Protection IC Datasheet
© 2022 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: GD. 09/20/22
LS1205ExD33 Series
18V, 5A eFuse with Programmable Current Limit and Output Voltage Clamp
The LS1205E integrated load switch provides an easy circuit
protection to power the system. The devices use few external
components and provide multiple protection modes. They are a
robust defense against overload, short circuit, input voltage surge
and excessive inrush current. The switch’s low R
DS(ON)
helps to
reduce power loss during normal operation. Set the current limit
level with an external resistor. Protect against input over-voltage
events via internal clamp circuitry to a safe output voltage.
Programmable soft-start controls the slew rate of the output
voltage to limit inrush current during plug in. It integrates thermal
fold-back function and over temperature shutdown protection.
They are available in low profile 10 leads DFN 3mm x 3mm
package.
Features & Benefits
Pinout Designation
Description
Applications
■ Wide Input Voltage Range
from 2.7V to 18V
■ LS1205EV: External
Selectable Input Range and
Clamping Output Voltage
Threshold
■ LS1205EF: Open Drain Fault
Indicator FAULT\
■ Output Discharging Function
■ Integrate a 25mΩ Low
RDS(ON) Protection Switch
■ External Programmable Soft-
Start Time
■ External Programmable
Current Limit up to 5A
■ Short-circuit Protection
■ Enable Control Pin
■ Thermal Shutdown Protection
& Auto Recovery
■ DFN3×3_10L Package
■ Pb-Free RoHS compliant
■ HDD and SSD Drives
■ Adapter Powered Devices
■ PC / Notebook
■ FAN Control
■ Networking
IN
IN
VCP
IN
ILIM
SS
EN
OUT
OUT
OUT
LS1205EV
C
O2
0.1μ F
C
O1
10μF
C
IN 2
0.1μ F
C
IN 1
10μF
C
SS
100nF
R
ILIM
2.2KΩ
R
EN1
10K
3.3V
IN
3.3V
OUT
GND
R
EN2
NC
R
L
100K
R
H
NC
H for 5V
OUT
L for 3.3V
OUT
Open for 12V
OUT
VCP Op tion :
C
EN
0.1μ F
IN
IN
FAULT\
IN
ILIM
SS
EN
OUT
OUT
OUT
LS1205EF
C
O2
0.1μ F
C
O1
10
μF
C
IN 2
0.1μ F
C
IN 1
10μF
C
SS
100nF
R
ILIM
2.2KΩ
12V
IN
12V
OUT
GND
R
Fault
100KΩ
Fault Indicator
R
EN2
NC
R
EN1
10KΩ
C
EN
0.1μ F
Typical Applications
LS1205EV LS1205EF
Pin
Name
Description
1, 2, 3 1, 2, 3 IN Power input pin.
4 - VCP
LS1205EV only output clamp voltage selection
based on the input voltage.Pull VCP pin to High
by connecting a resistor to IN or pull VCP pin
to Low by connecting a resistor to ground, or
float VCP Pin to select different output clamping
thresholds. Recommend to decoupling this pin
with 0.1µF capacitor.
VCP VIN
V
OUT
Clamping
Threshold
Typ
Low 3.3V >4V 3.8V
High 5V >6V 5.7V
FLOAT 12V >16V 14.4V
- 4 FAULT\
LS1205EF Only. Fault event indicator. Open-
drain output that asserts low to indicate input
under-voltage, input over-voltage, output short
and thermal shutdown fault events.
5 5 ILIM
Current limit program pin. Program the current
limit by connecting a resister to ground.
6 6 SS
Soft Start time program pin. Connect a capacitor
to ground to program the soft start time.
7 7 EN
Enable interface pin. EN has accurate ON/OFF
threshold of 1.29V and 1.19V respectively. Pull
it above ON threshold to enable the IC. Pull it
below OFF threshold to disable the IC.
8, 9,10 8, 9,10 OUT Power output pin.
EP EP GND Ground pin.
Pin Description
LS1205EV Top View LS1205EF Top View
RoHS
Pb
Protection IC Datasheet
© 2022 Littelfuse, Inc.
Specifications are subject to change without notice.
Revised: GD. 09/20/22
LS1205ExD33 Series
18V, 5A eFuse with Programmable Current Limit and Output Voltage Clamp
Absolute Maximum Rating (Reference to GND)
Notes:
1. Stress exceeding those listed “Absolute Maximum Ratings” may damage the device.
2. ESD HBM testing per JESD22-A114F
Symbol Value Units
VIN, EN, VCP, FAULT\ -0.3 to +20 V
The other Pins -0.3 to +6.5 V
ESD, Human Body Model (HBM) ±2000 V
Junction Temperature Range -40 to +125 °C
Storage Temperature Range -65 to +125 °C
Lead Temperature (Soldering 10s) 260 °C
Recommend Operating Conditions
Symbol Value Units
Input Voltage (V
IN
) +2.7 to +18 V
Junction Temperature Range +125 °C
Notes: The device is not guaranteed to function outside of the recommended operating conditions.
Symbol Value Units
Maximum Power Dissipation (T
A
=25°C ) 1.89 W
Thermal Resistance (θ
JA
)
53 °C/W
Thermal Resistance (θ
JC
)
25 °C/W
Notes:
1. Measured on JESD51-7, 4-Layer PCB.
2. The maximum allowable power dissipation is a function of the maximum junction temperature T
J_MAX
,
the junction to ambient thermal resistance θ
JA
, and the ambient temperature TA. The maximum allowable
continuous power dissipation at any ambient temperature is calculated by P
D_MAX
= (T
J_MAX
-T
A
)/θ
JA
. Exceeding
the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into
thermal shutdown. Internal thermal shutdown circuitry protects the device from permanent damage.
Thermal information
Soft -start UVLO
Charge
Pump
IN
SS
EN
GND
or
Thermal
Detect
Current
Limit
V
OUT
Clamping
Driver
OUT
ILIM
VCP
2µA
SWEN
Discharge
C ontrol
120Ω
Soft -start UVLO
Charge
Pump
IN
SS
EN
GND
or
Thermal
Detect
Current Limit &
Short protection
V
OUT
Clamping
Driver
OUT
ILIM
FAULT\
2µA
SWEN
VCP
Discharge
control
120Ω
LS1205EV
LS1205EF
Functional Block Diagram
Pinout Designation