MIC2954
Micrel
Note 11.
The MIC2954 features fold-back current limiting. The short circuit (V
OUT
= 0V) current limit is less than the maximum current with normal
output voltage.
Note 12.
Thermal regulation is defined as the change in output voltage at a time t after a change in power dissipation is applied, excluding load or line
regulation effects. Specifications are for a 200mA load pulse at V
IN
= 20V (a 4W pulse) for t = 10ms.
Note 13.
V
REF
≤
V
OUT
≤
(V
IN
– 1V), 2.3V
≤
V
IN
≤
30V, 100
µA
< I
L
≤
250 mA, T
J
≤
T
J(max).
Note 14.
Comparator thresholds are expressed in terms of a voltage differential at the FB pin below the nominal reference voltage measured at 6V
input. To express these thresholds in terms of output voltage change, multiply by the error amplifier gain = V
OUT
/V
REF
= (R1 + R2)/R2. For
example, at a programmed output voltage of 5V, the error output is guaranteed to go low when the output drops by
95mV
×
5V/1.235V = 384mV. Thresholds remain constant as a percent of V
OUT
as V
OUT
is varied, with the dropout warning occurring at
typically 5% below nominal, 7.5% guaranteed.
Note 15.
V
SHDN
≥
2V, V
IN
≤
30 V,V
OUT
= 0, with the FB pin connected to TAP.
Note 16.
When used in dual supply systems where the regulator load is returned to a negative supply, the output voltage must be diode clamped to
ground.
Note 17.
Maximum positive supply voltage of 60V must be of limited duration (<10ms) and duty cycle (<1%). The maximum continuous supply voltage
is 30V.
August 1999
5
MIC2954
MICREL [ MICREL SEMICONDUCTOR ]
