MAX1234ETI+T Maxim Integrated Products, MAX1234ETI+T Datasheet - Page 31

• Manufacturer Part Number: MAX1234ETI+T
• Description: IC CNTRLR TOUCH 28-TQFN
• Manufacturer: Maxim Integrated Products
• Type: Resistiver

Specifications of MAX1234ETI+T

• Touch Panel Interface: 4-Wire
• Number Of Inputs/keys: 1, 4 x 4 Keypad
• Resolution (bits): 8, 10, 12 b
• Data Interface: MICROWIRE™, QSPI™, Serial, SPI™
• Data Rate/sampling Rate (sps, Bps): 50k
• Voltage Reference: Internal
• Voltage - Supply: 4.75 V ~ 5.25 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-TQFN Exposed Pad
• Applications: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 13. Pressure Measurement Block Diagram
Figure 14. Battery Measurement Block Diagram
MEASURE Z1-RESISTANCE
V
Controllers Include DAC and Keypad Controller
FORCE LINE
FORCE LINE
FORCE LINE
BATTERY
0.5V TO
6.0V
OPEN CIRCUIT
X+
X-
X+
X-
SENSE LINE
FORCE LINE
Z2-RESISTANCE
X-POSITION
V
______________________________________________________________________________________
BAT
TOUCH
TOUCH
0.125V TO 1.5V
7.5kΩ
2.5kΩ
OPEN CIRCUIT
X+
X-
Y+
Y-
Y+
Y-
CONVERTER
Z1-RESISTANCE
DC/DC
SENSE LINE
±15kV ESD-Protected Touch-Screen
FORCE LINE
TOUCH
SENSE LINE
CONVERTER
OPEN CIRCUIT
2.7V
Y+
MEASURE X-POSITION
Y-
AV
FORCE LINE
MEASURE Z2-RESISTANCE
V
DD
V
Two dedicated analog inputs (BAT1 and BAT2) allow the
MAX1233/MAX1234 to monitor the battery voltages prior
to the DC/DC converter. Figure 14 shows the battery volt-
age monitoring circuitry. The MAX1233/ MAX1234 direct-
ly monitor battery voltages from 0.5V to 6V. An internal
resistor network divides down BAT1 and BAT2 by 4 so
that a 6V battery voltage results in a 1.5V input to the
ADC. To minimize power consumption, the divider is only
enabled during the sampling of BAT1 and BAT2. Figure
15 illustrates the process of battery input reading.
Figure 15. Battery Voltage-Reading Flowchart
NO
NO
STORE BATTERY INPUT 1 OR 2 IN
BAT1 OR BAT2 REGISTER
POWER UP REFERENCE
BATTERY INPUT 1 OR 2
AUTO POWER-DOWN
CONTROL REGISTER
AVERAGING DONE?
REFERENCE IN
HOST WRITES
START CLOCK
POWER UP
SET BUSY
CONVERT
IS DATA
MODE?
IS ADC
ADC
LOW
ADC
YES
YES
Battery-Voltage Monitors
POWER DOWN REFERENCE
BATTERY INPUT 1 OR
BATTERY INPUT 2
TURN OFF CLOCK
SET BUSY HIGH
POWER DOWN
DONE
ADC
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