
Microsemi
Linfinity Microelectronics Division
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 2
Copyright
2000
Rev. 1.1b,2005-03-09
WWW
.Microse
m
i
.CO
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LX1681/1682
Voltage-Mode PWM Controllers
PRODUCTION DATA SHEET
TM
ABSOLUTE MAXI MUM RATI NGS ( NOTE 1)
Supply Voltage (VC1).................................................................................................... 18V
Supply Voltage (VCC) ..................................................................................................... 7V
Output Drive Peak Current Source (500ns) ................................................................. 1.0A
Output Drive Peak Current Sink (500ns) ..................................................................... 1.0A
Input Voltage (SS/ENABLE Pin) ........................................................................-0.3 to 6V
Operating Junction Temperature................................................................................150°C
Storage Temperature................................................................................. -65°C to +150°C
RoHS / Pb-free Peak Package Solder Reflow Temp (40 second max. exposure) ........... 260°C (+0, -5)
Note: Exceeding these ratings could cause damage to the device. All voltages are with respect to
Ground. Currents are positive into, negative out of specified terminal.
TH ERM A L DATA
DM PACKAGE
THERMAL RESISTANCE
-JUNCTION TO AMBIENT,
θ
JA
165
°C/W
Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board
system. All of the above assume no ambient airflow.
PACKAGE PI N OUT
1
2
4
3
5
6
8
7
V
FB
SS
N.C.
GND
V
CC
CS
V
C1
TDRV
LX1681
DM PACKAGE
(Top View)
1
2
4
3
5
6
8
7
V
FB
SS
GND
BDRV
V
CC
CS
V
C1
TDRV
LX1682
DM PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
FUNCTIONAL PIN DESCRIPTION
PIN NAME
DESCRIPTION
VFB
Voltage Feedback. A 1.25V reference is connected to a resistor divider to set desired output voltage.
SS
Soft-Start And Hiccup Capacitor Pin. During start up the voltage of this pin controls the output voltage. An
internal 20k
resistor and the external capacitor set the time constant for soft-startup. Soft-start does not begin
until the supply voltage exceeds the UVLO threshold. When over-current occurs, this capacitor is used for timing
hiccup. The PWM can be disabled by pulling the SS pin below 0.3V
GND
Ground for IC.
TDRV
Gate Drive For Upper MOSFET.
BDRV
Gate Drive For Lower MOSFET.
VC1
Separate Supply For MOSFET Gate Drive. Connect to 12V.
CS
Over-Current Set. Connect resistor between CS pin and the source of the upper MOSFET to set current-limit
point.
VCC
IC Supply Voltage (nominal 5V) And High Side Drain Sense Voltage.
PP
AA
CC
KK
AA
GG
EE
DD
AA
TT
AA