LP5813 datasheet(20/60 Pages) TI

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LP5813

OUT0

OUT1

OUT2

OUT3

VIN

GND

OFF

VIN

SCL

SDA

SYNC

VOUT

LED_A0 LED_A1

LED_B0

LED_B2

VOUT

Red LED

Green LED

Blue LED

Figure 9-10. Mix drive mode, 2 scans (led_mode = 6h, scan_order_0 = 0h, scan_order_1 = 1h,

mix_sel_led = 8h)

LP5813

OUT0

OUT1

OUT2

OUT3

VIN

GND

OFF

VIN

SCL

SDA

SYNC

VOUT

LED_A0 LED_A1

LED_B0 LED_B2

LED_C1 LED_C2

VOUT

Red LED

Green LED

Blue LED

Figure 9-11. Mix drive mode, 3 scans (led_mode = 7h, scan_order_0 = 0h, scan_order_1 = 1h,

scan_order_2 = 2h, mix_sel_led = 8h)

9.3.2.4 Ghosting elimination

The LP5813 integrates ghosting elimination circuits to avoid both upside and downside ghosting phenomenon.

The ghosting elimination can be disabled by setting clamp_dis = 1h, which is default as 0 and enabling the

function.

Voltage on the outputs is clamped during PWM off time in the rest of switching period, or during blank time

period, which is set in 'clamp_sel' bit in Dev_Config12 register. Figure 9-12 and Figure 9-13 show the effect of

different clamp selection.

A middle voltage Vmid between VOUT and VOUT - Vf is used to clamp the OUTx (x = 0, 1, 2, 3), where Vf is

the forward voltage of LED. This scheme can achieve both pre-discharge for scan switch FET and pre-charge

for current sinks, which eliminate up-side and down-side ghosting issues in time-multiplexing topology. Since

the clamp voltage for scan switch FET and current sinks is the same value, the reverse voltage on LED during

deghosting is avoided. There are 4 options for Vmid which is selected in 'vmid_sel' bits in Dev_Config12 register,

which can be used for different forward voltage range of different type LEDs.

LP5813

SNVSC74 – SEPTEMBER 2023

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