Evaluation board available.
NX2305
SINGLE SUPPLY 12V SYNCHRONOUS PWM CONTROLLER
WITH NMOS LDO CONTROLLER, POWER GOOD & ENABLES
PRELIMINARY DATA SHEET
Pb Free Product
FEATURES
DESCRIPTION
n 12V PWM controller plus LDO controller
The NX2305 controller IC is a combination synchronous
Buck and LDO controller IC designed to convert single
12V supply to low cost dual on board supply applica-
tions. The synchronous controller is used for high cur-
rent high efficiency step down DC to DC converter appli-
cations while the LDO controller in conjunction with an
external low cost N ch MOSFET can be used as a very
low drop out regulator in applications such as converting
3.3V to 2.5V output. Internal UVLO keeps both regula-
tors off until the supply voltage exceeds 9V where inde-
pendent internal digital soft starts get initiated to ramp
up both outputs.The switching section has hiccup cur-
rent limit by sensing the Rdson of synchronous MOSFET.
The LDO controller has Feedback Under Voltage Lock
Out as a short circuit protection.Other features includes:
12V gate drive capability , Adaptive dead band control,
Power good flag for the switcher controller and separate
Enable pins for independent power sequencing.
n Hiccup current limit by sensing Rdson of MOSFET
12V high side and low side driver
n Fixed internal 300kHz for switching controller
n Dual Independent Digital Soft Start Function
n Adaptive Deadband Control
n Enable pin available to program the Vbus UVLO
n Shut Down switching and LDO via pulling down
EnSW or ENLDO pins
n
n Pb-free and RoHS compliant
APPLICATIONS
n
n
n
PCI Graphic Card on board converters
Mother board On board DC to DC applications
On board Single Supply 12V DC to DC such as
12V to 3.3V, 2.5V or 1.8V
n
Set Top Box and LCD Display
TYPICAL APPLICATION
10
R14
C11
open
C12
1uF
0.1uF
C1
VCC
5V REG
PVCC
R6
10k
L1 1uH
1N4148
VIN2
VIN1
+12V
PGOOD
+3.3V
C3
100uF
LDO OUT
C2
180uF
C9
47uF
M5
BST
C4
0.1uF
M1
C10 150pF
VOUT2
+1.6V/2A
IRFR3709Z
HDRV
SW
LDO FB
ENLDO
C8
R8
5k
L2 2.2uH
R9
5k
VOUT1
150uF
25mohm
+1.8V/10A
C7
2 x 470uF
R10
VIN2
+3.3V
OCP
LDRV
PGND
R11
1.4k
M2
0.75k
R1
4k
M3
IRFR3709Z
R2
1.1k
R3
10k
HI=SD
C6
3.9nF
R12
6.8k
VIN1
+12V
FB
ENSW
C5
R5
10k
R4
8k
R13
1.4k
COMP
M4
5.6nF
AGND
HI=SD
C13 100pF
Figure1 - Typical application of NX2305
ORDERING INFORMATION
Device
NX2305CMTR
NX2305CSTR
Temperature
0 to 70oC
Package
MLPQ-16L
SOIC -16L
Frequency
300kHz
300kHz
Pb-Free
Yes
Yes
0 to 70oC
Rev.5.0
08/19/08
1