Texas Instruments Evaluation Board for the LP3878-ADJ LP3878-ADJEVAL/NOPB LP3878-ADJEVAL/NOPB 数据表
产品代码
LP3878-ADJEVAL/NOPB
SNVS311B – MAY 2005 – REVISED APRIL 2013
However, if the output is pulled above the input, this diode will turn ON and current will flow into the regulator
output.
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
connected from V
IN
to V
OUT
(cathode on V
IN
, anode on V
OUT
), to limit the reverse voltage across the LP3878-ADJ
to 0.3V (see Absolute Maximum Ratings).
SETTING THE OUTPUT VOLTAGE
The output voltage is set using resistors R1 and R2 (see
).
The formula for output voltage is:
V
OUT
= V
ADJ
x (1 + (R
1
/ R
2
))
(3)
R2 must be less than 5 k
Ω
to ensure loop stability.
To prevent voltage errors, R1 and R2 must be located near the LP3878-ADJ and connected via traces with no
other currents flowing in them (Kelvin connect). The bottom of the R1/R2 divider must be connected directly to
the LP3878-ADJ ground pin.
other currents flowing in them (Kelvin connect). The bottom of the R1/R2 divider must be connected directly to
the LP3878-ADJ ground pin.
Copyright © 2005–2013, Texas Instruments Incorporated
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