LTC1759_15 Datasheet, PDF (1/28 Pages) Linear Technology – Smart Battery Charger

LTC1759
Smart Battery Charger
FEATURES
s _{Single Chip Smart Battery Charger Controller}
s _{100% Compliant (Rev 1.0) SMBus Support}
Allows for Operation with or without Host
s _{SMBus Accelerator Improves SMBus Timing}
s _{Hardware Interrupt and SMBAlert Response}
Eliminate Interrupt Polling
s _{High Efficiency Synchronous Buck Charger}
s _{0.5V Dropout Voltage; Maximum Duty Cycle > 99.5%}
s _{AC Adapter Current Limit Maximizes Charge Rate*}
s _{1% Voltage Accuracy; 5% Current Accuracy}
s _{Up to 8A Charging Current Capability}
s _{Dual 10-Bit DACs for Charger Voltage and Current}
Programming
s _{User-Selectable Overvoltage and Overcurrent Limits}
s _{High Noise Immunity Thermistor Sensor}
s _{Small 36-Lead Narrow (0.209") SSOP Package}
U
APPLICATIO S
s _{Portable Computers}
s _{Portable Instruments}
s _{Docking Stations}
*US Patent Number 5,723,970
DESCRIPTIO
The LTC^®1759 Smart Battery Charger is a single chip
charging solution that dramatically simplifies construc-
tion of an SBS compliant system. The LTC1759 imple-
ments a Level 2 charger function whereby the charger can
be programmed by the battery or by the host. A thermistor
on the battery being charged is monitored for tempera-
ture, connectivity and battery type information. The SMBus
interface remains alive when the AC power adapter is
removed and responds to all SMBus activity directed to it,
including thermistor status (via the ChargerStatus com-
mand). The charger also provides an interrupt to the host
whenever a status change is detected (e.g., battery
removal, AC adapter connection).
Charging current and voltage are restricted to chemistry
specific limits for improved system safety and reliability.
Limits are programmable by two external resistors. Addi-
tionally, the maximum average current from the AC adapter
is programmable to avoid overloading the adapter when
simultaneously supplying load current and charging cur-
rent. When supplying system load current, charging cur-
rent is automatically reduced to prevent adapter overload.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
15.8k
AC
ADAPTER
INPUT
+
0.1µF
10µF
35V
Al
V_DD
0.1µF
1µF
0.33µF
0.68µF
33k
33k
3.83k
1.5k
1k
V_DD
475k 10k
1k
LTC1759
7
UV
22
DCIN
16
V_DD
21
DCDIV
4
SYNC
8
INFET
5
SDB
12 _CHGEN
32
V_CC
9
CLP
25
V_LIMIT
10
CLN
24
I_LIMIT
2
TGATE
18
33
DGND BOOSTC
17
I_SET
34
GBIAS
28
PROG
1
BOOST
27
V_C
3
SW
11 _COMP1
35
BGATE
6
AGND
30
SPIN
20
RNR
29
SENSE
19
THERM
31
BAT1
14 _SDA
23
BAT2
15
SCL
13
INTB
26
V_SET
36
PGND
2.2µF
1k
0.033Ω
499Ω
0.47µF
1µF
0.1µF
0.68µF
Figure 1. 4A SMBus Smart Battery Charger
SYSTEM
POWER
22µF
15µH
0.025Ω
+
22µF
SMART
BATTERY
200Ω
200Ω
68Ω
0.047µF _0.015µF
INTB
SCL
SDA
SMBus
TO
HOST
1759 F01
1