Original RT8537 RT8537GQW marking OJD OJQ OJG OJW OJ9 OJX(0JG 0JD 0JQ 0JW 0J9 0JX) current mode boost LED driver with programmable dimming control
The RT8537GQW is a constant frequency, current mode step-up LED driver. In normal operation, when the PWM control circuit is set by the oscillator, the N-MOSFET is turned on, and when the current comparator resets the PWM control circuit, the N-MOSFET is turned off. When the N-MOSFET is off, the inductor current is conducted through the external diode.
Operating Quiescent Current into VIN: 2.3mA
Shutdown current: 1μA
Undervoltage Lockout Threshold: 2.5V Max
Undervoltage Lockout Hysteresis: 70mV
Oscillator Frequency: 1.5MHz max
Maximum duty cycle: 93%
Applications for mobile phone and smart phone, digital camera and GPS, portable DVD player.
RT3587 General Description:
The RT8537 is a current mode Boost-type LED driver with programmable brightness dimming control for portable devices. With the 40V integrated MOSFET, the RT8537 can support up to 10 LEDs in series and wide input voltage range from 2.9V to 18V. The Boost converter runs at 1.2MHz switching frequency which allows for the use of small external components. The LED current is adjustable by an external resister at FB pin and the feedback voltage is regulated to 200mV typically.
The RT8537 provides PWM dimming mode and 1 wire digital dimming mode for accurate LED current control from EN pin. In PWM dimming mode, the feedback reference voltage is changed with the PWM duty cycleproportionally and the available PWM frequency range is from 5kHz to 50kHz. In 1-wire digital dimming mode, it provides a programmable 32-step brightness dimming function with the EN pin setting.
The RT8537 provides protection functions including LED open protection, input under voltage lockout, current limit and over temperature protection.