Datasheet LTC3417A-1 (Analog Devices)

LTC3417A-1 Dual Synchronous 1.5A/1A 4MHz Step-Down DC/DC Regulator with POR
FEATURES DESCRIPTION
n
High Effi ciency: Up to 95%
The LTC®3417A-1 is a dual constant frequency, synchro- n
1.5A/1A Guaranteed Minimum Output Current
nous step-down DC/DC converter. Intended for medium n
Synchronizable to External Clock
power applications, it operates from a 2.25V to 5.5V input n
Power-On-Reset Output
voltage range and has a constant programmable switching n
No Schottky Diodes Required
frequency, allowing the use of tiny, low cost capacitors n
Programmable Frequency Operation: 1.5MHz or
and inductors 2mm or less in height. Each output voltage
Adjustable From 0.6MHz to 4MHz
is adjustable from 0.8V to 5V. Internal synchronous, low n
Low Ripple (< 35mV
R
P-P) BurstMode
®
Operation
DS(ON) power switches provide high effi ciency without n
Low R
the need for external Schottky diodes.
DS(ON) Internal Switches
n Short-Circuit Protected The open drain POR pin goes low when either output n VIN: 2.25V to 5.5V voltage falls 6% below regulation. The output will remain n Current Mode Operation for Excellent Line and Load low 150ms longer than the duration of the out of regula- Transient Response tion condition. n 125μA Quiescent Current in Sleep Mode n Ultralow Shutdown Current: I A user selectable mode input allows the user to trade Q < 1μA n Low Dropout Operation: 100% Duty Cycle off ripple voltage for light load effi ciency. Burst Mode n Phase Pin Selects 2nd Channel Phase Relationship operation provides high effi ciency at light loads, while with Respect to 1st Channel pulse skip mode provides low ripple noise at light loads. n Internal Soft-Start with Individual Run Pin Control A phase mode pin allows the second channel to operate n Available in Small Thermally Enhanced in-phase or 180° out-of-phase with respect to channel 1. (3mm × 5mm) DFN and 20-Lead TSSOP Packages Out-of-phase operation produces lower RMS current on VIN and thus lower stress on the input capacitor.
APPLICATIONS
To further maximize battery life, the P-channel MOSFETs n GPS/Navigation Systems are turned on continuously in dropout (100% duty cycle) n Automotive Instrumentation and both channels draw a total quiescent current of only n PC Cards 100μA. In shutdown, the device draws <1μA. n Industrial Power Supplies L, LT, LTC and LTM and Burst Mode are registered trademarks of Linear Technology n General Purpose Point of Load DC/DC Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131, 6144194.
OUT2 Effi ciency TYPICAL APPLICATION (Burst Mode Operation)
VIN 100 10 2.5V TO 5.5V REFER TO FIGURE 4 10μF V 100k IN 95 POR RESET 1 FREQ V 1.5μH 2.2μH EFFICIENCY OUT1 VOUT2 POWER LOSS (W) 1.8V SW1 SW2 2.5V 90 22pF 22pF 1.5A 1A 0.1 VIN RUN1 RUN2 VIN 85 LTC3417A-1 511k 866k 0.01 VFB1 VFB2 EFFICIENCY (%) 80 POWER LOSS 47μF 412k 412k 22μF 0.001 I 75 V TH1 ITH2 IN = 3.6V V 5.9k 2.87k OUT = 2.5V GND FREQ = 1MHz 70 0.0001 2200pF 6800pF 0.001 0.01 0.1 1 LOAD CURRENT (A) 3417A-1 TA01 3417A-1 TA01a 3417a1fa 1