IDT82P20416 Integrated Device Technology, IDT82P20416 Datasheet - Page 20

• Manufacturer Part Number: IDT82P20416
• Description: 16-channel Short Haul T1/e1/j1 Line Interface Unit
• Manufacturer: Integrated Device Technology

3
3.1
globally or on a per-channel basis. The configuration is determined by
the TEHWE pin, the TEHW pin and the T1E1 bit (b0, CHCF,...). Refer to
Table-1 for details of the operation mode selection.
3.2
3.2.1
Receive Differential mode, both RTIPn and RRINGn are used to receive
signal from the line side.
with T1 100 Ω, J1 110 Ω or E1 120 Ω twisted pair cable or E1 75 Ω
coaxial cable.
ance matching or external impedance matching for each channel in
different applications.
3.2.1.1 Receive Differential Mode
supported: Fully Internal Impedance Matching, Partially Internal Imped-
ance Matching and External Impedance Matching. Figure-3 shows an
overview of how these Impedance Matching modes are switched.
mable resistor (IM) only and does not use an external resistor. This
configuration saves external components and supports 1:1 Hitless
Protection Switching (HPS) applications without relays. Refer to
Section 4.4 Hitless Protection Switching (HPS) Summary.
programmable resistor (IM) and a value-fixed 120 Ω external resistor
(Rr). Compared with Fully Internal Impedance Matching, this configura-
tion provides considerable savings in power dissipation of the device.
For example, In E1 120 Ω PRBS mode, the power savings would be
0.44 W. For power savings in other modes, please refer to Chapter 8
Physical And Electrical Specifications.
only.
Table-1 Operation Mode Selection
Functional Description
IDT82P20416
The IDT82P20416 can be configured to T1/J1 mode or E1 mode
The receive line interface supports Receive Differential mode. In
In Receive Differential mode, the line interface can be connected
The receive impedance matching is realized by using internal imped-
In Receive Differential mode, three kinds of impedance matching are
Fully Internal Impedance Matching circuit uses an internal program-
Partially Internal Impedance Matching circuit consists of an internal
External Impedance Matching circuit uses an external resistor (Rr)
FUNCTIONAL DESCRIPTION
T1 / E1 / J1 MODE SELECTION
RECEIVE PATH
R
Operation Mode
X
TEHWE Pin
TERMINATION
TEHW Pin
T1E1 Bit
(The configuration of this bit is ignored).
Open
T1/J1
Global Programming
Open
20
Low
E1
16-CHANNEL SHORT HAUL T1/E1/J1 LINE INTERFACE UNIT
Protection Switch (HPS) hot-switchover, RTIPn/RRINGn must be forced
to enter high impedance state (i.e., External Impedance Matching). For
hot-swap, RTIPn/RRINGn must be always held in high impedance state
during /after power up; for HPS hot-switchover, RTIPn/RRINGn must
enter high impedance state immediately after switchover. Though each
channel can be individually configured to External Impedance Matching
through register access, it is too slow for hitless switch. Therefore, a
hardware pin - RIM - is provided to globally control the high impedance
for all 16 receivers.
all 16 receivers and the per-channel impedance matching configuration
bits - the R_TERM[2:0] bits (b2~0, RCF0,...) and the R120IN bit (b4,
RCF0,...) - are ignored.
Figure-3 Switch between Impedance Matching Modes
Rr = 120 Ω
To support some particular applications, such as hot-swap or Hitless
When RIM is low, only External Impedance Matching is supported for
RRING
RTIP
RIM
(The configuration of this pin is ignored)
R120IN
T1/J1
0
Per-Channel Programming
1 0
0
IM
RIN
1
R_TERM[1:0]
Low
R_TERM2
December 17, 2009
E1
1
Receive
path