Texas Instruments DEM-DAI3793A User Manual
www.ti.com
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
.
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
and
.
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
, and the ramp down waveform in
, 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