ltc3421 Linear Technology Corporation, ltc3421 Datasheet
ltc3421
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ltc3421 Summary of contents
Page 1
... Other features include shutdown, antiringing control, thermal limit and reference output. The LTC3421 is available in a small 4mm package. , LTC and LT are registered trademarks of Linear Technology Corporation. Burst Mode is a registered trademark of Linear Technology Corporation. ...
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... V OUT PGND PACKAGE 24-LEAD (4mm 4mm) PLASTIC QFN = 125 C/W 1 LAYER BOARD C/W 4 LAYER BOARD, = 2.6 C LTC3421EUF 3421 = 28k, unless otherwise noted. T MIN TYP MAX 0.88 1 0.5 2.25 5.25 2.40 5.25 1.196 1.220 1.244 0.1 1 0.2 2 0.6 1.1 0 ...
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... BURST Threshold Voltage Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC3421E 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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... LTC3421 W U TYPICAL PERFOR A CE CHARACTERISTICS Single Cell to 3.3V Efficiency 100 V = 1.5V IN Burst Mode OPERATION 1. 3.3V 10 OUT f = 1MHz OSC 0 0 100 1000 OUTPUT CURRENT (mA) 3421 G01 Burst Mode Operation V OUT 50mV/DIV AC COUPLED SW INDUCTOR CURRENT 0.5A/DIV 2.5 s/DIV ...
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... ENB = High and the output voltage is is above 2.2V, OUT pulled up to greater than 2.5V from a secondary source such as a coin cell through a Schottky diode, the V output and low-battery comparator becomes powered from the output voltage and enabled. LTC3421 = 25 C, unless otherwise specified) A Frequency Accuracy 1.03 1.01 0.99 ...
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... LTC3421 CTIO S R (Pin 5): Connect a resistor to ground to program the T oscillator frequency according to the formula: 28 100 , f OSC R T where kHz and OSC T SS (Pin 6): Soft-Start Pin. Connect a capacitor from this pin to ground to set the soft-start time according to the ...
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... AMP I SENSE AMP + LIMIT – ERROR – AMP CURRENT COMP + + + SLEEP 1% Burst Mode CONTROL OFF UV – – 3% EXPOSED GND PAD PGND LTC3421 18 V OUTS V OUT 17 V OUT 19 V OUT LIM LIMIT SS R 150k 1.22V FB – ...
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... LTC3421 U OPERATIO LOW VOLTAGE START-UP The LTC3421 includes an independent start-up oscillator designed to start-up at input voltages of 0.85V typical. The frequency and peak current limit during start-up are inter- nally controlled. The device can start-up under some load (see graph of Start-Up Current vs Input Voltage). Soft- start and inrush current limiting are provided during start well as normal mode ...
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... For manual control of Burst Mode operation, the RC network can be eliminated. To force fixed frequency PWM mode, BURST should be connected to V force Burst Mode operation, BURST should be grounded. LTC3421 pin is disconnected C during Burst Mode opera- C ...
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... V 2 • OUTPUT DISCONNECT AND INRUSH LIMITING The LTC3421 is designed to allow true output disconnect by eliminating body diode conduction of the internal P-channel MOSFET rectifier. This allows V volts during shutdown without drawing any current from the input source. It also allows for inrush current limiting at turn-on, minimizing surge currents seen by the input supply ...
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... V Ceramic Capacitors Should be as Close to the IC IN OUT Pins as Possible Inductor Selection The high frequency operation of the LTC3421 allows the use of small surface mount inductors. The minimum inductance value is proportional to the operating fre- quency and is limited by the following constraints: V • ...
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... ON(MIN) and GND pins as OUT Thermal Considerations To deliver the power that the LTC3421 is capable of imperative that a good thermal path be provided to dissipate the heat generated within the package. This can be accomplished by taking advantage of the large thermal pad on the underside of the IC recommended that mul- ...
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... IN OUT output current is 370mA. Short Circuit The LTC3421 output disconnect feature allows output short circuit while maintaining a maximum set current limit. The IC has incorporated internal features such as current limit and thermal shutdown for protection from an excessive overload or short circuit. In applications that require a pro- ...
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... V IN 2.7V TO 4.2V C1 SHDN ENB 3 V REF 23 + LBI Li-Ion 22 LBO LTC3421 7 SYNC 8 I LIM R1 60k SS R GND PGND PGND PGND 0.1 F 28k *LOCATE COMPONENTS CLOSE TO PINS C1: TAIYO YUDEN JMK212BJ106MM C5: TAIYO YUDEN JMK325BJ226MM Figure 4. Lithium-Ion Application with an Active Snubber Circuit ...
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... U UF Package 24-Lead Plastic QFN (4mm 4mm) (Reference LTC DWG # 05-08-1697) 0.70 0.05 PACKAGE OUTLINE 0.25 0.05 0.50 BSC 0.75 0.05 4.00 0.10 (4 SIDES) 2.45 0.10 (4-SIDES) 0.200 REF 0.00 – 0.05 LTC3421 BOTTOM VIEW—EXPOSED PAD 0.23 TYP R = 0.115 (4 SIDES) TYP 23 24 0.38 0. (UF24) QFN 0603 0.25 0.05 0.50 BSC 3421f 15 ...
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... SHDN 0.1 F ENB V OUTS REF OUT 23 19 LBI V OUT 22 20 LOW BAT LBO LTC3421 V OUT OUTPUT 7 1 SYNC LIM C 9 BURST R1 60k SS R GND PGND PGND PGND ...