LP5009 datasheet(17/51 Pages) TI

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8.3.3 Current Range Setting

The constant-current value (ISET) of all 12 channels is set by a single external resistor, RIREF. The value of RIREF

can be calculated by Equation 1.

IREF

SET

(1)

where:

• KIREF = 105

• VIREF = 0.7 V

With the IREF pin floating, the output current is close to zero. With the IREF pin shorted to GND, the LP50xx

device provides internal current-limit protection, and the output-channel maximum current is limited to ILIM.

The LP50xx device supports two levels of maximum output current, IMAX.

• When VCC is in the range from 2.7 V to 5.5 V, and the Max_Current_Option (bit) = 0, IMAX = 25.5 mA.

• When VCC is in the range from 3.3 V to 5.5 V, and the Max_Current_Option (bit) = 1, IMAX = 35 mA.

8.3.4 Automatic Power-Save Mode

When all the LED outputs are inactive, the LP50xx device is able to enter power-save mode automatically, thus

lowering idle-current consumption down to 10 μA (typical). Automatic power-save mode is enabled when register

bit Power_Save_EN = 1 (default) and all the LEDs are off for a duration of > 30 ms. Almost all analog blocks are

powered down in power-save mode. If any I2C command to the device occurs, the LP50xx device returns to

NORMAL mode.

8.3.5 Protection Features

8.3.5.1 Thermal Shutdown

The LP50xx device implements a thermal shutdown mechanism to protect the device from damage due to

overheating. When the junction temperature rises to 160°C (typical), the device switches into shutdown mode.

The LP50xx device releases thermal shutdown when the junction temperature of the device is reduced to 145°C

(typical).

8.3.5.2 UVLO

The LP50xx device has an internal comparator that monitors the voltage at VCC. When VCC is below VUVF, reset

is active and the LP50xx device is in the INITIALIZATION state.

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LP5009, LP5012

SLVSEH2B – MAY 2019 – REVISED AUGUST 2020

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LP5009 датащи(PDF) 17 Page - Texas Instruments