ADR1500

Rev. 0 | Page 7 of 8

OUTPUT ERROR

1mV/DIV 2µs/DIV

OUTPUT

0.5mV/DIV 2ms/DIV

2.4V

0V

Figure 10. Turn-On Settling Time

Attempts to drive a large capacitive load (in excess of 1000 pF)

can result in ringing. This is due to the additional poles formed

by the load capacitance and the output impedance of the reference.

A recommended method for driving capacitive loads of this

magnitude is shown in Figure 11.

+

–

Figure 11. Turn-On, Settling, and Transient Test Circuit

TRANSIENT RESPONSE

Many ADCs and DACs present transient current loads to the

reference. Poor reference response can degrade the converter’s

performance. Figure 12 displays both the coarse and fine

settling characteristics of the device to load transient of ±50 μA.

It shows the settling characteristics of the device for an

increased reverse current of 50 μA and the response when the

reverse current is decreased by 50 μA. The transients settle to

1 mV in about 3 μs.

1µs/DIV

20mV/DIV

1mV/DIV

20mV/DIV

1mV/DIV

Figure 12. Transient Settling Time

A resistor isolates the capacitive load from the output stage,

while the capacitor provides a single-pole, low-pass filter and

lowers the output noise.