MXB7843EUE MAXIM [Maxim Integrated Products], MXB7843EUE Datasheet - Page 14

• Manufacturer Part Number: MXB7843EUE
• Description: 2.375V to 5.25V, 4-Wire Touch-Screen Controller
• Manufacturer: MAXIM [Maxim Integrated Products]

occur at a faster clock rate since settling to better than 8
bits is all that is required. The clock rate can be as much
as 25% faster. The faster clock rate and fewer clock
cycles combine to increase the conversion rate.
The MXB7843 output data is in straight binary format as
shown in Figure 10. This figure shows the ideal output
code for the given input voltage and does not include
the effects of offset, gain, or noise.
2.375V to 5.25V, 4-Wire Touch-Screen
Controller
Figure 7. Conversion Timing, 24-Clock per Conversion, 8-Bit Bus Interface
Figure 8. 15-Clock/Conversion Timing
14
DCLK
DOUT
BUSY
DIN
DCLK
CS
DIN
BUSY
DOUT
CS
______________________________________________________________________________________
A/D STATE
DRIVERS1 AND 2
(SER/DFR HIGH)
DRIVERS1 AND 2
(SER/DFR LOW)
S
1
(START)
S
1
CONTROL BYTE 0
A2
IDLE
A1
IDLE
A0 MODE
4
RB1
OFF
OFF
TB
8
SER/
DFR
ACQUIRE
ACQUIRE
PD1
t
ACQ
B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
PD0
8
ON
Data Format
CONVERSION RESULT 0
9
(MSB)
11
15
10
S
1
9
12
RB2
OFF
ON
8
CONTROL BYTE 1
The 4-wire touch-screen controller works by creating a
voltage gradient across the vertical or horizontal resis-
tive network connected to the MXB7843, as shown in
the Typical Application Circuit. The touch screen is
biased through internal MOSFET switches that connect
each resistive layer to V
basis. For example, to measure the Y position when a
CONVERSION
7
6
CONVERSION
5
16
8
4
Basic Operation of the MXB7843
Applications Information
B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
3
2
1
DD
20
CONVERSION RESULT 1
(LSB)
RB3
0
and ground on an alternate
15
IDLE
S
1
IDLE
OFF
CONTROL BYTE 2
24