
Agere Systems Inc.
243
Data Sheet
July 2001
T8302 Internet Protocol Telephone
Advanced RISC Machine (
ARM
)
19 Electrical Specifications
(continued)
19.4 PHY Clock Crystal
The T8302 requires a 25 MHz clock source (derived from an oscillator or a crystal) for PHY timing. If a crystal s
used, it must be connected between XLO and XHI. The crystal specifications are shown below.
19.5 Real-Time Clock Crystal
The T8302 may use an optional a 32.768 KHz clock source (derived from an oscillator or a crystal) for real-time
clock timing. This crystal is only required if the internal RTC clock does not provide sufficient accuracy. If a crystal
is used, it must be connected between XRTC0 and XRTC1. The crystal specifications are shown below.
19.6 dc Electrical Characteristics
V
DD
= 3.3 V and Vss = 0.0 V unless otherwise specified.
Table 212. PHY Clock (XLO, XHI) Crystal Specifications
Parameter
Value
25 MHz
Frequency.
Oscillation Mode.
Effective Series Resistance.
Load Capacitance.
Shunt Capacitance.
Frequency Tolerance and Stability.
Fundamental, parallel resonance
A discussion of crystal selection for the T8302 may be found
in the application note
Crystal Selection for the T8301/T8302
Chip Set
.
±
50 ppm
Table 213. Real-Time Clock (XRTC0, XRTC1) Specifications
Parameter
Value
Frequency.
Oscillation Mode.
Effective Series Resistance.
Load Capacitance.
Shunt Capacitance.
Frequency Tolerance and Stability.
32.768 KHz
Fundamental, parallel resonance
A discussion of crystal selection for the T8302 may be found
in the application note
Crystal Selection for the T8301/T8302
Chip Set
.
±
20 ppm
Table 214. Reset Pulse
Parameter
Min
200
Max
—
Unit
ns
RESET# Minimum Pulse Width.
Table 215.
dc Electrical Characteristics
Parameter
Symbol
I
DD
V
DD
V
IH
V
IL
I
I
Condition
—
—
—
—
V
A
= 2.0 V
Min
—
3.135
2.0
—
—
Typ
—
—
—
—
—
Max
600
3.465
—
0.8
20
Unit
mA
V
V
V
μ
A
Supply Current.
Supply Voltage (3.3 V
±
5%).
Input High-Voltage.
Input Low-Voltage.
Input Current.