MXB7846EEE+T Maxim Integrated Products, MXB7846EEE+T Datasheet - Page 13

• Manufacturer Part Number: MXB7846EEE+T
• Description: IC CNTRLR TOUCH RES 16QSOP
• Manufacturer: Maxim Integrated Products
• Type: Temperature Sensorr

Specifications of MXB7846EEE+T

• Input Type: Analog
• Output Type: Digital
• Interface: 4-Wire
• Current - Supply: 950µA
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 6. PENIRQ Timing Diagram
Figure 7. Pressure Measurement Block Diagram
with Internal Reference and Temperature Sensor
2.375V to 5.25V, 4-Wire Touch-Screen Controller
MEASURE Z1
SCREEN TOUCHED HERE
PENIRQ
CS
DCLK
DIN
+
-
V
OPEN CIRCUIT
t
TOUCH
X+
X-
X+
X-
X+
X-
______________________________________________________________________________________
R
R
X- POSITION
TOUCH
TOUCH
R
S
INTERRUPT PROCESSOR
TOUCH
1
OPEN CIRCUIT
OPEN CIRCUIT
A2
2
Y+
Y-
Y+
Y-
SENSE LINE
A1
Y+
Y-
3
A0
NO RESPONSE TO TOUCH⎯MASK PENIRQ
MEASURE X- POSITION
4
V
V
+
+
-
-
M
5
MEASURE Z2
S/D
6
PD1
7
PD0
8
1
The first method performs pressure measurements
using a known X-plate resistance. After completing
three conversions (X-position, Z1, and Z2), use the fol-
lowing equation to calculate R
The second method requires knowing both the X-plate
and Y-plate resistance. Three conversions are required in
this method: the X-position, Y-position, and Z1-position.
Use the following equation to calculate R
The MXB7846 provides two temperature measurement
options: single-ended conversion and differential con-
version. Both temperature measurement techniques rely
on the semiconductor junction’s temperature character-
istics. The forward diode voltage (V
is a well-defined characteristic. The ambient tempera-
ture can be calculated by knowing the value of V
fixed temperature and then monitoring the change in
that voltage as the temperature changes. The single
conversion method requires calibration at a known tem-
perature, but only needs a single reading to calculate
2
R
TOUCH
R
TOUCH
3
−
=
⎧
⎨
⎩
R
⎧
⎪
⎨
⎩ ⎪
=
⎛
⎜
⎝
YPLATE
R
(
12
R
XPLATE
XPLATE
Z
Internal Temperature Sensor
1
13
×
⎞
⎟ ×
⎠
⎛
⎜
⎝
14
)
Y
×
POSITION
PENIRQ ENABLED
⎛
⎜
⎝
4096
⎛
⎜
⎝
15
X
X
POSITION
POSITION
TOUCH
4096
4096
16
⎞
⎟
⎠
⎫
⎬
⎭
BE
:
) vs. temperature
⎞
⎟ ×
⎠
⎞
⎟ ×
⎠
TOUCH:
⎡
⎢
⎢
⎣
⎡
⎢
⎢
⎣
⎛
⎜
⎝
⎛
⎜
⎝
4096
Z
Z
Z
2
1
1
⎞
⎟
⎠
BE
−
⎞
⎟
⎠
1
at a
−
⎤
⎥
⎥
⎦
13
1