FT240X USB 8-BIT FIFO IC Datasheet
Version 1.3
Document No.: FT_000626 Clearance No.: FTDI# 259
7.2 Battery Charge 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 FT240X 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.
VBUS
3V3OUT
VBUS 3V3OUT
VBUS
3V3OUT
0.1uF
0.1uF
600R/2A
3V3OUT
CN USB
VBUS
1
2
3
4
5
GND
GND
D-
D+
ID
DM
DP
27R
27R
GND
RESET#
10nF
N.F.
BCD
0.1uF
CBUS0
FT240X
0R
SLD GND
GND
GND
GND
VBUS VBUS
VBUS
VBATT
4.7uF
0.1uF
1
2
3
4
5
10
9
8
7
6
CHRG
VCC
FAULT
TIMER
GND
ACPR
GND GND
BAT
SHDN
PROG
NTC
1
+
NCT
-
BCD
NTC
TB3.5mm
LTC4053EDD
0.1uF
1uF
1R
2K2
1K5
GND
GND
GND
GND
GND
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
EEPROM Setting
VBUS
Battery Options
X-Chip Pin
CBUS0
Function
BCD
Battery Charger Enable
Force Power Enable
X
NTC
JP1
NCT Available
4K32 1%
De-acticate Sleep
1-2 NCT Enabled
2-3 NCT Disabled (Default)
JP1
SIP-3
JUMPER-2mm
GND
Figure 7.2 USB Battery Charging Detection (1 pin)
To use the FT240X 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
above is 1A as defined by the resistance on the PROG 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 above 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
26
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