Datasheet

N
D OLi Li
i 1
P V I
=
= ´
å
( )
J(MAX) A
(MAX)
JA
T T
PD
-
=
q
ULN2003LV
www.ti.com SLRS059A –APRIL 2012–REVISED APRIL 2012
APPLICATION INFORMATION
TTL and other Logic Inputs
ULN2003LV input interface is specified for standard 3V and 5V CMOS logic interface. However, ULN2003LV
input interface may support other logic input levels as well. Refer to Figure 10 and Figure 11 to establish VOL
and the corresponding typical load current levels for various input voltage ranges. Application Information section
shows an implmentation to drive 1.8V relays using ULN2003LV.
Input RC Snubber
ULN2003LV features an input RC snubber that helps prevent spurious switching in noisy environment. Connect
an external 1kΩ to 5kΩ resistor in series with the input to further enhance ULN2003LV’s noise tolerance.
High-impedance Input Drivers
ULN2003LV features a 300kΩ input pull-down resistor. The presence of this resistor allows the input drivers to
be tri-stated. When a high-impedance driver is connected to a channel input the ULN2003LV detects the channel
input as a low level input and remains in the OFF position. The input RC snubber helps improve noise tolerance
when input drivers are in the high-impedance state.
On-chip Power Dissipation
Use the below equation to calculate ULN2003LV on-chip power dissipation P
D
:
Where:
N is the number of channels active together.
V
OLi
is the OUT
i
pin voltage for the load current I
Li
. (1)
Thermal Reliability
It is recommended to limit ULN2003LV IC’s die junction temperature to less than 125°C. The IC junction
temperature is directly proportional to the on-chip power dissipation. Use the following equation to calculate the
maximum allowable on-chip power dissipation for a target IC junction temperature:
Where:
T
J(MAX)
is the target maximum junction temperature.
T
A
is the operating ambient temperature.
θ
JA
is the package junction to ambient thermal resistance. (2)
Improving Package Thermal Performance
The package θ
JA
value under standard conditions on a High-K board is listed in the DISSIPATION RATINGS. θ
JA
value depends on the PC board layout. An external heat sink and/or a cooling mechanism, like a cold air fan, can
help reduce θ
JA
and thus improve device thermal capabilities. Refer to TI’s design support web page at
www.ti.com/thermal for a general guidance on improving device thermal performance.
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