THL3514 Datasheet, PDF (7/16 Pages) THine Electronics, Inc. – The THL3514 is an LED driver with 24 channel constant

THL3514_Rev.1.01_E
FUNCTIONAL DESCRIPTION
External reference resistor
The constant current value of LED driver output channels are determined by the resistors connected between REXT0,
REXT1, REXT2 and GND. The external resistor value is calculated by the following equation.
0.6 [V]
REXT[kΩ]=
× 80
Iout [mA]
(Typical Value at Iout=20mA)
For example, when Iout=20mA, REXT=0.6/20 x 80=2.4[kΩ]
Writing to registers
The device includes 25-byte registers (R00-R18) for setting. Writing to registers is executed through the serial interface
and the value is maintained as long as power is applied. The register value can not be read.
Writing to registers should be invoked after the power supply (VDD) of all the devices in cascading and multidrop con-
nection gets stable above 3.0V.
Then after power-up, if using 2-pair serial LVDS input, initialization of 2-pair serial LVDS input must be done before
writing to registers. However, in case all the registers are continuously rewritten, in other words repeatedly refreshed, the
initialization of 2-pair serial LVDS input is not necessary after power-up and instantaneous interruption.
Please refer to the section “Initialization of 2-pair Serial LVDS Input” for details.
UVLO
The device has an internal UVLO (Under-Voltage Locked-Out) circuit to prevent the device from malfunction at low
supply voltage. Until power supply (VDD) has reached 2.5V (typical value), the UVLO holds the internal logic circuit in
a reset condition, and keeps the LED driver outputs and LVDS outputs in Hi-Z state. The UVLO circuit has hysteresis. If
power supply falls below 2.4V (typical value), the device gets into the above UVLO state in which the internal logic
circuit is reset and the regsiters are reset to default value.
Power Supply(VDD)
UVLO Threshold(2.5V typ.)
Hysterisys (0.1V typ.)
Internal Reset Signal
(Active-Low)
Short Circuit Protection
The device includes short circuit protection circuits for each pin of the external reference resistors, REXT0-REXT2 to
prevent the LED driver outputs from driving excessive current. If LED driver outputs turn on with the REXT0-REXT2
pin shorted to such as GND, overcurrent flowing in output transistors may causes permanent damage to the device.
The short circuit protection is a function to shutdown outputs immediately when the device detects short circuit condition
on REXT0-REXT2 pin. If short circuit condition is resolved, normal operation automatically resumes.
However, this function can not always prevent breakdown or damage to the device depending on usage situation and
duration of abnormality.
Thermal Shutdown
The device includes thermal shutdown circuit to prevent damages caused by excessive heat. If the junction temperature
exceeds the absolute maximum rating (Tj=150 °C), the thermal shutdown circuit turn off all LED driver outputs. The
thermal shutdown circuits has hysteresis. If Tj falls enough, normal operation automatically resumes.
However, this function can not always prevent breakdown or damage to the device depending on usage situation and
duration of abnormality.
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