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参数资料
| 型号： | LTC1502IS8-3.3#TR |
| 厂商： | Linear Technology |
| 文件页数： | 5/8页 |
| 文件大小： | 0K |
| 描述： | IC REG SWITCHED CAP 3.3V 8SOIC |
| 标准包装： | 2,500 |
| 类型： | 切换式电容器（充电泵） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 3.3V |
| 输入电压： | 0.9 V ~ 1.8 V |
| 频率 - 开关： | 500kHz |
| 电流 - 输出： | 10mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-SOIC |
LTC1502-3.3
TEST CIRCUIT
10 μ F
1 μ F
1
2
3
C2 V OUT
C1 + C3 +
LTC1502-3.3
C1 – /SHDN C3 –
8
7
6
1 μ F
10 μ F
I OUT
SWITCH
100 ?
4
GND
V IN
5
10 μ F
V IN
CLOSED FOR
100pF
SHUTDOWN
1502-3.3 TC
APPLICATIO N S I N FOR M ATIO N
Regulator Operation
The LTC1502-3.3 uses a quadrupler charge pump DC/DC
converter to produce a boosted output voltage. The
quadrupler charge pump consists of two voltage doubler
charge pumps (CP1 and CP2 on the Block Diagram)
cascaded in series. CP1 doubles the input voltage V IN and
the CP1 output voltage is stored on external capacitor C2.
The C2 pin also serves as the input for doubler CP2 whose
output is stored on the output capacitor C OUT . Each
doubler is controlled by a two-phase clock which is
generated in the Timing Control circuit. On phase one of
the clock, the flying capacitors C1 and C3 are charged to
their respective input voltages. On phase two each charged
flying capacitor is stacked on top of the input voltage and
discharged through an internal switch onto its respective
output. This sequence of charging and discharging the
CP1 and CP2 flying capacitors continues at the free
running oscillator frequency (500kHz typ) until the output
is in regulation.
Regulation is achieved by comparing the divided down
output voltage to a fixed voltage reference. The charge
pump clocks are disabled when the output voltage is
above the desired regulation point set by COMP1. When
the output has dropped below the lower trip point of
COMP1, the charge pump clocks are turned back on until
V OUT is boosted back into regulation.
Enhanced Start-Up
Enhanced start-up capability is provided by the COMP2
circuitry. COMP2 compares the divided down C2 voltage
to the input voltage V IN . The COMP2 output disables the
output charge pump CP2 whenever the divided C2 voltage
is lower than V IN . The CP2 output is thereby forced into a
high impedance state until the voltage on C2 has been
raised above V IN (the C2 pin should not be loaded for
proper start-up). This allows a higher internal gate drive
voltage to be generated (from the C2 pin) before the output
(V OUT ) is connected to a load. Hysteresis in COMP2 forces
CP2 to be turned ON and OFF while C OUT is charging up to
prevent a lockup condition if C2 droops too low during
start-up. By the time the output nears the regulation point,
the C2 voltage is well above the lower trip point of COMP2
and CP2 will remain enabled. This method of disabling the
output charge pump while an internal boosted gate drive
supply is developed allows the part to start up at low
voltages with a larger output current load than would
otherwise be possible.
Shutdown
Shutdown is implemented using an external pull-down
device on the C1 – /SHDN pin. The recommended external
pull-down device is an open-drain FET with resistive cur-
rent limiting (see Figure 1). The pull-down device must sink
up to 300 μ A and pull down below 0.2V to ensure proper
shutdown operation, however, the actual series resistance
is not critical. The pull-down device must also go into a Hi-
Z state for the LTC1502-3.3 to become active.
The timing control circuitry forces the CP1 switches into
a high impedance state every 16 clock cycles. The Hi-Z
duration is equal to one clock cycle. At the end of the
Hi-Z time interval, the voltage on the C1 – /SHDN pin is
sampled. If the C1 – /SHDN pin has been pulled to a logic
low state, the part will go into shutdown mode. When the
pull-down device is disabled, an internal pull-up current
5
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| LTC1503CMS8-1.8 | 功能描述:IC REG BUCK SWITCHED CAP 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1503CMS8-1.8#PBF | 功能描述:IC REG BUCK SWITCHED CAP 8MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1503CMS8-1.8#PBF | 制造商:Linear Technology 功能描述:DC/DC Charge Pump Converter IC |
| LTC1503CMS8-1.8#TR | 功能描述:IC REG BUCK SWITCHED CAP 8MSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
| LTC1503CMS8-1.8#TRPBF | 功能描述:IC REG BUCK SWITCHED CAP 8MSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:2,500 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:1.24 V ~ 30 V 输入电压:1.5 V ~ 12 V PWM 型:电流模式，混合 频率 - 开关:600kHz 电流 - 输出:500mA 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:8-SOIC |
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