FT121T-R FTDI, FT121T-R Datasheet - Page 13

• Manufacturer Part Number: FT121T-R
• Description: USB Interface IC USB CONTROLLER W/SPI SLAVE IC
• Manufacturer: FTDI

Specifications of FT121T-R

• Rohs: yes
• Product: USB 2.0
• Interface Type: SPI, USB
• Operating Supply Voltage: 4 V to 5.5 V
• Operating Supply Current: 3.9 mA
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: TSSOP-16
• Minimum Operating Temperature: - 40 C

5
The FT121 has 2 modes of operation for command and memory management: the default mode and the
enhanced mode. The buffer management schemes are different in these two modes. Upon reset the
default mode is functional. The enhanced mode is activated when any of the Set Endpoint Configuration
command (B0h – BFh) is received.
5.1 Endpoint Buffer Management in Default Mode
In default mode the FT121 has 3 bi-directional endpoints (EP0, EP1 and EP2). EP0 is the control endpoint,
with 16 bytes maximum packet size for both the control OUT and control IN endpoints. EP1 can be used
as either a bulk endpoint or an interrupt endpoint, with 16 bytes maximum packet size for both OUT and
IN endpoints. Table 5-1 shows the endpoint type and maximum packet size for EP0 and EP1.
Table 5-1 Endpoint configuration for EP0 and EP1
EP2 is the primary endpoint. It can be configured as either bulk/interrupt or isochronous endpoint. The
maximum packet size allowed for EP2 depends on the mode of configuration through Set Mode
command. Table 5-2 shows all the 4 endpoint configuration modes for EP2.
Table 5-2 Endpoint configuration for EP2
Configuration
EP2 Endpoint
Number (EP)
Endpoint
(default)
Mode
0
1
0
1
2
3
Endpoint Buffer Management
Index (EPI)
Index (EPI)
Endpoint
Endpoint
Copyright © 2012 Future Technology Devices International Limited
0
1
2
3
4
5
4
5
4
5
FT121 ENHANCED USB DEVICE CONTROLLER WITH SPI SLAVE IC
Endpoint
Direction
Endpoint
Direction
OUT
OUT
OUT
OUT
OUT
IN
IN
IN
IN
IN
Bulk/Interrupt
Bulk/Interrupt
Bulk/Interrupt
Bulk/Interrupt
Transfer Type
Transfer Type
Isochronous
Isochronous
Isochronous
Isochronous
Control
Control
Document No.: FT_000648
Clearance No.: FTDI#
Datasheet Version 1.0
Max Packet Size
Max Packet Size
128
128
16
16
16
16
64
64
64
64
312
13