FAN5404 Fairchild Semiconductor, FAN5404 Datasheet - Page 19

• Manufacturer Part Number: FAN5404
• Description: The FAN5404 combines a highly integrated switched-mode charger, to minimize single-cell Lithium-ion (Li-ion) charging time from a USB power source, and a boost regulator to power a USB peripheral from the battery
• Manufacturer: Fairchild Semiconductor

PWM Controller in Charge Mode
The IC uses a current-mode PWM controller to regulate the
output voltage and battery charge currents. The synchronous
rectifier (Q2) has a negative current limit that turns off Q2 at
140mA to prevent current flow from the battery.
Safety Timer
This section references Figure 41 and Figure 42.
At the beginning of charging, the IC starts a 15-minute timer
(t
Writing to any register through I
timer, which in turn starts a 32-second timer (t
the TMR_RST bit (REG0[7]) resets the t
timer times out, charging is terminated, the registers are set
to their default values, and charging resumes using the
default values with the t
Normal charging is controlled by the host with the t
running to ensure that the host is alive. Charging with the
t
the host. If the t
charger, sets the
the FAULT bits (REG0[2:0]). This sequence prevents
overcharge if the host fails to reset the t
V
When the IC detects that V
(4.4V), the IC applies a 110 load from VBUS to GND. To
clear the VBUS POR (Power-On-Reset) and begin charging,
VBUS must remain above V
t
validation sequence always occurs before charging is
initiated or re-initiated (for example, after a VBUS OVP fault
or a V
t
other non-compliant chargers are rejected.
© 2009 Fairchild Semiconductor Corporation
FAN5400 Family • Rev. 1.0.7
15MIN
VBUS_VALID
VBUS_VALID
15MIN
BUS
timer running is used for charging that is unattended by
RCH
POR / Non-Compliant Charger Rejection
). When this timer times out, charging is terminated.
recharge initiation).
(30ms) before the IC initiates charging. The VBUS
ensures that unfiltered 50/60hz chargers and
CE
15MIN
bit, and indicates a timer fault (110) on
15MIN
timer expires, the IC turns off the
timer running.
IN(MIN)1
BUS
2
C stops and resets the t
has risen above V
and below VBUS
32S
32S
timer.
timer. If the t
32S
). Setting
32S
OVP
IN(MIN)1
timer
15MIN
32S
for
19
USB-Friendly Boot Sequence
For all versions except FAN5401, FAN5404
At VBUS POR, when the battery voltage is above the weak
battery threshold (V
its I
registers to their default values and enables the charger
using an input current limit controlled by the OTG pin
(100mA if OTG is LOW and 500mA if OTG is HIGH). This
feature can revive a battery whose voltage is too low to
ensure reliable host operation. Charging continues in the
absence of host communication even after the battery has
reached V
charger remains active until t
processor begins writing to the IC, charging parameters are
set by the host, which must continually reset the t
continue
parameters. If t
the FAULT bits are set to 110, STAT is pulsed HIGH, and
charging continues with default charge parameters.
The FAN5401 and FAN5404 do not automatically initiate
charging at VBUS POR. Instead, they wait for the host to
initiate charging through I
Input Current Limiting
To minimize charging time without overloading VBUS current
limitations, the IC’s input current limit can be programmed by
the I
Table 7. Input Current Limit
For all versions except the FAN5401 and FAN5404, the OTG
pin establishes the input current limit when t
For the FAN5401 and FAN5404, no charging occurs
automatically at VBUS POR, so the input current limit is
established by the I
2
INLIM
C register settings. If V
I
INLIM
bits (REG1[7:6]).
OREG
charging
REG1[7:6]
00
01
10
11
32S
, whose default value is 3.54V, and the
.times out, the register defaults are loaded,
INLIM
LOWV
using
), the IC operates in accordance with
bits.
2
C commands.
15MIN
BAT
the
< V
Input Current Limit
times out. Once the host
programmed
LOWV
100mA
No limit
500mA
800mA
www.fairchildsemi.com
, the IC sets all
15MIN
32S
is running.
charging
timer to