Rainbow Electronics AT89C5131 - Manual (Page 11)

11
AT89C5131
4136A–USB–03/03
VREF PWR
3V Voltage Reference
VREF is used to supply the on-chip USB differential drivers.
It is internally connected to the on-chip voltage regulator output of the
standard versions, which must be connected to an external decoupling
capacitor and can be connected to D+ with a 15 k
Ω resistor.
It must be provided from outside on the Low Power versions, which have
no internal voltage regulator.
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Table 11. Power Signal Description (Continued)
Signal
Name Type Description
Alternate
Function