Datasheet LTC1704, LTC1704B (Analog Devices)

LTC1704/LTC1704B 550kHz Synchronous Switching Regulator Controller Plus Linear Regulator Controller
U FEATURES DESCRIPTIO
■
Dual Regulated Outputs: One Switching Regulator
The LTC®1704/LTC1704B include a high power synchro-
and One Linear Regulator
nous switching regulator controller plus a linear regulator ■
Excellent DC Accuracy:
±
1.5% for Switcher
controller. The switching regulator controller is designed
and
±
2% for Linear Regulator
to drive a pair of N-channel MOSFETs in a voltage mode, ■ External N-Channel MOSFET Architecture synchronous buck configuration to provide the main sup- ■ No External Current Sense Resistor Required ply. The constant frequency, true PWM architecture ■ Burst Mode® Operation at Light Load (LTC1704) switches at 550kHz, minimizing external component size, ■ Continuous Switching at Light Load (LTC1704B) cost and optimizing load transient performance. The ■ Linear Regulator with Programmable Current Limit LTC1704 features automatic transition to power saving ■ Linear Regulator with Programmable Start-Up Delay Burst Mode operation at light loads. The LTC1704B does ■ Low Shutdown Current: <150µA not shift into Burst Mode operation at light loads, eliminat- ■ High Efficiency Over Wide Load Current Range ing low frequency output ripple at the expense of light load ■ PGOOD Flag Monitors Both Outputs efficiency. The linear regulator controller is designed to ■ Small 16-Pin Narrow SSOP Package drive an external NPN power transistor to provide up to 2A
U
of current to an auxiliary load.
APPLICATIO S
The LTC1704/LTC1704B deliver better than ±1.5% DC ■ Multiple Logic Supply Generator accuracy at the switcher outputs and ±2% at the linear ■ Distributed Power Applications regulator outputs. High performance feedback loops allow ■ High Efficiency Power Conversion the circuit to keep total output regulation within ±5% under all transient conditions. An open-drain PGOOD , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. output indicates when both outputs are within ±10% of their regulated values.
U TYPICAL APPLICATIO 5V to 1.8V/15A and 1.5V/2A Application
10Ω VIN 5V CIN MBR0520LT1 + +
Switcher Efficiency
330µF + 1µF 5k 470k 10µF 10V 10µF ×3 16 15 11 100 CCP 1µF BOOST PVCC VCC QTA QTB 1 L1 12 TG PGOOD 90 0.68µH 2 10 SW REGILM 1000pF COUTSW V 80 OUTSW + 14 4 180µF QBB QBA 1.8V BG RUN/SS 4V 15A 0.1µF LTC1704 ×6 13.7k 3 8 70 I GND MAX EFFICIENCY (%) VOUTSW V 13 7 IN = 5V 10k 1.8k ON SEMI 60 1800pF PGND REGDR V D44H11 OUTSW = 1.8V 6 TA = 25°C FB QT = QB = 2xFDS6670A 50 8.06k 1800pF 330pF 698Ω 11k + 5 9 V 0 3 6 9 12 15 100µF OUTREG COMP REGFB 1.5V TANT ILOAD (A) 2A 806Ω C 1704 G04 IN: KEMET T510X337K010AS COUTSW: PANASONIC EEFUE0G181R 1704 TA01 L: SUMIDA CEP125-4712-T007 QTA, QTB, QBA, QBB: FAIRCHILD FDS6670A 1704bfa 1