lx1672 Microsemi Corporation, lx1672 Datasheet - Page 3

• Manufacturer Part Number: lx1672
• Description: Multiple Output Loadshare Pwm
• Manufacturer: Microsemi Corporation

Copyright © 2000
Rev. 1.0, 2005-08-10
PWGD
AGND
DGND
LDDIS
N
LDGD
VCCL
LDFB
DISX
HOX
EOX
VCC
CSX
PGX
VCX
RF2
SSX
LOX
VSX
FB1
FB2
AME
TM
Bi-Phase Operation: Phase 1 and 2 Voltage Feedback
Single Phase Operation: Phase 1 Voltage Feedback – connected to the output through a resistor network to
set desired output voltage of Phase 1
Error Amplifier Output – Sets external compensation for the corresponding phase denoted by “X”.
Bi-phase Operation: Load Sharing Voltage Sense Feedback – Connect filtered phase 2 switching output (pre-
inductor) to FB
Single Phase Operation: Phase 2 Voltage Feedback – connected to the output through a resistor network (post
inductor) to set desired output voltage of Phase 2.
Bi-Phase Operation: Load Sharing Voltage Sense Feedback Reference – Sets reference for current sharing
control loop. Connecting filtered phase 1 switching output (pre-inductor) to REF
phase 2 to be equal to phase 1.
Single Phase Operation: Phase 2 Voltage Reference – connected to SS2 pin as reference.
IC supply voltage (nominal 5V).
Power supply pin for all 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 corresponding phase denoted by “X”. Exceeding the current-limit threshold forces
the corresponding phase into hiccup mode protection. A minimum of 1KΩ must be in series with this input.
Soft-start/Hiccup Capacitor Pin – During start-up, the voltage on this pin controls the output voltage of its
respective regulator. An internal 20kΩ resistor and the external capacitor set the time constant for soft-start
function. The Soft-start function does not initialize until the supply voltage exceeds the UVLO threshold. 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 – Connects to gate of external N-Channel MOSFET for linear regulator
function.
Driver Power Ground. Connects to the source of the bottom N-channel MOSFETS of phase 1 where X=1, and
phase 2 where X=2 for the TSSOP. The MLPQ package has a common PG output .
High Side MOSFET Gate Driver – “X” denotes corresponding phase.
Low Side MOSFET Gate Driver – “X” denotes corresponding phase.
Phase High-Side MOSFET Gate Driver Supply – Connect to separate supply or boot strap supply to ensure
proper high-side gate driver supply voltage. “X” denotes corresponding phase. If the phase is not used connect to
VCC.
LDO Disable input. High disables the LDO output. This pin has a 100KΩ nominal pull down resistor
Voltage reference for Current sense. This is also the supply pin for the Current Sense Comparator.
PWM Disable Input – High disables the PWM output. This pin has a nominal 80KΩ pull down resistor. “X”
denotes corresponding phase.
Open drain output , high at end of Soft Start and no Fault. Pulls low if any Fault condition occurs.
This output is present on the MLP package only.
“X” denotes corresponding phase. This pin cannot be left floating, if the phase is not used connect to VCC
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]
2
to ensure proper current sharing between phase 1 and phase 2.
F U N C T I O N A L P I N D E S C R I P T I O N
Integrated Products Division
®
Microsemi
D
ESCRIPTION
Multiple Output LoadSHARE™ PWM
P
RODUCTION
D
2
ATA
forces average current in
S
HEET
LX1672
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