SMP9317S SUMMIT [Summit Microelectronics, Inc.], SMP9317S Datasheet - Page 2

• Manufacturer Part Number: SMP9317S
• Manufacturer: SUMMIT [Summit Microelectronics, Inc.]

PIN NAMES
2031-04 12/4/98
Analog Section
The SMP9317 is a 7-bit, voltage output digital-to-analog
converter (DAC). The DAC consists of a resistor network
that converts a 7-bit value into equivalent analog output
voltages in proportion to the applied reference voltage.
Reference Inputs
The voltage differential between the V
sets the full-scale output voltage range. V
to or greater than ground (i.e. a positive voltage). V
be greater than V
table on page 3 for guaranteed operating limits.
Output Buffer Amplifier
The voltage output is from a precision unity-gain follower
that can slew up to 1V/ s.
Digital Interface
The interface is designed to emulate a simple up/down
counter, but instead of a parallel count output, a
ratiometric voltage output is provided.
Chip Select (CS
high the SMP9317 is in standby mode and consumes the
least power. This mode is equivalent to a potentiometer
that is adjusted to the required setting. When CS is low
the SMP9317 will recognize transitions on the INC input
and will move the V
toward the V
UP/DN input.
The host may exit an adjustment routine in two ways:
deselecting the SMP9317 while INC is low will not per-
form a store operation (a subsequent power cycle will
recall the original data); deselecting the SMP9317 while
INC is high will store the current V
volatile memory.
Symbol
UP/DN
GND
V
INC
V
CS
V
V
OUT
DD
H
L
L
CS
CS
CS) is an active low input. Whenever CS is
CS
reference depending upon the state of the
Description
Increment Input, High to Low
Edge Trigger
Up/Down Input controlling relative
V
V+ reference input
Analog and Digital Ground
Trimmed Voltage Output
V- reference input
Active low chip select input
Supply Voltage (2.7V to 5.5V)
L
OUT
OUT
and less than or equal to V
either toward the V
movement
OUT
setting into non-
L
L
and V
must be equal
H
reference or
H
DD
H
inputs
. See
must
2
PINOUT
Increment (INC
CS is low and a high to low transition occurs on the INC
input, the V
depending upon the state of the UP/DN input.
UP/Down (UP/DN
movement relative to V
is high and there is a high to low transition on INC, the
V
When CS and UP/DN are low, and there is a high to low
transition on INC, the V
toward V
Power–Up/Power–Down Conditions
On power–up the SMP9317 loads the value of EEPROM
memory into the wiper position register. The value in the
register is changed using the CS, INC, and UP/DN pins.
The new data in the register will be lost at power-down
unless CS was brought high, with INC high, to initiate a
store operation after the last increment or decrement. On
the next device power–up, the value of EEPROM memory
will be loaded into the wiper position register. During
power-up the SMP9317 is write-protected in two ways:
1) A power-on reset, that trips at approximately 2.5V,
2) Resistor pull-ups on all logic inputs prevent data
Data Retention
The SMP9317 is guaranteed to perform at least
1,000,000 writes to EEPROM before a wear–out condi-
tion can occur. After EEPROM wearout, the SMP9317
continues to function as a volatile digital-potentiometer.
The wiper position can be changed during powered
conditions using the digital interface. However, on power–
up the wiper–position will be indeterminate.
On shipment from the factory, Summit Microelectronics
does not specify any EEPROM memory value. The value
must be set by the customer as needed.
OUT
holds CS and INC high internally.
change if the inputs are floating.
voltage will move (1/128
UP/DN
GND
L
INC
V H
.
OUT
INC
INC
INC
INC) is an edge triggered input. Whenever
DN
DN
DN
DN) is an input that will determine the V
voltage will either move toward V
1
2
3
4
H
OUT
and V
will move (1/128
L
. When CS is low, UP/DN
th
x V
8
7
6
5
2031 ILL1.0
SMP9317
H
-V
V DD
CS
V L
V OUT
L
) toward V
th
x V
H
H
or V
-V
OUT
H
L
L
)
.