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Junction‐to‐case thermal resistance is specified from the IC junction to the bottom of the case directly below the die. The
bonding wires are appending paths. The former is the lowest resistance path. Proper mounting is required to ensure the
best possible thermal flow this area of the package to the heat sink. Thermal compound at the case‐to‐heat‐sink interface
is strongly recommended. The case of all devices in this series is electrically connected to the output. Therefore, if the case
of the device must be electrically isolated, a thermally conductive spacer can be used, as long its thermal resistance is
considered.
Protection Diode
In general operation, RS1117A series don’t need any protection diodes. From the cross‐section structure of RS1117A series,
the output pin is connected to P+ substrate, and the input pin is connected to N‐ well. There is a parasitic reverse diode
between them. It can handle microsecond surge currents of 5A to 10A. Even with large output capacitance, it is very
difficult to get those values of surge currents in normal operation. Only with high value output capacitors, such as 1000uF.
And with the input pin instantaneously shorted to ground, can damage occur. A crowbar circuit at the input of the RS1117A
series can generate those kinds of currents, and a diode from output to input is recommended. Normal power supply
cycling or even plugging and unplugging in the system will not generate currents large enough to do any damage.
Voltage Code Information
Voltage Code
RS1117ASJ-A
RS1117ASJ-B
RS1117ASJ-C
RS1117ASJ-D
RS1117ASJ-E
RS1117AM-A
RS1117AM-B
Output Voltage
ADJ
Package
Output Voltage
RS1117AJ-A
RS1117AJ-B
RS1117AJ-C
RS1117AJ-D
RS1117AJ-E
RS1117AE-A
RS1117AE-B
Output Voltage
ADJ
Package
1.8V
1.8V
SOT-223
TO-252
2.5V
2.5V
3.3V
3.3V
5.0V
5.0V
ADJ
ADJ
1.8V
1.8V
SOT-89
TO-220AB
RS1117AM-C
RS1117AM-D
2.5V
3.3V
RS1117AE-C
RS1117AE-D
2.5V
3.3V
RS1117AM-E
5.0V
RS1117AE-E
5.0V
DS‐RS1117A‐16 September, 2009
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