MAX1233_05 Datasheet, PDF (23/45 Pages) Maxim Integrated Products – ±15kV ESD-Protected Touch-Screen Controllers Include DAC and Keypad Controller

±15kV ESD-Protected Touch-Screen
Controllers Include DAC and Keypad Controller
Bits 1-3: Touch-Screen Settling Time Control
These bits specify the time delay from pen-touch detec-
tion to a conversion start. This allows the selection of the
appropriate settling time for the touch screen being used.
Table 11 shows how to set the settling time. These bits
are identical, regardless of read or write.
Bit 0: ADC Internal Reference Voltage Control
This bit selects the ADC internal reference voltage,
either +1.0V or +2.5V. This bit is identical, regardless of
read or write. The reference control bit is shown in
Table 12.
Table 11. Touch-Screen Settling Time
Control*
ST2 ST1 ST0
SETTLING TIME
0
0
0 Settling time: 0µs
0
0
1 Settling time: 100µs
0
1
0 Settling time: 500µs
0
1
1 Settling time: 1ms
1
0
0 Settling time: 5ms
1
0
1 Settling time: 10ms
1
1
0 Settling time: 50ms
1
1
1 Settling time: 100ms
*Applicable only for X, Y, Z1, and Z2 measurements.
Internal ADC Reference Power-Down Control
The ADC control register controls the power setting of
the internal ADC reference. Zeros must be written to
bits A/D3–A/D0 to control internal reference power-up
followed by the appropriate logic at the RES1 and
RES0 bits. Table 13 shows the internal ADC reference
power-down control.
DAC Control Register
The MSB in this control register determines the power-
down control of the on-board DAC. Table 14 shows the
DAC control register. Writing a zero to bit 15 (DAPD)
powers up the DAC, while writing a 1 powers down the
DAC. Table 15 describes the DAC control register con-
tents, while Table 16 shows the DAC power-down bit.
Keypad Control Registers
The keypad control register, keypad mask register, and
keypad column mask control register control the key-
pad scanner in the MAX1233/MAX1234. The keypad
control register (Table 17) controls scanning and
debouncing, while the keypad mask register (Table 22)
and the keypad column mask control register (Table 24),
Table 15. DAC Control Register
Descriptions
BIT
15 (MSB)
[14:0]
NAME
DAPD
0
DESCRIPTION
DAC powered down
Reserved
Table 12. ADC Reference Control Bit
RFV
0
1
FUNCTION
+1.0V reference
+2.5V reference
Table 16. DAC Power-Down Bit
DAPC
0
1
FUNCTION
DAC powered up
DAC powered down
Table 13. Internal ADC Reference Auto Power-Up Control
RES1
RES0
ADC REFERENCE
SOURCE
ADC REFERENCE POWER MODE
0
0
0
1
1
0
1
1
Internal
Internal
External
External
Power up, wait for reference to settle, and power down again for each
temperature, battery, or auxiliary scan (auto power-up mode)
Always powered up
Always powered down
Always powered down
Table 14. DAC Control Register
BIT15 BIT14 BIT13 BIT12 BIT11 BIT10 BIT9 BIT8 BIT7 BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0
DAPD 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
______________________________________________________________________________________ 23