Datasheet

LM2592HV
SNVS075C –MAY 2001–REVISED APRIL 2013 www.ti.com
BLOCK DIAGRAM
Figure 24.
PIN FUNCTIONS
+V
IN
(Pin 1)This is the positive input supply for the IC switching regulator. A suitable input bypass capacitor must
be present at this pin to minimize voltage transients and to supply the switching currents needed by the
regulator.
Output (Pin 2)Internal switch. The voltage at this pin switches between approximately (+V
IN
− V
SAT
) and
approximately −0.5V, with a duty cycle of V
OUT
/V
IN
.
Ground (Pin 3)Circuit ground.
Feedback (Pin 4)Senses the regulated output voltage to complete the feedback loop. This pin is directly
connected to the Output for the fixed voltage versions, but is set to 1.23V by means of a resistive divider
from the output for the Adjustable version. If a feedforward capacitor is used (Adjustable version), then a
negative voltage spike is generated on this pin whenever the output is shorted. This happens because the
feedforward capacitor cannot discharge fast enough, and since one end of it is dragged to Ground, the
other end goes momentarily negative. To prevent the energy rating of this pin from being exceeded, a
small-signal Schottky diode to Ground is recommended for DC input voltages above 40V whenever a
feedforward capacitor is present (See Test Circuit and Layout Guidelines). Feedforward capacitor values
larger than 0.1 μF are not recommended for the same reason, whatever be the DC input voltage.
ON /OFF (Pin 5)The regulator is in shutdown mode, drawing about 90 μA, when this pin is driven to a high level
(≥ 2.0V), and is in normal operation when this Pin is left floating or driven to a low level (≤ 0.6V). The
typical value of the threshold is 1.3V and the voltage on this pin must not exceed 25V.
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