LT1946 LINER [Linear Technology], LT1946 Datasheet
LT1946
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LT1946 Summary of contents
Page 1
... The LT 1946 is a fixed frequency step-up DC/DC converter containing an internal 1.5A, 36V switch. Capable of gener- ating 8V at 430mA from a 3.3V input, the LT1946 is ideal for large TFT-LCD panel power supplies. The LT1946 switches at 1.2MHz, allowing the use of tiny, low profile inductors and low value ceramic capacitors. Loop com- ...
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... SHDN Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1946E is guaranteed to meet performance specifications from Specifications over the – operating temperature range are assured by design, characterization and correlation with statistical process controls ...
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... C A 600 400 200 0 0 0.2 0.4 0.6 0.8 1.0 1.2 FEEDBACK VOLTAGE (V) 1946 G02 Quiescent Current 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 –50 – 125 75 100 TEMPERATURE ( C) 1946 G05 LT1946 Current Limit 2.6 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0 –50 – 100 TEMPERATURE ( C) 1946 G03 Switching Waveforms for Figure 1 Circuit V OUT 20mV/DIV AC COUPLED V SW 5V/DIV ...
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... LT1946 CTIO S V (Pin 1): Error Amplifier Output Pin. Tie external com- C pensation network to this pin, or use the internal compen- sation network by shorting the (Pin 2): Feedback Pin. Reference voltage is 1.250V. Connect resistive divider tap here. Minimize trace area at FB. Set V according ...
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... When the FB pin voltage exceeds 0.5V, the oscillator returns to the normal frequency of 1.2MHz. A soft-start function is also provided by the LT1946. When the part is brought out of shutdown current is sourced out of the SS pin. By connecting an external capacitor to the SS pin, the rate of voltage rise on the pin can be set ...
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... Ceramic capacitors also make a good choice for the input decoupling capacitor, which should be placed as close as possible to the LT1946 4.7 F input capacitor is sufficient for most applications. Table 2 shows a list of several ceramic capacitor manufacturers. Consult the manufacturers for detailed information on their entire selection of ceramic parts ...
Page 7
... Like all other current mode switching regulators, the LT1946 needs to be compensated for stable and efficient operation. Two feedback loops are used in the LT1946: a fast current loop which does not require compensation, and a slower voltage loop which does. Standard Bode plot analysis can be used to understand and adjust the voltage feedback loop ...
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... W U Diode Selection A Schottky diode is recommended for use with the LT1946. The Microsemi UPS120 is a very good choice. Where the input to output voltage differential exceeds 20V, use the UPS140 (a 40V diode). These diodes are rated to handle an average forward current of 1A. For applications where the average forward current of the diode is less than 0 ...
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... 10.5k 33. 470pF C6 0 50mV/DIV AC COUPLED I LI 0.5A/DIV AV 150mA DD LOAD 100mA 400 500 1946 TA01a LT1946 20V 5mA C5 0 10V 450mA 275mA 3. 2 OFF –10V 1946 TA01 10mA Transient Response ...
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... LOAD CURRENT (mA) 10 12V Output Boost Converter OFF ON SHDN C1 LT1946 COMP GND 33. 470pF 100nF C1: 4.7 F, X5R OR X7R, 6.3V C2: 4.7 F, X5R OR X7R, 16V D1: MICROSEMI UPS120 OR EQUIVALENT ...
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... BSC 4.88 0.1 DETAIL “A” (.192 .004) 0 – 6 TYP 0.53 0.015 1.10 (.021 .006) (.043) DETAIL “A” MAX SEATING PLANE 0.22 – 0.38 (.009 – .015) LT1946 0.52 (.206 REF 3.00 0.102 (.118 .004) NOTE 0.86 (.034) REF 0.13 0.05 (.005 .002) 0.65 MSOP (MS8) 1001 ( ...
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... McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 Low Profile, Triple Output TFT Supply (8V, – 8V, 23V 0 5 28.7k OFF ON SHDN 8 SS LT1946 COMP V GND 5.23k 49. 470pF C8 0 2V/DIV ...