STANDARD PRODUCT
PM4351 COMET
DATA SHEET
PMC-1970624
ISSUE 10
COMBINED E1/T1 TRANSCEIVER
1. All COMET digital inputs and bi-directional pins present minimum capacitive
loading and operate at TTL logic levels.
2. All COMET digital outputs and bi-directional pins have at least 2 mA drive
capability. The BTCLK and BRCLK outputs, have 6 mA drive capability. The
transmit analog outputs (TXTIP and TXRING) have built-in short circuit
current limiting.
3. Inputs RSTB, TMS, TDI and TRSTB have internal pull-up resistors.
4. The VSSI and VSSO ground pins are not internally connected together.
Failure to connect these pins externally may cause malfunction or damage
the COMET.
5. The VDDI and VDDO power pins are not internally connected together.
Failure to connect these pins externally may cause malfunction or damage
the COMET.
6. The recommended power supply sequencing is as follows:
a) During power-up, the voltage on the BIAS pin must be kept equal to or
greater than the voltage on the VDDO3, VDDO2, VDDO1, VDDI2 and VDDI1
pins, to avoid damage to the device.
b) VDDI power must be supplied either before VDDO or simultaneously with
VDDO. Connection of VDDI and VDDO to a common VDD power plane is
recommended.
c) The VDDI power must be applied before input pins are driven or the input
current per pin be limited to less than the maximum DC input current
specification (20 mA).
d) Analog power supplies (TAVD1, TAVD2, TAVD3, TAVD4, RAVD1, RAVD2,
QAVD) must be applied after both VDDI and VDDO have been applied or
they must be current limited to the maximum latch-up current specification
(100 mA). In operation, the differential voltage measured between AVD
supplies and VDDI must be less than 0.5 V. The relative power sequencing of
the multiple AVD power supplies is not important.
e) Power down the device in the reverse sequence.
PROPRIETARY AND CONFIDENTIAL
31
PMC [ PMC-SIERRA, INC ]
