XE8806A SEMTECH [Semtech Corporation], XE8806A Datasheet - Page 80

• Manufacturer Part Number: XE8806A
• Description: Ultra Low-Power Low-Voltage
• Manufacturer: SEMTECH [Semtech Corporation]

PDPullup[x] is 0, the pull-ups on the pins PD[2x] and PD[2x+1] are disabled. When a bit PDPullup[x] is set to 1
and the bit PDSnapToRail[x] is set to 0, the pull-up resistor is connected to the pins PD[2x] and PD[2x+1]. When
both PDPullup[x] and PDSnapToRail[x] are 1, the snap-to-rail function is active on the pins PD[2x] and PD[2x+1].
The snap-to-rail function connects a pullup or pulldown resistor to the input pin depending on the value forced on
the input pin. This function can be used for instance when the input port is connected to a tristate bus. When the
bus is floating, the pullup or pulldown maintains the bus in the last low impedance state before it became floating
until another low impedance output is driving the bus. It also reduces the power consumption with respect to a
classic pullup since it selects the pullup or pulldown resistor so that it confirms the detected input state.
The function is summarised in the table below as a function of the different register settings.
At power-on reset, Port D is configured as an input port with all pull-ups active.
13.5 Port D electrical specification
Note 1: this value is indicative only since it depends on the package.
© Semtech 2006
sym
V
V
V
R
V
Cin
INH
INL
OL
PU
OH
Table 13-6: Snap-to-rail and pullup function
description
Input high voltage
Input low voltage
Output high voltage
Output low voltage
Pull-up resistance
Input capacitance
PDDir[2x(+1)]
1
0
0
0
0
PDPullup[x]
0.7*VBAT
VBAT-0.4
x
0
1
1
1
VSS
VSS
min
20
Table 13-7. Port D electrical specification
PDSnapToRail[x]
3.0
typ
50
13-4
0.2*VBAT
VSS+0.4
0
1
1
x
x
VBAT
VBAT
max
80
unit Comments
PD[2x(+1)] value
kΩ
pF
(last) externally
V
V
V
V
forced
VBAT=1.2V, I
VBAT=2.4V, I
VBAT=4.5V, I
VBAT=1.2V, I
x
x
x
0
1
VBAT=2.4V, I
VBAT=4.5V, I
VBAT≥2.4V
VBAT≥2.4V
XE8806A/XE8807A
=12.0mA
=15.0mA
Note 1
PD[2x(+1)] pull
OH
OH
OH
OL
not connected
not connected
=0.3mA
=0.3mA
=5.0mA
=8.0mA
pulldown
resistor
pullup
pullup
OL
OL
www.semtech.com