Datasheet LTC3548-2 (Analog Devices)
| Hersteller | Analog Devices |
| Beschreibung | Dual Synchronous, Fixed/Adjustable Output, 2.25MHz Step-Down DC/DC Regulator |
| Seiten / Seite | 16 / 1 — FEATURES. DESCRIPTION. High Effi ciency: Up to 95%. 1.8V/800mA Fixed … |
| Dateiformat / Größe | PDF / 418 Kb |
| Dokumentensprache | Englisch |
FEATURES. DESCRIPTION. High Effi ciency: Up to 95%. 1.8V/800mA Fixed Output and 400mA Adjustable. Output Voltage
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LTC3548-2 Dual Synchronous, Fixed /Adjustable Output, 2.25MHz Step-Down DC/DC Regulator
FEATURES DESCRIPTION
n
High Effi ciency: Up to 95%
The LTC®3548-2 is a dual, constant-frequency, synchro- n
1.8V/800mA Fixed Output and 400mA Adjustable
nous step-down DC/DC converter. Intended for low power
Output Voltage
applications, it operates from 2.5V to 5.5V input voltage n
Only 40μA Quiescent Current (Both Channels)
range and has a constant 2.25MHz switching frequency, n
2.25MHz Constant-Frequency Operation
allowing the use of tiny, low cost capacitors and inductors n
High Switch Current Limits: 1.2A and 0.7A
with a profi le ≤1.2mm. For channel 1, the output voltage is n
No Schottky Diodes Required
fi xed at 1.8V/800mA; for channel 2, the output voltage is n
Low RDS(ON) Internal Switches: 0.35Ω
adjustable from 0.6V to VIN Internal synchronous 0.35Ω, n Current Mode Operation for Excellent Line 1.2A/0.7A power switches provide high effi ciency without and Load Transient Response the need for external Schottky diodes. n Short-Circuit Protected A user selectable mode input is provided to allow the n Low Dropout Operation: 100% Duty Cycle user to trade-off noise ripple for low power effi ciency. n Ultralow Shutdown Current: IQ < 1μA Burst Mode® operation provides high effi ciency at light n Power-On Reset Output loads, while pulse-skipping mode provides low noise n Externally Synchronizable Oscillator ripple at light loads. n Small, Thermally Enhanced 3mm × 3mm DFN Package To further maximize battery run time, the P-channel
APPLICATIONS
MOSFETs are turned on continuously in dropout (100% duty cycle), and both channels draw a total quiescent cur- n PDAs/Palmtop PCs rent of only 40μA. In shutdown, the device draws <1μA. n Digital Cameras n Cellular Phones 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 Portable Media Players owners. Protected by U.S. Patents, including 5481178, 6127815, 6304066, 6498466, 6580258 6611131.. n PC Cards n Wireless and DSL Modems
TYPICAL APPLICATION Effi ciency and Power Loss vs Load Current
VIN 2.8V TO 5.5V 100 1000 10μF RUN2 V 100k IN RUN1 95 MODE/SYNC POR RESET 90 EFFICIENCY 100 POWER LOSS (mW) LTC3548-2 85 VOUT2 4.7μH 2.2μH VOUT1 POWER LOSS 2.5V SW2 SW1 1.8V 80 10 400mA 68pF 800mA 75 EFFICIENCY (%) VIN = 3.6V V V FB2 OUT1 70 1 VOUT = 1.8V 887k GND Burst Mode OPERATION 4.7μF 280k 10μF 65 CHANNEL 1 NO LOAD ON CHANNEL 2 35482 F01 60 0.1 1 10 100 1000
Figure 1. 2.5V/1.8V at 400mA/800mA Step-Down Regulators
LOAD CURRENT (mA) 35482 F01b 35482fb 1
FEATURES DESCRIPTION
n
High Effi ciency: Up to 95%
The LTC®3548-2 is a dual, constant-frequency, synchro- n
1.8V/800mA Fixed Output and 400mA Adjustable
nous step-down DC/DC converter. Intended for low power
Output Voltage
applications, it operates from 2.5V to 5.5V input voltage n
Only 40μA Quiescent Current (Both Channels)
range and has a constant 2.25MHz switching frequency, n
2.25MHz Constant-Frequency Operation
allowing the use of tiny, low cost capacitors and inductors n
High Switch Current Limits: 1.2A and 0.7A
with a profi le ≤1.2mm. For channel 1, the output voltage is n
No Schottky Diodes Required
fi xed at 1.8V/800mA; for channel 2, the output voltage is n
Low RDS(ON) Internal Switches: 0.35Ω
adjustable from 0.6V to VIN Internal synchronous 0.35Ω, n Current Mode Operation for Excellent Line 1.2A/0.7A power switches provide high effi ciency without and Load Transient Response the need for external Schottky diodes. n Short-Circuit Protected A user selectable mode input is provided to allow the n Low Dropout Operation: 100% Duty Cycle user to trade-off noise ripple for low power effi ciency. n Ultralow Shutdown Current: IQ < 1μA Burst Mode® operation provides high effi ciency at light n Power-On Reset Output loads, while pulse-skipping mode provides low noise n Externally Synchronizable Oscillator ripple at light loads. n Small, Thermally Enhanced 3mm × 3mm DFN Package To further maximize battery run time, the P-channel
APPLICATIONS
MOSFETs are turned on continuously in dropout (100% duty cycle), and both channels draw a total quiescent cur- n PDAs/Palmtop PCs rent of only 40μA. In shutdown, the device draws <1μA. n Digital Cameras n Cellular Phones 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 Portable Media Players owners. Protected by U.S. Patents, including 5481178, 6127815, 6304066, 6498466, 6580258 6611131.. n PC Cards n Wireless and DSL Modems
TYPICAL APPLICATION Effi ciency and Power Loss vs Load Current
VIN 2.8V TO 5.5V 100 1000 10μF RUN2 V 100k IN RUN1 95 MODE/SYNC POR RESET 90 EFFICIENCY 100 POWER LOSS (mW) LTC3548-2 85 VOUT2 4.7μH 2.2μH VOUT1 POWER LOSS 2.5V SW2 SW1 1.8V 80 10 400mA 68pF 800mA 75 EFFICIENCY (%) VIN = 3.6V V V FB2 OUT1 70 1 VOUT = 1.8V 887k GND Burst Mode OPERATION 4.7μF 280k 10μF 65 CHANNEL 1 NO LOAD ON CHANNEL 2 35482 F01 60 0.1 1 10 100 1000
Figure 1. 2.5V/1.8V at 400mA/800mA Step-Down Regulators
LOAD CURRENT (mA) 35482 F01b 35482fb 1