LP5523 datasheet(29/56 Pages) TI1

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00000000

10000000

11111111

PWM Bits

100

LP5523

www.ti.com

SNVS550D – SEPTEMBER 2009 – REVISED MAY 2013

The PWM duty cycle at temperature T (in centigrade) can be obtained as follows: PWMF = [PWMS - (25 - T) *

correction factor * PWMS] / 2, where PWMF is the final duty cycle at temperature T, PWMS is the set PWM duty

cycle (PWM duty cycle is set in registers 16H to 1EH) and the value of the correction factor is obtained from the

table above.

For example, if the set PWM duty cycle in register 16H is 90%, temperature T is

−10°C and the chosen

correction factor is +1.5% 1/°C, the final duty-cycle PWMF for D1 output will be [90% - (25°C − (−10°C) ) * 1.5%

1/°C * 90%]/2 = [90% - 35 * 0.015 * 90%]/2 = 21.4%. Default setting 00000 means that the temperature

compensation is non-active and the PWM output (0 to 100%) is set solely by PWM registers D1 PWM to D9

PWM.

07 D2 CONTROL to 0E D9 CONTROL

•

The control registers and control bits for D2 output to D9 output are similar to that given to D1, see the 06 –

Bit [5] and 06 – Bits [4:0] sections.

16 D1 PWM

•

This is the PWM duty cycle control for D1 output. D1 PWM register is effective during direct control operation

- direct PWM control is active after power up by default. Note: serial bus address auto increment is not

supported for register addresses from 16 to 1E.

–

16 — Bits [7:0] PWM

–

These bits set the D1 output PWM as shown in the figure below. Note: if the temperature compensation is

active, the maximum PWM duty cycle is 50% at +25°C. This is required to allow enough headroom for

temperature compensation over the temperature range

−40 °C to 90°C.

Figure 24. Direct PWM Control Bits vs. PWM Duty Cycle

17 D2 PWM to 1E D9 PWM

•

PWM duty cycle control for outputs D2 to D9. The control registers and control bits for D2 output to D9 output

are similar to that given to D1.

26 D1 CURRENT CONTROL

•

D1 LED driver output current control register. The resolution is 8-bits and step size is 100

μA. .

CURRENT bits

Output Current (typ.)

00000000

0.0 mA

00000001

0.1 mA

00000010

0.2 mA

...

10101111

17.5 mA default setting

....

11111110

25.4 mA

11111111

25.5 mA

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