Data Sheet
+V
IN
AD780
I
LOAD
0mA
OUTPUT CHANGE (50mV/DIV)
2
10mA
AD780
1µF
6
V
OUT
V
OUT
(C
L
= 1000pF)
249Ω
4
00841-016
V
L
V
OUT
0V
Figure 16. Transient Resistive Load Test Circuit
I
LOAD
0mA
10µs/DIV
Figure 19. Settling under Dynamic Capacitive Load
OUTPUT CHANGE (50mV/DIV)
10mA
LINE REGULATION
V
OUT
(C
L
= 0pF)
Line regulation is a measure of change in output voltage due to
a specified change in input voltage. It is intended to simulate
worst-case unregulated supply conditions and is measured in
µV/V. Figure 20 shows typical performance with 4.0 V < V
IN
<
15.0 V.
200
00841-017
T = 25°C
10µs/DIV
100
Figure 17. Settling under Transient Resistive Load
The dynamic load may be resistive and capacitive. For example,
the load may be connected via a long capacitive cable. Figure 18
and Figure 19 show the performance of the AD780 driving a
1000 pF, 0 mA to 10 mA load.
+V
IN
OUTPUT CHANGE (µV)
0
–100
00841-020
–200
2
4
10
INPUT VOLTAGE (V)
15
AD780
1µF
6
V
OUT
C
L
1000pF
249Ω
Figure 20. Output Voltage Change vs. Input Voltage
PRECISION REFERENCE FOR HIGH RESOLUTION
5 V DATA CONVERTERS
The AD780 is ideally suited to be the reference for most 5 V
high resolution ADCs. The AD780 is stable under any
capacitive load, has superior dynamic load performance, and its
3.0 V output provides the converter with the maximum
dynamic range without requiring an additional and expensive
buffer amplifier. One of the many ADCs that the AD780 is
suited for is the AD7884, a 16-bit, high speed sampling ADC
(see Figure 21). This part previously needed a precision 5 V
reference, resistor divider, and buffer amplifier to do this
function.
4
Figure 18. Capacitive Load Transient Response Test Circuit
00841-018
V
L
V
OUT
0V
Rev. F | Page 9 of 12
00841-019
AD [ ANALOG DEVICES ]
