Datasheet LTC3522 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Synchronous 400mA Buck-Boost and 200mA Buck Converters |
| Pages / Page | 20 / 1 — FEATURES. DESCRIPTION. Dual High Effi ciency DC/DC Converters:. … |
| File Format / Size | PDF / 284 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Dual High Effi ciency DC/DC Converters:. Buck-Boost. (VOUT: 2.2V to 5.25V, IOUT: 400mA
Model Line for this Datasheet
Text Version of Document
LTC3522 Synchronous 400mA Buck-Boost and 200mA Buck Converters
FEATURES DESCRIPTION
■
Dual High Effi ciency DC/DC Converters:
The LTC®3522 combines a 400mA buck-boost DC/DC con-
Buck-Boost (VOUT: 2.2V to 5.25V, IOUT: 400mA
verter with a 200mA synchronous buck DC/DC converter in
for VIN > 3V, VOUT = 3.3V)
a tiny 3mm × 3mm package. The 1MHz switching frequency
Buck (VOUT: 0.6V to VIN, IOUT: 200mA)
minimizes the solution footprint while maintaining high ■
2.4V to 5.5V Input Voltage Range
effi ciency. Both converters feature internal soft-start and ■
Pin Selectable Burst Mode
®
Operation
compensation, simplifying the design process. ■
25μA Total Quiescent Current for Both Converters in
The buck converter is current mode controlled and utilizes
Burst Mode Operation
an internal synchronous rectifi er for high effi ciency. The ■ Independent Power Good Indicator Outputs buck converter supports 100% duty cycle operation to ■ Integrated Soft-Start extend battery life. If the PWM pin is held low, the buck ■ Thermal and Overcurrent Protection converter automatically transitions from Burst Mode opera- ■ <1μA Quiescent Current in Shutdown tion to PWM mode. With the PWM pin held high, the buck ■ Small 0.75mm × 3mm × 3mm QFN Package converter remains in low noise, 1MHz PWM mode.
APPLICATIONS
The buck-boost converter provides continuous conduc- tion operation to maximize effi ciency and minimize noise. ■ Flash-Based MP3 Players At light loads, the buck-boost converter can be placed in ■ Medical Instruments Burst Mode operation to improve effi ciency and reduce ■ Digital Cameras no-load standby current. ■ PDAs, Handheld PCs ■ Personal Navigation Devices The LTC3522 provides a 1μA shutdown mode, overtem- perature shutdown and current limit protection on both , LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. converters. The LTC3522 is available in a 16-pin low profi le Protected by U.S. Patents, including 6404251 and 6166527. 3mm × 3mm QFN package.
TYPICAL APPLICATION Effi ciency vs VIN
100 BUCK-BOOST VIN 98 I 2.4V TO 4.2V + 96 OUT = 100mA V Li-Ion 4.7μF OUT = 3.3V L1 L2 94 8.2 PV V μH IN1 PVIN2 4.7μH 92 OUT2 BUCK 1.8V SW2 SW1A 90 IOUT = 100mA 200mA 88 V 6.8μF OUT = 1.8V 137k 12pF SW1B VOUT1 86 LTC3522 3.3V 84 FB2 VOUT1 300mA (400mA 82 68.1k ON SHDN2 1M 4.7μF EFFICIENCY (%) V 80 IN > 3V) OFF SHDN1 FB1 78 76 PGOOD2 432k PWM 74 BURST PWM PGOOD1 72 PGND1 GND PGND2 70 3522 TA01a 2.4 3.4 4.4 5.4 L1: COILCRAFT MSS6132-8.2μH VIN (V) L2: COILCRAFT MSS6132-4.7μH 3522 TA01b 3522fa 1
FEATURES DESCRIPTION
■
Dual High Effi ciency DC/DC Converters:
The LTC®3522 combines a 400mA buck-boost DC/DC con-
Buck-Boost (VOUT: 2.2V to 5.25V, IOUT: 400mA
verter with a 200mA synchronous buck DC/DC converter in
for VIN > 3V, VOUT = 3.3V)
a tiny 3mm × 3mm package. The 1MHz switching frequency
Buck (VOUT: 0.6V to VIN, IOUT: 200mA)
minimizes the solution footprint while maintaining high ■
2.4V to 5.5V Input Voltage Range
effi ciency. Both converters feature internal soft-start and ■
Pin Selectable Burst Mode
®
Operation
compensation, simplifying the design process. ■
25μA Total Quiescent Current for Both Converters in
The buck converter is current mode controlled and utilizes
Burst Mode Operation
an internal synchronous rectifi er for high effi ciency. The ■ Independent Power Good Indicator Outputs buck converter supports 100% duty cycle operation to ■ Integrated Soft-Start extend battery life. If the PWM pin is held low, the buck ■ Thermal and Overcurrent Protection converter automatically transitions from Burst Mode opera- ■ <1μA Quiescent Current in Shutdown tion to PWM mode. With the PWM pin held high, the buck ■ Small 0.75mm × 3mm × 3mm QFN Package converter remains in low noise, 1MHz PWM mode.
APPLICATIONS
The buck-boost converter provides continuous conduc- tion operation to maximize effi ciency and minimize noise. ■ Flash-Based MP3 Players At light loads, the buck-boost converter can be placed in ■ Medical Instruments Burst Mode operation to improve effi ciency and reduce ■ Digital Cameras no-load standby current. ■ PDAs, Handheld PCs ■ Personal Navigation Devices The LTC3522 provides a 1μA shutdown mode, overtem- perature shutdown and current limit protection on both , LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. converters. The LTC3522 is available in a 16-pin low profi le Protected by U.S. Patents, including 6404251 and 6166527. 3mm × 3mm QFN package.
TYPICAL APPLICATION Effi ciency vs VIN
100 BUCK-BOOST VIN 98 I 2.4V TO 4.2V + 96 OUT = 100mA V Li-Ion 4.7μF OUT = 3.3V L1 L2 94 8.2 PV V μH IN1 PVIN2 4.7μH 92 OUT2 BUCK 1.8V SW2 SW1A 90 IOUT = 100mA 200mA 88 V 6.8μF OUT = 1.8V 137k 12pF SW1B VOUT1 86 LTC3522 3.3V 84 FB2 VOUT1 300mA (400mA 82 68.1k ON SHDN2 1M 4.7μF EFFICIENCY (%) V 80 IN > 3V) OFF SHDN1 FB1 78 76 PGOOD2 432k PWM 74 BURST PWM PGOOD1 72 PGND1 GND PGND2 70 3522 TA01a 2.4 3.4 4.4 5.4 L1: COILCRAFT MSS6132-8.2μH VIN (V) L2: COILCRAFT MSS6132-4.7μH 3522 TA01b 3522fa 1
