Datasheet

LM25575, LM25575-Q1
www.ti.com SNVS479G –JANUARY 2007–REVISED APRIL 2013
PIN DESCRIPTIONS (continued)
Pin(s) Name Description Application Information
8 RAMP Ramp control signal An external capacitor connected between this pin and the AGND
pin sets the ramp slope used for current mode control.
Recommended capacitor range 50pF to 2000pF.
9 AGND Analog ground Internal reference for the regulator control functions
10 SS Soft-start An external capacitor and an internal 10µA current source set
the time constant for the rise of the error amp reference. The SS
pin is held low during standby, Vcc UVLO and thermal
shutdown.
11 OUT Output voltage connection Connect directly to the regulated output voltage.
12 PGND Power ground Low side reference for the PRE switch and the IS sense resistor.
13 IS Current sense Current measurement connection for the re-circulating diode. An
internal sense resistor and a sample/hold circuit sense the diode
current near the conclusion of the off-time. This current
measurement provides the DC level of the emulated current
ramp.
14 SW Switching node The source terminal of the internal buck switch. The SW pin
should be connected to the external Schottky diode and to the
buck inductor.
15 PRE Pre-charge assist for the bootstrap This open drain output can be connected to SW pin to aid
capacitor charging the bootstrap capacitor during very light load conditions
or in applications where the output may be pre-charged before
the LM25575 is enabled. An internal pre-charge MOSFET is
turned on for 250ns each cycle just prior to the on-time interval
of the buck switch.
16 BST Boost input for bootstrap capacitor An external capacitor is required between the BST and the SW
pins. A 0.022µF ceramic capacitor is recommended. The
capacitor is charged from Vcc via an internal diode during the
off-time of the buck switch.
NA EP Exposed Pad Exposed metal pad on the underside of the device. It is
recommended to connect this pad to the PWB ground plane, in
order to aid in heat dissipation.
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
Absolute Maximum Ratings
(1)(2)
V
IN
to GND 45V
BST to GND 60V
PRE to GND 45V
SW to GND (Steady State) -1.5V
BST to V
CC
45V
SD, V
CC
to GND 14V
BST to SW 14V
OUT to GND Limited to Vin
SYNC, SS, FB, RAMP to GND 7V
ESD Rating
(3)
Human Body Model 2kV
Storage Temperature Range -65°C to +150°C
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which
operation of the device is intended to be functional. For ensured specifications and test conditions, see the Electrical Characteristics.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/Distributors for availability and
specifications.
(3) The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
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