参数资料
| 型号： | BD9845FV-E2 |
| 厂商： | Rohm Semiconductor |
| 文件页数： | 7/16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
● Operation description of each block and function
1) REG (reference voltage unit)
As for REG (2.5V), reference voltage (2.5V) stabilized better than supply voltage input to VCC terminal is supplied as an
operation voltage of IC internal circuit, as well as output outside through VREF terminal. Insert a capacitor of 1uF to VREF
terminal.
As for REG (VCC-5V), voltage of VCC-5V is supplied as power supply (LDO) of driver circuit (DRV) of OUT terminal, as
well as output outside through C5V terminal. Insert a capacitor of 1uF to VCC terminal of C5V terminal.
2) ERR Amp (error amplifier)
In step-down application, inverting input INV of
error amplifier detects output voltage by sending
back feedback current from final output stage (on
Vo
load side) of switching regulator. R1 and R2
connected to this input terminal are resistor for
R1
1V
ErrAmp
setting output voltage. Non-inverting input of
amplifier is a reference input of error amplifier
itself by adding reference voltage (1.0V) inside IC.
12
Rf and Cf connected between FB, which is output
from error amplifier, and INV are for feedback of
error amplifier, and allows setting of loop gain.
FB is connected to PWM Comp and supplied as
R2
Rf
Cf
11
INV
non-inverting input.
Setting of output voltage (Vo) is as follows:
FB
Vo
=
R1+R2
? 1.0V
Fig.30
R2
3) OSC (triangular wave oscillating unit)
Generates triangular wave for inputting to PWM Comp.
First, timing capacitor C CT connected between CT terminal and GND is charged by constant current (200 uA) generated
inside IC. When CT voltage reaches 2.0 V typ, the comparator is switched, and then C CT is discharged by constant current
(200 μA). Then, when CT voltage reaches 1.5V, the comparator is switched again, and C CT is charged again. This
repetition generates triangular wave.
Oscillation frequency is determined by externally mounted C CT through theoretical formula below:
Fosc ≒
ICT/(2 ? C CT ?Δ Vosc)
ICT : CT sink/source current 200 uA typ
Δ Vosc : Triangular wave amplifying voltage ＝ (Vt0-Vt100) ＝ 0.50 V typ.
Here, error from theoretical formula is caused by delay of
internal circuit at a high frequency. See the graph in Fig 31 for
setting.
This triangular wave can be taken out through CT terminal. It is
also possible to input the oscillator externally by switching to
slave mode described later. Waveform input here in principle
must be triangular wave of Vpeak = (1.5V ? 2.0V) equivalent to
internal oscillation circuit.
10000
1000
External input voltage range
V CT : 1.4 V < V CT < 2.3 V
100
Ta=25 ℃
Standard external C CT range
C CT : MIN.47 pF – MAX.3000 pF
10
10
100
1000
10000
CT timing capacity (pF)
Fig.31
www.rohm.com
? 2011 ROHM Co., Ltd. All rights reserved.
7/15
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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