FAN4855 Datasheet, PDF (2/12 Pages) Fairchild Semiconductor – 500mA High Efficiency Boost Regulator with Adjustable Output, Shutdown and Low Battery Detect

Pin Configuration
VIN
SHDN
LBI
LB0
8-Pin TSSOP
1
8
2
7
3
6
4
5
TOP VIEW
GND
VL
VOUT
FB
Pin Description
Pin Name
Function
1
V_IN Battery Input Voltage. Supplies the IC during start-up. After the output is running, the IC draws
power from V_OUT.
2 SHDN Shut Down. Pulling this pin low shuts down the regulator, isolating the load from the input.
3
LBI Low-Battery Input. Pulling this pin below 0.39V causes the LBO pin to go low.
4
LBO Low-Battery Output. This pin provides an active low signal to alert the user when the LBI voltage
falls below its targeted value. The open-drain output can be used to reset a microcontroller.
5
FB Feedback Input. For setting the output voltage. Connect this pin to the resistor divider.
6
V_OUT Boost regulator output. Output voltage can be set to be in the 3 to 5V range. Startup at moderate
load is achievable at input voltages around 1.35V.
7
V_L Boost inductor connection. Connect an inductor between this pin and V_IN. When servicing the
output supply, this pin pulls low, charging the inductor, then shuts off dumping the energy through
the synchronous rectifier to the output.
8
GND Ground of the IC.
Absolute Maximum Ratings
Absolute Maximum Ratings are those values, beyond which the device could be permanently damaged. Absolute max-
imum ratings are stress ratings only and functional device operation is not implied.
Parameter
V_IN, V_OUT Voltages (Relative to GND)
Switch Voltage (V_L to GND)
Voltage on any other Pin
Peak Switch Current (Ipeak)
Output Current (I_OUT)
Continuous Power Dissipation
Thermal Resistance (θ_JA)
Junction Temperature
Storage Temperature Range
Lead Temperature (soldering, 10s)
Min.
-0.3
-0.3
-0.3
-65
Max.
6.5
V_OUT + 0.3
V_OUT + 0.3
— Internally Limited —
500
525
124
150
150
300
Units
V
V
V
mA
mW
°C/W
°C
°C
°C
2
FAN4855 Rev. 1.0.1
www.fairchildsemi.com