LM109H/NOPB National Semiconductor, LM109H/NOPB Datasheet - Page 3

• Manufacturer Part Number: LM109H/NOPB
• Description: IC REGULATOR 5V TO-39
• Manufacturer: National Semiconductor

Specifications of LM109H/NOPB

• Regulator Topology: Positive Fixed
• Voltage - Output: 5.05V
• Voltage - Input: 7.1 V ~ 25 V
• Number Of Regulators: 1
• Current - Output: 200mA
• Operating Temperature: -55°C ~ 150°C
• Mounting Type: Through Hole
• Package / Case: TO-205AD, TO-39-3 Metal Can
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Dropout (typical): -
• Current - Limit (min): -
• Lead Free Status / Rohs Status: RoHS Compliant part

Application Hints
1. Bypass the input of the LM109 to ground with
2. Avoid insertion of regulator into “live” socket if input
3. The output clamp zener is designed to absorb tran-
4. Paralleling of LM109s for higher output current is not
Crowbar Overvoltage Protection
Typical Performance Characteristics
Maximum Average
Power Dissipation (LM109K)
ceramic or solid tantalum capacitor if main filter capaci-
tor is more than 4 inches away.
voltage is greater than 10V. The output will rise to within
2V of the unregulated input if the ground pin does not
make contact, possibly damaging the load. The LM109
may also be damaged if a large output capacitor is
charged up, then discharged through the internal clamp
zener when the ground pin makes contact.
sients only. It will not clamp the output effectively if a fail-
ure occurs in the internal power transistor structure. Ze-
ner dynamic impedance is
current into the zener should not exceed 0.5A.
recommended. Current sharing will be almost nonexist-
ent, leading to a current limit mode operation for devices
with the highest initial output voltage. The current limit
devices may also heat up to the thermal shutdown point
( 175˚C). Long term reliability cannot be guaranteed
under these conditions.
Input Crowbar
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4 . Continuous RMS
Maximum Average
Power Dissipation (LM309K)
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0.2 µF
*Zener is internal to LM109.
*
at regulator input. LM109 bond wires will fuse at currents above 7A.
†
capacitor size, transformer impedance, and fuse blowing time.
††
*
3
Q2 is selected for surge capability. Consideration must be given to filter
Q1 must be able to withstand 7A continuous current if fusing is not used
Trip point is
5. Preventing latchoff for loads connected to negative
If the output of the LM109 is pulled negative by a high cur-
rent supply so that the output pin is more than 0.5V negative
with respect to the ground pin, the LM109 can latch off. This
can be prevented by clamping the ground pin to the output
pin with a germanium or Schottky diode as shown. A silicon
diode (1N4001) at the output is also needed to keep the
positive output from being pulled too far negative. The 10
resistor will raise +V
voltage:
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7.5V.
Output Crowbar
OUT
Output Impedance
by
0.05V.
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