425 KB

The following document contains information on Cypress products.
FUJITSU MICROELECTRONICS
DATA SHEET
DS04-71109-1Ea
ASSP for Power Supply Applications
Evaluation Board
MB39A112
■ DESCRIPTION
The MB39A112 evaluation board is a surface mount circuit board with 3 channels of down conversion circuit.
This evaluation board outputs voltage of 1.2 V, 3.3 V and 5.0 V from the output terminals of 3 systems, and
supplying a current of Max 1.5 A.
More ever, when the under voltage lockout protection circuit do operation or the short-circuit protection is detected
by the protection function, the FET is turned off and the output is stopped. In addition, each channel can be
controlled to be turned on and off, and can be set for a soft-start.
■ EVALUATION BOARD SPECIFICATIONS
Parameter
Terminal
Input voltage
Ripple voltage
Output current
Soft-start time
Value
Min
Typ
Max
Unit
VIN
7
12
20
V
⎯
2115
2350
2585
kHz
CH1
VO1
1.14
1.2
1.26
V
CH2
VO2
3.13
3.3
3.47
V
CH3
VO3
4.75
5.0
5.25
V
CH1
VO1
6
12
24
mV
CH2
VO2
16
33
64
mV
CH3
VO3
25
50
100
mV
CH1
VO1
800
1200
1500
mA
CH2
VO2
150
500
1000
mA
CH3
VO3
150
200
300
mA
CH1
⎯
6.3
10
18.6
ms
CH2
⎯
7.8
12
22.8
ms
CH3
⎯
7.8
12
22.8
ms
⎯
430
720
1420
μs
Oscillation frequency
Output voltage
(Ta = + 25 °C)
Short-circuit detection time
Copyright©2004-2008 FUJITSU MICROELECTRONICS LIMITED All rights reserved
2004.5
MB39A112
■ TERMINAL DESCRIPTION
Symbol
Description
VIN
Power supply terminal
VIN = 7 V to 25 V (Typ 12 V)
VOX
DC/DC converter output terminal
GND
GND terminal
GNDX
DC/DC converter GND terminal
ICGND
MB39A112 GND terminal
■ SWITCH DESCRIPTION
SW
Name
Function
OPEN
L
1
CS1
CH1 control
Output ON
Output OFF
2
CS2
CH2 control
Output ON
Output OFF
3
CS3
CH3 control
Output ON
Output OFF
■ SETUP AND CHECKUP
(1) Setup
• Connect power-supply terminals side to the VIN and GND, and connect the VO side to required loading device
or measuring instrument.
• Set SW1 to SW3 (CS1 to CS3) to OFF (output OFF) .
(2) Checkup
• Turn on VIN (power supply) , set SW1 to SW3 to ON (output ON) .
The IC works normally with the following outputs :
VO1 = 1.2 V (Typ) , VO2 = 3.3 V (Typ) , VO3 = 5 V (Typ)
2
MB39A112
■ COMPONENT LAYOUT
• On-board Component Layout
GND
VIN
Q1
VD1
VO1
CTL1
R6
Q4
R1
R8
R10
C10
C11
R21
Q6
20
R2
Q2
VD2
3
VH
FB2
10
R14
VO2
1
C4
11
R12
R13
C17
OUT2
C16
VCC
C13
R20
M1
1
C9
CS2
R18
FB3
D2
L2
CSCP C3
C15
OUT3
C14
R16
R3
R15
CS3
C12
R11
R17
SGND
2
3
4
CS L
GND2
6
4
Q3
VD3
VO3
3
1
GND1
6
4
VCCO
FB1
C8
CTL3
L1
R4
R9
C2
C1
CTL2
Q5
1
D1
R5
R7
CS1
C7
R19
3
OUT1
C6
D3
C5
2
L3
GND3
1
SW1
NC
CS3
CS2
CS1
CS OPEN
(Continued)
3
MB39A112
(Continued)
Board Layout
Top Side
Inside VIN (Layer3)
4
Inside GND (Layer2)
Bottom Side
MB39A112
■ CONNECTION DIAGRAM
R6
R7
2.2 kΩ 18 kΩ
A
Q4
*
CTL1
R19
−INE1
2
R8
100 kΩ
C7
0.1 μF
VREF
10 μA
CS1
1
R9
820 Ω
FB1
−
+
+
L
priority
Error
Amp1
+
−
R1
C1
2.2 μF
+
−
Drive2
Pch
18
OUT2
R2
0Ω
D2
SBE001
C3
2.2 μF
Io = 150 mA
CH3
+
−
VO2
3.3 V
lo2 = 0.15 A to 1 A
C4
4.7 μF
GND2
VO3
5.0 V
lo3 = 0.15 A to 0.3 A
10 μH
Drive3
Pch
17
OUT3
Io = 150 mA
VCCO − 5 V
R3
0Ω
C5
2.2 μF
D3
SBS005
C6
4.7 μF
GND3
C16
0.1 μF
16
VH
Bias
Voltage
VH
Error Amp power supply
SCPComp. power supply
15
GNDO
VCC
Power
VR ON/OFF
CTL
C9
0.1μF
OPEN
L
SW1
CS1
a
CS2
b
3
0Ω
2
VREF
R5
4
Error Amp
reference
(1.0 V/1.23 V)
1
bias
3.5 V
UVLO
c
CS3
NC
4
GND
6
GND1
Step-down
VD3
C
Q3
L3
MCH3308
PWM
Comp.3
H:UVLO
release
5
C2
4.7 μF
Step-down
3.3 μH
14
RT
R10
5.1 kΩ
D1
SBE001
VD2
B
Q2
L2
MCH3312
CH2
H: at SCP
OSC
VO1
1.2 V
lo1 = 0.8 A to 1.5 A
2 μH
PWM
Comp.2
SCP
2.0 V
0Ω
Io = 150 mA
2.7 V
2.5 V
Step-down
VD1
A
Q1
L1
MCH3312
R4
0Ω
1.0 V
+
−
CSCP
Drive1
Pch
C17
0.1 μF
OUT1
19
PWM
Comp.1
C8
*
3
0.022 μF
CH1 ON/OFF signal
a
(L:ON, H:OFF)
R11
R12
4.7 kΩ 56 kΩ −INE2
B
9
VREF
Error
R13
10 μA
36 kΩ
− Amp2
Q5
CS2
+
10
+
CTL2
R14
*
C12
820 Ω
L
0.1 μF
1.23
V
R20
priority
FB2
C11
*
8
0.01 μF
CH2 ON/OFF signal
b
(L:ON, H:OFF)
R15
R16
680 Ω 30 kΩ −INE3
12
C
VIN
VREF
Error
R17
(12 V)
10 μA
10 kΩ
− Amp3
Q6
CS3
+
11
+
CTL3
R18
* C13
1 kΩ
L
0.1 μF
1.23
V
R21
priority
GND
FB3
C14
*
13
0.01 μF
CH3 ON/OFF signal
H priority
c
(L:ON, H:OFF)
SCP
+
Comp.
+
Charge
current
1 A
C15
1000 pF
CH1
VCCO
20
7
CT
GND
C10
100 pF
ICGND
All channels are ON state
in above diagram
<20 Pin>
* : Not mounted
5
MB39A112
■ PARTS LIST
Symbol
Specification
No. (Circuit Part name
diagram
mark)
Model
name
Rating Rating Rating
1
2
3
Value
Deviation
Features
⎯
⎯
⎯
Package
Manufacturer Remarks
FUJITSU
MICROELECTRONICS
1 M1
IC
MB39A
112PFT
2 Q1
Pch FET
MCH3312
PD =
1W
VGSS ID =
= 20 V 2.0 A
⎯
⎯
⎯
MCPH3 SANYO
3 Q2
Pch FET
MCH3312
PD =
1W
VGSS ID =
= 20 V 2.0 A
⎯
⎯
⎯
MCPH3 SANYO
4 Q3
Pch FET
MCH3308
PD = VGSS ID =
0.8 W = 20 V 1.0 A
⎯
⎯
⎯
MCPH3 SANYO
5 Q4
Nch FET
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
Not
mounted
6 Q5
Nch FET
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
Not
mounted
7 Q6
Nch FET
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
Not
mounted
8 D1
SBD
SBE001
IF (AV) VRRM
= 2 A = 30 V
⎯
⎯
⎯
⎯
CPH6
SANYO
9 D2
SBD
SBE001
IF (AV) VRRM
= 2 A = 30 V
⎯
⎯
⎯
⎯
CPH6
SANYO
10 D3
SBD
SBS005
IF (AV) VRRM
= 1 A = 30 V
⎯
⎯
⎯
⎯
CPH3
SANYO
11 L1
Coil
A916CY2R0M
IDC1 = IDC2 =
3A
3.31A
⎯
2μ
±20%
RDC =
16 mΩ
⎯
TOKO
12 L2
Coil
A916CY3R3M
IDC1 = IDC2 =
2.57 A 2.81 A
⎯
3.3 μ
±20%
RDC =
21.4 mΩ
⎯
TOKO
13 L3
Coil
A916CY100M
IDC1 = IDC2 =
1.49 A 1.97 A
⎯
10 μ
±20%
RDC =
41.2 mΩ
⎯
TOKO
14 C1
Ceramic C3216JB
condenser 1E225K
25 V
⎯
2.2 μ
±10% characteristics
3216
TDK
Ceramic C3216JB
condenser 1C475M
16 V
3216
TDK
Ceramic C3216JB
condenser 1E225K
25 V
3216
TDK
Ceramic C3216JB
condenser 1C475M
16 V
3216
TDK
Ceramic C3216JB
condenser 1E225K
25 V
3216
TDK
Ceramic C3216JB
condenser 1C475M
16 V
3216
TDK
15 C2
16 C3
17 C4
18 C5
19 C6
⎯
⎯
⎯
⎯
FPT-20PM06
Temperature
B
⎯
⎯
4.7 μ
Temperature
±20% characteristics
B
⎯
⎯
2.2 μ
Temperature
±10% characteristics
B
⎯
⎯
4.7 μ
Temperature
±20% characteristics
B
⎯
⎯
2.2 μ
Temperature
±10% characteristics
B
⎯
⎯
4.7 μ
Temperature
±20% characteristics
B
(Continued)
6
MB39A112
Symbol
No.
Specification
(Circuit Part name
diagram
mark)
Model
name
Rating Rating Rating
1
2
3
Value
Deviation
⎯
0.1 μ
±10% characteristics
50V
Ceramic C1608JB
condenser 1H223K
50V
Ceramic C1608JB
condenser 1H104K
50V
Ceramic C1608CH
condenser 1H101J
50V
Ceramic C1608JB
condenser 1H103K
50V
Ceramic C1608JB
condenser 1H104K
50V
Ceramic C1608JB
condenser 1H104K
50V
Ceramic C1608JB
condenser 1H103K
50V
Ceramic C1608JB
condenser 1H102K
50V
Ceramic C1608JB
condenser 1H104K
50V
Ceramic C1608JB
condenser 1H104K
50V
31 R1
Jumper
RK73Z1J
1A
⎯
⎯
0Ω
Max
50 mΩ
32 R2
Jumper
RK73Z1J
1A
⎯
⎯
0Ω
33 R3
Jumper
RK73Z1J
1A
⎯
⎯
34 R4
Jumper
RK73Z1J
1A
⎯
35 R5
Jumper
RK73Z1J
1A
⎯
21 C8
22 C9
23 C10
24 C11
25 C12
26 C13
27 C14
28 C15
29 C16
30 C17
Package
Manufacturer Remarks
Temperature
Ceramic C1608JB
condenser 1H104K
20 C7
Features
⎯
1608
TDK
1608
TDK
1608
TDK
1608
TDK
1608
TDK
1608
TDK
1608
TDK
1608
TDK
1608
TDK
1608
TDK
1608
TDK
⎯
1608
KOA
Max
50 mΩ
⎯
1608
KOA
0Ω
Max
50 mΩ
⎯
1608
KOA
⎯
0Ω
Max
50 mΩ
⎯
1608
KOA
⎯
0Ω
Max
50 mΩ
⎯
1608
KOA
B
Temperature
⎯
⎯
0.022 μ ±10% characteristics
B
Temperature
⎯
⎯
0.1 μ
±10% characteristics
B
⎯
⎯
Temperature
100 p
±5% characteristics
CH
Temperature
⎯
⎯
0.01 μ ±10% characteristics
B
Temperature
⎯
⎯
0.1 μ
±10% characteristics
B
Temperature
⎯
⎯
0.1 μ
±10% characteristics
B
Temperature
⎯
⎯
0.01 μ ±10% characteristics
B
Temperature
⎯
⎯
1000 p ±10% characteristics
B
Temperature
⎯
⎯
0.1 μ
±10% characteristics
B
Temperature
⎯
⎯
0.1 μ
±10% characteristics
B
(Continued)
7
MB39A112
(Continued)
Symbol
No.
(Circuit Part name
diagram
mark)
Rating Rating Rating
1
2
3
Value
Deviation
Features
Package
Manufacturer Remarks
36 R6
Resistor
PR0816P1/16 W
222-D
⎯
⎯
2.2 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
37 R7
Resistor
PR0816P1/16 W
183-D
⎯
⎯
18 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
38 R8
Resistor
PR0816P1/16 W
104-D
⎯
⎯
100 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
39 R9
Resistor
PR0816P1/16 W
821-D
⎯
⎯
820 Ω ±0.5%
±25
ppm/ °C
1608
ssm
40 R10
Resistor
PR0816P1/16 W
512-D
⎯
⎯
5.1 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
41 R11
Resistor
PR0816P1/16 W
472-D
⎯
⎯
4.7 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
42 R12
Resistor
PR0816P1/16 W
563-D
⎯
⎯
56 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
43 R13
Resistor
PR0816P1/16 W
363-D
⎯
⎯
36 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
44 R14
Resistor
PR0816P1/16 W
821-D
⎯
⎯
820 Ω ±0.5%
±25
ppm/ °C
1608
ssm
45 R15
Resistor
PR0816P1/16 W
681-D
⎯
⎯
680 Ω ±0.5%
±25
ppm/ °C
1608
ssm
46 R16
Resistor
PR0816P1/16 W
303-D
⎯
⎯
30 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
47 R17
Resistor
PR0816P1/16 W
103-D
⎯
⎯
10 kΩ ±0.5%
±25
ppm/ °C
1608
ssm
48 R18
Resistor
PR0816P1/16 W
102-D
⎯
⎯
1 kΩ
±0.5%
±25
ppm/ °C
1608
ssm
49 R19
Resistor
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
Not
mounted
50 R20
Resistor
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
Not
mounted
51 R21
Resistor
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
⎯
Not
mounted
52 SW1
Switch
DMS-4H
⎯
⎯
⎯
⎯
⎯
⎯
⎯
MATSUKYU
Terminal
pin
WT-2-1
⎯
⎯
⎯
⎯
⎯
⎯
⎯
MacEight
53
⎯
SANYO
TOKO
TDK
KOA
ssm
MATSUKYU
MacEight
8
Specification
Model
name
SANYO Electric Co., Ltd.
TOKO, Inc.
TDK Corporation
KOA Corporation
SUSUMU CO., LTD.
Matsukyu Co., Ltd.
MacEight Co., Ltd.
MB39A112
■ INITIAL SETTINGS
(1) Output voltage
R6 + R7 + R8
× 1.0 =: 1.2 V
R8
R11 + R12 + R13
CH2 : VO2 (V) =
× 1.23 =: 3.3 V
R13
R15 + R16 + R17
CH3 : VO3 (V) =
× 1.23 =: 5 V
R17
CH1 : VO1 (V) =
(2) Oscillation frequency
fOSC (kHz) =
1200000
=: 2350 (kHz)
C10 (pF) × R10 (kΩ)
(3) Soft-start time
CH1 : ts1 (s) = 1.0 × C7 (μF) =: 10 (ms)
CH2 : ts2 (s) = 0.123 × C12 (μF) =: 12 (ms)
CH3 : ts3 (s) = 0.123 × C13 (μF) =: 12 (ms)
(4) Short-circuit detection time
tscp (s) = 0.72 × C15 (μF) =: 720 (μs)
9
MB39A112
■ REFERENCE DATA
1. Conversion efficiency vs. Input voltage
• CH1
Conversion Efficiency vs. Load Current (CH1)
Conversion efficiency η (%)
100
90
80
70
60
50
VIN = 12 V
Setting VO1 = 1.2 V
SW1 = ON
SW2 = OFF
SW3 = OFF
40
30
20
10
100
1000
10000
Load current Io1 (mA)
• CH2
Conversion Efficiency vs. Load Current (CH2)
Conversion efficiency η (%)
100
90
80
70
60
50
VIN = 12 V
Setting VO2 = 3.3 V
SW1 = OFF
SW2 = ON
SW3 = OFF
40
30
20
10
100
1000
10000
Load current Io2 (mA)
• CH3
Conversion Efficiency vs. Load Current (CH3)
Conversion efficiency η (%)
100
90
80
70
60
50
VIN = 12 V
Setting VO3 = 5.0 V
SW1 = OFF
SW2 = OFF
SW3 = ON
40
30
20
10
100
Load current Io3 (mA)
10
1000
MB39A112
2. Load Reguration (VIN = 12 V)
• CH1
Output Voltage vs. Load Current (CH1)
Output voltage Vo1 (V)
1.5
VIN = 12 V
Setting VO1 = 1.2 V
SW1 = ON
SW2 = OFF
SW3 = OFF
1.4
1.3
1.2
1.1
1
10
100
1000
10000
Load current Io1 (A)
• CH2
Output Voltage vs. Load Current (CH2)
Output voltage Vo2 (V)
3.5
3.4
3.3
3.2
VIN = 12 V
Setting VO2 = 3.3 V
SW1 = OFF
SW2 = ON
SW3 = OFF
3.1
3
10
1000
100
10000
Load current Io2 (A)
• CH3
Output Voltage vs. Load Current (CH3)
Output voltage Vo3 (V)
5.3
VIN = 12 V
Setting VO3 = 5.0 V
SW1 = OFF
SW2 = OFF
SW3 = ON
5.2
5.1
5
4.9
4.8
10
100
1000
Load current Io3 (A)
11
MB39A112
3. Line regulation
• CH1
Output Voltage vs. Input Voltage (CH1)
Output voltage Vo1 (V)
1.5
VIN = 12 V
Setting VO1 = 1.2 V
SW1 = ON
SW2 = OFF
SW3 = OFF
1.4
1.3
1.2
1.1
1
6
8
10
12
14
16
18
20
22
Input voltage VIN (V)
• CH2
Output Voltage vs. Input Voltage (CH2)
Output voltage Vo2 (V)
3.5
VIN = 12 V
Setting VO2 = 3.3 V
SW1 = OFF
SW2 = ON
SW3 = OFF
3.4
3.3
3.2
3.1
3
6
8
10
12
14
16
18
20
22
Input voltage VIN (V)
• CH3
Output Voltage vs. Input Voltage (CH3)
Output voltage Vo3 (V)
5.3
VIN = 12 V
Setting VO3 = 5.0 V
SW1 = OFF
SW2 = OFF
SW3 = ON
5.2
5.1
5
4.9
4.8
6
8
10
12
14
16
18
Input voltage VIN (V)
12
20
22
MB39A112
4. Soft-start operation waveforms
• CH1
2.0
VO1 [V]
1.5
1.0
0.5
0
3
CS1 [V]
2
=: 10.6 ms
1
0
0
5
VIN = 12 V
setting VO1 = 1.2 V
10 15 20 25 30 35 40 45 50 (ms)
• CH2
4
VO2 [V]
3
2
1
0
3
CS2 [V]
2
=: 12.7 ms
VIN = 12 V
setting VO2 = 3.3 V
1
0
0
5
10 15 20 25 30 35 40 45 50 (ms)
• CH3
VO3 [V]
6
4
2
0
3
CS3 [V]
2
=: 13.2 ms
VIN = 12 V
setting VO3 = 5.0 V
1
0
0
5
10 15 20 25 30 35 40 45 50 (ms)
13
MB39A112
■ COMPONENT SELECTION METHODS
CH1
FET
Flyback diode
GND
VIN
Q1
CTL1
VO1
D1
R5
R7
104
183
CS1
C7
R8
3
M1
C10
C11
C17
OUT2
R2
C16
0
Q2
VD2
3
VH
FB3
3R3
D2
1
303
103
R17
4
D3
C5
1
2
3
Inductor
Output smoothing condenser
GND2
Flyback diode
Q3
VD3
VO3
100
SD
8
L3
3
CS L
CH2
6
4
JH
681
C15
OUT3
C14
R16
R3
0
R15
3
2
C4
L2
CSCP C3
CS3
SGND
1
VO2
11
R18
102
472
CS2
C12
R11
R12
363
563
821
FET
SA
1
J4
FB2
10
R14
4
JM
512
MB39A112
ES0309
M00
VCC
GND1
6
0
20
1
R10
R13
VCCO
FB1
C9
Q6
R4
C13
R20
821
C8
CTL3
C2
L1
C1
0
R9
2R0
1
OUT1
SA
1
J4
R19
R1
222
Q5
JM
R6
CTL2
R21
VD1
0
Q4
Output smoothing condenser
Inductor
2
C6
L3
GND3
1
4
SW1
OFF
MCC
NC
CS3
CS2
CS1
FET
CS OPEN
Inductor
Flyback diode
CH3
Board Photograph
14
Output smoothing condenser
MB39A112
1. CH1 1.2 V output
VIN = 12 V (Typ) , Vo1 = 1.2 V, Io = 1.5 A, fOSC = 2300 kHz
a) P-ch MOS FET (MCH3312 (SANYO product) )
VDS = −30 V, VGS = ±20 V, ID = −2 A, RDS (ON) = 205 mΩ (Typ) , Qg = 5.5 nC (Typ)
Drain current : Peak value
The peak drain current of this FET must be within its rated current.
If the FET’s peak drain current is ID, it is obtained by the following formula.
ID ≥ IO +
VIN − Vo1
2L
tON
12 − 1.2
2 × 2 × 10−6
≥ 1.5 +
×
1
× 0.1
2300 × 103
≥ 1.62 A
b) Inductor (A916CY-2R0M : TOKO product)
2.0 μH (tolerance ±20%) , rated current = 3.0 A
The L value for all load current conditions
It is set so that the peak to peak value of the ripple current is 1/2 of the load current or less.
L≥
≥
2 (VIN − Vo1)
tON
IO
2 × (12 − 1.2)
×
1.5
1
2300 × 103
× 0.1
≥ 0.63 μH
The load current satisfying the continuous current condition
IO ≥
Vo1
2L
tOFF
≥
1.2
2 × 2.0 × 10−6
≥
0.12 A
×
1
2300 × 103
× (1 − 0.1)
15
MB39A112
Ripple current : Peak value
The peak ripple current must be within the rated current of the inductor.
If the peak ripple current is IL, it is obtained by the following formula.
VIN − Vo1
tON
2L
IL ≥ IO +
≥ 1.5 +
12 − 1.2
2 × 2.0 × 10−6
×
1
× 0.1
2300 × 103
≥ 1.62 A
Ripple current : peak-to-peak value
If the peak-to-peak ripple current is ΔIL, it is obtained by the following formula.
ΔIL =
=
VIN − Vo1
tON
L
12 − 1.2
2.0 × 10−6
×
1
× 0.1
2300 × 103
=: 0.23 A
c) Flyback diode (SBE001 : SANYO product)
VR (DC reverse voltage) = 30 V, average output current = 2.0 A, peak surge current = 20 A
VF (forward voltage) = 0.55 V, at IF = 2.0 A
VR : The value enough to satisfy the input voltage → 30 V
On time of the diode is assumed to be tD (Max) , the diode mean current IDi is obtained by the following formula.
IDi ≥
Io × (1 −
Vo1
) = 1.5 × (1 − 0.1) =: 1.35 A
VIN
On time of the diode is assumed to be tD (Max) , the diode peak current IDip is obtained by the following formula.
IDip ≥
16
(Io +
Vo1
tOFF) =: 1.62 A
2L
MB39A112
2. CH2 3.3 V output
VIN = 12 V (Typ) , Vo2 = 3.3 V, Io = 1.0 A, fOSC = 2300 kHz
a) P-ch MOS FET (MCH3312 (SANYO product) )
VDS = −30 V, VGS = ±20 V, ID = −2 A, RDS (ON) = 205 mΩ (Typ) , Qg = 5.5 nC (Typ)
Drain current : Peak value
The peak drain current of this FET must be within its rated current.
If the FET’s peak drain current is ID, it is obtained by the following formula.
ID ≥ IO +
VIN − Vo2
2L
tON
12 − 3.3
2 × 3.3 × 10−6
≥ 1.0 +
×
1
× 0.275
2300 × 103
≥ 1.16 A
b) Inductor (A916CY-3R3M : TOKO product)
3.3 μH (tolerance ±20%) , rated current = 2.57 A
The L value for all load current conditions
It is set so that the peak to peak value of the ripple current is 1/2 of the load current or less.
L≥
≥
2 (VIN − Vo2)
tON
IO
2 × (12 − 3.3)
×
1.0
1
2300 × 103
× 0.275
≥ 2.08 μH
The load current satisfying the continuous current condition
IO ≥
Vo2
2L
tOFF
≥
3.3
2 × 3.3 × 10−6
≥
0.16 A
×
1
(1 − 0.275)
2300 × 103 ×
17
MB39A112
Ripple current : Peak value
The peak ripple current must be within the rated current of the inductor.
If the peak ripple current is IL, it is obtained by the following formula.
VIN − Vo2
tON
2L
IL ≥ IO +
≥ 1.0 +
12 − 3.3
2 × 3.3 × 10−6
×
1
× 0.275
2300 × 103
≥ 1.16 A
Ripple current : peak-to-peak value
If the peak-to-peak ripple current is ΔIL, it is obtained by the following formula.
ΔIL =
=
VIN − Vo2
tON
L
12 − 3.3
3.3 × 10−6
×
1
× 0.275
2300 × 103
=: 0.315 A
c) Flyback diode (SBE001 : SANYO product)
VR (DC reverse voltage) = 30 V, average output current = 2.0 A, peak surge current = 20 A
VF (forward voltage) = 0.55 V, at IF = 2.0 A
VR : The value enough to satisfy the input voltage → 30 V
On time of the diode is assumed to be tD (Max) , the diode mean current IDi is obtained by the following formula.
IDi ≥ Io × (1 −
Vo2
) = 1.0 × (1 − 0.275) =: 0.725 A
VIN
On time of the diode is assumed to be tD (Max) , the diode peak current IDip is obtained by the following formula.
IDip ≥
18
(Io +
Vo2
tOFF) =: 1.16 A
2L
MB39A112
3. CH3 5 V output
VIN = 12 V (Typ) , Vo3 = 5 V, Io = 0.3 A, fOSC = 2300 kHz
a) P-ch MOS FET (MCH3308 (SANYO product) )
VDS = −30 V, VGS = ±20 V, ID = −1 A, RDS (ON) = 720 mΩ (Typ) , Qg = 2.6 nC (Typ)
Drain current : Peak value
The peak drain current of this FET must be within its rated current.
If the FET’s peak drain current is ID, it is obtained by the following formula.
ID ≥ IO +
≥ 0.3 +
VIN − Vo3
2L
tON
12 − 5
2 × 10 × 10−6
×
1
× 0.417
2300 × 103
≥ 0.36 A
b) Inductor (A916CY-100M : TOKO product)
10 μH (tolerance ±20%) , rated current = 1.49 A
The L value for all load current conditions
It is set so that the peak to peak value of the ripple current is 1/2 of the load current or less.
L≥
≥
2 (VIN − Vo3)
tON
IO
2 × (12 − 5)
0.3
1
2300 × 103
×
× 0.417
≥ 8.46 μH
The load current satisfying the continuous current condition
IO ≥
≥
Vo3
2L
tOFF
5
2 × 10 × 10−6
×
1
2300 × 103
× (1 − 0.417)
≥ 63.4 mA
19
MB39A112
Ripple current : Peak value
The peak ripple current must be within the rated current of the inductor.
If the peak ripple current is IL, it is obtained by the following formula.
VIN − Vo3
tON
2L
IL ≥ IO +
≥ 0.3 +
12 − 5
2 × 10 × 10−6
×
1
× 0.417
2300 × 103
≥ 0.36 A
Ripple current:Peak-to-peak value
If the peak-to-peak ripple current is ΔIL, it is obtained by the following formula.
ΔIL =
VIN − Vo3
tON
L
=
12 − 5
10 × 10−6
×
1
× 0.417
2300 × 103
=: 0.127 A
c) Flyback diode (SBS005 : SANYO product)
VR (DC reverse voltage) = 30 V, average output current = 1.0 A, peak surge current = 10 A
VF (forward voltage) = 0.35 V, at IF = 0.5 A
VR : The value enough to satisfy the input voltage → 30 V
On time of the diode is assumed to be tD (Max) , the diode mean current IDi is obtained by the following formula.
IDi ≥
Io × (1 −
Vo3
) = 0.3 × (1 − 0.417) =: 0.175 A
VIN
On time of the diode is assumed to be tD (Max) , the diode peak current IDip is obtained by the following formula.
IDip ≥
20
(Io +
Vo2
tOFF) =: 0.36 A
2L
MB39A112
■ ORDERING INFORMATION
EV board part No.
MB39A112EVB-01
EV board version No.
Remarks
MB39A112EV Board Rev 1.0
21
MB39A112
MEMO
22
MB39A112
MEMO
23
FUJITSU MICROELECTRONICS LIMITED
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Hong Kong
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of reference to show examples of operations and uses of FUJITSU MICROELECTRONICS device; FUJITSU MICROELECTRONICS
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Edited
Strategic Business Development Dept.
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