9
FN6227.2
September 9, 2009
Pin Description
Potentiometer Pins
RH AND RL
The high (RH) and low (RL) terminals of the ISL22416 are
equivalent to the fixed terminals of a mechanical
potentiometer. RH and RL are referenced to the relative
position of the wiper and not the voltage potential on the
terminals. With WR set to 127 decimal, the wiper will be
closest to RH, and with the WR set to 0, the wiper is closest
to RL.
RW
RW is the wiper terminal and is equivalent to the movable
terminal of a mechanical potentiometer. The position of the
wiper within the array is determined by the WR register.
SHDN
The SHDN pin forces the resistor to end-to-end open circuit
condition on RH and shorts RW to RL. When SHDN
is
returned to logic high, the previous latch settings put RW at
the same resistance setting prior to shutdown. This pin is
logically ANDed with SHDN bit in ACR register. SPI interface
is still available in shutdown mode and all registers are
accessible. This pin must remain HIGH for normal operation.
FIGURE 15. DCP CONNECTION IN SHUTDOWN MODE
FIGURE 11. TC FOR RHEOSTAT MODE IN ppm FIGURE 12. FREQUENCY RESPONSE (2.6MHz)
FIGURE 13. MIDSCALE GLITCH, CODE 3Fh TO 40h FIGURE 14. LARGE SIGNAL SETTLING TIME
Typical Performance Curves (Continued)
TCr (ppm/°C)
0
50
100
150
200
250
300
16 36 56 76 96
TAP POSITION (DECIMAL)
50k
10k
OUTPUT
INPUT
WIPER AT MID POINT (POSITION 40h)
R
TOTAL
= 9.5k
SIGNAL AT WIPER
(WIPER UNLOADED)
WIPER MID POINT MOVEMENT
FROM 3Fh TO 40h
SIGNAL AT WIPER
(WIPER UNLOADED MOVEMENT
FROM 7Fh TO 00h)
SCL
ISL22416
