Texas Instruments DEM-DAI3793A, Руководство пользователя

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Power Up/Down Time (ms) Options
Power Up/Down Time (ms) Options
It is possible to select the V
COM
ramp up/down time from GND level to a common voltage level or
vice-versa by choosing a V
COM
capacitor value and time by choosing one of the available checkboxes. A
4.7 μ F V
COM
capacitor is chosen as the default setting (this capacitor is also mounted on the EVM).
The 4.7 μ F V
COM
capacitor is the recommended value for operating the EVM. This configuration is the
recommended power-on sequence discussed in the product data sheet .
To select a different V
COM
value, choose the appropriate value from the V
COM
capacitor drop-down menu.
Be sure to change the capacitor on the EVM to the same value (1.0 μ F, 2.2 μ F or 10 μ F).
The combination of PTM[1:0] and RES[4:0] determines the V
COM
ramp up/down time, as described in
Table 3-2 and Table 3-3 .
To set the ramp up or down time without directly accessing the registers, users can select a V
COM
capacitor value and time in the group box. The ramp up waveform with the default setting is shown in
Figure 3-5 , and the ramp down waveform in Figure 3-6 , as references.
Table 3-2. PCM3793A/94A Resistor 125(7dh)
RES[4:0]: Resistor Value Control
RES [4:0] V
COM
Resistor Value
10000 60 k
Ω
11000 24 k
Ω
11100 12 k
Ω
11110 6 k
Ω
Others Reserved
Table 3-3. PCM3793A/94A Resistor 125(7dh) PMT[1:0]: Power Up/Down Time Control and
Register Direct Access
V
COM
Capacitor Power-Up Time Power-Down Time Register Direct
[ μ F] RES[4:0] PTM[1:0] [ms] [ms] Access
10 11110 00 450 750 0x7D1E
11100 11 900 1500 0x7D7C
11000 Do not set — — —
10000 Do not set — — —
4.7 11110 01 250 400 0x7D3E
11100 00 450 750 0x7D1C (default)
11000 11 900 1500 0x7D78
10000 Do not set — — —
2.2 11110 10 100 300 0x7D5E
11100 01 250 400 0x7D3C
11000 00 450 750 0x7D18
10000 11 900 1500 0x7D70
1.0 11110 Do not set — — —
11100 10 100 300 0x7D5C
11000 01 250 400 0x7D38
10000 00 450 750 0x7D10
SBAU127 – July 2007 Set-Up Guide 25
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