Datasheet

MAX5236/MAX5237
Detailed Description
The MAX5236/MAX5237 10-bit, voltage-output DACs
are easily configured with a 3-wire SPI/
QSPI/MICROWIRE serial interface. The devices include
a 16-bit data-in/data-out shift register and have an input
consisting of an input register and a DAC register. In
addition, these devices employ precision trimmed inter-
nal resistors to produce a gain of 1.6384V/V, maximiz-
ing the output voltage swing, and a programmable
shutdown output impedance of 1kΩ or 200kΩ. The full-
scale output voltage is 4.092V for the MAX5237 and
2.046V for the MAX5236. These devices produce a
weighted output voltage proportional to the digital input
code with an inverted rail-to-rail ladder network (Figure 3).
External Reference
The reference inputs accept both AC and DC values
with a voltage range extending from 0.25V to 2.6V for
the MAX5237 and 0.25V to 1.5V for the MAX5236. For
proper operation do not exceed the input voltage
range limits. Determine the output voltage using the fol-
lowing equation:
V
OUT
_ = (V
REF
_ x NB / 1024) x 1.6384V/V
where NB is the numeric value of the DACs binary input
code (0 to 1023), V
REF
_ is the reference voltage, and
1.6384V/V is the gain of the internal output amplifier.
The code-dependent reference input impedance
ranges from a minimum of 28kΩ to several GΩ at code
0. The code-dependent reference input capacitance is
typically 23pF.
Output Amplifier
The output amplifiers have internal resistors that pro-
vide for a gain of 1.6384V/V. These trimmed resistors
minimize gain error. The output amplifiers have a typical
slew rate of 0.6V/µs and settle to 1/2LSB within 10µs
(typ) with a load of 5kΩ in parallel with 100pF. Use the
serial interface to set the shutdown output impedance
of the amplifiers to 1kΩ or 200kΩ.
Single-Supply 3V/5V, Voltage-Output, Dual,
Precision 10-Bit DACs
10 ______________________________________________________________________________________
Pin Description
PIN NAME FUNCTION
1 OUTA DAC A Output
2 REFA Reference for DAC A
3 GND Ground
4 LDAC Load DACs A and B
5 CS Chip Select Input
6 SCLK Shift Register Serial Clock Input
7 DIN Serial Data Input
8V
DD
Positive Supply
9 REFB Reference for DAC B
10 OUTB DAC B Output
2µs/div
MAX5237
MAJOR CARRY GLITCH
CS
2V/div
MAX5236/7 toc28
OUT_
50mV/div
AC-COUPLED
0
0.50
0.25
1.25
1.00
0.75
2.00
1.75
1.50
2.25
0 0.500.25 0.75 1.00 1.25
MAX5236
FULL-SCALE OUTPUT VOLTAGE
vs. REFERENCE VOLTAGE
MAX5236/7 toc29
V
REF
(V)
V
OUT
(V)
0
1.0
0.5
2.5
2.0
1.5
4.0
3.5
3.0
4.5
0 1.00.5 1.5 2.0 2.5
MAX5237
FULL-SCALE OUTPUT VOLTAGE
vs. REFERENCE VOLTAGE
MAX5236/7 toc30
V
REF
(V)
V
OUT
(V)
Typical Operating Characteristics (continued)
(V
DD
= +5V (MAX5237) V
DD
= +3V (MAX5236), R
L
= 5kΩ, C
L
= 100pF, V
REF
= +1.25V (MAX5236), V
REF
= +2.5V (MAX5237), C
REF
= 0.1µF ceramic || 2.2µF electrolytic, both DACs on, V
OUT
= full scale, T
A
= +25°C, unless otherwise noted.)