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GM7620 Dataheets PDF



Part Number GM7620
Manufacturers Gamma Microelectronics
Logo Gamma Microelectronics
Description Fixed Frequency Step-up Dc-to-dc Converter
Datasheet GM7620 DatasheetGM7620 Datasheet (PDF)

PRELIMINARY GM7620 FIXED FREQUENCY STEP-UP DC/DC CONVERTER www.DataSheet4U.com 1.2MHz Fixed Frequency Switching Inherently Matched LED Current Adjustable Control of LED Current Drives Five White LEDs from 2V Drives Six White LEDs from 2.7V Drives Eight White LEDs from 3V Disconnects LEDs In Shutdown Uses Tiny Ceramic Capacitors Uses Tiny 1mm-Tall Inductors Regulates Current Even When VIN > VOUT Operates with VIN as Low as 1V Up to 80% Efficiency The GM7620 is a fixed frequency step-up DC/DC.

  GM7620   GM7620



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PRELIMINARY GM7620 FIXED FREQUENCY STEP-UP DC/DC CONVERTER www.DataSheet4U.com 1.2MHz Fixed Frequency Switching Inherently Matched LED Current Adjustable Control of LED Current Drives Five White LEDs from 2V Drives Six White LEDs from 2.7V Drives Eight White LEDs from 3V Disconnects LEDs In Shutdown Uses Tiny Ceramic Capacitors Uses Tiny 1mm-Tall Inductors Regulates Current Even When VIN > VOUT Operates with VIN as Low as 1V Up to 80% Efficiency The GM7620 is a fixed frequency step-up DC/DC converter designed to operate as a constant-current source. Because it directly regulates output current, the GM7620 is ideal for driving light emitting diodes (LEDs) whose light intensity is proportional to the current passing through them, not the voltage across their terminals. With an input voltage range of 1V to 10V, the device works from a variety of input sources. The GM7620 accurately regulates LED current even when the input voltage is higher than the LED voltage, greatly simplifying batterypowered designs. A single external resistor sets LED current between 5mA and 40mA, which can then be easily adjusted using either a DC voltage or a pulse width modulated (PWM) signal. When the GM7620 is placed in shutdown, the LEDs are disconnected from the output, ensuring a quiescent current of under 1mA for the entire circuit. The device’s 1.2MHz switching frequency permits the use of tiny, low profile chip inductors and capacitors to minimize footprint and cost in space-conscious portable applications. The GM7620 is available in 6-lead plastic SOT-23 package. Applications: Handheld Computers Cellular Telephones Digital Cameras Portable MP3 Players TYPICAL APPLICATION (Li-ION Driver for 4 White LEDs) L1 6.8µH VIN 2.7V to 4.2V 6 VIN C1 4.7µF GM7620 PWM DIMMING CONTROL 5 SHDN RSET 4 RSET 1.5k LED 3 GND 2 15mA 1 SW C2 1µF D1 Revision 1, December 2002 1 www.gammamicro.com PRELIMINARY GM7620 FIXED FREQUENCY STEP-UP DC/DC CONVERTER PIN CONNECTIONS AND FUNCTIONS PIN CONNECTIONS (Top View) SW 1 www.DataSheet4U.com 6 VIN 5 SHDN 4 RSET GND 2 LED 3 6-lead SOT-23 PIN 1 2 3 4 5 6 PARAMETER SW GND LE D RSET SHDN VIN DESCRIPTION Switch Pin. This is the collector of the internal NPN power switch. Minimize the metal trace area connected to this pin to minimize EMI. Ground Pin. Tie this pin directly to local ground plane. LED Pin. This is the collector of the internal NPN LED switch. Connect the cathode of the bottom LED to this pin. A resistor between this pin and ground programs the LED current (that flows into the LED pin). This pin is also used to provide LED dimming. Shutdown Pin. Tie this pin higher than 0.85V to turn on the GM7620; tie below 0.25V to turn it off. Input Supply Pin. Bypass this pin with a capacitor to ground as close to the de vice as possible. ORDERING INFORMATION . GM7620 PACKAGE SOT23-6 PART No. GM7620ST26 Revision 1, December 2002 2 www.gammamicro.com PRELIMINARY GM7620 FIXED FREQUENCY STEP-UP DC/DC CONVERTER ELECTRICAL CHARA.


D1761 GM7620 D27512


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