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参数资料
| 型号： | LTC1503CMS8-2#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源模块 |
| 英文描述： | 1-OUTPUT DC-DC REG PWR SUPPLY MODULE |
| 封装： | PLASTIC, MSOP-8 |
| 文件页数： | 10/12页 |
| 文件大小： | 187K |
| 代理商： | LTC1503CMS8-2#TR |
7
LTC1503-1.8/LTC1503-2
maintain regulation. This will only occur as VIN/VOUT nears
a 3-to-2 or 1-to-1 transition point. For example, under light
load conditions, the LTC1503-X can operate in 2-to-1
mode when VIN equals 4.1V with greater than 90% effi-
ciency. However, when the load is increased, the part can
no longer supply enough output current in 2-to-1 mode to
maintain regulation. This causes VOUT to droop below the
regulation point until COMP2 trips and forces the part to
skip from 2-to-1 mode to 3-to-2 mode. The COMP2
threshold is about 17mV (VOUT referred) below the main
comparator regulation point. Hysteresis in COMP2 will
force the part to transition in and out of mode skipping.
This will result in a slight VOUT decrease of approximately
20mV under mode skipping conditions.
Shutdown/Soft-Start Operation
The SHDN/SS pin is used to implement both low current
shutdown and soft-start. The soft-start feature limits
inrush currents when the regulator is initially powered up
or taken out of shutdown. Forcing a voltage lower than
0.35V (typ) will put the part into shutdown mode. Shut-
down mode disables all control circuitry and forces the
charge pump VOUT into a high impedance state. A 2A pull-
up current on the SHDN/SS pin will force the part into
active mode if the pin is left floating or is driven with an
open-drain output that is in a high impedance state. If the
pin is not driven with an open-drain device, it must be
forced to a logic high voltage of 2.2V (min) to ensure
proper VOUT regulation. The SHDN/SS pin should not be
driven to a voltage higher than VIN.
To implement soft-start, the SHDN/SS pin must be driven
with an open-drain device and a capacitor must be
connected from the SHDN/SS pin to GND. Once the open-
drain device is turned off, a 2
A pull-up current will begin
charging the external SS capacitor and force the voltage
on the pin to ramp towards VIN. As soon as the SHDN
threshold is reached (0.35V typ), the internal reference
voltage which controls the VOUT regulation point will
follow the ramp voltage on the SHDN/SS pin (minus a
0.35V offset to account for the SHDN threshold) until the
reference reaches its final band gap voltage. This occurs
when the voltage on the SHDN/SS pin reaches
Figure 1b. Step-Down Charge Pump in 3-to-2 Mode
In 1-to-1 mode, switch S1 and S2 are connected in series
between VIN and VOUT as needed to boost VOUT back into
regulation (see Figure 1c). The REG ENABLE signal from
the main comparator (COMP1) controls switches S1 and
S2 directly. Since all of the VOUT current is sourced from
VIN, the efficiency in 1-to-1 mode is approximately equal
to that of a linear regulator.
Figure 1c. Step-Down Charge Pump in 1-to-1 Mode
Mode Selection and Mode Skipping
The optimal step-down conversion mode is chosen based
on VIN to VOUT differential voltage and output load condi-
tions. Two internal comparators are used to select the
default step-down mode based on the VIN and VOUT
voltage. A separate comparator (COMP2) is used to sense
a droop on VOUT due to a heavy output load and force the
charge pump to skip to a higher output current mode to
S1
φ1
S5
φ2
S7
φ2
S4
φ2
S2
φ1
C1
(EXTERNAL)
C2
(EXTERNAL)
C1+
C1–
C2–
GND
C2 +
1503-1.8/2 F01b
VIN
VOUT
S3
φ1
S6
φ2
S2
S1
C1
(EXTERNAL)
C1+
C1–
1503-1.8/2 F01c
VIN
VOUT
APPLICATIO S I FOR ATIO
WU
UU
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相关代理商/技术参数 |
参数描述 |
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| LTC1503CS8-1.8 | 功能描述:IC REG BUCK SWITCHED CAP 8SOIC 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 |
| LTC1503CS8-1.8#PBF | 功能描述:IC REG BUCK SWITCHED CAP 8SOIC 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:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
| LTC1503CS8-1.8#TR | 功能描述:IC REG BUCK SWITCHED CAP 8SOIC 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 |
| LTC1503CS8-1.8#TRPBF | 功能描述:IC REG BUCK SWITCHED CAP 8SOIC 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:500 系列:- 类型:切换式电容器（充电泵），反相 输出类型:固定 输出数:1 输出电压:-3V 输入电压:2.3 V ~ 5.5 V PWM 型:Burst Mode? 频率 - 开关:900kHz 电流 - 输出:100mA 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:SOT-23-6 细型，TSOT-23-6 包装:带卷 (TR) 供应商设备封装:TSOT-23-6 其它名称:LTC1983ES6-3#TRMTR |
| LTC1503CS8-2 | 功能描述:IC REG BUCK SWITCHD CAP 2V 8SOIC 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:250 系列:- 类型:降压（降压） 输出类型:固定 输出数:1 输出电压:1.2V 输入电压:2.05 V ~ 6 V PWM 型:电压模式 频率 - 开关:2MHz 电流 - 输出:500mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:6-UFDFN 包装:带卷 (TR) 供应商设备封装:6-SON（1.45x1） 产品目录页面:1032 (CN2011-ZH PDF) 其它名称:296-25628-2 |
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