TLC5916 Datasheet, PDF (18/30 Pages) Texas Instruments – 8-BIT CONSTANT-CURRENT LED SINK DRIVERS

TLC5916, TLC5917
8-BIT CONSTANT-CURRENT LED SINK DRIVERS
SLVS695 – JUNE 2007
APPLICATION INFORMATION (continued)
Operation Phases
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Operation Mode Switching
In order 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).
Switching to Special Mode
Switching to Normal Mode
1
2
3
4
5
CLK
1
2
3
4
5
CLK
OE(ED2) ¹
0
1
1
1
OE(ED2) ¹
0
1
1
1
LE(ED1) ⁰
0
0
1
0
LE(ED1) ⁰
0
0
0
0
Actual Mode
Mode Special
Phase _{(Normal or Special) Switching Mode}
Actual Mode
Mode
Normal
Phase _{(Normal or Special) Switching Mode}
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.
Normal Mode Phase
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.
Special Mode Phase
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.
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