TECHNICAL NOTE
Large Current External FET Controller Type Switching Regulators
Single-output High-frequency Step-down
Switching Regulator
(Controller type)
BD9850FVM
High temperature
operating
ESD
Resistance
Now available
Now available
Dual-output Step-up, Negative, Step-down
Switching Regulator
(Controller type)
BD9851EFV
Description
The BD9850FVM is a 1-channel DC/DC step-down switching regulator controller, while the BD9851EFV is a 2-channel DC/DC
step-down switching regulator controller. The BD9850FVM is adaptable for a maximum switching frequency of 2 MHz and the
BD9851EFV for that of 3 MHz. Both provide space saving in all applications.
Features
1) Adaptable for 2-MHz switching frequency (externally variable) (BD9850FVM)
Adaptable for 3-MHz switching frequency (externally variable) (BD9851EFV)
2) FET direct drive
3) High-accuracy reference voltage (Accuracy: ±1%)
4) Built-in Under Voltage Lock Out circuit (UVLO)
5) Built-in Thermal Shutdown circuit (TSD)
6) The BD9851EFV provides two channels:
Channel 1 available for selection of step-down/step-up switching
Channel 2 available for selection of step-down/inverting switching.
7) Compact MSOP8 package (BD9850FVM) / HTSSOP-B20 package (BD9851EFV)
Applications
TFT panel, TA/ Router, digital consumer electronics, PC, and portable CD/DVD/DVC
Product lineup
Input range
Oscillation frequency range
External synchronization
Standby function
Operating temperature
Package
BD9850FVM
4V to 9V
100kHz to 2MHz
Not provided
Not provided
–40˚C to 85˚C
MSOP8
BD9851EFV
4V to 18V
10kHz to 3MHz
Not provided
Provided
–40˚C to 85˚C
HTSSOP-B20
Sep. 2008
ROHM CO.,
LTD .
Absolute maximum ratings
(Ta=25˚C)
BD9850FVM
Item
Power supply voltage
Storage temperature
Operating temperature
Power dissipation
Maximum junction temperature
Symbol
Vcc
Tstg
Topr
Pd
Tjmax
Rating
10
–55 to +150
–40 to +85
587
*
+150
Unit
V
ºC
ºC
mW
ºC
*
Reduce by 4.7 mW/ ºC over 25ºC (When mounted on PCB of 70mm
×70mm ×1.6mm)
BD9851EFV
Item
Power supply voltage
(Between Vcc and GND)
Between V
REF
and GND
Between OUT1 and PVcc1
Between OUT2 and PVcc2
Between OUT1, OUT2 and PGND
Power dissipation
Operating temperature
Maximum junction temperature
Storage temperature
Symbol
Vcc
V
REF
Vouth
Voutl
Pd
Topr
Tjmax
Tstg
Rating
20
7
20
20
1000
(
*
)
Unit
V
V
V
V
mW
ºC
ºC
ºC
–40 to +85
+150
–55 to +150
(
*
)Reduce by 8.0 mW/ºC over 25ºC (When mounted on PCB of 70mm×70mm
×1.6mm)
Recommended operating range
BD9850FVM
Item
Power supply voltage
Oscillation frequency
Operating temperature
Symbol
Vcc
fosc
Topr
min.
4
100
–40
Limits
Typ.
7
–
–
max.
9
2000
+ 85
Unit
V
kHz
ºC
BD9851EFV
Item
Power supply voltage
Oscillation frequency
Timing resistor
Timing capacitor
Symbol
Vcc
fosc
R
RT
C
CT
min.
4
10
3.3
33
Limits
Typ.
12
300
–
–
max.
18
3000
47
10000
Unit
V
kHz
kΩ
pF
2/16
BD9850FVM
Electrical characteristics (Unless otherwise specified, Ta=25˚C, Vcc=7V, fosc=600kHz)
Limits
Item
Symbol
min.
Typ.
max.
[Oscillator block]
Oscillation frequency
Frequency regulation
Oscillator amplitude voltage
[Soft start/ SW block]
CTL/SS pin sink current
CTL / SS pin clamp voltage
CTL threshold voltage
[PWM comparator block]
0% threshold voltage
100% threshold voltage
[Error Amp block]
Threshold voltage
Frequency bandwidth
Voltage gain
Input bias current
Maximum output voltage
Minimum output voltage
Output source current
Output sink current
[V
REF
block]
V
REF
output voltage
F
REF
load regulation
V
REF
current capacitance
[Total device]
Standby current
Average supply current
[Output block]
ON resistance
Output transient time
[Under voltage lockout block]
Threshold voltage
Hysteresis width
VUT
VUThy
3.7
0.05
3.8
0.10
3.9
0.15
V
V
Vcc sweep down
R
ON
Tr/Tf
0.9
–
2.5
20
8.0
–
Ω
nsec
Cout = 1000pF
ICCS
ICCA
420
3.4
610
5.0
960
7.8
μA
mA
At no load
V
REF
ΔV
REFl0
IV
REF
2.475
–
–45
2.500
–
–16
2.525
10
–1
V
mV
mA
I
VREF
= 0mA
I
VREF
= 0mA to –1mA
V
IN
BW
Av
IIB
VCH
VCL
IOl
IOO
0.98
1.5
–
–150
2.3
–
–3.1
12
1.00
3.0
70
–70
2.4
0.03
–1.6
50
1.02
–
–
–
2.6
0.20
–1.0
125
V
MHz
dB
hA
V
V
mA
mA
V
FB
= 1.0V
V
FB
= 1.0V
AV = 0dB
D0
D100
1.5
2.0
1.6
2.1
1.7
2.2
V
V
fosc = 600kHz
fosc = 600kHz
ISS
VSS
VCTLTH
–1.90
2.2
1.2
–1.00
2.4
1.3
1.00
2.6
1.4
μA
V
V
V
CTL/SS
= 1.5V
fosc
FDV
Vpptr
510
–5
–
600
0
0.5
690
5
–
kHz
%
V
R
RT
= 24kΩ
Vcc = 4V to 9V
Unit
Conditions
*
*
*
*
*
Design guarantee
*
Not designed to be radiation-resistant.
3/16
BD9851EFV
Electrical characteristics (Unless otherwise specified, Ta=25˚C, Vcc=12V, fosc=300kHz, STB=3V)
Limits
Item
Symbol
Unit
min.
Typ.
max.
[Total device]
Standby mode circuit current
Operation mode circuit current
[Reference voltage block]
Output voltage
Input stability
Load stability
Short circuit mode output current
[Oscillator block]
Oscillation frequency
Oscillation frequency regulation
[Error Amp block]
Threshold voltage
Input offset voltage
Common-mode input voltage range
Input bias current
Voltage gain
Frequency bandwidth
Maximum output voltage
Minimum output voltage
Output sink current
Output source current
[PWM comparator block]
0% threshold voltage
100% threshold voltage
DTC bias current
[FET driver block]
R
ON
N
ON resistance
R
ON
P
Vselh
Vsell
[Control block]
Threshold voltage
Sink current
Vstb
Istb
0.6
6
1.5
15
1.5
15
V
μA
STB =3V
1.5
1
Vcc–0.2
0
3
2
–
–
3
2
–
–
Ω
Ω
V
V
When OUT = Lo
When OUT=Hi
In step-down switching
In step-down switching
Vth0
Vth100
Idtc
1.21
1.74
–1
1.31
1.84
–
1.41
1.94
1
V
V
μA
FB voltage
FB voltage
Vthea
Vofst
Vcm
Ibias
Av
Bw
Vfbh
Vfbl
Isink
Isource
0.98
–10
0.3
–150
60
3
V
REF
–0.1
–
1.6
–260
1.00
0
–
–70
75
6
–
–
6
–160
1.02
10
2.0
–
90
13
V
REF
0.1
16
–90
V
mV
V
nA
dB
MHz
V
V
mA
μA
FB pin
FB pin
DC
*Design
guarantee
MHz
*Design
guarantee
Ch1
Ch2
Ch2
fosc
Dfosc
270
–2
300
0
330
2
kHz
%
R
RT
=24kΩ, C
CT
=220pF
Vcc=4Vto18V
V
REF
DVli
DVlo
Ios
2.475
–
–
–45
2.500
–
–
–12
2.525
10
10
–3
V
mV
mV
mA
Io=–0.1mA
Vcc=4Vto18V, Io=–0.1mA
Io=–0.1mA to –1mA
Iccst
Icc
–
1.5
–
2.5
5
4.1
μA
mA
STB=0V
FB1, FB2=0V
Conditions
SEL1 input voltage range
[Short circuit protection circuit (SCP) block]
Timer start voltage
Threshold voltage
Standby mode voltage
Source current
Vtime
Vthscp
Vstscp
Vsoscp
2.2
1.4
–
–3.2
2.3
1.5
10
–2.0
2.3
1.5
10
–2.0
V
V
mV
μA
FB voltage
SCP voltage
SCP voltage
SCP=0.75V
[Under voltage lockout block (UVLO)]
Threshold voltage
Hysteresis width
Vuvlo
DVuvlo
3.58
0.05
3.7
0.11
4/16
3.7
0.11
V
V
Vcc sweep down
*
Design guarantee
Characteristic data
(BD9850FVM)
1.02
1.015
100
90
87
ERROR-AMP. THRESHOLD VOLTAGE : VINV(V)
1.01
70
1.005
1
0.995
0.99
0.985
10
0.98
–40
–20
0
20
40
60
80
0
1.5
1.6
1.7
1.8
1.9
2
2.1
2.2
ON DUTY : DON(%)
AMBIENT TEMPERATURE : Ta(˚C)
60
50
40
30
20
FB VOLTAGE : VFB(V)
Fig.1 Error Amp threshold voltage vs. Ambient temperature
Fig.2 FB voltage vs. ON Duty
1000
900
1000
900
800
OUT SOURCE CURRENT : IOUT [mA]
800
700
600
500
400
300
200
100
0
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
Vcc=10V
Vcc=10V
Vcc=7V
OUT SINK CURRENT : IOUT [mA]
700
600
500
400
300
200
100
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
Vcc=7V
Vcc=4V
Vcc=4V
(V
CC
-OUT)VOLTAGE : VO(V)
OUT VOLTAGE : VO(V)
Fig.3 (Vcc-OUT) Voltage vs. Output source current
Fig.4 Output voltage vs. Output sink current
2.53
650
640
OSCILLATING FREQUENCY : FOSC [kHz]
2.52
630
620
610
RT= 24kΩ
600
590
580
570
560
550
–40
–20
0
20
40
60
80
V
REF
VOLTAGE:V
REF
[V]
2.51
2.5
2.49
2.48
2.47
–40
–20
0
20
40
60
80
AMBIENT TEMPERATURE : Ta [˚C]
AMBIENT TEMPERATURE : Ta [˚C]
Fig.5 V
REF
vs. Ambient temperature
Fig.6 Oscillation frequency vs. Ambient temperature
5/16
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