DS_FT231X Datasheet, PDF (28/44 Pages) List of Unclassifed Manufacturers – Future Technology Devices International Ltd FT231X

FT231X USB TO FULL HANDSHAKE UART IC
Datasheet
Version 1.2
Document No.: FT_000565 Clearance No.: FTDI# 261
7.4 USB Battery Charging Detection
A recent addition to the USB specification (http://www.usb.org/developers/devclass_docs/BCv1.2_011912.zip) is
to allow for additional charging profiles to be used for charging batteries in portable devices. These
charging profiles do not enumerate the USB port of the peripheral. The FT231X device will detect that a
USB compliant dedicated charging port (DCP) is connected. Once detected while in suspend mode, a
battery charge detection signal is provided to allow external logic to switch to charging mode as opposed
to operation mode.
To use the FT231X with battery charging detection the CBUS pins must be reprogrammed to allow for the
BCD Charger output to switch the external charger circuitry on. The CBUS pins are configured in the
internal MTP memory with the free utility FTPROG. If the charging circuitry requires an active low signal
to enable it, the CBUS pin can be programmed to BCD Charger# as an alternative.
When connected to a USB compliant dedicated charging port (DCP, as opposed to a standard USB host)
the device USB signals will be shorted together and the device suspended. The BCD charger signal will
bring the LTC4053 out of suspend and allow battery charging to start. The charge current in the example
below is 1A as defined by the resistance on the PROG pin.
VBUS
3V3OUT
VBUS 3V3OUT
VBUS 3V3OUT
CN USB
VBUS
D-
D+
ID
GND
1
2
3
4
5
600R/2A
27R
27R
10nF
3V3OUT
DM
DP
RESET#
N.F.
0R
SLD GND
GND
0.1uF
GND
CBUS0
FT231X
GND
0.1uF
GND
0.1uF
GND
BCD
VBUS VBUS
VBUS
VBATT
0.1uF
4.7uF
GND GND
0.1uF
1
2
3
4
5
CHRG
VCC
FAULT
TIMER
GND
ACPR
BAT
SHDN
PROG
NTC
10
9
8
7
6
LTC4053EDD
2K2
BCD
NTC
1K5
1+
NCT
-
TB3.5mm
1uF
1R
GND
EEPROM Setting
X-Chip Pin
CBUS0
Function
BCD
GND
GND
Battery Options
Battery Charger Enable X
Force Power Enable
De-acticate Sleep
GND GND
VBUS
GND GND
1A when connected to a dedicated charger port
0A when enumerated
0A when not enumerated and not in sleep
0A when in sleep
NTC
4K32 1%
JUMPER-2mm
JP1
SIP-3
GND
JP1
NCT Available
1-2 NCT Enabled
2-3 NCT Disabled (Default)
Figure 7.4 USB Battery Charging Detection (1 pin)
Alternatively the PWREN# And SLEEP pins may be used to control the LTC4053 such that a battery may
be charged from a standard host (low current) or from a dedicated charging port (high current). In such
a design as shown below the charge current would need to be limited to 0.4A to ensure that the USB host
power limit is not exceeded.
Copyright © 2013 Future Technology Devices International Limited
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