EZ-USB Series 2100
More Endpoint Buffer
Memory
The EZ-USB chip supports more
endpoints and provides more
endpoint buffer memory than any
other USB-device solution in the
market. The USB specification
describes an endpoint as a source
or sink of data. In the EZ-USB
chip, endpoints are constructed
as RAM (bulk, control, interrupt
endpoints) or FIFOs (isochronous
endpoints). With support for 31
endpoints (the maximum in the
USB specification), it gives the
peripheral designer ultimate
flexibility. Unlike other USB
peripheral alternatives, the
EZ-USB architecture also sup-
ports the maximum packet size
for each endpoint. Thus 64-byte
packets are available for all
control, bulk, and interrupt
endpoints. Isochronous endpoints
are double buffered with a packet
size of up to 1024 bytes, the
maximum allowable under the
USB specification.
Control
The EZ-USB family supports one
control endpoint. To simplify
firmware programming, the
EZ-USB chip provides data from
control transfers in two separate
buffers. It also has a unique
capability to manage the three-
phase transfer in hardware,
relieving device firmware from
this task.
Bulk/Interrupt
Bulk endpoints are used when
data integrity must be guaran-
teed, but without critical delivery
time. The EZ-USB family provides
14 bulk endpoints: seven IN and
seven OUT. These endpoints can
be programmed to be double-
buffered, which improves trans-
fer bandwidth in some applica-
tions. Bulk data is accessible as
RAM or FIFO data. The IN and
OUT endpoints can also be used
as interrupt endpoints.
Isochronous
These endpoints support stream-
ing data such as audio or video.
The EZ-USB family supports 16
isochronous endpoints: eight IN
and eight OUT. A pool of FIFOs
can be allocated among the
endpoint to a maximum of
1 Kbyte. Isochronous endpoints
are double-buffered, as required
by the USB specification, so the
actual size of iscochronous buffer
memory is 2 Kbytes.
Low Power—Even for
Bus-Powered Devices
The EZ-USB family meets the
tough power specifications of
USB. Running off of a 3.3V power
supply, it can accommodate bus-
powered devices and self-pow-
ered peripherals. In addition,
with a 50 mA current draw under
full operating conditions, the
EZ-USB family provides current
headroom for peripheral func-
tions. This meets the USB require-
ment of 100 mA maximum
current for attached peripherals
prior to configuration. Total
maximum power required by an
EZ-USB chip under active condi-
tions is 170 mW. Other solutions
require five times more power.
Thirty-one
Endpoints
for Ultimate
Flexibility
