MCP4152-502E/MF View Datasheet(PDF) - Microchip Technology
Part Name
Description
Manufacturer
MCP4152-502E/MF Datasheet PDF : 88 Pages
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MCP413X/415X/423X/425X
5.2 Wiper
Each tap point (between the RS resistors) is a
connection point for an analog switch. The opposite
side of the analog switch is connected to a common
signal which is connected to the Terminal W (Wiper)
pin.
A value in the volatile wiper register selects which
analog switch to close, connecting the W terminal to
the selected node of the resistor ladder.
The wiper can connect directly to Terminal B or to
Terminal A. A zero-scale connections, connects the
Terminal W (wiper) to Terminal B (wiper setting of
000h). A full-scale connections, connects the Terminal
W (wiper) to Terminal A (wiper setting of 100h or 80h).
In these configurations the only resistance between the
Terminal W and the other Terminal (A or B) is that of the
analog switches.
A wiper setting value greater than full-scale (wiper
setting of 100h for 8-bit device or 80h for 7-bit devices)
will also be a Full-Scale setting (Terminal W (wiper)
connected to Terminal A). Table 5-1 illustrates the full
wiper setting map.
Equation 5-2 illustrates the calculation used to deter-
mine the resistance between the wiper and terminal B.
EQUATION 5-2: RWB CALCULATION
RWB
=
R----A----B---N--
( 256 )
+
RW
8-bit Device
N = 0 to 256 (decimal)
RWB
=
R----A----B---N--
( 128 )
+
RW
N = 0 to 128 (decimal)
7-bit Device
TABLE 5-1: VOLATILE WIPER VALUE VS.
WIPER POSITION MAP
Wiper Setting
7-bit Pot 8-bit Pot
Properties
3FFh
081h
080h
07Fh
041h
040h
03Fh
001h
000h
3FFh
101h
100h
0FFh
081
080h
07Fh
001
000h
Reserved (Full-Scale (W = A)),
Increment and Decrement
commands ignored
Full-Scale (W = A),
Increment commands ignored
W=N
W = N (Mid-Scale)
W=N
Zero Scale (W = B)
Decrement command ignored
A POR/BOR event will load the Volatile Wiper register
value with the default value. Table 5-2 shows the
default values offered. Custom POR/BOR options are
available. Contact the local Microchip Sales Office.
TABLE 5-2:
DEFAULT FACTORY
SETTINGS SELECTION
Wiper Code
8-bit 7-bit
-502
-103
-503
-104
5.0 kΩ
Mid-scale 80h 40h
10.0 kΩ Mid-scale 80h 40h
50.0 kΩ Mid-scale 80h 40h
100.0 kΩ Mid-scale 80h 40h
DS22060B-page 38
© 2008 Microchip Technology Inc.
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