Single-chip Type with Built-in FET Switching Regulators
Simple Step-down
Switching Regulators
with Built-in Power MOSFET
BD9325FJ,BD9326EFJ,BD9327EFJ
No.10027ECT06
●Description
The BD9325FJ, BD9326EFJ and BD9327EFJ are step-down regulators that integrate a low resistance high side N-channel MOSFET.
It achieves 2A / 3A / 4A continuous output current over a wide input supply range.
Current mode operation provides fast transient response and easy phase compensation.
●Features
1) Wide operating INPUT Range 4.75V½18.0V
2) Selectable 2A / 3A / 4A Output Current
3) Selectable 0.16Ω / 0.12Ω / 0.11ΩInternal MOSFET Switch
4) Low ESR Output Ceramic Capacitors are Available
5) Low Stanby Current during Shutdown Mode
6) 380kHz Operating Frequency
7) Feedback voltage 0.9V ±1.5% Accuracy at room temp. (±3.0% for -40℃ to 85℃ temperature range)
8) Protection circuit: UnderVoltage lockout protection circuit
Thermal shutdown circuit
OverCurrent protection circuit
9) SOP-J8 Package for 2A model, HTSOP-J8 Package for 3A, 4A models (with Exposed thermal PAD)
●Applications
Distributed Power System
Pre-Regulator for Linear Regulator
●Line
up matrix
LINE-UP
FET ON-RESISTANCE
OUTPUT CURRENT
Package
BD9325FJ
0.16
Ω
2.0 A
SOP-J8
BD9326EFJ
0.12
Ω
3.0A
HTSOP-J8
BD9327EFJ
0.11
Ω
4.0 A
HTSOP-J8
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© 2010 ROHM Co., Ltd. All rights reserved.
1/14
2010.08 - Rev.C
BD9325FJ, BD9326EFJ, BD9327EFJ
●Absolute
maximum ratings (Ta = 25°C)
Parameter
Supply Voltage
Switch Voltage
Power Dissipation for HTSOP-J8
Power Dissipation for SOP-J8
Operating Temperature Range
Storage Temperature Range
Junction Temperature
BST Voltage
EN Voltage
All other pins
Technical Note
Symbol
V
IN
V
SW
Pd1
Pd2
Topr
Tstg
Tjmax
V
BST
V
EN
V
OTH
Ratings
20
20
3760
675
*1
*2
Unit
V
V
mW
mW
℃
℃
℃
V
V
V
-40½+85
-55½+150
150
V
SW
+7
20
7
*1 Derating in done 30.08 mW/℃ for operating above Ta≧25℃(Mount on 4-layer 70.0mm×70.0mm×1.6mm board)
*2 Derating in done 5.4 mW/℃ for operating above Ta≧25℃(Mount on 1-layer 70.0mm×70.0mm×1.6mm board)
●Operation
Range (Ta= -40½85℃)
Parameter
Supply Voltage
SW Voltage
Output current for BD9325FJ
Output current for BD9326EFJ
Output current for BD9327EFJ
**
Pd, ASO should not be exceeded
Symbol
V
IN
V
SW
I
SW2
I
SW3
I
SW4
Ratings
Min
4.75
-0.5
-
-
-
Typ
12
-
-
-
-
Max
18
18
2**
3**
4**
Unit
V
V
A
A
A
●Electrical
characteristics (Unless otherwise specified V
IN
=12V Ta=25℃)
Limits
Parameter
Symbol
Min
Typ
Error amplifier block
FB input bias current
Feedback voltage1
Feedback voltage2
SW block – SW
Hi-side FET On-resistance for BD9325FJ
Hi-side FET On-resistance for BD9326EFJ
Hi-side FET On-resistance for BD9327EFJ
Lo-side FET On-resistance
Leak current N-channel
Switch Current Limit for BD9325FJ
Switch Current Limit for BD9326EFJ
Switch Current Limit for BD9327EFJ
Maximum duty cycle
General
Enable Sink current
Enable Threshold voltage
Under Voltage Lockout threshold
Under Voltage Lockout Hysteresis
Soft Start Current
Soft Start Time
Operating Frequency
Circuit Current
Quiescent Current
*** See the series line-up table below.
Max
2
0.914
0.927
-
-
-
-
10
-
-
-
-
275
1.4
4.75
-
62
-
460
4.3
170
Unit
Conditions
I
FB
V
FB1
V
FB2
R
ON2
R
ON3
R
ON4
R
ONL
I
LEAKN
I
LIMIT2
I
LIMIT3
I
LIMIT4
M
DUTY
I
EN
V
EN
V
UVLO
V
HYS
I
SS
T
SS
F
OSC
I
CC
I
QUI
-
0.886
0.873
-
-
-
-
-
2.5
3.5
4.5
-
86
1.1
4.05
-
23
-
300
-
-
0.1
0.900
0.900
0.16
0.12
0.11
10
0
-
-
-
90
181
1.18
4.40
0.1
41
1.6
380
2.1
80
µA
V
V
Ω
Ω
Ω
Ω
µA
A
A
A
%
µA
V
V
V
uA
ms
kHz
mA
µA
V
FB
= 1.5V, V
EN
= 12V
V
EN
= 0V
V
SS
= 0 V
C
SS
= 0.1 µF
V
IN
rising
Voltage follower
Ta=-40℃½85℃
I
SW
= -0.8A ***
I
SW
= -0.8A ***
I
SW
= -0.8A ***
I
SW
= 0.1A
V
IN
= 18V, V
SW
= 0V
***
***
***
V
FB
= 0V
V
EN
= 12V
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© 2010 ROHM Co., Ltd. All rights reserved.
2/14
2010.08 - Rev.C
BD9325FJ, BD9326EFJ, BD9327EFJ
●Block
diagram
VIN
EN
VREF
EN;PULL UP to VIN
OCP
UVLO
IBIAS
FB
+
ERR
－
Technical Note
5V
OSC
VREG
BST
12V
VIN
TSD
S
DRV
LVS
SW
SLOPE
+
PWM
－
OUTPUT
COMP
SS
Soft Start
LOGIC
R
LVS
GND
Fig.1 Block Diagram
●Typical
application circuit
C_PC1
3300pF
C_SS
0.1μF
COMP
SS
EN
R_PC
15k
FB
R_DW
10k
R_UP
27k
Thermal Pad
(For BD9326EFJ, BD9327EFJ)
BST
GND
VIN
SW
L
VIN 12V
C_VC1
10μF
10μH
D
C_BS
0.1μF
V
OUT
3.3V
C_CO1
20μF
Fig.2 Application Circuit
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© 2010 ROHM Co., Ltd. All rights reserved.
3/14
2010.08 - Rev.C
BD9325FJ, BD9326EFJ, BD9327EFJ
●Block
operation
・VREG
A block to generate constant-voltage for DC/DC boosting.
・VREF
A block that generates internal reference voltage of 2.9 V (Typ.).
Technical Note
・TSD/UVLO
TSD (Thermal shutdown)/UVLO (Under Voltage Lockout) protection block. The TSD circuit shuts down IC at 175℃ (Typ.)
The UVLO circuit shuts down the IC when the VCC is Low Voltage.
・Error
amp block (ERR)
This is the circuit to compare the reference voltage and the feedback voltage of output voltage. The COMP pin voltage
resulting from this comparison determines the switching duty. At the time of startup, since the soft start is operated by the
SS pin voltage, the COMP pin voltage is limited to the SS pin voltage.
・Oscillator
block (OSC)
This block generates the oscillating frequency.
・SLOPE
block
This block generates the triangular waveform from the clock created by OSC. Generated triangular waveform is sent to the
PWM comparator.
・PWM
block
The COMP pin voltage output by the error amp is compared to the SLOPE block's triangular waveform to determine the
switching duty. Since the switching duty is limited by the maximum duty ratio which is determined internally, it does not
become 100%.
・DRV
block
A DC/DC driver block. A signal from the PWM is input to drive the power FETs.
・Soft
start circuit
Since the output voltage rises gradually while restricting the current at the time of startup, it is possible to prevent the
output voltage overshoot or the rush current.
●Pin
assignment and pin function
Pin No.
1
2
3
4
5
6
7
8
Pin name
BST
VIN
SW
GND
FB
COMP
EN
SS
Function
High-Side Gate Drive Boost Input
Power Input
Power Switching Output
Ground
Feed Back Input
Compensation Node
Enable Input
Soft Start Control Input
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© 2010 ROHM Co., Ltd. All rights reserved.
4/14
2010.08 - Rev.C
BD9325FJ, BD9326EFJ, BD9327EFJ
●Typical
performance characteristics (Unless otherwise specified, V
IN
= 12V Ta = 25℃)
2.5
2.4
2.3
2.2
2.1
160
140
120
100
0.1
0.08
0.06
0.04
Technical Note
Icc [mA]
2
1.9
1.8
1.7
1.6
1.5
Icc [uA]
80
60
40
20
0
IFB [uA]
4
6
8
10
12
14
16
18
0.02
0
-0.02
-0.04
-0.06
-0.08
-0.1
0
0.5
1
1.5
2
4
6
8
10
12
14
16
18
VIN : [V]
VIN : [V]
V
FB
[V]
Fig.3 Circuit Current
(No switching)
Fig.4 Quiescent Current
(IC not active)
Fig.5 Input Bias Current
0.25
370
360
0.923
0.2
Operating Frequency [kHz]
60
80
0.913
BD9325FJ
Ron [Ω]
0.15
Feedback voltage [V]
350
340
330
320
310
0.903
0.893
0.1
BD9326EFJ
0.883
0.05
0.873
0
-40
-20
0
20
40
60
80
100
-40
-20
0
20
Ta [℃]
40
300
-40
-20
0
20
40
60
80
TEMPERATURE : [C]
TEMPERATURE : [C]
Fig.6 Feedback voltage
Fig.7 Hi-Side On-resistance
Fig.8 Operating Frequency
95
90
85
EFFICIENCY [%]
80
75
70
65
60
55
50
0
0.2
0.4
0.6
0.8
1
Iout [A]
1.2
100
BD9326EFJ
BD9325FJ
V
OUT
SOFTSTART TIME [ms]
10
V
SS
1
V
SW
I
OUT
1.4
1.6
1.8
2
0.1
0.01
0.001
0.01
0.1
1
C
SS
[uF]
Fig.9 STEP Down Efficiency
(VIN= 12V V
OUT
= 3.3V L=10µH)
Fig.10 OverCurrent Protection
(V
OUT
is shorted to GND)
Fig.11 Soft Start Time
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© 2010 ROHM Co., Ltd. All rights reserved.
5/14
2010.08 - Rev.C
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