The R1201x Series is a PWM control type step-up DC/DC converter IC with low supply current. It can drive white LEDs in constant current with high efficiency by using an inductor, a resistor and capacitors as external components.
The R1201x Series are PWM control type step-up DC/DC converter ICs featuring low supply current. These devices are fully dedicated to driving White LEDs with constant current and include an internal NMOS FET, forward diode, oscillator, and various protection circuits such as current limit, over-voltage protection (OVP), and under-voltage lockout (UVLO). A built-in diode allows the drive of up to 5 serial white LEDs without requiring an external diode.
The ICs allow for LED current setting via an external resistance value and support dimming control through a CE pin using PWM signals between 200Hz and 300kHz. The oscillator frequency can be selected from 1MHz or 1.2MHz, and the maximum duty cycle is typically fixed at 91%. Available packages include DFN1616-6 and SOT-23-6.
| Supply Current (Typ.) | 450uA (R1201xxx3A/4A) |
|---|---|
| Standby Current | Max. 5uA |
| Input Voltage Range | 1.8V to 5.5V |
| Feedback Voltage | 0.2V |
| Temperature-Drift Coefficient of Feedback Voltage | +150ppm/°C |
| Maximum Duty Cycle (Typ.) | 91% |
| Switch ON Resistance (Typ.) | 1.35 Ohm |
| UVLO Detector Threshold (Typ.) | 1.6V |
| Lx Current Limit Protection (Typ.) | 700mA |
| OVP Detector Threshold Options | 9.5V, 14.0V, 18.5V, 20.6V, 21.6V |
| LED Dimming Control Frequency Range | 200Hz to 300kHz |
| Operating Temperature Range | -40 to 85 °C |
The ICs can drive up to 5 serial white LEDs because a diode is built-in.
The oscillator frequency can be selected from 1MHz or 1.2MHz.
The LEDs current can be set by an external resistance value using the feedback voltage of 0.2V.
If the CE pin input is "L" in the fixed time (Typ. 0.5ms), the IC becomes the standby mode and turns OFF LEDs.