参数资料
| 型号： | SC171MLTRT |
| 厂商： | Semtech |
| 文件页数： | 13/27页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 1A 10MLPD |
| 标准包装： | 1 |
| 系列： | EcoSpeed® |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.75 V ~ 5.23 V |
| 输入电压： | 3 V ~ 5.5 V |
| 频率 - 开关： | 200kHz ~ 1MHz |
| 电流 - 输出： | 1A |
| 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： | 10-VFDFN 裸露焊盘 |
| 包装： | 标准包装 |
| 供应商设备封装： | 10-MLPD（3x3） |
| 其它名称： | SC171MLDKR |
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SC171
Smart Power Save
ApplicationsInformation(continued)
Ultrasonic Power Save Operation
The SC171 provides ultrasonic power save operation at
light loads, with the minimum operating frequency fixed
at 25kHz. This is accomplished using an internal timer
that monitors the time between consecutive high-side
gate pulses. If the time exceeds 40μs, DL drives high to
turn the low-side MOSFET on. This draws current from
V OUT through the inductor, forcing both V OUT and V FB to
fall. When V FB drops to the 750mV threshold, the next DH
on-time is triggered. After the on-time is completed the
high-side MOSFET is turned off and the low-side MOS-
FET turns on. The low-side MOSFET remains on until the
inductor current ramps down to zero, at which point the
low-side MOSFET is turned off.
Because the on-times are forced to occur at intervals
no greater than 40μs, the frequency will not fall below
~25kHz. Figure 5 shows ultrasonic power save opera-
tion.
minimum f SW ~ 25kHz
power save enabled, this can force V OUT to slowly rise
and reach the over-voltage threshold, resulting in a hard
shutdown. Smart power save prevents this condition.
When the FB voltage exceeds 10% above nominal (ex-
ceeds 825mV), the device immediately disables power-
save, and DL drives high to turn on the low-side MOSFET.
This draws current from V OUT through the inductor and
causes V OUT to fall. When V FB drops back to the 750mV trip
point, a normal T ON switching cycle begins. This method
prevents a hard OVP shutdown and also cycles energy
from V OUT back to V IN . Figure 6 shows typical waveforms
for the Smart Power Save feature.
V OUT drifts up to due to leakage
current flowing into C OUT V OUT discharges via inductor
and low-side MOSFET
Threshold (825mV)
Normal V OUT ripple
FB
threshold
DH and DL off
High-side
Drive (DH)
Single DH on-time pulse
after DL turn-off
Low-side
Drive (DL)
FB Ripple
Voltage (V FB )
FB threshold
(750mV)
DL turns on when Smart
PSAVE threshold is reached
DL turns off when FB
threshold is reached
Normal DL pulse after DH
on-time pulse
Inductor
Current
(0A)
Figure 6 — Smart Power Save
Current Limit Protection
DH
DL
On-time
(T ON )
40μs time-out
DH On-time is triggered when
V FB reaches the FB Threshold
The device features fixed current limiting, which is ac-
complished by using the R DS(ON) of the lower MOSFET for
current sensing. While the low-side MOSFET is on, the
inductor current flows through it and creates a voltage
across the R DS(ON) . During this time, the voltage across the
MOSFET is negative with respect to ground. During this
time, If this MOSFET voltage drop exceeds the internal
After the 40μsec time-out, DL drives high if V FB
has not reached the FB threshold.
Figure 5 — Ultrasonic Power Save Operation
Smart Power Save Protection
Active loads may leak current from a higher voltage into
the switcher output. Under light load conditions with
? 2010 Semtech Corporation
reference voltage, the current limit will activate. The cur-
rent limit then keeps the low-side MOSFET on and will
not allow another high side on-time, until the current in
the low-side MOSFET reduces enough to drop below the
internal reference voltage once more. This method regu-
lates the inductor valley current at the level shown by I LIM
in Figure 7.
13
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相关代理商/技术参数 |
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| SC172 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:2A EcoSpeedTM Synchronous Step-Down Regulator with Optional Ultrasonic Power Save |
| SC17-2 | 制造商:Thomas & Betts 功能描述:DRIVE RING - 1 1/4" |
| SC172MLTRT | 制造商:Semtech Corporation 功能描述:Conv DC-DC Single Step Down 3V to 5.5V 10-Pin MLPD EP T/R 制造商:Semtech Corporation 功能描述:IC DC-DC CONV 1MHz 10-MLPD 制造商:Semtech Corporation 功能描述:IC, DC-DC CONV, 1MHz, 10-MLPD 制造商:Semtech Corporation 功能描述:SC172 Series 5.5 V 1 MHz 2 A Synchronous EcoSpeed Step-Down Regulator - MLPD-10 制造商:Semtech Corporation 功能描述:IC, DC-DC CONV, 1MHz, 10-MLPD; Primary Input Voltage:5.5V; No. of Outputs:1; Output Voltage:5.225V; Output Current:2A; No. of Pins:10; Operating Temperature Min:-40C; Operating Temperature Max:85C; Package / Case:10-MLPD 制造商:SEMTECH 功能描述:SC172 Series 5.5 V 1 MHz 2 A Synchronous EcoSpeed Step-Down Regulator - MLPD-10 |
| SC173 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:3A EcoSpeedTM Synchronous Step-Down Regulator with Optional Ultrasonic Power Save |
| SC173A | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:3A EcoSpeedTM Synchronous Step-Down Regulator with Automatic Power Save |
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