LX7186A
1.4MHz, 1A Synchronous
Buck Converter
Features
Description
The LX7186A is 1.4MHz fixed frequency, current-
mode, synchronous PWM buck (step-down) DC-DC
converter, capable of driving a 1A load with high
efficiency, excellent line and load regulation. The
device integrates synchronous P-channel and N-
channel power MOSFET switches with low on-
resistance. They accept an input voltage range from
2.5V to 5.5V and will enter 100% duty cycle at
dropout making them ideal for powering portable
equipment that runs from a single Li-ion battery.
A standard series of inductors are available from
several different manufacturers optimized for use
with the LX7186A. This feature greatly simplifies the
design of switch-mode power supplies.
The converter includes standard safety features
such as over-current, short-circuit and thermal
shutdown protection. This device is available in
both TSOT-5L and UDFN 2x2 6L packages.
Input Supply Range: 2.5V to 5.5V
Output Adjustable from 0.6V to VIN – 0.5V
100% Duty Cycle in Dropout
Integrated NMOS & PMOS Switches
Current Mode Control
1A Maximum Output Current
Fixed 1.4MHz Frequency
High Efficiency: Up To 96%
Built-in Soft-start
Built-in UV & OT Protection
Built-in Short Circuit Protection
RoHS Compliant & Halogen Free
TSOT-5L or UDFN 2x2 6L Packages
Applications
Datacom
Portable Devices
Smart Phone
VIN
C
IN
4.7µF
1 (6)
VIN
SW
5 (2)
L
2.2µH
VOUT
R1
C
OUT
22µF
LX7186A
ON
OFF
3 (4)
4 (3)
FB
EN
R2
GND
TSOT-5L (UDFN 2x2 6L)
2 (1, 5)
Figure 1 ·
Typical Application of LX7186A
October 2013 Rev. 1.5
www.microsemi.com
© 2013 Microsemi Corporation
1
1.4MHz 1A Synchronous Buck Converter
Pin Configuration and Pinout
1
6
VIN
GND
EN
1
5
SW
GND
2
VIN
5
186A
YWWA
86A
4
2
3
SW
GND
4
FB
3
FB
EN
YWWA = bottom mark
Figure 2 ·
Pinout TSOT-5 Top View
Marking: Front Mark 86A
Bottom Mark YWWA
Year/Work Week/Lot Code
Figure 3 ·
Pinout UDFN 2x2 6L Top View
Marking: Line1 186A
Line2 YWWA
Year/Work Week/Lot Code
Ordering Information
Ambient
Temperature
Type
Package
Part Number
LX7186AISG
TSOT-5L
-40°C to 85°C
RoHS Compliant,
Pb-free
UDFN 2x2 6L
LX7186AILU-TR
Tape and Reel
LX7186AISG-TR
LX7186AILU
Tape and Reel
Bulk / Tube
Packaging Type
Bulk / Tube
Pin Description
Pin Number
Pin Designator
TSOT-5L UDFN 2x2 6L
1
2
3
6
1, 5
4
VIN
GND
EN
Supply Input Pin. A 4.7µF ceramic capacitor should be connected
between the VIN pin and GND pin to bypass the supply.
Ground Pin.
Enable Input. Setting this pin above 1.5V enables the IC. Setting this pin
below 0.4V shuts down the IC. When the IC is in shutdown mode, all
functions are disabled to decrease the supply current below 1µA.
Feedback Pin. This pin is connected to an external resistor divider to
program the system output voltage.
Power Switch Output Pin. Inductor connection to drain of the internal
PFET and NFET switches.
Description
4
5
3
2
FB
SW
2
1.4MHz 1A Synchronous Buck Converter
Absolute Maximum Ratings
Parameter
VIN to GND
EN, FB to GND
SW to GND
Junction Temperature
Storage Temperature
Peak Package Solder Reflow Temperature (40s, reflow)
Lead Soldering Temperature (10 seconds)
-65
Min
-0.3
-0.3
-0.3
Max
6
VIN + 0.3
VIN + 0.3
150
150
260 (+0,-5)
260
Units
V
V
V
°C
°C
°C
°C
Note:
Performance is not necessarily guaranteed over this entire range. These are maximum stress ratings only.
Exceeding these ratings, even momentarily, can cause immediate damage, or negatively impact long-term
operating reliability
Operating Ratings
Min
VIN
V
OUT
Ambient Temperature
Output Current
2.5
0.6
-40
0
Max
5.5
VIN – 0.5
85
1
Units
V
V
°C
A
Thermal Properties
Package
TSOT-5
UDFN 2x2 6L
Thermal Resistance
θ
JA
θ
JA
Typ
160
86
Units
°C/W
°C/W
Note:
The
JA
number assumes no forced airflow. Junction Temperature is calculated using T
J
= T
A
+ (PD x
JA
). In
particular, θ
JA
is a function of the PCB construction. The stated number above is for a four-layer board in
accordance with JESD-51 (JEDEC).
Electrical Characteristics
Note:
Unless otherwise specified, the following specifications apply at VIN = V
EN
= 3.3V. -40°C < T
A
< 85°C.
Symbol
Parameter
Test Condition
Min
Typ
Max
Units
Operating Current
I
Q
I
SHDN
VIN UVLO
V
UVLO
V
HYS
Under Voltage Lockout
UVLO Hysteresis
VIN rising
2.3
200
V
mV
Quiescent Current
Shutdown Supply Current
V
FB
= 0.65V
V
EN
= GND
62
0.1
100
1
µA
µA
4
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