Datasheet LTC3548A (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual Synchronous 400mA/800mA, 2.25MHz Step-Down DC/DC Regulator |
| Pages / Page | 20 / 1 — FEATURES. DESCRIPTION. High Efficiency: Up to 95%. Low Ripple … |
| File Format / Size | PDF / 255 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. High Efficiency: Up to 95%. Low Ripple (<35mVP-P) Burst Mode Operation;. IQ = 40μA
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LTC3548A Dual Synchronous 400mA/800mA, 2.25MHz Step-Down DC/DC Regulator
FEATURES DESCRIPTION
n
High Efficiency: Up to 95%
The LTC®3548A is a dual, constant frequency, synchronous n
Low Ripple (<35mVP-P) Burst Mode Operation;
step-down DC/DC converter. Intended for low power ap-
IQ = 40μA
plications, it operates from a 2.5V to 5.5V input voltage n
2.25MHz Constant Frequency Operation
range and has a constant 2.25MHz switching frequency, n
High Switch Current: 0.7A and 1.2A
enabling the use of tiny, low cost capacitors and inductors n
No Schottky Diodes Required
1mm or less in height. Each output voltage is adjustable n
Low RDS(ON) Internal Switches: 0.35
Ω from 0.6V to 5V. Internal synchronous 0.35Ω, 0.7A/1.2A n Current Mode Operation for Excellent Line power switches provide high efficiency without the need and Load Transient Response for external Schottky diodes. n Short-Circuit Protected A user-selectable mode input is provided to allow the user n Low Dropout Operation: 100% Duty Cycle to trade-off ripple noise for low power efficiency. Burst n Ultralow Shutdown Current: IQ <1μA Mode® operation provides the highest efficiency at light n Output Voltages from 5V down to 0.6V loads, while pulse-skipping mode provides the lowest n Power-On Reset Output ripple noise at light loads. n Externally Synchronizable Oscillator n Optional External Soft-Start To further maximize battery life, the P-channel MOSFETs n Small Thermally Enhanced MSOP and 3mm are turned on continuously in dropout (100% duty cycle), × 3mm DFN Packages and both channels draw a total quiescent current of only 40μA. In shutdown, the device draws <1μA.
APPLICATIONS
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective n PDAs/Palmtop PCs owners. Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, n 6611131. Digital Cameras n Cellular Phones n Wireless and DSL Modems
TYPICAL APPLICATION Efficiency/Power Loss Curves 2.5V/1.8V at 400mA/800mA Step-Down Regulators
100 1 2.5V 90 VIN 1.8V 2.5V TO 5.5V 80 10μF 0.1 100k POWER LOSS (W) 70 RUN/SS2 VIN RUN/SS1 60 MODE/SYNC POR RESET 50 0.01 V 4.7μH 2.2μH OUT2 VOUT1 2.5V SW2 SW1 1.8V 40 400mA 22pF LTC3548A 22pF 800mA EFFICIENCY (%) 30 0.001 20 V V V IN = 3.3V FB2 FB1 Burst Mode OPERATION 887k 887k 10 4.7μF 280k GND 442k 10μF NO LOAD ON OTHER CHANNEL 0 0.0001 1 10 100 1000 3548A TA01 LOAD CURRENT (mA) 3548A TA02 3548afa 1
FEATURES DESCRIPTION
n
High Efficiency: Up to 95%
The LTC®3548A is a dual, constant frequency, synchronous n
Low Ripple (<35mVP-P) Burst Mode Operation;
step-down DC/DC converter. Intended for low power ap-
IQ = 40μA
plications, it operates from a 2.5V to 5.5V input voltage n
2.25MHz Constant Frequency Operation
range and has a constant 2.25MHz switching frequency, n
High Switch Current: 0.7A and 1.2A
enabling the use of tiny, low cost capacitors and inductors n
No Schottky Diodes Required
1mm or less in height. Each output voltage is adjustable n
Low RDS(ON) Internal Switches: 0.35
Ω from 0.6V to 5V. Internal synchronous 0.35Ω, 0.7A/1.2A n Current Mode Operation for Excellent Line power switches provide high efficiency without the need and Load Transient Response for external Schottky diodes. n Short-Circuit Protected A user-selectable mode input is provided to allow the user n Low Dropout Operation: 100% Duty Cycle to trade-off ripple noise for low power efficiency. Burst n Ultralow Shutdown Current: IQ <1μA Mode® operation provides the highest efficiency at light n Output Voltages from 5V down to 0.6V loads, while pulse-skipping mode provides the lowest n Power-On Reset Output ripple noise at light loads. n Externally Synchronizable Oscillator n Optional External Soft-Start To further maximize battery life, the P-channel MOSFETs n Small Thermally Enhanced MSOP and 3mm are turned on continuously in dropout (100% duty cycle), × 3mm DFN Packages and both channels draw a total quiescent current of only 40μA. In shutdown, the device draws <1μA.
APPLICATIONS
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective n PDAs/Palmtop PCs owners. Protected by U.S. Patents including 5481178, 6580258, 6304066, 6127815, 6498466, n 6611131. Digital Cameras n Cellular Phones n Wireless and DSL Modems
TYPICAL APPLICATION Efficiency/Power Loss Curves 2.5V/1.8V at 400mA/800mA Step-Down Regulators
100 1 2.5V 90 VIN 1.8V 2.5V TO 5.5V 80 10μF 0.1 100k POWER LOSS (W) 70 RUN/SS2 VIN RUN/SS1 60 MODE/SYNC POR RESET 50 0.01 V 4.7μH 2.2μH OUT2 VOUT1 2.5V SW2 SW1 1.8V 40 400mA 22pF LTC3548A 22pF 800mA EFFICIENCY (%) 30 0.001 20 V V V IN = 3.3V FB2 FB1 Burst Mode OPERATION 887k 887k 10 4.7μF 280k GND 442k 10μF NO LOAD ON OTHER CHANNEL 0 0.0001 1 10 100 1000 3548A TA01 LOAD CURRENT (mA) 3548A TA02 3548afa 1
