FT230X USB TO BASIC UART IC
Document No.: FT_000566 Clearance No.: FTDI# 260
Version 1.2
7.4 USB Battery Charging Detection
A recent addition to the USB specification (
)
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 FT230X 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 FT230X 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
600R/2A
CN USB
VBUS
D-
D+
ID
GND
1
2
3
4
5
10nF
27R
27R
0.1uF
0.1uF
VCCIO
VCC
3V3OUT
DM
DP
RESET#
GND
GND
N.F.
GND
GND
0R
0.1uF
CBUS0
FT230X
BCD
SLD
GND
GND
GND
GND
VBUS VBUS
VBUS
VBATT
0.1uF
4.7uF
1
2
3
4
5
10
9
8
7
6
GND
GND
CHRG
VCC
FAULT
TIMER
GND
GND
ACPR
BAT
SHDN
PROG
NTC
BCD
NTC
+
NCT
-
TB3.5mm
1
0.1uF
LTC4053EDD
2K2
1K5
1uF
11
1R
GND
GND
GND
GND
GND
EEPROM Setting
X-Chip Pin
CBUS0
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
Function
BCD
Battery Options
Battery Charger Enable X
Force Power Enable
De-acticate Sleep
VBUS
NTC
4K32 1%
JP1
NCT Available
1-2
2-3
GND
NCT Enabled
NCT Disabled (Default)
JUMPER-2mm
JP1
SIP-3
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
28
FTDI [ FUTURE TECHNOLOGY DEVICES INTERNATIONAL LTD. ]
