LTC1759
Smart Battery Charger
FEATURES
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DESCRIPTIO
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Single Chip Smart Battery Charger Controller
100% Compliant (Rev 1.0) SMBus Support
Allows for Operation with or without Host
SMBus Accelerator Improves SMBus Timing
Hardware Interrupt and SMBAlert Response
Eliminate Interrupt Polling
High Efficiency Synchronous Buck Charger
0.5V Dropout Voltage; Maximum Duty Cycle > 99.5%
AC Adapter Current Limit Maximizes Charge Rate*
1% Voltage Accuracy; 5% Current Accuracy
Up to 8A Charging Current Capability
Dual 10-Bit DACs for Charger Voltage and Current
Programming
User-Selectable Overvoltage and Overcurrent Limits
High Noise Immunity Thermistor Sensor
Small 36-Lead Narrow (0.209") SSOP Package
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.
APPLICATIO S
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Portable Computers
Portable Instruments
Docking Stations
*US Patent Number 5,723,970
TYPICAL APPLICATIO
AC
ADAPTER
INPUT
0.1µF
15.8k
1k
0.033Ω
+
10µF
35V V
DD
Al
0.1µF
7
16
4
5
12
33k
33k
25
24
18
3.83k
17
28
27
11
6
20
19
UV
V
DD
LTC1759
DCIN
DCDIV
INFET
V
CC
CLP
CLN
TGATE
BOOSTC
GBIAS
BOOST
SW
BGATE
SPIN
SENSE
BAT1
BAT2
V
SET
PGND
22
21
8
32
9
10
2
33
34
1
3
35
30
29
31
23
26
36
2.2µF
0.1µF
0.47µF
499Ω
SYSTEM
POWER
1µF
22µF
SYNC
SDB
CHGEN
V
LIMIT
I
LIMIT
DGND
I
SET
PROG
V
C
COMP1
AGND
RNR
THERM
SDA
SCL
INTB
0.68µF
1µF
0.33µF
0.68µF
1.5k
1k
V
DD
475k
10k
1k
14
15
13
Figure 1. 4A SMBus Smart Battery Charger
U
15µH
0.025Ω
U
U
+
22µF
SMART
BATTERY
200Ω
200Ω
68Ω
0.047µF 0.015µF
INTB
SCL
SDA
SMBus
TO
HOST
1759 F01
1
LINER [ LINEAR TECHNOLOGY ]
