
DAC8426
–8–
REV. C
a) Large Signal
b) Settling Time Response (Negative Transition)
c) Settling Time Response (Positive Transition)
Figure 3. Dynamic Response
The outputs can withstand an indefinite short-circuit to AGND
to typically 50 mA. The output may also be shorted to any volt-
age between VDD and VSS; however, care must be taken to not
exceed the device maximum power dissipation.
The amplifier’s emitter follower output stage consists of an in-
trinsic NPN bipolar transistor with a 400
A NMOS pull-down
current-source load connected to VSS. This circuit configuration
shown in Figure 4 enables the output amplifier to develop out-
put voltages very close to AGND. Only the negative supply of the
four output buffer amplifiers are connected to VSS. Operating
the DAC8426 from dual supplies (VDD = +15 V and VSS = –5 V)
improves negative going output settling time near zero volts.
When operating single supply (VDD = +15 V and VSS = 0 V) the
output sink current decreases as the output approaches zero
voltage. Within 200 mV of AGND (single-supply operation) the
internal sinking capability appears resistive at a value of approxi-
mately 1200
. The buffer amplifier output current and voltage
characteristics are plotted in Figure 5.
Test Conditions, All Photos:
VDD = +15 V
CREFOUT = 10 F
RL = 2 k
Digital Input Sequence 0, 255, 0