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FAN5400 View Datasheet(PDF) - Fairchild Semiconductor

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FAN5400 Datasheet PDF : 37 Pages
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Special Charger
FAN5403-05 Only
The FAN5403, FAN5404, and FAN5405 have additional
functionality to limit input current in case a current-limited
“special charger” is supplying VBUS. The FAN5403-05
slowly increases the charging current until either:
IINLIM or IOCHARGE is reached
or
VBUS=VSP.
If VBUS collapses to VSP when the current is ramping up, the
FAN5403-05 charge with an input current that keeps
VBUS=VSP. When the VSP control loop is limiting the charge
current, the SP bit (REG5[4]) is set.
Table 8. VSP as Function of SP Bits (REG5[2:0])
SP (REG5[2:0])
DEC
BIN
HEX
VSP
0
000
00
4.213
1
001
01
4.293
2
010
02
4.373
3
011
03
4.453
4
100
04
4.533
5
101
05
4.613
6
110
06
4.693
7
111
07
4.773
Safety Settings
FAN5403-FAN5405 Only
The FAN5403-05 contain a SAFETY register (REG6) that
prevents the values in OREG (REG2[7:2]) and IOCHARGE
(REG4[6:4]) from exceeding the values of the VSAFE and
ISAFE values.
After VBAT exceeds VSHORT, the SAFETY register is loaded
with its default value and may be written only before any
other register is written. After writing to any other register,
the SAFETY register is locked until VBAT falls below VSHORT.
The ISAFE (REG6[6:4]) and VSAFE (REG6[3:0]) registers
establish values that limit the maximum values of IOCHARGE
and VOREG used by the control logic. If the host attempts to
write a value higher than VSAFE or ISAFE to OREG or
IOCHARGE, respectively; the VSAFE, ISAFE value appears
as the OREG, IOCHARGE register value, respectively.
Table 9. ISAFE (IOCHARGE Limit) as Function of ISAFE
Bits (REG6[6:4])
ISAFE (REG6[6:4])
ISAFE (mA)
DEC BIN HEX VRSENSE (mV)
68m100m
0
000 00
37.4
550
374
1
001 01
44.2
650
442
2
010 02
51.0
750
510
3
011 03
57.8
850
578
4 100 04
64.6
950
646
5
101 05
71.4
1050
714
6
110 06
78.2
1150
782
7
111 07
85.0
1250
850
Table 10. VSAFE (VOREG Limit) as Function of VSAFE
Bits (REG6[3:0])
VSAFE (REG6[3:0])
DEC BIN HEX
Max. OREG
(REG2[7:2])
VOREG
Max.
0 0000 00
100011
4.20
1
0001 00
100100
4.22
2
0010 01
100101
4.24
3
0011 02
100110
4.26
4
0100 03
100111
4.28
5
0101 04
101000
4.30
6
0110 05
101001
4.32
7
0111 06
101010
4.34
8
1000 07
101011
4.36
9
1001 08
101100
4.38
10 1010 09
101101
4.40
11 1011 0A
101110
4.42
12 1100 0B
101111
4.44
13 1101 0C
110000
4.44
14 1110 0D
110001
4.44
15 1111 0E
110010
4.44
Thermal Regulation and Protection
When the IC’s junction temperature reaches TCF (about 120°C),
the charger reduces its output current to 550mA to prevent
overheating. If the temperature increases beyond TSHUTDOWN;
charging is suspended, the FAULT bits are set to 101, and
STAT is pulsed HIGH. In Suspend Mode, all timers stop and the
state of the IC’s logic is preserved. Charging resumes at
programmed current after the die cools to about 120°C.
© 2009 Fairchild Semiconductor Corporation
FAN5400 Family • Rev. 1.0.7
24
www.fairchildsemi.com
 

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