Data Sheet

Copyright © Future Technology Devices International Limited 28
FT230X USB TO BASIC UART IC
Version 1.4
Document No.: FT_000566 Clearance No.: FTDI# 260
7.4 USB Battery Charging Detection
An addition to the USB specification (http://www.usb.org) 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 FT_PROG. 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 Figure 7.4 is
1A as defined by the resistance on the PROG pin.
X-Chip Pin Function
EEPROM Setting
CBUS0 BCD
Battery Options
Battery Charger Enable
Force Power Enable
De-acticate Sleep
X
GND
GND
0.1uF
0.1uF
GND
GND
600R/2A
10nF
VBUS 3V3OUT
0.1uF
0R
GNDSLD GND
27R
27R
VBUS
1
D-
2
D+
3
GND
5
ID
4
CN USB
VCC
2
FAULT
3
TIMER
4
GND
5
NTC
6
PROG
7
SHDN
8
BAT
9
ACPR
10
CHRG
1
GND
11
LTC4053EDD
GND
3V3OUT 3V3OUT
4.7uF
0.1uF
GND
VBUSVBUS
GND
VBATT
GND
GND
1K5
GND
1
TB3.5mm
VBUS VBUS
NTC
0.1uF
GND
VBUS
1uF
1R
GND
VBUS
BCD
2K2
GND
JP1
1-2
2-3
NCT Enabled
NCT Available
JP1
SIP-3
NTC
GND
NCT Disabled (Default)
JUMPER-2mm
4K32 1%
GND
DP
DM
3V3OUT
RESET#
VCC
GND
CBUS0
VCCIO
FT230X
BCD
1A when connected to a dedicated charger port
0A when enumerated
0A when in sleep
0A when not enumerated and not in sleep
+
-
NCT
N.F.
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 in Figure 7.5 the charge current would need to be limited to 0.4A to ensure that the
USB host power limit is not exceeded.