Datasheet LT1945 (Analog Devices)

LT1945 Dual Micropower DC/DC Converter with Positive and Negative Outputs
FEATURES DESCRIPTION
n
Generates Well-Regulated Positive and
The LT®1945 is a dual micropower DC/DC converter in a
Negative Outputs
10-pin MSOP package. Each converter is designed with n
Low Quiescent Current:
a 350mA current limit and an input voltage range of 1.2V
20μA in Active Mode (per Converter)
to 15V, making the LT1945 ideal for a wide variety of ap-
<1μA in Shutdown Mode
plications. Both converters feature a quiescent current of n
Operates with VIN as Low as 1.2V
only 20μA at no load, which further reduces to 0.5μA in n Low VCESAT Switch: 250mV at 300mA shutdown. A current limited, fi xed off-time control scheme n Uses Small Surface Mount Components conserves operating current, resulting in high effi ciency n High Output Voltage: Up to ±34V over a broad range of load current. The 36V switch allows n Tiny 10-Pin MSOP Package high voltage outputs up to ±34V to be easily generated without the use of costly transformers. The LT1945’s
APPLICATIONS
low off-time of 400ns permits the use of tiny, low profi le n inductors and capacitors to minimize footprint and cost Small TFT LCD Panels n in space-conscious portable applications. Handheld Computers n Battery Backup L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Digital Cameras
TYPICAL APPLICATION Dual Output (+12V, –20V) Converter Effi ciency at VIN = 3.6V
C4 90 L1 0.1μF 10μH D1 VIN –20V 85 2.7V 10mA +12V OUTPUT TO 5V 8 10 80 100pF 365k –20V OUTPUT VIN SW1 75 2 1 SHDN1 NFB1 70 C1 LT1945 D2 C2 4.7μF 1μF 4 5 65 EFFICIENCY (%) SHDN2 FB2 24.9k 60 GND PGND PGND SW2 3 7 9 6 55 115k 50 0.1 1 10 100 C3 LOAD CURRENT (mA) 1μF 4.7pF 1945 TA01a L2 1M 10μH D3 12V 20mA C1: TAIYO YUDEN JMK212BJ475 1945 TA01 C2, C3: TAIYO YUDEN TMK316BJ105 C4: TAIYO YUDEN EMK107BJ104 D1, D2, D3: ZETEX ZHCS400 L1, L2: MURATA LQH3C100 1945fa 1