MXB7843EEE-T Maxim Integrated, MXB7843EEE-T Datasheet - Page 18

• Manufacturer Part Number: MXB7843EEE-T
• Description: Touch Screen Converters & Controllers
• Manufacturer: Maxim Integrated
• Type: Resistive Touch Controllersr

Specifications of MXB7843EEE-T

• Input Type: 1 TSC
• Data Rate: 125 KSPS
• Resolution: 8 bit, 12 bit
• Interface Type: 3-Wire, 4-Wire, QSPI, SPI
• Supply Voltage: 2.375 V to 5.25 V
• Supply Current: 270 uA
• Operating Temperature: - 40 C to + 85 C
• Package / Case: QSOP-16
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: -40 C
• Mounting Style: SMD/SMT
• Supply Voltage - Max: 5.25 V
• Supply Voltage - Min: 2.375 V

ground. Connect the digital system ground to the star
ground at this point only. For lowest noise operation,
minimize the length of the ground return to the star
ground’s power supply.
Power-supply decoupling is also crucial for optimal
device performance. Analog supplies can be decou-
pled by placing a 10µF tantalum capacitor in parallel
with a 0.1µF capacitor bypassed to GND. To maximize
performance, place these capacitors as close as possi-
ble to the supply pin of the device. Minimize capacitor
lead length for best supply-noise rejection. If the supply
is very noisy, a 10Ω resistor can be connected in series
as a lowpass filter.
While using the MXB7843, the interconnection between
the converter and the touch screen should be as short
as possible. Since touch screens have low resistance,
longer or loose connections may introduce error. Noise
can also be a major source of error in touch-screen
applications (e.g., applications that require a backlight
LCD panel). EMI noise coupled through the LCD panel
to the touch screen may cause flickering of the convert-
ed data. Utilizing a touch screen with a bottom-side
metal layer connected to ground decouples the noise
to ground. In addition, the filter capacitors from Y+, Y-,
X+, and X- inputs to ground also help further reduce
the noise. Caution should be observed for settling time
of the touch screen, especially operating in the single-
ended measurement mode and at high data rates.
Integral nonlinearity (INL) is the deviation of the values
on an actual transfer function from a straight line. This
straight line can be either a best-straight-line fit or a line
drawn between the endpoints of the transfer function,
once offset and gain errors have been nullified. The
2.375V to 5.25V, 4-Wire Touch-Screen
Controller
Figure 11. MICROWIRE Interface
18
______________________________________________________________________________________
MICROWIRE
MASKABLE
INTERRUPT
MISO
MOSI
SCK
I/O
Integral Nonlinearity
CS
DCLK
DOUT
DIN
BUSY
MXB7843
Definitions
static linearity parameters for the MXB7843 are mea-
sured using the end-point method.
Differential nonlinearity (DNL) is the difference between
an actual step width and the ideal value of 1LSB. A
DNL error specification of less than 1LSB guarantees
no missing codes and a monotonic transfer function.
Aperture jitter (t
the time between the samples.
Aperture delay (t
falling edge of the sampling clock and the instant when
an actual sample is taken.
TRANSISTOR COUNT: 12,000
PROCESS: 0.6µm BiCMOS
Figure 12. QSPI/SPI Interface
Figure 13. TMS320 Serial Interface
TMS320LC3x
QSPI/SPI
INTERRUPT
MASKABLE
AJ
AD
CLKX
CLKR
) is the sample-to-sample variation in
MISO
MOSI
SCK
FSR
DX
DR
I/O
XF
) is the time defined between the
Differential Nonlinearity
Chip Information
CS
SCLK
DIN
DOUT
BUSY
CS
DCLK
DOUT
DIN
BUSY
Aperture Delay
Aperture Jitter
MXB7843
MXB7843