PM7543FSZ Analog Devices Inc, PM7543FSZ Datasheet - Page 7

• Manufacturer Part Number: PM7543FSZ
• Description: DAC 1-CH R-2R 12-Bit 16-Pin SOIC
• Manufacturer: Analog Devices Inc

Specifications of PM7543FSZ

• Package: 16SOIC
• Resolution: 12 Bit
• Architecture: R-2R
• Digital Interface Type: Serial
• Number Of Outputs Per Chip: 1
• Output Type: Current
• Full Scale Error: ±2 LSB
• Integral Nonlinearity Error: ±1 LSB
• Settling Time: 1µs
• Number Of Bits: 12
• Data Interface: Serial
• Number Of Converters: 1
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (0.300", 7.5mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power Dissipation (max): -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

ANALOG DEVICESfAX-ON-DEMAND HOTLINE - Page 20
The twelve
the R-2R resistor ladder, and therefore, can introduce bit errors.
REV. D
constant current in each ladder leg, regardless of digital input
code. This
tance
driven by any reference
within the limits stated in the Absolute Maximum Ratings chart.
across each switch remains constant. If, for example, switch 1
of Figure 1 was designed with an "ON" resistance of 10 ohms,
Time required for the analog output of the DAC to settle to within
zero to full scale.
to the V REFinput voltage when all digital inputs are HIGH.
Capacitancefrom
OUTPUT LEAKAGE CURRENT
then transferred, in parallel, to the 12-bit DAC register.
An asynchronous
register to a zero code (0000 0000 0000) without altering data
stored in the registers.
A simplified circuit of the PM-7543 DAC is shown in Figure 1. An
inverted R-2R ladder network consisting of silicon-chrome, thin-
film resistors, and twelve pairs of NMOS current-steering
switches. These switches steer binarily weighted currents into
either loun or IOUT2' Switching current to IOUT1 o r IOUT2 y ields a
It was essential to design these switches such that the switch
"ON" resistance
switch 2 for 20 ohms, etc., a constant 5mV drop would then be
maintained across each switch.
To further insure accuracy across the full
permanently
SPECIFICATION
The resolutionof a DACis the number
scale range (FSR) is divided (or resolved) into, where "n" is
equal to the number of bits.
SETTLING TIME
1/2 LSB of its final value for a given digital input stimulus; i.e.
GAIN
Ratio of the DAC's external operational amplifier output voltage
FEEDTHROUGH
Error caused
Feedthrough
OUTPUT CAPACITANCE
Current appearing at loun when all digital inputs are LOW, or at
IOUT2 terminal when all inputs are HIGH.
GENERAL CIRCUIT INFORMATION
The PM-7543 is a 12-bit multiplying D/A converter with a very
low temperature coefficient, R-2R resistor
input
cuitry forms an interface in which serial data can be loaded,
under microprocessor control, into a 12-bit shift register and
RESOLUTION
and control logic,
at V AE
constant current results in a constant input resis-
output current-steering
F
equal to R (typically 11kQ). The V
"ON" MaS switches were included in series with
error limits are specified with all switches OFF.
by capacitive
be binarily
ERROR
lOUT'
CLEAR function allows resetting the DAC
DEFINITIONS
and two
to ground.
voltage or current, AC or DC, that is
scaled so that the voltage drop
coupling
data registers. The digital cir-
switches are in series with
of states
from VREF to output.
ladder network, data
temperature range,
REF
(2n) that the full-
input may be
-7-
the feedback resistor and the R-2R ladder's terminating
tor. The "Simplified DAC Circuit," Figure 1 ,shows the location of
these switches. These series switches are equivalently
to two times switch 1 (MSB) and to switch 12 (LSB) to maintain
series switches.
The PM-7543 data inputs have been designed with ESD resis-
tance incorporated
charges applied to the digital inputs are shunted to the supply
and ground rails through forward biased diodes.
These protection diodes were designed to clamp the inputs well
below dangerous levels during static discharge conditions.
FIGURE 2: Digital Input Protection
FIGURE 1: Simplified DAC Circuit
constant relative voltage drops with varying temperature.
ing any testing of the resistor ladder or
coming inspection),
ESO PROTECTION
input protection circuitry.
Figure 2 shows the input protection diodes. High voltage static
v."
BIT 1 IMSBI
6
,
I ,
5,
20...
DTliTTl,CMOS
,oon
(SWITCHES
BIT 2
INPUTS
6
,
I
I
200J!
5.
won
through careful layout and the inclusion of
VDD must be present to turn "ON" these
SHOWN FOR DIGITAL INPUTS "HIGH")
BIT3
6
,
~-"
DIGITAL INPUTS
20kJJ
Von
r--,
10kl1
BIT 12 IlSBJ
.. THESE
~
6
i
-=
I
I
I
I
I
I
I
5,.
20kll
SWITCHES
RFEEDBACK
20kl1
PM-7543
PERMANENTLY
1Okll
(such as in-
RHlDBACK
lOUT>
IOU",
scaled
resIs-
..ON
Dur-