UM232R FTDI, UM232R Datasheet - Page 22
![Interface Modules & Development Tools USB to Serial UART Dev Mod for FT232R](/photos/15/89/158917/um232r_sml.jpg)
UM232R
Manufacturer Part Number
UM232R
Description
Interface Modules & Development Tools USB to Serial UART Dev Mod for FT232R
Manufacturer
FTDI
Type
Development Moduler
Specifications of UM232R
Interface Type
USB, Serial, UART
Data Bus Width
Serial
Operating Supply Voltage
1.8 V to 5.25 V
Product
Interface Modules
Supported Devices
FT232R
Svhc
No SVHC (18-Jun-2010)
Development Tool Type
Development Kit
Kit Features
Single Chip USB To Asynchronous Serial Data Transfer Interface, Auto Transmit Buffer
Rohs Compliant
Yes
Supported Families
FT232RL
Features
Single Chip USB To Asynchronous Serial Data Transfer Interface, Auto Transmit Buffer Control
Tool / Board Applications
USB To
For Use With/related Products
FT232R
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
7.4 Bus Powered with 3.3V Logic Drive / IO Supply Voltage
Figure 7.4 USB Bus Powered 3.3V Logic Drive
Figure 7.4 shows a configuration where a jumper switch is used to allow the FT232R to be interfaced with a
3.3V or 5V logic devices. The FT232R‟s VCCIO pin is either supplied with 5V from the USB bus (connect
together pins 2 and 3 in J1), or with 3.3V from the FT232R‟s 3V3OUT pin (connect together pins 1 and 2 on
J1 as shown) the supply to UM232R‟s 3V3 pin can also be used to supply up to 50mA to external logic.
Please note the following in relation to bus powered designs of this type:
Another possible configuration would be to use a discrete low dropout regulation which is supplied by the
5V on the USB bus to supply 2.8V – 1.8V to the VIO pin and to the external logic. VCC would be supplied
with the 5V from the USB bus (available from the module‟s USB pin). With VIO connected to the output of
the low dropout regulator, this will cause the FT232R I/O pins to drive out at 2.8V – 1.8V logic levels.
For USB bus powered circuit some considerations have to be taken into account when selecting the
regulator:
The regulator must be capable of sustaining its output voltage with an input voltage of 4.35V. A Low Drop
Out (L.D.O.) regulator must be selected.
The quiescent current of the regulator must be low in order to meet the USB suspend total current
requirement of <= 500 μA during USB suspend.
An example of a regulator family that meets these requirements is the MicroChip / Telcom TC55 Series of
devices (www.microchip.com). These devices can supply up to 250mA current and have a quiescent current
of under 1 μA.
© Copyright 2009 Future Technology Devices International Ltd
ii) The maximum current source from USB Bus during normal operation should not exceed 100mA,
i) PWREN# or SLEEP‟ signals should be used to power down external logic during USB suspend mode, in
order to comply with the limit of 500 μA. If this is not possible, use the configuration shown in
7.3.
otherwise a bus powered design with power switching
UM232R USB - Serial UART Development Module Incorporating Clock Generator
12
1
J1
UM232R
1
J2
©
2
FTDI 2008
2
3
1
(Section
13
24
7.3) should be used.
Document Reference No.: FT_000051
Clearance No.: FTDI# 125
Datasheet Version 1.04
Section
21