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PDF BD9850FVM Data sheet ( Hoja de datos )
| Número de pieza | BD9850FVM | |
| Descripción | Single-output High-frequency Step-down Switching Regulator | |
| Fabricantes | ROHM Semiconductor | |
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TECHNICAL NOTE
Large Current External FET Controller Type Switching Regulators
Single-output High-frequency Step-down
Switching Regulator(Controller type)
BD9850FVM
Dual-output Step-up, Negative, Step-down
Switching Regulator(Controller type)
BD9851EFV
High temperature
operating
Now available
ESD
Resistance
Now available
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
ROHM CO., LTD .
Sep. 2008
1 page  
Characteristic data
(BD9850FVM)
1.02
1.015
1.01
1.005
1
0.995
0.99
0.985
0.98
–40 –20 0 20 40 60
AMBIENT TEMPERATURE : Ta(˚C)
80
Fig.1 Error Amp threshold voltage vs. Ambient temperature
100
90
87
70
60
50
40
30
20
10
0
1.5 1.6 1.7 1.8 1.9
2 2.1 2.2
FB VOLTAGE : VFB(V)
Fig.2 FB voltage vs. ON Duty
1000
900
800
700 Vcc=10V
600
Vcc=7V
500
400
300 Vcc=4V
200
100
0
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2
(VCC-OUT)VOLTAGE : VO(V)
Fig.3 (Vcc-OUT) Voltage vs. Output source current
1000
900
800
700
600
500
400
300
200
100
Vcc=10V
Vcc=7V
Vcc=4V
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2
OUT VOLTAGE : VO(V)
Fig.4 Output voltage vs. Output sink current
2.53
2.52
2.51
2.5
2.49
2.48
2.47
–40 –20 0 20 40 60
AMBIENT TEMPERATURE : Ta [˚C]
80
Fig.5 VREF vs. Ambient temperature
650
640
630
620
610
RT=24kΩ
600
590
580
570
560
550
–40 –20 0 20 40 60
AMBIENT TEMPERATURE : Ta [˚C]
80
Fig.6 Oscillation frequency vs. Ambient temperature
5/16
5 Page 
• Setting of oscillation frequency (BD9851EFV)
Connecting a resistor to the RT pin (pin 2) and a capacitor to the CT pin allows
for the setting of oscillation frequency.
RRT
CCT
RT (2)
CT (3)
1000
1000
100
CCT=33pF
CCT=220pF
CCT=1200pF
Fig. 19 Setting procedure for BD9851EFV oscillation frequency
1000
1000
100
RRT=4.7kΩ
RRT=24kΩ
10
1 10
Timing Resistance (kΩ)
Fig. 20 RT vs. Oscillation frequency
100
10
10
10 100
Timing Capacitance(pF)
Fig. 20 CT vs. Oscillation frequency
1000
• Setting of timer of short circuit protection circuit (BD9851EFV)
Setting procedure
TSCP = 7.45 × 105 × CSCP
TSCP : Time from output short circuit to latch stop [sec]
OSCP : Capacitance of capacitor between the SCP and
GND pins [F]
CSCP
Application
SCP (14)
• Setting of maximum duty (BD9851EFV)
Setting procedure
DUTY(max.) = 100 × (VDTC – Vth0) / (Vth100 – Vth0)
VDTC = 2.5 × R2 / (R1 + R2)
DUTY(max.)
VDTC
Vth0
Vth100
: Maximum duty [%]
: DTC pin voltage [V]
: 0% duty threshold voltage [V]
: 100% duty threshold voltage [V]
Application
VREF (17)
R1
DTC (13)(7)
R2
• Pin treatment of unused channels (BD9851EFV)
(18) (17)
Vcc VREF
(18)
Vcc
SEL1 NON2 INV FB DTC PVcc OUT
(1) (16) (15) (13) (12) (11)
(4) (5) (6) (7) (8) (9)
Upper : Pin No. to be treated when the CH1 is not used
Lower : Pin No. to be treated when the CH2 is not used
Fig. 22 Pin treatment procedure for unused channel on BD9851EFV
In order to use one channel, treat the pins of unused channel as shown above.
11/165
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet BD9850FVM.PDF ] | |
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