
C
T
680pF
RB
RA
2.2kΩ
47kΩ
Line Regulation: 100mV (Vin=8V~16V, @Io=200mA)
Load Regulation: 5mV (Vin=12V, @Io=80mA~200mA)
Fig.2 Step-Up Converter
L1
BM34063
R1
8
7
1
2
3
4
V
out
D1
RSC
V
in
C1
6
5
Q1
C
T
R2
C
out
RB
RA
Fig.3 Step-Up Converter With External NPN Switch
BM34063
8
7
1
2
3
4
L1
200uH
V
out
5V / 500mA
C
out
RSC
0.25
6
5
D1
1N5819
470uF
V
in
C
T
470pF
C1
100uF
RB
RA
1.2kΩ
3.6kΩ
Line Regulation: 40mV (Vin=10V~20V, @Io=500mA)
Load Regulation: 5mV (Vin=15V, @Io=10mA~500mA)
Short Circuit Current: 1.3A (Vin=15V, @RL=0.1Ω
Fig.4 Step-Down Converter
2004/06/15
4
BM34063
DC-DC CONVERTER
BM34063
R2
8
7
1
2
3
4
R1
Q1
L1
V
out
RSC
V
in
6
5
C
T
D1
C
out
RB
C1
RA
Fig.5 Step-Down Converter With External PNP Saturation Switch
D1
BM34063
8
1
2
3
4
1N5819
V
out
-12V / 100mA
RSC
0.25
7
6
5
L1
100uH
C
out
470uF
V
in
4.5V-6V
C
T
680pF
C1
100uF
RA
RB
8.2kΩ
953Ω
Line Regulation: 20mV (Vin=4.5V~6V, @Io=100mA)
Load Regulation: 100mV (Vin=5V, @Io=10mA~100mA)
Fig.6 Voltage Inverting Converter
BM34063
8
1
2
3
4
R2
R1
Q1
RSC
7
6
L1
D1
C
T
V
out
V
in
5
RA
C1
RB
C
out
Fig.7 Voltage Inverting Converter With External PNP Saturation Switch
2004/06/15
5
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