Part Number: MT7201
Function: 1A, LED Driver with Internal Switch
Package: SOT89-5 Type
Manufacturer: Maxic Technology
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Description
The MT7201 is a continuous mode inductive step-down converter, designed for driving single or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 7~40V and provides an externally adjustable output current of up to 1A. Depending upon supply voltage and external components, this can provide up to 32 watts of output power. The MT7201 includes the output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current. Output current can be adjusted above, or below the set value, by applying an external control signal to the ‘ADJ’ pin. The ADJ pin will accept either a DC voltage or a PWM waveform. Depending upon the control frequency, this will provide either a continuous or a gated output current. The PWM filter components are contained within the chip. The PWM filter provides a soft-start feature by controlling the rise of input/output current. The soft-start time can be increased using an external capacitor from the ADJ pin to ground. Applying a voltage of 0.2V or lower to the ADJ pin turns the output off and switches the device into a low current standby state. The device is assembled in a SOT89-5 pin package.
Features
Pass 4KV ESD test Simple low parts count 1A output current Single pin on/off and brightness control using DC voltage or PWM Internal PWM filter Soft-start High efficiency (up to 97%) Wide input voltage range: 7V to 40V Output shutdown Up to 1MHz switching frequency Inherent open-circuit LED protection Typical 2% output current accuracy APPLICATION Low voltage halogen replacement LEDs Automotive lighting Low voltage industrial lighting LED back-up lighting Illuminated signs APPLICATION CIRCUIT PIN CONFIGURATION 0.1Ω LX 1 5 VIN VIN ISENSE 4.7μF GND 2 SOT89-5 47μH MT7201 LX GND ADJ ADJ 3 (Top view) MT7201 Rev. 1.5 4 ISENSE www.maxictech.com Copyright © 2008 Maxic Technology Corporation Page 1 MT7201 1A LED driver with internal switch Absolute maximum ratings (voltages to GND unless otherwise stated) Input voltage (VIN) ISENSE voltage (VSENSE) LX output voltage (VLX) Adjust pin input voltage (VADJ) Switch output current (ILX) Power dissipation (Ptot) Operating temperature (TOP) Storage temperature (TST) Junction temperature (Tj MAX) -0.3V to +40V +0.3V to -5V (measured with respect to VIN) -0.3V to +40V -0.3V to +6V 1.25A 1W -40 to 105°C -55 to 150°C 150°C Thermal resistance Junction to ambient (RθJA) 140°C/W Pin description Name LX GND ADJ Pin No. 1 2 3 Description Drain of Power MOS switch Ground Multi-function On/Off and brightness control pin: Leave floating for normal operation.(VADJ=VREF=1.2V giving nominal average output current IOUTnom=0.1/RS) Drive to voltage below 0.2V to turn off output current Drive with DC v […]