TPS92633MPWPR datasheet(13/48 Pages) TI

13 / 48 page

If device detects a fault, it pulls down the FAULT pin by an internal constant current, I(FAULT_pulldown) as a fault

indication to the fault bus.

7.3.2 Enable and Shutdown (EN)

The TPS92633 device has an enable input. When EN is low, the device is in sleep mode with ultra low quiescent

current I(SD). This low current helps to save system-level current consumption in applications where battery

voltage directly connects to the device without high-side switches.

7.3.3 Reference Current (IREF)

The TPS92633 device has IREF pin to generate a high accuracy and low temperature shift current reference.

The calculated result for I(IREF) is 100 µA when R(IREF) is 12.3 kΩ. The I(IREF) can be programmed by external

resistor, R(IREF) in the range from 25 µA to 250 µA. The voltage on the IREF pin is regulated to the 1.235 V

typically, and the current output on IREF pin can be calculated by using Equation 1.

(IREF)

(1)

where

• V(IREF) = 1.235 V (typical)

• R(IREF) = 12.3 kΩ recommended

The R(IREF) resistor needs to be placed as close as possible to the IREF pin with a 1-nF ceramic capacitor in

parallel to achieve the noise immunity. The off-board R(IREF) setup is not allowed due to the concern of reference

current instability.

7.3.4 Constant-Current Output and Setting (INx)

The TPS92633 device is a high-side current driver for driving LEDs. The device controls each output current

through regulating the voltage drop on an external high-side current-sense resistor, R(SNSx) between SUPPLY

and INx independently for each channel. An integrated error amplifier drives an internal power transistor to

maintain the voltage drop on the current-sense resistor R(SNSx) to V(CS_REG), therefore regulates the current

output to target value. When the output current is in regulation, the current value for each channel can be

calculated by using Equation 2.

(CS _ REG)

(OUTx _ Tot)

(SNSx)

(2)

where

• V(CS_REG) is variable according to Equation 3

• x = 1, 2 or 3 for output channel 1, 2 or 3

When the supply voltage drops below total LED string forward voltage plus required headroom voltage, the sum

of V(DROPOUT) and V(CS_REG), the TPS92633 is not able to deliver enough current output as set by the value of

R(SNSx), and the voltage across the current-sense resistor R(SNSx) is less than V(CS_REG).

7.3.5 Analog Current Control (ICTRL)

The TPS92633 supports analog constant current control for all three output channels together through adjusting

the V(CS_REG) voltage. As described in Constant-Current Output and Setting (INx), the TPS92633 regulates

each channel output current by maintaining the voltage drop on each R(SNSx) same to V(CS_REG). The V(CS_REG)

voltage is adjustable by an external resistor on ICTRL pin. The TPS92633 outputs a constant current, I(ICTRL),

on the ICTRL pin and measures the voltage on the ICTRL pin, V(ICTRL), to determine the V(CS_REG). The I(ICTRL)

current is 10 times of the I(IREF), and the V(ICTRL) is multiplied result of I(ICTRL) and R(ICTRL). The TPS92633

internally clamps the V(ICTRL) to maximum 2.75 V. The V(CS_REG) voltage can be calculated by using Equation 3.

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TPS92633

SLVSFE8 – JUNE 2021

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