LTC3700

Features:

Dual Output Regulator in Tiny 10-Pin MSOP
High Efficiency: Up to 94%
Wide V_IN Range: 2.65V to 9.8V
Constant Frequency 550kHz Operation
150mA LDO Regulator with Current Limit and
Thermal Shutdown Protection
High Output Currents Easily Achieved
Burst Mode^® Operation at Light Load
Low Dropout: 100% Duty Cycle
Current Mode Operation for Excellent Line and Load
Transient Response
0.8V Reference Allows Low Output Voltages
Low Quiescent Current: 260µA Total
Shutdown Mode Draws Only 10µA Supply Current
Common Power Good Output for Both Supplies


Pinout




Specifications

Buck Input Supply Voltage (V_IN)...................0.3V to 10V
SENSE, PGATE Voltages.................0.3V to (VIN + 0.3V)

VFB, ITH/RUN Voltages................................0.3V to 2.4V
PGATE Peak Output Current (<10µs)........................... 1A
LDO Input Supply Voltage (VIN2)...................0.3V to 6V
LDO, VFB2 Voltages........................0.3V to (V_IN2 + 0.3V)
PGOOD Voltage............................................0.3V to 10V
LDO Peak Output Current (< 10µs).......................500mA
Storage Ambient Temperature Range....65°C to 150°C
Operating Temperature Range (Note 2)...40°C to 85°C
Junction Temperature (Note 3)..............................150°C
Lead Temperature (Soldering, 10 sec)...................300°C

Description

The LTC®3700 is a constant frequency current mode step-down (buck) DC/DC controller with excellent AC and DCload and line regulation. The on-chip 150mA low dropout(LDO) linear regulator can be powered from the buck controller's input supply, its own independent input supply or the buck regulator's output. The buck controller of LTC3700 incorporates an undervoltage lockout feature that shuts down the controller when the input voltage falls below 2.1V. The buck regulator provides a ±2.5% output voltage accu-racy. The LTC3700 consumes only 210µA of quiescent current in nor- mal operation with the LDO consuming an additional 50µA.In shutdown, a mere 10µA (combined) is consumed. For applications where efficiency is a prime consideration, the buck controller is configured for Burst Mode operation which enhances efficiency at low output current. To fur- ther maximize the life of a battery source, the external P-channel MOSFET is turned on continuously in dropout (100% duty cycle). High constant operating frequency of 550kHz allows the use of a small external inductor. The LDO is protected by both current limit and thermal shutdown circuits.