
21145
6
Preliminary 
Datasheet
P = Power
Pins labeled rsv are reserved for future use and must be left unconnected.
The following signals have an internal pull-up:
sr_do
mii/sym_tclk
Signal sr_cs has an internal pull-down.
Table 1
 provides a functional description of each of the 21145 signals. These signals are listed 
alphabetically.
Table 1. Functional Description of 21145 Signals (Sheet 1 of 8)
Signal
Type
Pin 
Number, 
176-pin
Pin 
Number, 
144-pin
Description
ad<31:0>
I/O
31, 32, 33, 
35, 36, 37, 
39, 40, 47, 
48, 49, 51, 
52, 53, 56, 
57, 76, 77, 
80, 81, 82, 
84, 85, 86, 
92, 93, 94, 
96, 97, 98, 
100, 101
23, 24, 25, 
27, 28, 29, 
31, 32, 39, 
40, 41, 43, 
44, 45, 47, 
48, 61, 62, 
64, 65, 66, 
68, 69, 70, 
76, 77, 78, 
80, 81, 82, 
84, 85
32-bit PCI address and data lines. Address and data bits 
are multiplexed on the same pins. During the first clock 
cycle of a transaction, the address bits contain a physical 
address (32 bits). During subsequent clock cycles, these 
same lines contain 32 bits of data. A 21145 bus 
transaction consists of an address phase followed by one 
or more data phases. The 21145 supports both read and 
write bursts (in master operation mode only). Little and 
big endian byte ordering can be used.
br_a<0>/cb_pads_l/
mdm_wr (on 176 pins)
br_a<0>/cb_pads_l 
(on 144 pins)
I/O
105
87
For the 176-pin 21145 only
:
During operation, when accessing the modem chipset 
(mdm_chip_sel is asserted), this pin is used as the 
modem write line and is active low. 
When the modem is not accessed (mdm_chip_sel is 
deasserted), this pin is used as the expansion ROM 
address line bit 0. In a 256KB configuration, this pin also 
carries in two consecutive address cycles, expansion 
ROM address bits 16 and 17. 
For both the 144-pin and 176-pin 21145
:
During reset, this pin also determines the type of signals 
to use for the PCI/CardBus output pins, either PCI or 
CardBus. By default, this pin selects PCI signaling. To 
select CardBus signaling, this pin must be connected to a 
pull-down resistor.
br_a<1>/mdm_rd
O
106
NA
For the 176-pin 21145 only
:
During operation, when accessing the modem chipset 
(mdm_chip_sel is asserted), this pin is used as the 
modem read line and is active low. 
When the modem is not accessed (mdm_chip_sel is 
deasserted), this pin is used as the expansion ROM 
address line bit 1.   This pin also latches the expansion 
ROM address and control lines by the two external 
latches.