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Operation Phases

Operation Mode Switching

1

2

3

4

5

1

0

1

1

1

0

0

0

0

0

Actual Mode

(Normal or Special)

Mode

Switching

Normal

Mode

CLK

OE(ED2)

LE(ED1)

Phase

1

2

3

4

5

1

0

1

1

1

1

0

0

0

0

Actual Mode

(Normal or Special)

Mode

Switching

Special

Mode

CLK

OE(ED2)

LE(ED1)

Phase

Switching to Special Mode

Switching to Normal Mode

Normal Mode Phase

Special Mode Phase

TLC5916, TLC5917

8-BIT CONSTANT-CURRENT LED SINK DRIVERS

SLVS695A – JUNE 2007 – REVISED MARCH 2008

To switch between its two modes, TLC5916/TLC5917 monitors the signal OE(ED2). When an one-clock-wide

pulse of OE(ED2) appears, TLC5916/TLC5917 enters the two-clock-period transition phase, the Mode Switching

phase. After power on, the default operation mode is the Normal Mode (see Figure 15).

Figure 15. Mode Switching

As shown in Figure 15, once a one-clock-wide short pulse (101) of OE(ED2) appears, TLC5916/TLC5917 enters

the Mode Switching phase. At the fourth rising edge of CLK, if LE(ED1) is sampled as voltage high,

TLC5916/TLC5917 switches to Special Mode; otherwise, it switches to Normal Mode. The signal LE(ED1)

between the third and the fifth rising edges of CLK cannot latch any data. Its level is used only to determine into

which mode to switch. However, the short pulse of OE(ED2) can still enable the output ports. During mode

switching, the serial data can still be transferred through SDI and shifted out from SDO.

NOTES:

1. The signal sequence for the mode switching may be used frequently to ensure that TLC5916/TLC5917 is in

the proper mode.

2. The 1 and 0 on the LE(ED1) signal are sampled at the rising edge of CLK. The X means its level does not

affect the result of mode switching mechanism.

3. After power on, the default operation mode is Normal Mode.

Serial data is transferred into TLC5916/TLC5917 via SDI, shifted in the Shift Register, and output via SDO.

LE(ED1) can latch the serial data in the Shift Register to the Output Latch. OE(ED2) enables the output drivers to

sink current. These functions differ only as described in Operation Mode Switching, in which case, a short pulse

triggers TLC5916/TLC5917 to switch the operation mode. However, as long as LE(ED1) is high in the Mode

Switching phase, TLC5916/TLC5917 remains in the Normal Mode, as if no mode switching occurred.

In the Special Mode, as long as OE(ED2) is not low, the serial data is shifted to the Shift Register via SDI and

shifted out via SDO, as in the Normal Mode. However, there are two differences between the Special Mode and

the Normal Mode, as shown in the following sections.

18

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