LX2750 Datasheet, PDF (1/11 Pages) Microsemi Corporation – SINGLE INPUT SUPPLY PWM CONTROLLER WITH LDO CONTROLLER

LX2750
SINGLE INPUT SUPPLY PWM CONTROLLER WITH LDO
CONTROLLER
PRODUCTION DATA SHEET
Pb Free Product
DESCRIPTION
The LX2750 controller IC is a compact
Buck controller IC with 16 lead MLPQ
synchronous
package de-
n
n
signed for step-down DC to DC converter applications.
Selectable feedforward voltage mode control or con-
stant on time control provides fast dynamic response.
Selectable diode emulation mode greatly improves the
light load efficiency. The LX2750 controller is optimized
to convert single supply 12V bus voltage to as low as
n
n
n
n
0.8V output voltage. An internal regulator converts bus
voltage to 5V, which provides voltage supply to inter-
nal logic and driver circuit. The LX2750 employs pro-
n
n
grammable loss-less current limiting by sensing the
Rdson of synchronous MOSFET followed by hiccup
feature. Feedback under voltage also triggers hiccup.
n
n
Internal UVLO keeps the controller off until the bus
supply voltage exceeds 9V where internal digital soft _n
starts get initiated to ramp up output. The LX2750 em- _n
ploys NMOS LDO controller. Other features include:
5V gate drive for HDRV signal, 12V gate drive for LDRV _n
signal, programmable frequency, adaptive deadband _n
control.
FEATURES
Single Input 12V Bus Voltage
Excellent Dynamic Response with Selectable
Feedforward Voltage Mode Control or Constant On
Time Control
Diode Emulation Mode Available
Programmable Switching Frequency Up to 2MHz
Internal Digital Soft Start Function
Programmable Over Current Protection Triggers
Hiccup
NMOS LDO Controller Available
FB UVLO Followed by Hiccup Feature in Both
Controllers
5V High Side Driver and 12 V Low Side Driver
Pb-free and RoHS Compliant
APPLICATIONS
Graphic Card on Board Converters
On Board DC to DC such as
12V to 3.3V, 2.5V or 1.8V
Set Top Box and LCD Display
ASIC Power Supplies
TYPICAL APPLICATION
VIN1
+12V
7 _VIN
BST ¹⁵
Connected to 5VREG Voltage mode
Connected to GND Constant on time mode
Connected to 5VREG synchronous mode
Connected to GND Diode emulation mode
10 _VCC
12 _PGOOD
8 _MODE
9 _FCCM
16 _RT
HDRV ¹⁴
SW ¹³
LDRV ¹¹
FB ²
VOUT1
+1.8V@8A
GPIO
6 _{VREF_OC}
5 REFIN
17 _GND(PAD)
COMP ¹
LDO_DRV ³
LDO_FB ⁴
VOUT2
+1.1V
Figure1 - Typical application of LX2750
ORDERING INFORMATION
Device
LX2750CLQ
Temperature
0 to 70^o C
Package
Frequency
3X3 MLPQ-16L 200kHz to 2MHz
Pb-Free
Yes
Note: Available in Tape & Reel. Append the letters "TR" to the part number. (i.e. LX2750CLQ-TR)
Rev. 1.0a
Microsemi
1
07/14/10
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: [phone]