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参数资料
| 型号： | LTC1503IS8-1.8#TR |
| 厂商： | Linear Technology |
| 文件页数： | 8/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SWITCHED CAP 8SOIC |
| 标准包装： | 2,500 |
| 类型： | 降压（降压），切换电容（充电泵） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 1.8V |
| 输入电压： | 2.4 V ~ 6 V |
| 频率 - 开关： | 600kHz |
| 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： | 8-SOIC（0.154"，3.90mm 宽） |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 8-SOIC |
LTC1503-1.8/LTC1503-2
APPLICATIO S I FOR ATIO
approximately 1.9V. Since the ramp rate on the SHDN/SS
pin controls the ramp rate on V OUT , the average inrush
current can be controlled through selection of C SS and
C OUT . For example, a 4.7nF capacitor on SHDN/SS results
in a 4ms ramp time from 0.35V to 1.9V on the pin. If C OUT
is 10 μ F, the 4ms V REF ramp time results in an average
C OUT charge current of only 5mA (see Figure 2c).
Capacitor Selection
For best performance, it is recommended that low ESR
capacitors be used for C IN and C OUT to reduce noise and
ripple. If the ESR of the output capacitor is too high
(> 0.5 ? ), both efficiency and output load regulation may
be degraded. The C IN and C OUT capacitors should be either
ceramic or tantalum and should be 10 μ F or greater. If the
input source impedance is very low (< 0.5 ? ), C IN may not
5
V OUT
LTC1503-X
SHDN/SS
1
R LOAD
be needed. Ceramic capacitors are recommended for the
flying caps C1 and C2 with values of 0.47 μ F to 2.2 μ F.
Smaller values may be used in low output current applica-
tions (e.g., I OUT < 10mA). For best performance choose
ON OFF V CTRL
C SS
1503-1.8/2 F02a
the same capacitance value for both C1 and C2.
Output Ripple
V CTRL
2V/DIV
V OUT
1V/DIV
(a)
Normal LTC1503-X operation produces voltage ripple on
the V OUT pin. Output voltage ripple is required for the parts
to regulate. Low frequency ripple exists due to the hyster-
esis in the sense comparator and propagation delays in the
charge pump enable/disable circuits. High frequency ripple
is also present mainly from the ESR (equivalent series
resistance) in the output capacitor. Typical output ripple
(V IN = 3.6V) under maximum load is 25mV peak-to-peak
with a low ESR 10 μ F output capacitor.
The magnitude of ripple voltage depends on several fac-
LTC1503-2
C SS = 0nF
C OUT = 10 μ F
R LOAD = 50 ?
2ms/DIV
(b)
1503-1.8/2 F02b
tors. High input voltages increase the output ripple since
more charge is delivered to C OUT per charging cycle. Large
output current load and/or a small output capacitor (< 10 μ F)
results in higher ripple due to higher output voltage dV/dt.
High ESR capacitors (ESR > 0.5 ? ) on the output pin cause
V CTRL
2V/DIV
V OUT
1V/DIV
high frequency voltage spikes on V OUT with every clock
cycle.
There are several ways to reduce the output voltage ripple
(see Figure 3). A larger C OUT capacitor (22 μ F or greater)
will reduce both the low and high frequency ripple due to
the lower C OUT charging and discharging dV/dt and the
lower ESR typically found with higher value (larger case
LTC1503-2
2ms/DIV
1503-1.8/2 F02b
size) capacitors. A low ESR ceramic output capacitor will
8
C SS = 4.7nF
C OUT = 10 μ F
R LOAD = 50 ?
(c)
Figure 2. Shutdown/Soft-Start Operation
minimize the high frequency ripple, but will not reduce the
low frequency ripple unless a high capacitance value is
chosen. A reasonable compromise is to use a 10 μ F to 22 μ F
tantalum capacitor in parallel with a 1 μ F to 3.3 μ F ceramic
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| LTC1503IS8-2 | 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: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 |
| LTC1503IS8-2#PBF | 功能描述:IC REG BUCK SWITCHD CAP 2V 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: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 |
| LTC1503IS8-2#TR | 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: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 |
| LTC1503IS8-2#TRPBF | 功能描述:IC REG BUCK SWITCHD CAP 2V 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: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 |
| LTC1504ACS8 | 功能描述:IC REG BUCK SYNC ADJ 0.5A 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 |
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