LX1671CLQ-TR MICROSEMI [Microsemi Corporation], LX1671CLQ-TR Datasheet - Page 3

• Manufacturer Part Number: LX1671CLQ-TR
• Description: Multiple Output LoadSHARE PWM
• Manufacturer: MICROSEMI [Microsemi Corporation]

Copyright © 2000
Rev. 1.2b, 2006-02-13
AGND
DGND
LDDIS
N
LDGD
RSVD
VCCL
LDFB
HOX
EOX
VCC
CSX
PGX
VCX
RF2
SSX
LOX
VSX
FB1
FB3
FB2
AME
TM
Bi-Phase Operation: Phase 1 and 2 Voltage Feedback
Single Phase Operation: Phase 1 Voltage Feedback , connect 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”.
Phase 3 Voltage . Feedback, connect to the output through a resistor network to set desired output voltage of
Phase 3.
Bi-Phase Operation: Load Sharing Voltage Sense Feedback – Connect filtered phase 2 switching output (pre-
inductor) to FB2 to ensure proper current sharing between phase 1 and phase 2.
Single Phase Operation: Phase 2 Voltage Feedback, connect to the output through a resistor network to set
desired output voltage of Phase 2.
B-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 a reference.
IC supply voltage (nominal 5V).
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.
Enable & 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. Pulling the SS
pin below 0.3V disables the corresponding phase denoted by “X”.
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& 2 where X=1,
and phase 3 where X=3.
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
Active High disables LDO output.
Power Supply pin for all Low side drivers.
Voltage reference for Current sense. This pin is also the supply pin for the Current Sense Comparator.
Do not make any connection to this pin
“X” denotes corresponding phase. This pin cannot be left floating, if a phase is not used connect to VCC.
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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
Integrated Products, Power Management
®
Microsemi
D
ESCRIPTION
Multiple Output LoadSHARE™ PWM
P
RODUCTION
D
2
ATA
forces average current in
S
HEET
LX1671
Page 3