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目录
一,产品概述(General Description) The JTMA7066 has two synchronous buck PWM control-lers and one linear controller with high precision internal references voltage to offer accurate outputs. The PWM controllers are designed to drive two N-channel MOSFETs in synchronous buck topology, and the linear controller drives an external N-channel MOSFET. The device re-quires 12V and 5V power supplies, if the 5V supply is not available, VCC12 can offer an optional shunt regulator 5.8V for 5V supply.All outputs have independent soft-start and enable func-tions by SS/EN pins to control. Connect a capacitor from each SS/EN pin to the ground for setting the soft-start time, and pulling the SS/EN pin below 1V to disable regulator. Pull the SS2/EN2 to VCC, enter the DDR mode,the SS1/EN1 controls both VOUT1 and VOUT2, and al-lows VOUT2 to track VOUT1. It also offers the phase shift function by REFOUT pin to select the phase shift between VOUT1 and VOUT2 in DDR mode or Independent mode. When all SS/EN pins exceed 3.3V and no faults are detected, the PGOOD pin goes high to indicate the regu-lators are ready. If any of the SS/EN pins goes below 3.2V or any of the outputs has a fault condition, the PGOOD pin will be pulled low. The internal oscillator is nominally 300kHz (keep the FS/SYNC pin open or short to GND), and it offers the pro-grammable frequency function from 70kHz to 800kHz; con-necting a resistor from FS/SYNC to VCC12 to decrease the frequency, conversely, connect a resistor from FS/SYNC to GND to increase the frequency.The IC also pro-vides the synchronous frequency function. Connect the LGATE signal of another converter to FS/SYNC pin; forc-ing the switching frequency to follow the external clock. The possible synchronous frequency is from 150kHz to 800kHz. There is no Rds(on) sensing or under-voltage sens-ing on JTMA7066. However, it provides a simple short-circuit protection by monitoring the COMP1 and COMP2 for over-voltage. When any of two pins exceeds their trip point and the condition persists for 1-2 internal clock cycle (3-6µs at 300kHz), then it will shut down all regulators. 二.产品特点(Features) 1.)Two Synchronous Buck Converters and A Linear Regulator 2.)VIN Range up to 12V 3.)Input Power Supplies Require 12V and 5V or 4.)Use 12V to Generate a Shunt Regulator 5.8V 5.)0.6V Reference for VOUT1 and VOUT3 with 0.8% Accurate 6.)3.3V Reference for VOUT2 with 0.8% Accurate 7.)Buffered VTT Reference Output 8.)Three Outputs have Independent Soft-Start and Enable 9.)Internal 300kHz Oscillator and Programmable 10.)Frequency Range from 70 kHz to 800kHz 11.)Synchronous Switching Frequency 12.)DDR Mode or Independent Mode Selection 13.)Phase Shift Selection 14.)Power Good Function (责任编辑：oumao18) |
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