参数资料
| 型号： | SC192IMLTRT |
| 厂商： | Semtech |
| 文件页数： | 6/15页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK ADJ 0.7A 10MLPD |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.75 V ~ 5.5 V |
| 输入电压： | 2.7 V ~ 5.5 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 750kHz |
| 电流 - 输出： | 700mA |
| 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： | 10-VFDFN 裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 10-MLPD（3x3） |
| 产品目录页面： | 1357 (CN2011-ZH PDF) |
| 其它名称： | SC192IMLDKR |
SC192
POWER MANAGEMENT
Description
Description
The SC192 step-down, pulse-width-modulated (PWM),
DC-DC converter has an adjustable output range from
0.75V to the input voltage. The device has an internal
synchronous rectifier and does not require a schottky
diode on the LX pin.
At moderate to heavy loads, the converter operates in
the PWM mode with a fixed frequency of 750kHz. At light
loads the converter enters the power save mode by
modulating the frequency, pulse-frequency-modulation
(PFM) which achieves high efficiency under light load
conditions.
Normal Mode
This is a standard fixed frequency current mode topol-
ogy. The current feedback is through the PMOS current
path and is amplified and summed with the internal slope
compensation network and DC offset. The voltage feed-
back loop is through the resistor divider attached to the
ADJ pin. The transconductance error amplifier output is
the compensation (COMP) pin with the usual external
compensation network attached. The PWM COMP pin
closes the loop by comparing the summed current feed-
back and the COMP signal to determine the length of the
ON time. The period is set by the on-board oscillator or
external clock attached to the SYNC pin.
Power Save Mode
If SYNC/PWM is DC low, power save mode is used at
light loads to improve efficiency. When the output cur-
rent reaches a low enough level, the part goes into a
voltage hysteresis mode of operation. The current level
for this is set to be the current reversal protection on
the NMOS device. The output voltage is then allowed to
decay to a lower threshold with the part in a reduced
quiescent current (PSAVE) state. After this lower thresh-
old is reached the part is reawoken to normal operation,
but with a current offset on the COMP pin to drive the
output voltage regulation point to be above an upper
threshold point. However the offset is removed once the
upper threshold is reached. If the load current is now
sufficiently large the part will return to normal regulation,
if not another PSAVE cycle will start.
Frequency Foldback
When the ADJ pin is low the output switching frequency
is folded back in several discrete steps to protect against
a short to GND on the output and improve inrush cur-
rent control during start-up.
PRELIMINARY
Forced PWM
If SYNC/PWM is DC high, the forced PWM mode is en-
abled. This ensures that the switching frequency of the
converter is maintained over the full range of output
loads. This means that the current reversal threshold of
the NMOS is changed to a negative value and the 100%
duty cycle and power save modes are also disabled.
100% Duty-Cycle Operation
Normally the control loop constrains the duty cycle of
the converter with minimum on and off times, but if the
output voltage droops to the lower power-save thresh-
old and the ON time is not terminated by the PWM com-
parator or PMOS current limit, then the next PMOS on
time is allowed to extend until either the PWM compara-
tor or PMOS current limit trips. This is then followed by a
minimum off time. This maximum on time/minimum off
time is allowed to continue until the upper power-save
threshold is reached. This allows the part to go into a
dropout mode of operation if the input supply collapses
down to the output voltage. If this happens, the output
voltage is equal to the input voltage minus the voltage
drop across the P-channel MOSFET.
Soft Start
The soft start mode is enabled after every shutdown cycle
to limit inrush current from the battery. In conjunction
with the frequency foldback this controls the maximum
current during start-up. The PMOS current limit is stepped
from 25%, to 50%, to 75%, and then 100% by an inter-
nal 2ms timer. As soon as the part reaches regulation,
soft start mode is disabled.
? 2007 Semtech Corp.
6
www.semtech.com
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相关代理商/技术参数 |
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| SC194A | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:1A Synchronous Buck Converter with Integrated Power Devices |
| SC194AEVB | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:1A Synchronous Buck Converter with Integrated Power Devices |
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| SC194AMLTRT | 功能描述:IC REG BUCK ADJ 1A 10MLP 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:50 系列:- 类型:升压（升压） 输出类型:可调式 输出数:1 输出电压:5 V ~ 25 V 输入电压:2.3 V ~ 5.5 V PWM 型:电流模式 频率 - 开关:600kHz，1.2MHz 电流 - 输出:1A 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-TSSOP，8-MSOP（0.118"，3.00mm 宽） 包装:管件 供应商设备封装:8-MSOP |
| SC194B | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Selectable 3.6V/3.3V/3.0V/2.5V 1A Synchronous Buck Converter |
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