
21145
Preliminary
 Datasheet
9
int_l
O/D
21
15
Interrupt request asserts when one of the appropriate bits 
of CSR5 sets and causes an interrupt, provided that the 
corresponding mask bit in CSR7 is not asserted.  
Interrupt request deasserts by writing a 1 into the 
appropriate CSR5 bit. 
If more than one interrupt bit is asserted in CSR5 and the 
host does not clear all input bits, the 21145 deasserts int_l 
for one cycle to support edge-triggered systems.
iref
I
132
108
Current reference input for the analog phase-locked loop 
logic.
irdy_l
I/O
60
51
Initiator ready indicates the bus master’s ability to 
complete the current data phase of the transaction.
A data phase is completed on any rising edge of the clock 
when both irdy_l and target ready trdy_l are asserted. 
Wait cycles are inserted until both irdy_l and trdy_l are 
asserted together.
When the 21145 is the bus master, it asserts irdy_l during 
write operations to indicate that valid data is present on 
the 32-bit ad lines. During read operations, the 21145 
asserts irdy_l to indicate that it is ready to accept data.
mdm_a<4:0>
O
120, 121, 
122, 142, 
143
NA
Modem address lines. Address lines that are not needed 
in order to access the modem should be left 
unconnected. For example, if the modem chipset has only 
8 registers, mdm_a<4:3> should be left unconnected.
mdm_chip_sel
O
119
NA
Modem chip select. This pin is active low.
mdm_int
I
144
NA
Modem interrupt line. When asserted, the 21145 asserts 
the int_l pin. This pin is active high. It must be connected 
to a pull-down resistor. 
mdm_pwr_down
O
79
NA
Modem power down. This pin is asserted when the 
modem function is in D3 power state. It can be used by 
the modem chipset power control. The polarity of this pin 
is determined by the Func1_HwOptions<5> bit in the 
serial ROM.
mdm_ring_ind
I
18
NA
Modem ring indicator. The assertion of this pin affects the 
assertion of the wake pin.
The polarity of this pin is determined by the 
Func1_HwOptions<4> bit in the serial ROM. This pin 
must not be left floating. 
mdm_rst
O
70
NA
Modem reset. This pin is asserted for 15 
μ
s from the end 
of the 21145’s power-up reset pulse, and on moving from 
the D3 to the D0 power state.
mdm_spkr_en
O
65
NA
Modem speaker enable. This pin reflects the Audio 
enable bits of the modem function Status Changed 
registers.
If the Func1_HwOptions<7> bit in the serial ROM is set, 
the value of the FEMR<5> is driven on the 
MDM_SPKR_EN pin.
If the Func1_HwOptions<7> is cleared, the value of 
FEMR<6> is driven on the MDM_SPKR_EN pin.
Table 1. Functional Description of 21145 Signals (Sheet 4 of 8)
Signal
Type
Pin 
Number, 
176-pin
Pin 
Number, 
144-pin
Description