LP3943

SNVS256C – NOVMEBER 2003 – REVISED OCTOBER 2015

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7.3 Feature Description

Some of the features of the LP3943 device are:

1. 16 low-side switches to control the current in 16 strings of LEDs with a maximum of 25 mA per switch or a

maximum of 200 mA total.

2. Programmable internal PWM dimming:

(a) Duty cycle control (8 bits). Any of the 16 current switches can be mapped to either PWM0 register or

PWM1 register. Each register offers 8-bit PWM duty cycle control.

(b) PWM Frequency control (8 bits). Any of the 16 current switches can be mapped to either PSC0 register

or PSC1 register. Each register offers 8-bit PWM frequency control from 0.625 Hz to 160 Hz.

3. RESET input.

4. Auto increment for I2C writes to reduce number of I2C clock pulses .

5. The LP3943 provides for an externally selectable I2C slave address via the ADR0, ADR1, and ADR2 inputs.

See Figure 4.

7.4 Device Functional Modes

1. Output set to high impedance. This is set by programming bits [B0 and B1] to 00 in the LS0, LS1, LS2, or

LS3 registers (see Table 2)

2. Output set to ON state (current switch pulls low). This turns the LED on at the full current in the specified

current switch bits [B0 and B1] set to 01 in the LS0, LS1, LS2, or LS3 registers (see Table 12).

3. Output set to toggle at the programmed PWM duty cycle and PWM frequency. This turns on or off the

specified current switch at the programmed PWM frequency and duty cycle. Each current switch is mapped

to either of the PWM0/PSC0 or PWM1/PSC1 pairs by setting [B0 and B1] to 10 or 11 in the LS0, LS1, LS2,

or LS3 registers (see Table 12).

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