LP5569ARTWR datasheet(18/93 Pages) TI2

18 / 93 page

CHARGE PUMP

CURRENT SINK

SATURATION

MONITOR

MODE

CONTROL

REGISTERS

COMPARATOR

PWM

VOFS

MODE

VIN

VOUT

LEDx

LP5569

SNVSAP8A – JULY 2017 – REVISED SEPTEMBER 2017

www.ti.com

Product Folder Links: LP5569

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Figure 18. Forward-Voltage-Monitoring and Gain-Control Block

8.3.3 Energy Efficiency

8.3.3.1 LED Powering

The red LED (R) element of an RGB LED typically has a forward voltage of about 2 V. These LEDs can be

powered directly from the input voltage because battery voltage is typically high enough to drive red LEDs over

the whole operating voltage range. This allows driving of three RGB LEDs with good efficiency because the red

LEDs

not

load

the

charge

pump.

When

the

LEDx_CONTROL

(address

07h–0Fh)

EXTERNAL_POWERx bit = 1, the LEDx output is configured for external supply, and forward-voltage monitoring

is disabled.

8.3.4 Automatic Power-Save Mode

When the LED outputs are not active, the LP5569 device is able to enter the power-save mode automatically,

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

MISC register (address 2Fh) POWERSAVE_EN bit = 1. Almost all analog blocks are powered down in power

save, if an external clock signal is used. The charge pump enters the weak 1× mode using a passive current-

limited keep-alive switch, which keeps the output voltage at the battery level to reduce output-voltage transients.

During program execution, the LP5569 device can enter power save if there is no PWM activity in any of the LED

driver outputs. To prevent short power-save sequences during program execution, the device has an instruction

look-ahead filter. In power-save mode, program execution continues without interruption. When an instruction

that requires PWM activity is executed, a fast internal start-up sequence is started automatically.

8.3.5 Protection Features

8.3.5.1 Thermal Shutdown (TSD)

The LP5569 device implements a thermal shutdown mechanism to protect the device from damage due to

overheating. When the junction temperature rises to 150°C (typical), the device switches into shutdown mode.

The LP5569 device releases thermal shutdown when the junction temperature of the device decreases to 130°C

(typical).

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