lx1673 Microsemi Corporation, lx1673 Datasheet - Page 3

• Manufacturer Part Number: lx1673
• Description: High Frequency Pwm Regulator
• Manufacturer: Microsemi Corporation

Copyright © 2004
Rev 1.0, 3/18/2005
LDVCC
PWGD
AGND
DGND
PGND
LDDIS
N
LDGD
BDRV
VCCL
TDRV
LDFB
EAO
VCC
EA+
VC1
EA-
DIS
CS
SS
VS
AME
TM
Voltage Feedback – Output voltage is connected through a resistor network to this pin for feedback to set the
desired output voltage of the switching PWM output.
Error Amplifier Output – Sets error amplifier gain and external compensation if used.
Voltage Reference – Connect to the SS pin or any other external voltage. Used in conjunction with EA-, and an
external resistor divider, to set the desired output voltage for the PWM output.
IC supply voltage (nominal 5V).
Power supply pin for Low side drivers.
Low Dropout Regulator Voltage Feedback – Sets output voltage of external MOSFET via resistor network.
Over-Current Limit Set – Connecting a resistor between CS pin and the source of the high-side MOSFET sets the
current-limit threshold for the PWM output. A minimum of
PWM Soft-start/Hiccup Capacitor Pin – During start-up, the voltage on this pin controls the output voltage of the
switching regulator. An internal
function. The Soft-start function does not initialize until the supply voltage on V
When an over-current condition occurs, this capacitor is used for the timing of hiccup mode protection.
Analog ground reference.
Digital ground reference.
Low Dropout Regulator Gate Drive – Connect to gate of external N-Channel MOSFET for linear regulator
function.
MOSFET Driver Power Ground. Connects to the source of the bottom N-channel MOSFETS of the switching
regulator.
High Side MOSFET Gate Driver
Low Side MOSFET Gate Driver
High-Side MOSFET Gate Driver Supply – Connect to separate supply or boot strap supply to ensure proper high-
side gate driver supply voltage.
LDO Disable Input – High disables LDO output. This pin has a
Voltage reference for Short Circuit Current sense. This pin is also the supply pin for the Current Sense
Comparator. This pin cannot be left floating, if current limit is not used connect to VCC.
Power Good Output – Open drain output, goes high at end of Soft Start and no Fault. Pulls low if any Fault
condition occurs.
LDO VCC Supply – Connect to voltage supply greater than supply rail for LDO MOSFET drain.
PWM Disable Input –High disables the PWM output. This pin has a
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F U N C T I O N A L P I N D E S C R I P T I O N
20K
Integrated Products Division
Ω
®
Microsemi
resistor and the external capacitor set the time constant for soft-start
D
ESCRIPTION
High Frequency PWM Regulator
1K
Ω
P
100K
RODUCTION
must be in series with this pin.
80K
Ω
Ω
pull down resistor.
pull down resistor.
CC
D
ATA
exceeds the UVLO threshold.
S
HEET
LX1673
Page 3