UMFT231XC-01 FTDI, UMFT231XC-01 Datasheet - Page 7

• Manufacturer Part Number: UMFT231XC-01
• Description: Interface Development Tools USB to UART Dev Mod w/ USB Charge Detect
• Manufacturer: FTDI
• Type: USB to UARTr

Specifications of UMFT231XC-01

• Rohs: yes
• Product: Development Modules
• Tool Is For Evaluation Of: FT231XS
• Interface Type: UART, USB
• Operating Supply Voltage: 3.3 V
• Dimensions: 50 mm x 37.5 mm
• Tradename: X-Chip

5 Battery Charging using an X-Chip
An illustration of an X-Chip being used for battery charging functions is shown in Figure 5.1. The PROG
pin of the LTC4053 holds a current detection function that maintains a voltage of 1.5V to this pin and is
used to detect the current flowing from V
amount of current from V
current permitted to flow from VBUS to the battery. The battery charging current is defined by I
(I
between V
It is important that there is no other current source to the PROG pin other than V
in the battery charging current. The FTDI FT231X uses open drain outputs with no internal pull-ups for
BCD# and PWREN# to support this requirement. The X-Chip will allow the same CBUS function to be
reused with more than one pin, so if BCD# or PWREN# are needed elsewhere in the circuit a second
assignment of the required function should be made to a second pin and this pin can be routed
elsewhere.
The SHDN# pin of the LTC4053 is an active low input and when a logic low is applied to SHDN# the
current supply to the battery is suspended.
Figure 5.1 – Simplified X-Chip - Battery Charger interface
The required configuration of the BCD# Options of the MTP ROM for this application are given in Table
5.1.
A list of all the different current limits of the UMFT231XC is given in Table 5.2. If the BCD Options of the
MTP ROM is configured as shown in Table 5.1, when connected to dedicated charger port BCD# will be
tied to ground, PWERN# will be floating and SLEEP will be driven high. The current values give in Table
5.2 can be altered by changing the values of R12, R13 or R14 of the UMFT231XC. The default values of
these resistors are given in Figure 5.1.
A description of the signals used to control the limit of the current to battery is given in Table 5.3.
(1) Battery Charger Enable
VBUS
PROG
(2) Force Power Enable
(3) De-activate Sleep
).1000, where I
BCD Options:
VCC
PROG
FTDI X-Chip
and Ground.
CHG
PWREN#
SLEEP#
is the current charging the battery, I
PROG
BCD#
through the resistor network to Ground is directly proportion the amount of
Disable
Enable
Enable
GND
R11
2K2
R13
R14
PROG
be driven low when a dedicated charger
Disables the option of forcing PWREN#
Prevents SLEEP# pin from driving low
function, allows for BCD_Charger# to
(1.5V) at this pin through a resistor network to Ground. The
Enables the use of BCD_Charger#
to be driven low when a dedicated
when a dedicated charger port is
1K5
4K32
charger port is connected.
Document Reference No.: FT_000521
port is connected.
Copyright © 2012 Future Technology Devices International Limited
GND
connected.
R12
16K5
VBUS
PROG
is 1.5V/R
SHDN#
PROG
VCC
LTC4053EDD
PROG
UMFT231XC Datasheet
and R
PROG
(1) Battery Charger Enable
(2) Force Power Enable
Clearance No.: FTDI#
(3) De-activate Sleep
PROG
to prevent an offset
BCD# Options:
BAT
is the resistance
Version 1.0
CHG
GND
=
273
7