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参数资料
| 型号： | LTC1625IS |
| 厂商： | Linear Technology |
| 文件页数： | 14/24页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 16-SOIC |
| 标准包装： | 50 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 165kHz |
| 占空比： | 99% |
| 电源电压： | 3.9 V ~ 36 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： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
LTC1625
APPLICATIO N S I N FOR M ATIO N
Note that R DS(ON) also varies with the gate drive level. If
gate drives other than the 5.2V INTV CC are used, this must
be accounted for when selecting the MOSFET R DS(ON) .
V PROG pin is left open and the V OSENSE pin is connected to
feedback resistors as shown in Figure 6b. The output
voltage is set by the divider as:
V OUT = 1 . 19 V ? 1 +
R 1 ?
Particular care should be taken with applications where
EXTV CC is connected to the output. When the output
voltage is between 4.7V and 5.2V, INTV CC will be con-
nected to the output and the gate drive is reduced. The
resulting increase in R DS(ON) will also lower the current
limit. Even applications with V OUT > 5.2V will traverse this
?
?
R 2 ?
?
LTC1625
region during start-up and must take into account the
reduced current limit.
V OUT = 5V: INTV CC
V OUT = 3.3V: GND
V PROG
Topside MOSFET Driver Supply (C B , D B )
V OUT
+
C OUT
V OSENSE
An external bootstrap capacitor (C B in the functional
diagram) connected to the BOOST pin supplies the gate
drive voltage for the topside MOSFET. This capacitor is
charged through diode D B from INTV CC when the SW node
is low. Note that the voltage across C B is about a diode
SGND
1625 F06a
Figure 6a. Fixed 3.3V or 5V V OUT
drop below INTV CC . When the top MOSFET turns on, the
switch node voltage rises to V IN and the BOOST pin rises
OPEN
LTC1625
V PROG
to approximately V IN + INTV CC . During dropout operation,
C B supplies the top driver for as long as ten cycles between
refreshes. Thus, the boost capacitance needs to store
about 100 times the gate charge required by the top
MOSFET. In many applications 0.22 μ F is adequate.
+
C OUT
R2
R1
V OSENSE
SGND
1625 F06b
When adjusting the gate drive level , the final arbiter is the
total input current for the regulator. If you make a change
and the input current decreases, then you improved the
efficiency. If there is no change in input current, then there
is no change in efficiency.
Output Voltage Programming
The LTC1625 has a pin selectable output voltage deter-
mined by the V PROG pin as follows:
V PROG = 0V V OUT = 3.3V
V PROG = INTV CC V OUT = 5V
V PROG = Open V OUT = Adjustable
Remote sensing of the output voltage is provided by the
V OSENSE pin. For fixed 3.3V and 5V output applications an
internal resistive divider is used and the V OSENSE pin is
connected directly to the output voltage as shown in
Figure 6a. When using an external resistive divider, the
14
Figure 6b. Adjustable V OUT
Run/Soft Start Function
The RUN/SS pin is a dual purpose pin that provides a soft
start function and a means to shut down the LTC1625. Soft
start reduces surge currents from V IN by gradually in-
creasing the controller’s current limit I TH(MAX) . This pin
can also be used for power supply sequencing.
Pulling the RUN/SS pin below 1.4V puts the LTC1625 into
a low quiescent current shutdown (I Q < 30 μ A). This pin can
be driven directly from logic as shown in Figure 7. Releas-
ing the RUN/SS pin allows an internal 3 μ A current source
to charge up the external capacitor C SS . If RUN/SS has
been pulled all the way to ground there is a delay before
starting of approximately:
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1625IS#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 特色产品:LM3753/54 Scalable 2-Phase Synchronous Buck Controllers 标准包装:1 系列:PowerWise® PWM 型:电压模式 输出数:1 频率 - 最大:1MHz 占空比:81% 电源电压:4.5 V ~ 18 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:-5°C ~ 125°C 封装/外壳:32-WFQFN 裸露焊盘 包装:Digi-Reel® 产品目录页面:1303 (CN2011-ZH PDF) 其它名称:LM3754SQDKR |
| LTC1625IS#PBF | 制造商:Linear Technology 功能描述:IC SYNC STEP-DOWN REGULATOR 16-SOIC |
| LTC1625IS#TR | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1625IS#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-SOIC 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:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX |
| LTC1625ISPBF | 制造商:Linear Technology 功能描述:No RSENSE Current Mode Regulator SOIC16 |
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