16-Channel Constant Current LED Driver With Error Detection and Current Gain
IT1507 is a 16-channel constant current LED driver with smart error detection and output current gain. The constant current for each output channel is from 4mA to 75mA set by an external resistor. IT1507 shares the data input and data output to extend the functionality, such as in-message error detection and current gain control in LED display systems.
IT1507 contains a 16-bit shift register and a 16-bit output latch, which convert: serial input data into parallel output format. At the output stages, sixteen regulated current ports are designed to provide constant current sinks with small skew between each channel to drive LEDs within a wide range of forward voltage (VF) variation. IT1507 can sustain maximum 18V at the output ports. The high clock frequency, DCLK up to 30MHz, also supports the system requirements of high volume data transmission.
With in-message error detection, IT1507 detects individual LED for both open- and short-circuit errors on-the-fly without extra components. The serial data can be shifted into IT1507 through the SDI pin, and the outputs perform open- and short-circuit detection at the same time. Besides, the VTH for short-circuit detection is settable for the variation of different LED forward voltage. Thus the system controller can detect the short-circuit error easily.
Users also can adjust the output current level of IT1507 by setting a programmable configuration code. The code is sent into IT1507 through the SDI pin. Falling edges of LE will latch the code in the shift register into a built-in 16-bit configuration register, instead of the output latch. The gain code will change the voltage at the terminal R-EXT and control the output current regulation. The output current can be adjusted by a gain range from 12.5% to 200%.
16 channels with constant-current
Constant output current range:
Excellent channel output current mismatch ratio:
- Between channels: <±1,5%(typ.);
- Between ICs: <±3%(typ.)
In-message error detectio
- Both open-circuit and short-circuit LEDs can be detected
- Settable VTH for LED short-circuit detection
- On-the-fly error detection
- Data-in, error-out; both errors are merged and coded with zeros
64-step programmable current gain: from 12.5% to 200%
Fast response of output current
- Min. output pulse width of OEN, 40ns with good uniformity between output channels
Staggered delay of outputs to prevent from current surge
Maximum data clock frequency: 30MHz
Schmitt trigger input