Datasheet LT3472 (Analog Devices)

LT3472 Boost and Inverting DC/DC Converter for CCD Bias
U FEATURES DESCRIPTIO
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Generates 15V at 20mA, –8V at 50mA
The LT®3472 dual channel switching regulator generates
from a Li-Ion Cell
positive and negative outputs for biasing CCD imagers. ■
Internal Schottky Diodes
The device delivers up to –8V at 50mA and 15V at 20mA ■ VIN Range: 2.2V to 16V from a lithium-ion cell, providing bias for many popular ■ Output Voltages Up to ±34V CCD imagers. Switching at 1.1MHz, the LT3472 uses tiny, ■ Capacitor-Programmable Soft-Start low profile capacitors and inductors and generates low ■ Sequencing: Positive Output Reaches 88% of Final noise outputs that are easy to filter. Schottky diodes are Value Before Negative Output Begins internal and the output voltages are set with one resistor ■ Requires Only One Resistor to Set Output Voltage per channel, reducing external component count. The ■ Constant Switching Frequency Ensures Low entire solution is less than 1mm profile and occupies just Noise Outputs 50mm2. ■ Available in a 10-Lead (3mm × 3mm) DFN Package Internal sequencing circuitry disables the negative chan-
U
nel until the positive channel has reached 88% of its final
APPLICATIO S
value, ensuring that the sum of the two outputs is always ■ CCD Bias positive. Separate soft-start capacitors for each output ■ TFT LCD Bias allow the ramp of each output to be independently ■ OLED Bias controlled. ■ ± Rail Generation for Op Amps The LT3472 is available in a low profile (0.75mm) 10-pin , LTC and LT are registered trademarks of Linear Technology Corporation. 3mm × 3mm DFN package.
U TYPICAL APPLICATIO Li-Ion CCD Bias Supply
VIN
Conversion Efficiency
3V TO 4.2V 2.2µF 85 1µF 22µH 47µH 80 POS CHANNEL 75 SWP VIN SWN VPOS 70 NEG CHANNEL 15V VPOS DN 20mA 65 550k FBP LT3472 47µH 60 4.7pF 320k VNEG FBN –8V EFFICIENCY (%) 55 10pF 50mA SHDN SHDN 50 SSP GND SSN 45 40 2.2µF 100nF 100nF 2.2µF 0 10 20 30 40 50 LOAD CURRENT (mA) 3472 TA01b 3472 TA01a 3472f 1