S9518 Datasheet, PDF (2/8 Pages) Summit Microelectronics, Inc. – Nonvolatile DACPOT Electronic Potentiometer With Debounced Push Button Interface

S9518
PIN NAMES
Symbol
UP
DWN
VH
GND
V_OUT
VL
STR
V_DD
Description
PINOUT
PB Input, Moves VOUT Toward
VH Input
PB Input, Moves V_OUT Toward
V_L Input
Vref High
Ground
Trimmed Voltage Output
Vref Low
Store Input, Providing a Control
Input to Initiate a Store Operation
Supply Voltage (2.7V to 5.5V)
2017 PGM T1.0
UP 1
DWN 2
VH 3
GND 4
8 V_DD
7 STR
6 VL
5 VOUT
2017 ILL1.1
Analog Section
The S9518 is an 8-bit, voltage output digital-to-analog
converter (DAC). The DAC consists of a resistor network
that converts 8-bit digital values into equivalent analog
output voltages in proportion to the applied reference
voltage.
Reference Inputs
The voltage differential between the VL and VH inputs
sets the full-scale output voltage range. VL must be equal
to or greater than ground (a positive voltage). VH must be
greater than VL and less than or equal to VDD. See
specifications on page 5 for guaranteed operating limits.
Output Buffer Amplifier
The voltage output is from a precision unity-gain follower
that can slew up to 1V/µs.
Digital Interface
The interface provides simple push button control of an
up/down counter that drives the DAC. The DAC output is
a ratiometric voltage output.
UP is an active low push-button input. An internal pull-up
resistor, with nominal value of 50kohm, eliminates an
external resistor that would be required with push button
control. A 30ms debounce period is included in the input
timing to prevent multiple pulsing of the counter. Either a
switch closure to ground or a LOW logic level will, after the
debounce time, change the potentiometer tap position.
UP moves the output voltage towards the VH reference
input. If the UP push-button is kept depressed, the
counter will continue to increment at the rate of one count
every 250ms for one second. After one second the
counter increments faster, one count every 50ms, until
the push-button is released. Changes to the DAC output
using the UP input do not alter the data stored in
EEPROM. The STR input updates the nonvolatile
EEPROM memory.
DWN is an active low push-button input that decrements
the counter and moves the potentiometer output voltage
towards the VL reference input. The DWN control input
also includes an internal 50kohm pull-up resistor and a
30ms debounce period to prevent multiple pulsing. A
LOW logic level will also change the potentiometer tap
position after the debounce period. If the DWN push-
button is kept depressed, the counter continues to decre-
ment at the rate of one count every 250ms for one second.
After one second the counter decrements at one count
every 50ms until the push-button is released. Changes to
the DAC output using the DWN input do not alter the data
stored in EEPROM.
STR This input can be used in two ways:
1) If the input is tied LOW, then AUTOSTORE is en-
abled. When VDD powers-down an automatic store
cycle takes place that updates the nonvolatile
EEPROM memory.
2) STR is an active low push-button input that also
updates the nonvolatile memory. The input is
debounced but does not have an internal pull-up
resistor. For every valid push, the S9518 will store the
current potentiometer position to EEPROM.
2017-04 4/24/99
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