Document
SC171
POWER MANAGEMENT
1A EcoSpeedTM Synchronous Step-Down Regulator with Optional Ultrasonic Power Save
Features
VIN: 3V to 5.5V VOUT: 0.75V to 95% x VIN IOUT: Up to 1A 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
Applications
Networking Equipment, Embedded Systems Medical Equipment, Office Automation Instrumentation, Portable Systems Consumer Devices (DTV, Set-top Box, ... ) 5V POL Converters
Description
The SC171 is an integrated, synchronous 1A EcoSpeedTM step-down regulator, which incorporates Semtech’s advanced, patented adaptive on-time architecture to achieve best-in-class performance in dynamic point-ofload 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.
Typical Application Circuit
3 to 5.5V
VIN BST
LX
SC 171
VOUT = 0.75 V to 95% VIN
VDD
FB
PGOOD
Power Good
Enable / Power Save
EN/ PSV PGND
TON AGND
October 11 , 2010
© 2010 Semtech Corporation
Pin Configuration
BST VIN LX PGND PGOOD
VDD
AGND TON EN/PSV FB
10 Pin MLPD
θJA= 40°C/W.
Marking Information
TOP MARKING
SC171
Ordering Information
Device
Top Mark
Package(2)
SC171MLTRT(1)
171
MLPD-10 3x3
SC171EVB
Evaluation Board
Notes: 1) Available in tape and reel packaging only. A reel contains 3000 devices. 2) Available in lead-free packaging only. WEEE compliant and Halogen free. This component and all homogenous sub-components are RoHS compliant.
171 yyww xxxx
yyww= Date Code(Example:0952) xxxx = Semtech Lot Number(Example:3901)
© 2010 Semtech Corporation
SC171
Absolute Maximum Ratings
Recommended Operating Conditions
LX to GND(3)……………………… - 0.3(DC) to +6.0V(DC) Max VIN to PGND, EN/PSV to AGND ………………… -0.3 to +6.0V VIN to VDD…………………………………………………+0.3V BST to LX ………………………………………… -0.3 to +6.0V BST to PGND…………………………………… -0.3 to +12V VDD to AGND, VOUT to AGND………………… -0.3V to +6.0V FB, PGOOD, TON …………………………… -0.3 to VDD + 0.3V AGND to PGND………………………………… -0.3 to +0.3V Peak IR Reflow Temperature ……………….…………… 260°C ESD Protection Level (2)………………………………………2kV
Supply Input Voltage……………………………… 3V to 5.5V Maximum Continuous Output Current …………………… 1A
Thermal Information
Storage Temperature …………………………… -60 to +150°C Maximum Junction Temperature ……………………… 150°C Operating Junction Temperature ……………… -40 to +125°C Thermal Resistance, Junction to Ambient(1) ………… 40°C/W
Exceeding the above specifications may result in permanent damage to the device or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not recommended.
NOTES(1) Calculated from package in still air, mounted to 3” x 4.5”, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards. (2) Tested according to JEDEC standard JESD22-A114-B (3) Due to parasitic board inductance, the transient LX pin voltage at the point of measurement may appear larger than that which exists on
silicon. The device is designed to tolerate the short duration transient voltages that will appear on the LX pin due to the deadtime diode conduction, for inductor currents up to the current limit setting of the device. See application section for details.
Electrical Characteristics
Unless specified: VIN =5V, TA=+25°C for Typ, -40°C to +85°C for Min and Max, TJ < 125°C
Parameter Input Supplies VIN, VDD Input Voltage VDD UVLO Threshold VDD UVLO Hysteresis
VIN, VDD Supply Current
Controller FB On-Time Threshold Frequency Programming Range FB Input Bias Current © 2010 Semtech Corporation
Symbol
Conditions
Rising UVLO VTH
EN/PSV= 0V IOUT=0A, PSAVE, fSW=25kHz(1) Forced Continuous Conduction Mode EN floating, IOUT=0A , Not Switching
See RTO.