LM2936MM-3.3/NOPB National Semiconductor, LM2936MM-3.3/NOPB Datasheet - Page 11

• Manufacturer Part Number: LM2936MM-3.3/NOPB
• Description: IC REG ULTRA LOW CURR 3.3V 8MSOP
• Manufacturer: National Semiconductor

Specifications of LM2936MM-3.3/NOPB

• Regulator Topology: Positive Fixed
• Voltage - Output: 3.3V
• Voltage - Input: Up to 40V
• Voltage - Dropout (typical): 0.2V @ 50mA
• Number Of Regulators: 1
• Current - Output: 50mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Other names: LM2936MM-3.3; LM2936MM-3.3TR

Applications Information
Unlike other PNP low dropout regulators, the LM2936 re-
mains fully operational to 40V. Owing to power dissipation
characteristics of the available packages, full output current
cannot be guaranteed for all combinations of ambient tem-
perature and input voltage. As an example, consider an
LM2936Z–5.0 operating at 25˚C ambient. Using the formula
for maximum allowable power dissipation given in (Note 3) ,
we find that P
contribution of the quiescent current to total power dissipa-
tion the maximum input voltage (while still delivering 50 mA
output current) is 17.3V. The LM2936Z–5.0 will go into ther-
mal shutdown if it attempts to deliver full output current with
an input voltage of more than 17.3V. Similarly, at 40V input
and 25˚C ambient the LM2936Z–5.0 can deliver 18 mA
maximum.
Under conditions of higher ambient temperatures, the volt-
age and current calculated in the previous examples will
drop. For instance, at the maximum ambient of 125˚C the
LM2936Z–5.0 can only dissipate 128 mW, limiting the input
voltage to 7.34V for a 50 mA load, or 3.5 mA output current
for a 40V input.
The junction to ambient thermal resistance θ
two distinct components: the junction to case thermal resis-
tance rating θ
rating θ
For the SO-8 and TO-252 surface mount packages the θ
rating can be improved by using the copper mounting pads
on the printed circuit board as a thermal conductive path to
extract heat from the package.
CA
. The relationship is defined as: θ
JC
Dmax
; and the case to ambient thermal resistance
= 641 mW at 25˚C. Including the small
JA
JA
= θ
rating has
JC
+ θ
CA
JA
.
11
On the SO-8 package the four ground pins are thermally
connected to the backside of the die. Adding approximately
0.04 square inches of 2 oz. copper pad area to these four
pins will improve the θ
this extra pad are is placed directly beneath the package
there should not be any impact on board density.
On the TO-252 package the ground tab is thermally con-
nected to the backside of the die. Adding 1 square inch of 2
oz. copper pad area directly under the ground tab will im-
prove the θ
While the LM2936 has an internally set thermal shutdown
point of typically 160˚C, this is intended as a safety feature
only. Continuous operation near the thermal shutdown tem-
perature should be avoided as it may have a negative affect
on the life of the device.
While the LM2936 maintains regulation to 60V, it will not
withstand a short circuit above 40V because of safe operat-
ing area limitations in the internal PNP pass device. Above
60V the LM2936 will break down with catastrophic effects on
the regulator and possibly the load as well. Do not use this
device in a design where the input operating voltage may
exceed 40V, or where transients are likely to exceed 60V.
SHUTDOWN PIN
The LM2936BM has a pin for shutting down the regulator
output. Applying a Logic Level High (
pin will cause the output to turn off. Leaving the Shutdown
pin open, connecting it to Ground, or applying a Logic Level
Low (
<
0.6V) will allow the regulator output to turn on.
JA
rating to approximately 50˚C/W.
JA
rating to approximately 110˚C/W. If
>
2.0V) to the Shutdown
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