semtech 公司的sc174是 4a降压稳压器,它采用semtech先进的专利架构,在点负载(pol)应用时有最好的动态范围.输入电压从3v到5.5v,输出电压从0.75v 到 95% x vin可编程,输出电流高达4a,峰值效率高达95%,具有短路,过压和欠压以及超温保护,内部有软起动和超级降功耗,主要用在网络设备,嵌入系统,医疗设备,办公自动化,仪表和手提设备,消费类电子和5v pol转换器.本文介绍了sc174主要特性,方框图,多种典型应用电路以及pcb布局图.
the sc174 is an integrated, synchronous 4a ecospeedtm step-down regulator, which incorporates semtech’s advanced, patented adaptive on-time architecture to achieve best-in-class performance in dynamic point-of load applications. the input voltage range is 3v to 5.5v with a programmable output voltage from 0.75v up to 95% x vin. the device features low-rds(on) internal switches and optional psave mode for high efficiency across the output load range.
adaptive on-time control provides programmable pseudo- fixed frequency operation and excellent transient performance. the switching frequency can be set from 200khz to 1mhz - allowing the designer to reduce external lc filtering and minimize light load (standby) losses. disabling psave operation reduces output voltage ripple at light load for ceramic output capacitors.
additional features include cycle-by-cycle current limit, soft start, input uvlo and output ov protection, and over temperature protection. the open-drain pgood pin provides output status. standby current is less than 10μa when disabled.
the device is available in a low profile, thermally enhanced mlpd-3x3mm 10-pin package.
sc174主要特性:
vin: 3v to 5.5v
vout: 0.75v to 95% x vin
iout: up to 4a
low rds(on) switches
up to 95% peak efficiency
high output accuracy
small ceramic capacitors
power good pin (open-drain)
patented adaptive on-time control:
excellent transient response
programmable pseudo-fixed frequency
fault protection features:
cycle-by-cycle current limit
short circuit protection
over and under output voltage protection
over-temperature
internal soft start
ultrasonic power save
smart power save
ultra-small lead-free 3x3mm,10-pin mlpd package
fully weee and rohs compliant
sc174应用:
networking equipment, embedded systems
medical equipment, office automation
instrumentation, portable systems
consumer devices (dtv, set-top box, ... )
5v pol converters
图1.sc174方框图
图2.sc174典型应用电路
图3.sc174 pcb布局电路图
图4.sc174 pcb布局图
图5.sc174 应用电路:1.2v输出/0-4a负载电流(vin=3v 到5.5v)
图5.sc174 应用电路:3.3v输出/0-4a负载电流(vin= 5.0v)
