October 2001

9

MICRF005

MICRF005

Micrel

Polarity of the droop is unknown, meaning the AGC voltage

could droop up or down. Worst-case from a recovery stand-

point is downward droop, since the AGC pullup current is

1/10th magnitude of the pulldown current. The downward

droop is replenished according to the Equation (6):

(6)

I

C

V

t

AGC

= ∆

∆

where:

I = AGC pullup current for the initial [tbd]ms (67.5

µA)

C

∆t = droop recovery time

∆V = droop voltage

For example, if user desires

∆t = 10ms and chooses a 4.7µF

C

same equation with 200nA worst case pin leakage and

assuming 1

µA of capacitor leakage in the same direction, the

maximum allowable

∆t (shutdown time) is about 0.56s for

droop recovery in 10ms.