lm5025bmtcx National Semiconductor Corporation, lm5025bmtcx Datasheet - Page 3

• Manufacturer Part Number: lm5025bmtcx
• Description: Active Clamp Voltage Mode Pwm Controller
• Manufacturer: National Semiconductor Corporation

Pin Descriptions
Pin
10
11
12
13
14
15
16
7
8
9
-
OUT_A
OUT_B
COMP
PGND
AGND
Name
SYNC
UVLO
V
SS
RT
EP
CC
Output from the internal high voltage start-up
regulator. The V
7.6V.
Main output driver
Active Clamp output driver
Power ground
Analog ground
Soft-start control
Input to the Pulse Width Modulator
Oscillator timing resistor pin
Oscillator UP/DOWN synchronization input
Line Under-Voltage shutdown
Exposed PAD, underside of the LLP package
option
(Continued)
CC
Description
voltage is regulated to
3
If an auxiliary winding raises the voltage on this pin
above the regulation setpoint, the internal start-up
regulator will shutdown, reducing the IC power
dissipation.
Output of the main switch PWM output gate driver.
Output capability of 3A peak sink current.
Output of the Active Clamp switch gate driver.
Capable of 1.25A peak sink current..
Connect directly to analog ground.
Connect directly to power ground.
An external capacitor and an internal 20µA current
source set the soft-start ramp. The SS current
source is reduced to 1uA following a CS2
over-current event or an over temperature event.
PWM duty cycle is controlled by the voltage applied
to the COMP pin. The COMP pin voltage is reduced
by a fixed 1V offset and compared with the RAMP
pin signal.
An external resistor connected from RT to ground
sets the internal oscillator frequency.
The internal oscillator can be synchronized to an
external clock with a frequency 20% lower than the
internal oscillator’s free running frequency. There is
no constraint on the maximum sync frequency.
An external voltage divider from the power source
sets the shutdown comparator levels. The
comparator threshold is 2.5V. Hysteresis is set by an
internal current source (20µA) that is switched on or
off as the UVLO pin potential crosses the 2.5V
threshold.
Internally bonded to the die substrate. Connect to
GND potential with low thermal impedance.
Application Information
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