TLC5926_15 Datasheet, PDF (17/39 Pages) Texas Instruments – 16-Channel Constant-Current LED Sink Drivers

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TLC5926, TLC5927
SLVS677C – JULY 2008 – REVISED OCTOBER 2015
1
2
3
4
5
CLK
OE(ED2) 1
0
1
1
1
LE(ED1) ⁰
0
0
0
0
Figure 11. Switching to Normal Mode
9.4.1 Operation Mode Switching
In order to switch between its two modes, TLC592x monitors the signal OE(ED2). When a one-clock-wide pulse
of OE(ED2) appears, TLC592x enters the two-clock-period transition phase, the Mode Switching phase. After
power on, the default operation mode is the Normal Mode (see Figure 12).
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
Phase _{(Normal or Special)}
Mode
Switching
Special
Mode
Actual Mode
Phase _{(Normal or Special)}
Mode
Switching
Normal
Mode
Figure 12. Mode Switching
As shown in Figure 12, once a one-clock-wide short pulse (101) of OE(ED2) appears, TLC592x enters the Mode
Switching phase. At the fourth rising edge of CLK, if LE(ED1) is sampled as voltage high, TLC592x 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 the TLC592x 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.
9.4.2 Normal Mode Phase
Serial data is transferred into TLC592x through SDI, shifted in the Shift Register, and output through 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 TLC592x to switch the operation mode. However, as long as LE(ED1) is high in the Mode Switching
phase, TLC592x remains in the Normal mode, as if no mode switching occurred.
9.4.3 Special Mode Phase
In the Special mode, as long as OE(ED2) is not low, the serial data is shifted to the Shift Register through SDI
and shifted out through 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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