TPS61040
TPS61041
www.ti.com
SLVS413C–OCTOBER 2002–REVISED AUGUST 2007
SOFT START
All inductive step-up converters exhibit high inrush current during start-up if no special precaution is made. This
can cause voltage drops at the input rail during start up and may result in an unwanted or early system shut
down.
I
LIM
4
The TPS61040/41 limits this inrush current by increasing the current limit in two steps starting from
for 256
I
LIM
2
cycles to
for the next 256 cycles, and then full current limit (see Figure 14).
ENABLE
Pulling the enable (EN) to ground shuts down the device reducing the shutdown current to 1 μA (typical).
Because there is a conductive path from the input to the output through the inductor and Schottky diode, the
output voltage is equal to the input voltage during shutdown. The enable pin needs to be terminated and should
not be left floating. Using a small external transistor disconnects the input from the output during shutdown as
shown in Figure 18.
UNDERVOLTAGE LOCKOUT
An undervoltage lockout prevents misoperation of the device at input voltages below typical 1.5 V. When the
input voltage is below the undervoltage threshold, the main switch is turned off.
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature (unless otherwise noted)
(1)
UNIT
(2)
Supply voltages on pin VIN
–0.3 V to 7 V
–0.3 V to VIN + 0.3 V
30 V
(2)
Voltages on pins EN, FB
Switch voltage on pin SW
(2)
Continuous power dissipation
Operating junction temperature
Storage temperature
See Dissipation Rating Table
–40°C to 150°C
–65°C to 150°C
260°C
TJ
Tstg
Lead temperature (soldering 10 seconds)
(1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating
conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) All voltage values are with respect to network ground terminal.
DISSIPATION RATING TABLE
DERATING
T
A ≤ 25°C
FACTOR
ABOVE
TA = 70°C
POWER RATING POWER RATING
TA = 85°C
PACKAGE
RθJA
POWER RATING
TA = 25°C
DBV
DRV
250°C/W
76°C/W
357 mW
3.5 mW/°C
13 mW/°C
192 mW
688 mW
140 mW
500 mW
1300 mW
4
Submit Documentation Feedback
Copyright © 2002–2007, Texas Instruments Incorporated
Product Folder Link(s): TPS61040 TPS61041
TI [ TEXAS INSTRUMENTS ]
