Data Sheet
15 | P a g e Espressif Systems Oct 12, 2013
ESP8266 802.11bgn Smart Device
Optional hold functionality can be built into the IO if requested. When the IO is not driven by the
internal or external circuitry, the hold functionality can be used to hold the state to the last used
state.
The hold functionality introduces some positive feedback into the pad. Hence, the external driver
that drives the pad must be stronger than the positive feedback. The required drive strength is
however small – in the range of 5uA.
Parameter
Symbol
Min
Max
Unit
Input low voltage
V
IL
-0.3
0.25V
IO
V
Input high voltage
V
IH
0.75VIO
3.6
V
Input leakage current
I
IL
50
nA
Output low voltage
V
OL
0.1V
IO
V
Output high voltage
V
OH
0.8VIO
V
Input pin capacitance
C
pad
2
pF
VDDIO
V
IO
1.7
3.6
V
Maximum drive capability
I
MAX
12
mA
Temperature
T
amb
-20
100
C
All digital IO pins are protected from over-voltage with a snap-back circuit connected between
the pad and ground. The snap back voltage is typically about 6V, and the holding voltage is 5.8V.
This provides protection from over-voltages and ESD. The output devices are also protected
from reversed voltages with diodes.