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PDF BD9853AFV Data sheet ( Hoja de datos )
| Número de pieza | BD9853AFV | |
| Descripción | Single/Dual-output High-frequency Step-down Switching Regulator | |
| Fabricantes | ROHM Semiconductor | |
| Logotipo |  |
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Large Current External FET Controller Type Switching Regulators
Single/Dual-output High-frequency
Step-downSwitchingRegulator(Controllertype)
BD9853AFV
No.09028EAT05
●Description
The BD9853AFV is a 2-ch synchronous DC/DC controller that can operate at a maximum switching frequency of 2MHz,
enabling the use of a smaller external coil than conventional lower-frequency switching regulators. This makes the
BD9853AFV a suitable choice for downsizing applications.
●Features
1) Synchronous Switching Regulator Controller 2channels
2) FET(Pch/Nch) Direct Drive
3) Adjustable Oscillator Frequency with External Resistor (Max. 2MHz)
4) Under Voltage Lockout Function (UVLO)
5) Thermal Shut Down Function (TSD)
6) Short Circuit Protection (SCP)
7) Independent ON/OFF Function in Each Channel with Soft Start Pin
8) SSOP-B16 Package
SSOPB16
●Applications
TVSTB, PC, Portable CD・DVD,DVC etc.
●Absolute Maximum Ratings (Ta = 25℃)
Parameter
Symbol
Limits
Unit
Supply Voltage (VCC-GND)
Vcc
18
VREGA-GND Voltage
VREGA
7
VCC-VREGB Voltage
VREGB
7
Power Dissipation
Pd 562(*1)
Operating Temperature Range
Topr
-40 to +85
Junction Temperature
Tjmax
+150
Storage Temperature Range
Tstg -55 to +150
* Reduced by 4.49mW for each increase in Ta of 1℃ over 25℃ (When mounted on a board 70×70×1.6tmm grass-epoxy PCB)
V
V
V
mW
℃
℃
℃
●Recommended Operating Conditions
Parameter
Supply Voltage
Oscillator Frequency
Limits
Symbol
Min. Typ. Max.
Vcc 4.5 12 16
fosc
100
1000
2000
Unit
V
KHz
www.rohm.com
© 2009 ROHM Co., Ltd. All rights reserved.
1/16
2009.05 - Rev.A
1 page  
BD9853AFV
●Block Diagram
VCC
VCC
VOUT1
FB1
INV1
SCP/SOFT1
VOUT2
FB2
INV2
SCP/SOFT2
RT
Technical Note
both channel
ON/OFF
5V
REGA
VCC-5V
REGB
REGA
REGB
STB
VCC
SOFT1
0.8V
(Push-Pull)
TSD VREF VCC
VCC
⊿ ｔ REGA
REGB
OUT1H Pch
OUT1L Nch
GND
VOUT1
SOFT2
0.8V
(Push-Pull)
OSC
Timer
Latch
0.56V
VCC
⊿ ｔ REGA
REGB
GND
VCC
OUT2H Pch
OUT2L Nch
GND
VOUT2
Fig. 9
www.rohm.com
© 2009 ROHM Co., Ltd. All rights reserved.
5/16
2009.05 - Rev.A
5 Page 
BD9853AFV
Technical Note
Setting the Short Circuit Protection (SCP) delay time
When the soft start is complete for each channel, the output voltage stabilizes at the set value 1.35V(typ) for the
SCP/SOFT1, 2 pins.
When any type of short circuit occurs, the voltage at the point of the fault is reduced. In this case, when voltage at the INV
pin falls to 0.56V(typ) or below, the SCP comparator sensor detects the short and further charges the SCP/SOFT pins for
the shorted channel from the 1.35V(typ) level. When the SCP/SOFT pins are charged to 2.3V(typ), the Pch/Nch MOSFET
is switched OFF.
The elapsed time from the occurrence of the output short to the point the external FET switches OFF is calculated with the
following formula:
tscp＝
0.95[V](typ)×Cscp/soft［F］
Isosofc (typ: 2.3μA)[A]
tscp : SCP delay time, Cscp/soft : SCP/SOFT pin connection capacitance,Isoscp : charge current
* If the current more than the capacity of power supply when the short between VOUT and GND occurs, input voltage starts to fall and under voltage lockout
(UVLO) is activated at Vin < 4.15 V (typ.). The UVLO has FET driver output (OUT1H, OUT2H, OUT1L, OUT2L) off and external FETs become off. When
external FETs are not operating, input voltage returns because of the short between VOUT and GND and the UVLO is canceled. But input voltage starts to
fall again because the UVLO is not activated.
There is possibility that a series of behavior “output short → input voltage fall → UVLO activated → external FETs off → input voltage returns → UVLO
canceled → output short”. So please make provision like inserting FUSE in input line.
Pin conditions with the only single channel use
Pin conditions are shown in the following, when the only single channel out of 2 channels is used.
Use only CH1
・SCP/SOFT2, INV2 ⇒ GND short
・FB2, OUT2H, OUT2L ⇒ OPEN
Use only CH2
・SCP/SOFT1, INV1 ⇒ GND short
・FB1, OUT1H, OUT1L ⇒ OPEN
●Application example
VCC
VCC
VCC
4.7μF
VOUT1
(3.3V)
4.7μH
C6-K3L
(MITSUMI)
10kΩ
120pF
22kΩ
10μF
(ceramic）
100kΩ
RB081
L-20
(ROHM)
39kΩ
1μF
0.1μF
RSS040P03
(ROHM)
1 VCC
2 OUT1H
REGB
OUT2H
16
15
RSS040P03
(ROHM)
1μF
8.2kΩ
3 OUT1L
4 REGA
5 RT
OUT2L
STB
GND
14
13
12
VCC
6
RSS065 10kΩ 680pF
NO3
(ROHM)
7
0.015μF
8
FB1
INV1
SCP/SOFT1
FB2
INV2
SCP/SOFT2
11
220pF 3.3kΩ
10
9
0.015μF
RSS065
NO3
(ROHM)
4.7μF
4.7μH
C6-K3L
(MITSUMI)
VOUT2
(2.5V)
RB081
L-20
(ROHM)
10μF
(ceramic）
100kΩ
15kΩ
68pF
47kΩ
www.rohm.com
© 2009 ROHM Co., Ltd. All rights reserved.
11/16
2009.05 - Rev.A
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet BD9853AFV.PDF ] | |
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