TLC5960DA datasheet(15/33 Pages) TI

15 / 33 page

Internal

CLK

3.2 s

MinimumOntime

CTRL1

CTRL2

CTRL3

CTRL4

52 s

81 s

t =3.2 s

13 s

m ´

26 s

TLC5960

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SBVS147 – SEPTEMBER 2010

BUILT-IN PHASE SHIFT AND PWM INPUT MINIMUM ON-TIME REQUIREMENT

The TLC5960 is equipped with a built-in phase shift function to prevent noise from affecting all eight channels.

The gate drive timing has a sequential delay time between each combination of channels. This built-in delay time

(tD) is typically 13µs, and consists of four internal clock cycles. Figure 18 describes the phase shift sequence. G1

turns on immediately after the CTRL1 input goes high. After the unit delay of tD, the G2 output powers on. On the

other hand, G3, which is driven by control input CTRL2, already has twice the unit delay from the turn-on timing

of CTRL2. G4 turns on after G3 with a sequential unit delay. CTRL3 turns on G5 and G6; these outputs have a

built-in (tD × 4) and (tD × 5) phase shift, respectively. Finally, CTRL4 turns on G7 and G8; these outputs have

built-in (tD × 6) and (tD × 7) phase shift, respectively, from CTRL4 on-timing. This description is for the HVM 2CH

mode; however, the phase shift function is available in all of the HVM modes. In 4CH HVM mode, CTRL1 drives

G1, G2, G6, and G7. These output delays are fixed at 0, tD, (tD × 5), and (tD × 6), respectively. CTRL3 turns on

the other four channels, G3, G4, G7, and G8. These phase shifts are also fixed at (tD × 2), (tD × 3), (tD × 6), and

(tD × 7), respectively. The phase shift function works in the same manner in the 8CH HVM mode.

The internal clock cycle is equal to the minimum on-time of the TLC5960 gate driver. The gate drivers are

designed to drive the external FET turn-on and turn-off within 1µs for both rise and fall times, typically. Therefore,

the internal clock cycle of 3.2µs defines the minimum on-time pulse width on the LED strings in the

TLC5960-based system.

Figure 18. Built-In Phase Shift Output Sequence

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TLC5960DA Datasheet(PDF) 15 Page - Texas Instruments