参数资料
| 型号： | BD9845FV-E2 |
| 厂商： | Rohm Semiconductor |
| 文件页数： | 11/16页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 14-SSOP |
| 标准包装： | 1 |
| PWM 型： | 控制器 |
| 输出数： | 1 |
| 频率 - 最大： | 1.5MHz |
| 占空比： | 100% |
| 电源电压： | 3.6 V ~ 35 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 14-LSSOP（0.173"，4.40mm 宽） |
| 包装： | 标准包装 |
| 产品目录页面： | 1373 (CN2011-ZH PDF) |
| 其它名称： | BD9845FV-E2DKR |
BD9845FV
Technical Note
● Example of application circuit
Vin
VREF
VREF
VCC
VREF
VCC
STB
VCC
VCC-5V
5VREG
C5V
CT
OSC
UVLO
TSD
INV
VREF
VCC
SS
-
+ ERR
-
+ PWM
DRV
OUT
Vo
(Step-down)
+
+
VCC
VCC-5V
FB
DT
OCP2
-
OCP
+
VCC-5V
OCP+
OCP-
GND
Fig.37
1) Setting of output unit coil (L) and capacitor (Co)
Set the coil and capacitor as follows in step-down application:
<Setting of L-value>
When load current gets heavy, the current flowing through the coil gets continuous, and the relation below is established:
Vin: Input voltage
L
=
Tsw
? IL
?
(Vin-Vo)×Vo
Vin
Tsw: 1/(switching frequency)
Delta IL: Ripple current of coil
Normally set Delta IL below 30% of the maximum output current (Iomax).
When L-value is made greater, ripple current (Delta IL) becomes smaller. In general, the greater the L-value is, the smaller
the permissible current of coil gets, and when the current exceeds permissible current, the coil is saturated and L-value
changes. Contact the coil manufacturer and check permissible current.
<Setting of output capacitor Co>
Select an output capacitor Co by ESR (equivalent serial resistance) property of capacitor.
Output ripple voltage (Delta Vo) is almost ESR of output capacitor, therefore,
? Vo ≒
? IL × ESR
ESR: Equivalent serial resistance of output capacitor Co
The relation above is established.
Ripple component by output capacitor is small enough to be neglected in comparison with ripple component by ESR in
many cases. As for Co value, it is recommended to use a sufficiently large capacitor with a capacity that satisfies ESR
condition.
<Switching element>
Determine a switching element by peak current. Peak current Isw <peak> flowing through the switching element is equal
to peak current flowing through the coil, therefore the equation below is established.
Isw (peak) = Io + ? IL/2
Select a switching element of permissible current having a sufficient margin over peak current calculated by the equation.
www.rohm.com
? 2011 ROHM Co., Ltd. All rights reserved.
11/15
2011.08 - Rev.D
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相关代理商/技术参数 |
参数描述 |
|---|---|
| BD9846FV | 制造商:ROHM 制造商全称:Rohm 功能描述:Silicon Monolithic Integrated Circuit |
| BD9846FV-E2 | 功能描述:IC REG CTRLR BUCK PWM 20-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:500kHz 占空比:96% 电源电压:4 V ~ 36 V 降压:无 升压:是 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:无 工作温度:-40°C ~ 125°C 封装/外壳:24-WQFN 裸露焊盘 包装:带卷 (TR) |
| BD9848FV | 制造商:ROHM 制造商全称:Rohm 功能描述:Silicon Monolithic Integrated Circuit |
| BD9848FV-E2 | 制造商:ROHM Semiconductor 功能描述: |
| BD9850FVM | 制造商:ROHM 制造商全称:Rohm 功能描述:Single-output High-frequency Step-down Switching Regulator(Controller type) |
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