SMP9317 View Datasheet(PDF) - Summit Microelectronics
Part Name
Description
Manufacturer
SMP9317
Summit Microelectronics
SMP9317 Datasheet PDF : 6 Pages
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SMP9317
PIN NAMES
PINOUT
Symbol
Description
INC
Increment Input, High to Low
Edge Trigger
INC 1
8 VDD
UP/DN
VH
GND
Up/Down Input controlling relative
VOUT movement
V+ reference input
Analog and Digital Ground
UP/DN 2
VH 3
GND 4
7 CS
6 VL
5 VOUT
VOUT
Trimmed Voltage Output
2031 ILL1.0
VL
V- reference input
CS
Active low chip select input
VDD
Supply Voltage (2.7V to 5.5V)
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 VL and VH inputs
sets the full-scale output voltage range. VL must be equal
to or greater than ground (i.e. a positive voltage). VH must
be greater than VL and less than or equal to VDD. See
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/µs.
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) is an active low input. Whenever CS is
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 VOUT either toward the VH reference or
toward the VL reference depending upon the state of the
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 VOUT setting into non-
volatile memory.
Increment (INC) is an edge triggered input. Whenever
CS is low and a high to low transition occurs on the INC
input, the VOUT voltage will either move toward VH or VL
depending upon the state of the UP/DN input.
UP/Down (UP/DN) is an input that will determine the VOUT
movement relative to VH and VL. When CS is low, UP/DN
is high and there is a high to low transition on INC, the
VOUT voltage will move (1/128th x VH-VL) toward VH.
When CS and UP/DN are low, and there is a high to low
transition on INC, the VOUT will move (1/128th x VH-VL)
toward VL.
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,
holds CS and INC high internally.
2) Resistor pull-ups on all logic inputs prevent data
change if the inputs are floating.
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.
2031-04 12/4/98
2
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