LRC LR9641 Schematic [ru]

LESHAN RADIO COMPANY, LTD.

42V Input Standoff Voltage, 0.7A Step-Down Converte

DESCRIPTION

The LR9641 is a wide input range, high-efficiency,
and high frequency DC-to-DC step-down
switching regulator, capable of delivering up to

0.7A of output current. With a fixed switching
frequency of 660KHz, this current mode PWM
controlled converter allows the use of small
external components, such as ceramic input and
output caps, as well as small inductors.LR9641
also employs a proprietary control scheme that
switches the device into a power save mode
during light load, thereby extending the range of
high efficiency operation. An OVP function
protects the IC itself and its downstream system
against input voltage surges. With this OVP
function, the IC can stand off input voltage as
high as 42V, making it an ideal solution for
industrial applications such as smart meters as
well as automotive applications.
In automotive systems, power comes from the
battery, with its voltage typically between 9V and
24V. Including cold crank and double battery
jump-starts, the minimum input voltage may be
as low as 4V and the maximum up to 36V, with
even higher transient voltages. With these high
input voltages, linear regulators cannot be used
for high supply currents without overheating the
regulator. Instead, high efficiency switching
regulators such as LR9641 must be used to
minimize thermal dissipation.
LR9641 is available SOT23-6 Packages.

FEATURES

• Wide Input Operating Range from 4V to 38V

• Standoff Input Voltage: 42V

• High Efficiency at 12V In 5V Out: Up to 92%:

• High Efficiency PFM mode at light load

• Capable of Delivering 0.7A

• No External Compensation Needed

• Current Mode control

• Logic Control Shutdown

• Thermal shutdown and UVLO

• Available in SOT23-6 Package

APPLICATIONS

• Smart Meters

• Industrial Applications

• Automotive Applications

PIN OUT

TYPICAL APPLICATION

r

LR9641

Ver 1.2

1/8

MARK and ORDERING INFORMATION

r from the output to FB and GND to set VOUT

Mark Explanation

aa: Type
b: Year
c: Week

PINOUT DESCRIPTION

PIN # NAME DESCRIPTION

1 BST Bootstrap pin. Connect a 10nF capacitor from
2 GND Ground
3 FB
4 EN Enable pin for the IC. Drive this pin high to
5 IN Supply Voltage. Bypass with a 10μF ceramic cap
6 SW Inductor Connection. Connect an inductor Betwe

Feedback Input. Connect an external resistor divide

enable the part, low to disable.

BLOCK DIAGRAM

LESHAN RADIO COMPANY, LTD.

this pin to SW

acitor to GND

en SW and the regulator output.

EN

IN

REG

&REF

+

EA

FB

-

UVLO &

Thermal

shutdown

+

-

PWM

Logic

OSC

COMP

network

Slope Comp

Σ

GND

BST

DRIVER

Current

Sense

+

-

SW

2/8

LESHAN RADIO COMPANY, LTD.

ABSOLUTE MAXIMUM RATING

Parameter Value

Input Voltage Range
Max Operating Junction Temperature(Tj)
SW, EN Voltage
BST Voltage
FB Voltage
SW to ground curren
Operating Temperature(To)

Package Thermal Resistance (
Storage Temperature(Ts)

SOT23-6

jc)

θ

–0.3V to VIN+0.3V

–0.3V to SW+6V

–0.3V to 6V

Internally limited

-40
110

-55

Note: Exceed these limits to damage to the device. Exposure t
rating conditions may affect device reliability.

ELECTRICAL CHARACTERISTICS

(VIN = 12V, unless otherwise specified. Typical va

PARAMETER CONDITIONS MIN TYP MAX UNITS

Input Standoff Voltage

Input Voltage Range

Input UVLO Rising, Hysteresis=140mV

Input OVP Rising, Hysteresis=1.3V

Input Supply Current VFB =0.85V

Input Shutdown Current

FB Feedback Voltage

FB Input Current

Switching Frequency

Maximum Duty Cycle

FoldBack Frequency VFB = 0V

High side Switch On Resistance ISW =200mA

High side Switch Current Limit

SW Leakage Current VIN=12V,VSW=0, EN= GND

EN Input Current VIN=12V ,VEN =5V
EN Input Low Voltage Rising, Hysteresis=100mV

Thermal Shutdown Hysteresis=40°C

lues are at TA = 25

-0.3V-42V
150

°

C

C

°

C –85

°

C / W

°

C

°

C - 150

°

o absolute maximum

°

C .)

42 V

4 38 V

3.80 V
38 V

0.6 mA
6 μA

0.800

0.01 μA
660 KHz

90 %

60 KHz
400 mΩ

1.2 A
10 μA
1 5 μA

0.8 1.1 1.4 V
150 °C

V

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