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参数资料
| 型号： | LTC1775CS#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 15/24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： | 4 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： | 0°C ~ 70°C |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 包装： | 管件 |
LTC1775
APPLICATIO S I FOR ATIO
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
region during start-up and must take into account the
reduced current limit.
Topside MOSFET Driver Supply (C B , D B )
reduce the signal swing at the gate by a diode drop. Thus,
the LTC1775 requires an increased EXTV CC voltage of
about 6V (such as provided by the Figure 6 circuit) when
using this driver.
Output Voltage Programming
The LTC1775 has a pin selectable output voltage deter-
mined by the V PROG pin as follows:
An external bootstrap capacitor (C B in the functional dia-
gram) 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 drop below
V PROG
0V
INTV CC
Open
V OUT
3.3V
5V
Adjustable
INTV CC . When the top MOSFET turns on, the switch node
voltage rises to V IN and the BOOST pin rises to approxi-
mately V IN + INTV CC . During dropout operation, C B sup-
plies the top driver for as long as ten cycles between re-
freshes. Thus, the boost capacitance needs to store about
100 times the gate charge required by the top MOSFET. In
many applications 0.1 μ F to 0.47 μ F is adequate.
When adjusting the gate drive level , the final arbiter is the
total input current for the regulator. If you make a change
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 8a. When using an external resistive divider, the
V PROG pin is left open and the V OSENSE pin is connected to
feedback resistors as shown in Figure 8b. The output
voltage is set by the divider as:
V OUT = 1 . 19 V ? 1 +
?
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.
?
?
R 2 ?
R 1 ?
External Gate Drive Buffer
The LTC1775 drivers are adequate for driving up to about
30nC into MOSFET switches. When using large single, or
multiple, MOSFET switches, external buffers may be re-
quired to provide additional gate drive capability. Special
CONNECT FOR
V OUT = 5V
CONNECT FOR
V OUT = 3.3V
V OUT
+
C OUT
LTC1775
V PROG INTV CC
V OSENSE
purpose gate driver circuits such as the LTC1693 are ideal
in such cases. Alternately, the external buffer circuit shown
SGND
1775 F08a
in Figure 7 can be used. Note that the bipolar devices
Figure 8a. Fixed 3.3V or 5V V OUT
BOOST
Q1
INTV CC
Q3
V OUT
OPEN
LTC1775
V PROG
TG
FMMT619
Q2
GATE
OF M1
BG
FMMT619
Q4
GATE
OF M2
+
C OUT
R2
V OSENSE
FMMT720
FMMT720
R1
SW
PGND
1775 F07
SGND
1775 F08b
Figure 7. Optional External Gate Driver
Figure 8b. Adjustable V OUT
15
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC1775IGN | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP 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 |
| LTC1775IGN#PBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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: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 |
| LTC1775IGN#TR | 功能描述:IC REG CTRLR BUCK PWM CM 16-SSOP 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 |
| LTC1775IGN#TRPBF | 功能描述:IC REG CTRLR BUCK PWM CM 16-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: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 |
| LTC1775IS | 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 |
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