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STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
PROPRIETARY AND CONFIDENTIAL
27
Pin No.
Pin Name
Type
-RI
-NI
Function
RDB
Input
23
G3
Active Low Read Enable (RDB). RDB is pulsed low to enable a COMET
register read access. The COMET drives the D[7:0] bus with the contents of
the addressed register while RDB and CSB are both low.
WRB
Input
24
J2
Active Low Write Strobe (WRB). WRB is pulsed low to enable a COMET
register write access. The D[7:0] bus contents are clocked into the addressed
normal mode register on the rising edge of WRB while CSB is low.
ALE
Input
45
G9
Address Latch Enable (ALE). This signal latches the address bus contents,
A[8:0], when low, allowing the COMET to be interfaced to a multiplexed
address/data bus. When ALE is high, the address latches are transparent.
D[0]
D[1]
D[2]
D[3]
D[4]
D[5]
D[6]
D[7]
I/O
26
27
28
29
32
33
34
35
H3
J4
H4
F4
G5
F5
H6
J7
Bi-directional Data Bus (D[7:0]). This bus is used during read and write
accesses to internal COMET registers.
A[0]
A[1]
A[2]
A[3]
A[4]
A[5]
A[6]
A[7]
A[8]
Input
36
37
38
39
40
41
42
43
44
J6
H5
H7
J8
G6
J9
H8
G7
H9
Address bus (A[8:0]).
This bus selects specific registers during COMET
register accesses.
RSTB
Input
22
H2
Active Low Reset (RSTB). When forced low, RSTB will asynchronously reset
the COMET. RSTB is a Schmitt-trigger input with integral pull-up. When
resetting the device, RSTB must be asserted for a minimum of 100 ns to
ensure that the COMET is completely reset.
INTB
OD
Output
25
J3
Active Low Open-drain Interrupt (INTB). INTB drives low when an unmasked
interrupt event is detected on any of the internal interrupt sources. Note that
INTB will remain low until all active, unmasked interrupt sources are
acknowledged at their source at which time, INTB will tristate.