Datasheet X9312 (Intersil) - 2

X9312 PIN DESCRIPTIONS PIN NAMES RH/VH and RL/VL Symbol Description
The high (RH/VH) and low (RL/VL) terminals of the RH/VH High terminal X9312 are equivalent to the fixed terminals of a R mechanical potentiometer. The minimum voltage is 0V W/VW Wiper terminal and the maximum is +15V. The terminology of R R L/VL L/VL Low terminal and RH/VH references the relative position of the VSS Ground terminal in relation to wiper movement direction VCC Supply voltage selected by the U/D input and not the voltage potential on the terminal. U/D Up/Down control input INC Increment control input
R /V W W
CS Chip select control input Rw/Vw is the wiper terminal and is equivalent to the movable terminal of a mechanical potentiometer. The
PRINCIPLES OF OPERATION
position of the wiper within the array is determined by the control inputs. The wiper terminal series resistance There are three sections of the X9312: the input is typically 40Ω. control, counter and decode section; the nonvolatile memory; and the resistor array. The input control
Up/Down (U/D)
section operates just like an up/down counter. The The U/D input controls the direction of the wiper output of this counter is decoded to turn on a single movement and whether the counter is incriminated or electronic switch connecting a point on the resistor decremented. array to the wiper output. Under the proper conditions
Increment (INC)
the contents of the counter can be stored in nonvolatile memory and retained for future use. The The INC input is negative-edge triggered. Toggling resistor array is comprised of 99 individual resistors INC will move the wiper and either increment or connected in series. At either end of the array and decrement the counter in the direction indicated by the between each resistor is an electronic switch that logic level on the U/D input. transfers the potential at that point to the wiper.
Chip Select (CS)
The wiper, when at either fixed terminal, acts like its The device is selected when the CS input is LOW. The mechanical equivalent and does not move beyond the current counter value is stored in nonvolatile memory last position. That is, the counter does not wrap when CS is returned HIGH while the INC input is also around when clocked to either extreme. HIGH. After the store operation is complete the X9312 will be placed in the low power standby mode until the The electronic switches on the device operate in a device is selected once again. “make before break” mode when the wiper changes tap positions. If the wiper is moved several positions,
PIN CONFIGURATION
multiple taps are connected to the wiper for tIW (INC to VW change). The RTOTAL value for the device can temporarily be reduced by a significant amount if the
DIP/SOIC
wiper is moved several positions. INC 1 8 VCC When the device is powered-down, the last wiper U/D 2 7 CS position stored will be maintained in the nonvolatile
X9312
R memory. When power is restored, the contents of the RH/VH 3 6 L/VL memory are recalled and the wiper is set to the value VSS 4 5 RW/VW last stored. 2 FN8176.0 March 15, 2005