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Data Sheet

ManualsBrandsUnbranded ManualsActive ComponentsLP2985IM5-3.0/NOPB PMIC - LDO voltage regulator Positive, fixed SOT 23 5
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V
IN
V
OUT
PNP
GND
SCHOTTKY DIODE
V
IN
V
OUT
PNP
GND
LP2985-N
www.ti.com
SNVS018V –MARCH 2000–REVISED JUNE 2013
REVERSE INPUT-OUTPUT VOLTAGE
The PNP power transistor used as the pass element in the LP2985-N has an inherent diode connected between
the regulator output and input. During normal operation (where the input voltage is higher than the output) this
diode is reverse-biased).
Figure 37. Reverse Current Path
However, if the output is pulled above the input, this diode will turn ON and current will flow into the regulator
output. In such cases, a parasitic SCR can latch which will allow a high current to flow into V
IN
(and out the
ground pin), which can damage the part.
In any application where the output may be pulled above the input, an external Schottky diode must be
connected from V
IN
to V
OUT
(cathode on V
IN
, anode on V
OUT
), to limit the reverse voltage across the LP2985-N to
0.3V (see ABSOLUTE MAXIMUM RATINGS).
Figure 38. Reverse Current Protection
DSBGA MOUNTING
The DSBGA package requires specific mounting techniques which are detailed in Texas Instruments Application
Note 1112 (SNVA009). Referring to the section Surface Mount Technology (SMT) Assembly Considerations,
it should be noted that the pad style which must be used with the 5-pin package is the NSMD (non-solder mask
defined) type.
For best results during assembly, alignment ordinals on the PC board may be used to facilitate placement of the
DSBGA device.
DSBGA LIGHT SENSITIVITY
Exposing the DSBGA device to direct sunlight will cause misoperation of the device. Light sources such as
Halogen lamps can also affect electrical performance if brought near to the device.
The wavelenghts which have the most detrimental effect are reds and infra-reds, which means that the
fluorescent lighting used inside most buildings has very little effect on performance. A DSBGA test board was
brought to within 1 cm of a fluorescent desk lamp and the effect on the regulated output voltage was negligible,
showing a deviation of less than 0.1% from nominal.
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