DS4303 Maxim Integrated Products, Inc., DS4303 Datasheet - Page 7

• Manufacturer Part Number: DS4303
• Description: Electronically Programmable Voltage Reference
• Manufacturer: Maxim Integrated Products, Inc.

During the V
nally adjusts the onboard DAC until V
After V
cy, V
EEPROM. The storage period lasts for the duration of
the EEPROM write time, t
procedure has completed, V
and if necessary V
adjustment procedure can be repeated to fine-tune
V
Following each self-adjust procedure, V
indefinitely, even if the DS4303 is power cycled.
Figure 2 details an example of how the DS4303 can be
adjusted in an application. During factory alignment, a
three/four-node bed-of-nails is used to: (1) provide the
adjustment voltage through the V
ADJ input, and (3) sense the needed feedback para-
meter. During manufacture, an automated test proce-
dure adjusts V
parameter is optimized. After the bed-of-nails operation
is complete, both the V
Figure 2. Application Circuit
OUT
OUTTA
within the V
OUT
Automated Programming Procedure
has stabilized to within the tracking accura-
, of V
OUT
OUT,
OUTQ
IN
self-adjust period, the DS4303 inter-
STEP 1:
SET REFERENCE
VOLTAGE
STEP 2:
TOGGLE ADJ
STEP 3:
DETERMINE IF
THE REFERENCE
VOLTAGE NEEDS
ADJUSTMENT
IN
by changing V
, it will be automatically stored in
AUTOMATED TEST EQUIPMENT
can be readjusted and the entire
range.
IN
and ADJ inputs are left open
W
. After the first adjustment
VOLTAGE SOURCE
OUT
CONTROLLED
DIGITAL PIN DRIVER
DIGITALLY
MEASUREMENT
IN
IN
CONTROLLED
DIGITALLY
can be measured,
, until the feedback
pin, (2) control the
OUT
_____________________________________________________________________
OUT
matches V
Electronically Programmable
is saved
IN
.
BED-OF-NAILS
ACCESS
TEST
circuit. V
the same procedure. The closed-loop nature of the
adjustment process removes all the system inaccura-
cies such as resistor tolerances, amplifier offsets, gain
mismatches, and even the inaccuracies in the automat-
ed equipment that provides the reference voltage.
The typical operating circuit shows an example of how
the DS4303 can replace most existing calibration solu-
tions. Many power supplies use a shunt voltage refer-
ence to provide the internal reference voltage, and
fine-tune adjustments are often made with hand-select-
ed discrete resistors. The DS4303 replaces this cum-
bersome arrangement with a solution that is capable of
being adjusted by automated techniques. An additional
benefit of the DS4303 is the ability to provide a much
lower voltage (down to 300mV) than is possible with
shunt voltage references. Another benefit of the
DS4303 is the ability to be adjusted after the unit has
been fully assembled and tested, resulting in a much
more flexible manufacturing arrangement, lower inven-
tory costs, and a quicker time-to-market.
GND
ADJ
V
IN
DEVICE UNDER TEST (DUT)
OUT
PARAMETER MEASURED
DURING CALIBRATION
Voltage Reference
SAMPLE AND
EEPROM
VOLTAGE
DS4303
INFINITE
can be readjusted at any time by following
HOLD
V
V
2.4V TO 3.6V
CC
OUT
Typical Operating Circuit
ADJUSTMENT
CIRCUITRY
REQUIRING
VOLTAGE
7