FUJITSU SEMICONDUCTOR
DATA SHEET
DS04-27239-1E
ASSP For Power Supply Applications
(General-Purpose DC/DC Converter)
3-ch DC/DC Converter IC
MB39A112
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DESCRIPTION
The MB39A112 is a 3-channel DC/DC converter IC using pulse width modulation (PWM) , and the MB39A112 is
suitable for down-conversion.
3-channel is built in TSSOP-20P package. Each channel can be controlled and soft-start.
The MB39A112 contains a constant voltage bias circuit for output block, capable of implementing an efficient
high-frequency DC/DC converter. It is ideal for built-in power supply such as ADSL modems.
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REATURES
• Supports for down-conversion (CH1 to CH3)
• Power supply voltage range
: 7 V to 25 V
• Error amplifier threshold voltage : 1.00 V
±
1% (CH1)
: 1.23 V
±
1% (CH2, CH3)
• Oscillation frequency range
: 250 kHz to 2.6 MHz
• Built-in soft-start circuit independent of loads
• Built-in timer-latch short-circuit protection circuit
• Built-in totem-pole type output for P-channel MOS FET devices
• Built-in constant voltage (VCCO
−
5 V) bias circuit for output block
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PACKAGE
20-pin plastic TSSOP
(FPT-20P-M06)
MB39A112
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PIN ASSIGNMENT
(TOP VIEW)
CS1 : 1
−INE1
: 2
FB1 : 3
VCC : 4
RT : 5
CT : 6
GND : 7
FB2 : 8
−INE2
: 9
CS2 : 10
20 : VCCO
19 : OUT1
18 : OUT2
17 : OUT3
16 : VH
15 : GNDO
14 : CSCP
13 : FB3
12 :
−INE3
11 : CS3
(FPT-20P-M06)
2
MB39A112
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PIN DESCRIPTION
Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
Symbol
CS1
−
INE1
FB1
VCC
RT
CT
GND
FB2
−
INE2
CS2
CS3
−
INE3
FB3
CSCP
GNDO
VH
OUT3
OUT2
OUT1
VCCO
I/O
I
O
O
I
I
O
O
O
O
O
Descriptions
CH1 soft-start setting capacitor connection terminal.
CH1 error amplifer inverted input terminal.
CH1 error amplifer output terminal.
Control circuit power supply terminal.
Triangular-wave oscillation frequency setting resistor connection terminal.
Triangular-wave oscillation frequency setting capacitor connection terminal.
Ground terminal.
CH2 error amplifier output terminal.
CH2 error amplifier inverted input terminal.
CH2 soft-start setting capacitor connection terminal.
CH3 soft-start setting capacitor connection terminal.
CH3 error amplifier inverted input terminal.
CH3 error amplifier output terminal.
Timer-latch short-circuit protection capacitor connection terminal.
Ground terminal.
Power supply terminal for driving output circuit. (VH
=
VCCO
−
5 V) .
CH3 external Pch MOS FET gate driving terminal.
CH2 external Pch MOS FET gate driving terminal.
CH1 external Pch MOS FET gate driving terminal.
Power supply terminal for driving output circuit. (Connect to same potential
as VCC terminal).
3
MB39A112
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BLOCK DIAGRAM
Threshold voltage
1.0 V
±
1%
VREF
10
µA
CS1 1
L
priority
−INE1
2
CH1
PWM
Comp.1
Drive1
Pch
20 VCCO
−
+
+
1.0 V
Error
Amp1
+
−
19 OUT1
FB1 3
I
O
=
150 mA
−INE2
9
VREF
10
µA
CS2 10
L
priority
Threshold voltage
1.23 V
±
1%
−
+
+
1.23 V
I
O
=
150 mA
Error
Amp2
+
−
PWM
Comp.2
CH2
Drive2
Pch
18 OUT2
FB2 8
−INE3
12
10
µA
CS3 11
Threshold voltage
1.23 V
±
1%
VREF
−
+
+
1.23 V
I
O
=
150 mA
Error
Amp3
+
−
PWM
Comp.3
CH3
Drive3
Pch
17 OUT3
L
priority
FB3 13
H
priority
SCP
Comp.
+
+
+
−
2.7 V
VCCO
−
5 V
Bias
Voltage
VH
16 VH
SCP
15 GNDO
H: at SCP
CSCP 14
2.5 V
2.0 V
OSC
UVLO
Error Amp Power Supply
SCP Comp. Power Supply
4 VCC
H: UVLO release
bias
3.5 V
VREF
ErrorAmp Reference
1.0 V/1.23 V
VR
Power
ON/OFF
CTL
GND
5
RT
6
CT
7
GND
4
MB39A112
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ABSOLUTE MAXIMUM RATINGS
Parameter
Power supply voltage
Output current
Peak output current
Power dissipation
Storage temperature
Symbol
Vcc
Io
I
OP
P
D
T
STG
Conditions
VCC, VCCO terminal
OUT1, OUT2, OUT3 terminal
Duty
≤
5
%
(t
=
1/fosc
×
Duty)
Ta
≤ +
25
°C
Rating
Min
−
55
Max
28
20
400
1280*
+
125
Unit
V
mA
mA
mW
°C
* : The package is mounted on the dual-sided epoxy board (10 cm
×
10 cm) .
WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current,
temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings.
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RECOMMENDED OPERATING CONDITIONS
Parameter
Power supply voltage
Input voltage
Output current
Oscillation frequency
Timing capacitor
Timing resistor
VH terminal capacitor
Soft-start capacitor
Short-circuit detection
capacitor
Operating ambient
temperature
Symbol
Vcc
V
IN
I
O
I
VH
fosc
C
T
R
T
C
VH
C
S
C
SCP
Ta
VH terminal
CS1, CS2, CS3 terminal
CSCP terminal
Conditions
VCC, VCCO terminal
−
INE terminal
OUT1, OUT2, OUT3 terminal
VH terminal
Value
Min
7
0
−
15
0
250
22
4.7
−
30
Typ
12
-
1200
100
10
0.1
0.1
0.01
+
25
Max
25
Vcc
−
1.8
15
30
2600
1000
22
1.0
1.0
1.0
+
85
Unit
V
V
mA
mA
kHz
pF
kΩ
µF
µF
µF
°C
WARNING: The recommended operating conditions are required in order to ensure the normal operation of the
semiconductor device. All of the device’s electrical characteristics are warranted when the device is
operated within these ranges.
Always use semiconductor devices within their recommended operating condition ranges. Operation
outside these ranges may adversely affect reliability and could result in device failure.
No warranty is made with respect to uses, operating conditions, or combinations not represented on
the data sheet. Users considering application outside the listed conditions are advised to contact their
FUJITSU representatives beforehand.
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Analogue and Mixed Signal
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