Datasheet

Power-Down Reference Pin Operation

3-6

Power-Down Threshold Voltage Levels (REF > Midrail)

Supply Voltage

(V)

Reference Pin

Voltage (V)

Enable Level

(V)

Disable Level

(V)

Floating or 5 ≥4 ≤3.5

±5

2.5 ≥0.5 ≤1

±5

1 ≥0 ≤−0.5

Floating or 5 ≥4 ≤3.5

4 ≥3 ≤2.5

3.5 ≥2.5 ≤2

3.3 Floating or 3.3 ≥2.7 ≤1.8

In the above table, the threshold levels are derived by the following equations:

REF − 1 V for enable

REF − 1.5 V for disable

Note that in order to maintain these threshold levels, the reference pin can be

any voltage between (Vs+/2) + 1 V to Vs+, or left floating. The reference pin

is internally connected to the positive rail, therefore it can be left floating to

maintain these threshold levels.

For 3.3-V operation, the reference pin must be connected to the positive rail

or left floating.

The recommended mode of operation is to tie the reference pin to midrail, thus

setting the threshold levels to midrail +1.0 V, and midrail +1.8 V.