DAC7724 Datasheet, PDF (13/15 Pages) Burr-Brown (TI) – 12-Bit Quad Voltage Output DIGITAL-TO-ANALOG CONVERTER

+10.000V
0.1µF
–15V
–10V to +10V
–10V to +10V
1µF to 10µF
0.1µF
Reset DACs⁽¹⁾
Load DAC Registers
Data Bus
DAC7724
DAC7725
1 V_REFH
2 V_OUTB
3 V_OUTA
4 V_SS
5 GND
6 RESET
7 LDAC
8 DB0
9 DB1
10 DB2
11 DB3
12 DB4
13 DB5
14 DB6
V_REFL 28
V_OUTC 27
V_OUTD 26
V_CC 25
V_DD 24
CS 23
A0 22
A1 21
R/W 20
DB11 19
DB10 18
DB9 17
DB8 16
DB7 15
0.1µF
–10.000V
+15V
–10V to +10V
–10V to +10V
+
0.1µF
1µF to 10µF
+5V
Chip Select
Address Bus
or Decoder
+
0.1µF
1µF to 10µF
Read/Write
Data Bus
NOTE: (1) Reset LOW sets all DACs to code 800_H on the DAC7724 and to code 000_H on the DAC7725.
FIGURE 3. Basic Dual-Supply Operation of the DAC7724/25.
ANALOG OUTPUTS
When V_SS = –15V (dual supply operation), the output
amplifier can swing to within 4V of the supply rails, guar-
anteed over the –40°C to +85°C temperature range. With
V_SS = 0V (single-supply operation) and R_LOAD connected to
ground, the output can swing to ground. Note that the
settling time of the output op-amp will be longer with
voltages very near ground. Additionally, care must be taken
when measuring the zero-scale error when V_SS = 0V. Since
the output voltage cannot swing below ground, the output
voltage may not change for the first few digital input codes
(000_H, 001_H, 002_H, etc.) if the output amplifier has a nega-
tive offset. At the negative offset limit of –4 LSB (-9.76mV),
for the single-supply case, the first specified output starts at
code 004_H.
REFERENCE INPUTS
For dual-supply operation, the reference inputs, V_REFL and
V_REFH, can be any voltage between V_SS + 4V and V_CC – 4V
provided that V_REFH is at least 1.25V greater than V_REFL.
For single-supply operation (V_SS = 0V), V_REFL value can be
above 0V, with the same provision that V_REFH is at least
1.25V greater than V_REFL. The minimum output of each
DAC is equal to V_REFL plus a small offset voltage (essen-
tially, the offset of the output op-amp). The maximum
output is equal to V_REFH plus a similar offset voltage. Note
that V_SS (the negative power supply) must either be con-
nected to ground or must be in the range of –14.25V to
–15.75V. The voltage on V_SS sets several bias points within
the converter, if V_SS is not in one of these two configura-
tions, the bias values may be in error and proper operation
of the device is not guaranteed.
The current into the V_REFH input and out of V_REFL depends
on the DAC output voltages and can vary from a few
microamps to approximately 0.3mA. The reference input
appears as a varying load to the reference. If the reference
can sink or source the required current, a reference buffer is
not required. See “Reference Current vs Code” in the Typi-
cal Performance Curves.
The analog supplies (or the analog supplies and the refer-
ence power supplies) have to come up first. If the power
supplies for the references come up first, then the V_CC and
V_SS supplies will be “powered from the reference via the
ESD protection diodes” (see page 4).
Bypassing the reference voltage or voltages with at least a
0.1uF capacitor placed as close to the DAC7724/25 package
is strongly recommended.
®
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DAC7724, 7725