TECHNICAL NOTE
Single-chip Type with built-in FET Switching Regulator Series
Low Noise Step-down
High Efficiency Step-down
Switching Regulator
with Built-in Power MOSFET
BD8962MUV
●Description
ROHM’s high efficiency step-down switching regulator BD8962MUV is a power supply designed to produce a low voltage
including 0.8 volts from 5.5/3.3 volts power supply line. Offers high efficiency with synchronous rectifier. Employs a current
mode control system to provide faster transient response to sudden change in load.
●Features
1) Offers fast transient response with current mode PWM control system.
2) Offers highly efficiency for all load range with synchronous rectifier (Nch/Nch FET)
3) Incorporates soft-start function.
4) Incorporates thermal protection and ULVO functions.
5) Incorporates short-current protection circuit with time delay function.
6) Incorporates shutdown function Icc=0μA(Typ.)
7) Employs small surface mount package : VQFN020V4040
●Use
Power supply for LSI including DSP, Micro computer and ASIC
●Absolute
Maximum Rating (Ta=25℃)
Symbol
Limits
Unit
Parameter
BD8962MUV
-0.3½+7 *
1
V
CC
V
V
CC
Voltage
1
-0.3½+7 *
V
PV
CC
PV
CC
Voltage
-0.3½+13
V
V
BST
BST Voltage
-0.3½+7
V
V
BST
-
SW
BST_SW Voltage
-0.3½+7
VEN
V
EN Voltage
-0.3½+7
VSW, VITH
V
SW,ITH Voltage
2
Pd1
0.34 *
W
Power Dissipation 1
3
Pd2
0.70 *
W
Power Dissipation 2
4
W
Pd3
1.21 *
Power Dissipation 3
5
W
Pd4
3.56 *
Power Dissipation 4
-40½+105
℃
Topr
Operating temperature range
-55½+150
℃
Tstg
Storage temperature range
℃
Tj
+150
Maximum junction temperature
＊1
＊2
＊3
＊4
＊5
Pd should not be exceeded.
1-layer. mounted on a 74.2mm×74.2mm×1.6mm glass-epoxy board, occupied area by copper foil : 10.29mm
2
4-layer. mounted on a 74.2mm×74.2mm×1.6mm glass-epoxy board, occupied area by copper foil : 10.29mm
2
, in each layers
4-layer. mounted on a 74.2mm×74.2mm×1.6mm glass-epoxy board, occupied area by copper foil : 5505mm
2
, in each layers
IC only
●Operating
Conditions (Ta=-40½+105℃)
Parameter
Power Supply Voltage
EN Voltage
Output voltage Setting Range
SW average output current
＊6
＊
Symbol
V
CC
PV
CC
VEN
V
OUT
I
SW
Min.
2.7
2.7
0
0.8
-
BD8962MUV
Typ.
3.3
3.3
-
-
-
Unit
Max.
5.5
5.5
5.5
2.5*
6
3.0*
7
V
V
V
V
A
Jul. 2008
In case set output voltage 1.6V or more, VccMin =
Vout+1.2V.
7
Pd should not be exceeded.
●Electrical
Characteristics
◎BD8962MUV
(Ta=25℃ V
CC
=PV
CC
=3.3V, EN=V
CC
, R
1
=10kΩ, R
2
=5kΩ
Parameter
Symbol
Min.
Typ.
Standby current
I
STB
-
0
Active current
I
CC
-
250
EN Low voltage
-
GND
V
ENL
EN High voltage
2.0
Vcc
V
ENH
EN input current
-
1
I
EN
Oscillation frequency
0.8
1
F
OSC
High side FET ON resistance
-
82
R
ONH
Low side FET ON resistance
-
70
R
ONL
ADJ Voltage
0.788
0.800
V
ADJ
ITH
SI
nk current
10
18
I
THSI
ITH
S
ource
C
urrent
10
18
I
THSO
UVLO threshold voltage
2.400
2.500
V
UVLO1
UVLO release voltage
2.425
2.550
V
UVLO2
Soft start time
2.5
5
T
SS
Timer latch time
0.5
1
T
LATCH
Output Short circuit
V
SCP
-
0.40
Threshold Voltage
●Block
Diagram, Application Circuit
【BD8962MUV】
V
CC
EN
VREF
,unless otherwise specified.)
Max.
Unit
Conditions
10
μA
EN=GND
500
μA
Standby mode
0.8
V
Active mode
-
V
10
μA
V
EN
=3.3V
1.2
MHz
115
mΩ
PV
CC
=3.3V
98
mΩ
PV
CC
=3.3V
0.812
V
-
μA
V
ADJ
=1V
-
μA
V
ADJ
=0.6V
2.600
V
V
CC
=3.3V→0V
2.700
V
V
CC
=0V→3.3V
10
ms
2
ms
0.56
V
V
ADJ
=0.8V→0V
4.0±0.1
4.0±0.1
D8962
V
CC
BST
Current
Comp
+
R Q
S
Current
Sense/
Protect
+
Driver
Logic
SW
PV
CC
Output
PV
CC
Input
Lot No.
1.0Max.
S
Gm Amp
0.02
+0.03
-0.02
(0.22)
0.08 S
+
SLOPE
CLK
OSC
V
CC
UVLO
TSD
SCP
ITH
R
ITH
C
ITH
C0.2 2.1±0.1
1
5
Soft
Start
PGND
GND
0.4±0.1
16
15
11
2.1±0.1
20
6
10
ADJ
1.0
0.5
0.25
+0.05
-0.04
R1 R2
(Unit : mm)
Fig.1 BD8962MUV TOP View
●Pin
No. & function table
Pin
Pin
No.
name
1
SW
SW pin
2
SW
SW pin
3
4
5
6
7
8
9
10
SW
SW
SW
PVCC
PVCC
PVCC
BST
VCC
SW pin
SW pin
SW pin
Highside FET source pin
Highside FET source pin
Highside FET source pin
Bootstrapped voltage input pin
VCC power supply input pin
2/16
Fig.2 BD8962MUV Block Diagram
Function
Pin
No.
11
12
13
14
15
16
17
18
19
20
Pin
name
GND
ADJ
ITH
N.C.
N.C.
N.C.
EN
PGND
PGND
PGND
Function
Ground
Output voltage detect pin
GmAmp output pin/Connected phase
compensation capacitor
Non Connection
Non Connection
Non Connection
Enable pin(High Active）
Lowside FET source pin
Lowside source pin
Lowside source pin
●Characteristics
data【BD8962MUV】
2.0
2.0
2.0
【V
OUT
=1.2V】
OUTPUT VOLTAGE:VOUT[V]
【V
OUT
=1.2V】
OUTPUT VOLTAGE:VOUT[V]
【V
OUT
=1.2V】
OUTPUT VOLTAGE:VOUT[V]
1.6
1.6
1.6
1.2
1.2
1.2
0.8
0.8
0.8
0.4
Ta=25℃
Io=3A
0
1
2
3
4
INPUT VOLTAGE:V
CC
[V]
5
0.4
VCC=5V
Ta=25℃
Io=0A
0
1
2
3
EN VOLTAGE:VEN[V]
4
5
0.4
VCC=5V
Ta=25℃
0
1
2
3
4
5
6
7
OUTPUT CURRENT:I
OUT
[A]
8
0.0
0.0
0.0
Fig.3 Vcc - V
OUT
Fig.4 V
EN
- V
OUT
100
90
80
EFFICIENCY:
η
[%]
70
60
50
40
30
20
10
0
10
【
VOUT=1.2
】
Fig.5 I
OUT
- V
OUT
1.22
1200
1000
FREQUENCY:F
OSC
[MHz]
800
600
400
200
0
-40
-20
0
20
40
60
80
100
【V
OUT
=1.2V】
OUTPUT VOLTAGE:VOUT[V]
1.21
1.20
1.19
VCC=5V
Io=0A
1.18
-40
-20
0
20
40
60
80
TEMPERATURE:Ta[℃]
100
VCC=5V
Ta=25℃
100
1000
OUTPUT CURRENT:I
OUT
[mA]
10000
VCC=5V
Fig. 6 Ta - V
OUT
150
125
ON RESISTANCE:R
ON
[Ω]
Fig.7 Efficiency
2.0
1.8
TEMPERATURE:Ta[℃]
Fig.8 Ta - Fosc
400
350
CIRCUIT CURRENT:I
CC
[μA]
300
250
200
150
100
50
0
-40
-20
0
20
40
60
80
100
1.6
EN VOLTAGE:VEN[V]
100
75
50
1.4
1.2
1.0
0.8
0.6
0.4
High side
Low side
25
VCC=3.3V
0
-40
-20
0
20
40
60
80
TEMPERATURE:Ta[℃]
100
0.2
0.0
VCC=5V
VCC=5V
-40
-20
0
20
40
60
80
100
TEMPERATURE:Ta[℃]
Fig.9 Ta – R
ONN
, R
ONP
1.1
TEMPERATURE:Ta[℃]
Fig.10 Fig.11 Ta - V
EN
【V
OUT
=1.2V】
【PWM
SW
V
CC
=PV
CC
=EN
Fig.11 Ta - Icc
V
OUT
=1.2V】
FREQUENCY:F
OSC
[MHz]
1
0.9
0.8
V
OUT
Ta=25℃
V
OUT
VCC=5V
Ta=25℃
Io=0A
VCC=5V
Ta=25℃
0.7
2.7
3.4
4.1
4.8
INPUT VOLTAGE:V
CC
[V]
5.5
Fig.12 Vcc - Fosc
【V
OUT
=1.2V】
V
OUT
Fig.13 Soft start waveform
【V
OUT
=1.2V】
V
OUT
Fig.14 SW waveform Io=10mA
I
OUT
VCC=5V
Ta=25℃
I
OUT
VCC=5V
Ta=25℃
Fig. 16 Transient Response
Io=1→3A(10μs)
Fig.17 Transient Response
Io=3→1A(10μs)
3/16
●Information
on advantages
Advantage 1：Offers fast transient response with current mode control system.
Conventional product (Load response I
O
=1A→3A)
BD8962MUV (Load response I
O
=1A→3A)
V
OUT
145mV
V
OUT
62mV
I
OUT
I
OUT
Voltage drop due to sudden change in load was reduced by about 50%.
Fig.18 Comparison of transient response
Advantage 2： Offers high efficiency for all load range with synchronous rectifier.
100
Utilizes the synchronous rectifying mode and the low on-resistance
MOS FETs incorporated as power transistor.
ON resistance of Highside MOS FET : 82mΩ(Typ.)
ON resistance of Lowside MOS FET : 70mΩ(Typ.)
EFFICIENCY:
η
[%]
90
80
70
60
50
40
30
20
10
0
10
【
VOUT=1.2
】
VCC=5V
Ta=25℃
100
1000
OUTPUT CURRENT:I
OUT
[mA]
10000
Fig.19 Efficiency
Advantage 3：・Supplied in smaller package due to small-sized power MOS FET incorporated.
・Output
capacitor Co required for current mode control: 22μF ceramic capacitor
・Inductance
L required for the operating frequency of 1 MHz: 2.2μH inductor
・Incorporates
FET + Boot strap diode
Reduces a mounting area required.
V
CC
EN
VREF
Current
Comp
VCC
BST
PVCC
20mm
3.3V
Input
C
f
R
2
Rf
15mm
R
1
R
ITH
C
ITH
Co
C
IN
C
BST
L
+
Gm Amp
SLOPE
RQ
S
CLK
Current
Sense/
Protect
+
Driver
Logic
PVCC
SW
Output
+
Soft
Start
OSC
VCC
UVLO
TSD
SCP
PGND
GND
ADJ
ITH
R
ITH
C
ITH
R1 R2
Fig.20 Example application
4/16
●Operation
BD8962MUV is a synchronous rectifying step-down switching regulator that achieves faster transient response by employing
current mode PWM control system.
○Synchronous
rectifier
It does not require the power to be dissipated by a rectifier externally connected to a conventional DC/DC converter IC, and its
P.N junction shoot-through protection circuit limits the shoot-through current during operation, by which the power dissipation of
the set is reduced.
○Current
mode PWM control
Synthesizes a PWM control signal with a inductor current feedback loop added to the voltage feedback.
・PWM
(Pulse Width Modulation) control
The oscillation frequency for PWM is 1 MHz. SET signal form OSC turns ON a highside MOS FET (while a lowside MOS FET
is turned OFF), and an inductor current I
L
increases. The current comparator (Current Comp) receives two signals, a current
feedback control signal (SENSE: Voltage converted from I
L
) and a voltage feedback control signal (FB), and issues a RESET
signal if both input signals are identical to each other, and turns OFF the highside MOS FET (while a lowside MOS FET is turned
ON) for the rest of the fixed period. The PWM control repeat this operation.
SENSE
Current
Comp
RESET
Level
Shift
Gm Amp.
ITH
OSC
R Q
FB
SET
S
Driver
Logic
SW
Load
I
L
V
OUT
V
OUT
Fig.21 Diagram of current mode PWM control
Current
Comp
SET
PVCC
SENSE
FB
GND
GND
GND
I
L
(AVE)
RESET
SW
I
L
V
OUT
V
OUT
(AVE)
Fig.22 PWM switching timing chart
5/16
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