1
LT1769
1769fa
Constant-Current/
Constant-Voltage 2A Battery
Charger with Input Current Limiting
Simple Solution to Charge NiCd, NiMH and Lithium
Rechargeable Batteries—Charging Current
Programmed by Resistors or DAC
Adapter Current Limit Allows Maximum Possible
Charging Current During System Use*
Precision 0.5% Accuracy for Voltage Mode Charging
Available in 20-Lead Exposed Pad TSSOP and
28-Lead Narrow SSOP Packages
High Efficiency Current Mode PWM with 3A Internal
Switch
5% Charge Current Accuracy
Adjustable Undervoltage Lockout
Automatic Shutdown When AC Adapter is Removed
Low Reverse Battery Drain Current: 3µA
Current Sensing Can Be at Either Terminal of the Battery
Charging Current Soft Start
Shutdown Control
The LT
®
1769 current mode PWM battery charger is a
simple, efficient solution to fast charge modern recharge-
able batteries including lithium-ion (Li-Ion), nickel-metal-
hydride (NiMH) and nickel-cadmium (NiCd) that require
constant-current and/or constant-voltage charging. The
internal switch is capable of delivering 2A** DC current
(3A peak current). Charge current can be programmed by
resistors or a DAC to within 5%. With 0.5% reference voltage
accuracy, the LT1769 meets the critical constant-voltage
charging requirement for Li-Ion cells.
A third control loop is provided to regulate the current
drawn from the input AC adapter. This allows simulta-
neous operation of the equipment and battery charging
without overloading the adapter. Charge current is reduced
to keep the adapter current below specified levels.
The LT1769 can charge batteries ranging from 1V to 20V.
Ground sensing of current is not required and the battery’s
negative terminal can be tied directly to ground. A saturat-
ing switch running at 200kHz gives high charging effi-
ciency and small inductor size. A blocking diode is not
required between the chip and the battery because the
chip goes into sleep mode and drains only 3µA when the
wall adapter is unplugged.
Figure 1. 2A Lithium-Ion Battery Charger
Chargers for NiCd, NiMH, Lead-Acid, Lithium
Rechargeable Batteries
Switching Regulators with Precision Current Limit
, LTC and LT are registered trademarks of Linear Technology Corporation.
*US patent number 5,723,970
**See LT1510 for 1.5A charger; see LT1511 for 3A charger
FEATURES
DESCRIPTIO
U
APPLICATIO S
U
TYPICAL APPLICATIO
U
SW
BOOST
COMP1
CLN
UV
OVP SENSE BAT
C1
1µF
R
S4
ADAPTER
CURRENT SENSE
R7
500
R5
UNDERVOLTAGE
LOCKOUT
R6
5k
V
IN
(ADAPTER INPUT)
11V TO 28V
V
BAT
C
PROG
1µF
C
IN
*
15µF
300
R
PROG
4.93k
1%
0.33µF
C2
0.47µF
R
S3
200
1%
R
S2
200
1%
L1**
22µH
D2
1N4148
2nF
10k
R
S1
0.05
BATTERY CURRENT
SENSE
R3
390k
0.25%
BATTERY
VOLTAGE SENSE
R4
162k
0.25%
C
OUT
22µF
TANT
8.4V
Li-Ion
LT1769
NOTE: COMPLETE LITHIUM-ION CHARGER,
NO TERMINATION REQUIRED. R
S4
, R7
AND C1 ARE OPTIONAL FOR I
IN
LIMITING
*TOKIN OR UNITED CHEMI-CON/MARCON
CERAMIC SURFACE MOUNT
**22µH SUMIDA CDRH125
SEE APPLICATIONS INFORMATION FOR
INPUT CURRENT LIMIT AND UNDERVOLTAGE LOCKOUT
††
GENERAL SEMICONDUCTOR. FOR T
J
LESS THEN 100°C
MBRS130LT3 CAN BE USED
V
CC
TO MAIN
SYSTEM LOAD
SPIN
D1
††
SS24
GND
CLP
D3
††
SS24
1511 • F01
PROG
V
C
+
2
LT1769
1769fa
ABSOLUTE MAXIMUM RATINGS
W
WW
U
PACKAGE/ORDER INFORMATION
W
U
U
ORDER PART
NUMBER
*ALL V
CC
PINS SHOULD
BE CONNECTED
TOGETHER CLOSE TO
THE PINS
** ALL GND PINS ARE
FUSED TO INTERNAL DIE
ATTACH PADDLE FOR
HEAT SINKING. CONNECT
THESE PINS TO
EXPANDED PC LANDS
FOR PROPER HEAT
SINKING. 35°C/W
THERMAL RESISTANCE
ASSUMES AN INTERNAL
GROUND PLANE
DOUBLING AS A HEAT
SPREADER
LT1769CGN
LT1769IGN
T
JMAX
= 125°C, θ
JA
= 35°C/ W**
1
2
3
4
5
6
7
8
9
10
11
12
13
14
TOP VIEW
GN PACKAGE
28-LEAD PLASTIC SSOP
28
27
26
25
24
23
22
21
20
19
18
17
16
15
GND**
GND**
GND**
SW
BOOST
UV
GND**
GND**
OVP
CLP
CLN
COMP1
SENSE
GND**
GND**
GND**
GND**
V
CC1
*
V
CC2
*
V
CC3
*
GND**
PROG
V
C
UV
OUT
COMP2
BAT
SPIN
GND**
Supply Voltage
(V
CC
, CLP and CLN Pin Voltage)......................... 30V
BOOST Pin Voltage with Respect to V
CC
................. 25V
I
BAT
(Average)........................................................... 2A
Operating Junction Temperature Range
Commercial ........................................... 0°C to 125°C
Industrial ......................................... 40°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
(Note 1)
Operating Ambient Temperature
Commercial ............................................ 0°C to 70°C
Industrial ........................................... 40°C to 85°C
Storage Temperature Range ................. 65°C to 150°C
Lead Temperature (Soldering, 10 sec)..................300°C
ORDER PART
NUMBER
LT1769CFE
LT1769IFE
FE PACKAGE
20-LEAD PLASTIC TSSOP
1
2
3
4
5
6
7
8
9
10
TOP VIEW
20
19
18
17
16
15
14
13
12
11
SW
BOOST
UV
GND
GND
OVP
CLN
CLP
COMP1
SENSE
GND
V
CC1
V
CC2
V
CC3
PROG
V
C
GND
UV
OUT
BAT
SPIN
T
JMAX
= 125°C, θ
JA
= 35°C/W
THE BOTTOM METAL
PLATE OF THIS PACKAGE
IS FUSED TO INTERNAL
GROUND AND IS FOR
HEAT SINKING. SOLDER
THE BOTTOM METAL
PLATE ONTO PCB
GROUND PLANE FOR
HEAT SINKING.
ELECTRICAL CHARACTERISTICS
The denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 16V, V
BAT
= 8V, R
S2
= R
S3
= 200 (see Block Diagram),
V
CLN
= V
CC
. No load on any outputs unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Overall
Supply Current V
PROG
= 2.7V, V
CC
20V 4.5 6.8 mA
V
PROG
= 2.7V, 20V < V
CC
25V 4.6 7.0 mA
Sense Amplifier CA1 Gain and Input Offset Voltage 8V V
CC
25V , 0V V
BAT
20V
(With R
S2
= 200, R
S3
= 200)R
PROG
= 4.93k 93 100 107 mV
(Measured across R
S1
)(Note 2) R
PROG
= 49.3k 81012 mV
T
A
< 0°C713mV
V
CC
= 28V, V
BAT
= 20V
R
PROG
= 4.93k 90 110 mV
R
PROG
= 49.3k 713mV
T
A
< 0°C614mV
EXPOSED PAD IS GROUND
(MUST BE SOLDERED TO PCB)
EXPOSED PAD SIZE:
3.0
(.188)
×
4.1
(.162)
3
LT1769
1769fa
ELECTRICAL CHARACTERISTICS
The denotes specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
CC
= 16V, V
BAT
= 8V, R
S2
= R
S3
= 200 (see Block Diagram),
V
CLN
= V
CC
. No load on any outputs unless otherwise noted.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Overall
V
CC
Undervoltage Lockout (Switch OFF) Threshold Measured at UV Pin 678 V
UV Pin Input Current 0.2V V
UV
8V 0.1 5 µA
UV Output Voltage at UV
OUT
Pin In Undervoltage State, I
UVOUT
= 70µA 0.1 0.5 V
UV Output Leakage Current at UV
OUT
Pin 8V V
UV
, V
UVOUT
= 5V 0.1 3 µA
Reverse Current from Battery (When V
CC
Is V
BAT
20V, V
UV
0.4V 3 15 µA
Not Connected, V
SW
Is Floating)
Boost Pin Current V
CC
= 20V, V
BOOST
= 0V 0.1 10 µA
V
CC
= 28V, V
BOOST
= 0V 0.25 20 µA
2V V
BOOST
– V
CC
< 8V (Switch ON) 6 9 mA
8V V
BOOST
– V
CC
25V (Switch ON) 8 12 mA
Switch
Switch ON Resistance 8V V
CC
V
MAX
, I
SW
= 2A,
V
BOOST
– V
SW
2V 0.15 0.25
I
BOOST
/I
SW
During Switch ON V
BOOST
= 24V, I
SW
2A 25 35 mA/A
Switch OFF Leakage Current V
SW
= 0V, V
CC
20V 2 100 µA
20V < V
CC
28V 4 200 µA
Minimum I
PROG
for Switch ON 2420 µA
Minimum I
PROG
for Switch OFF 1 2.4 mA
Maximum V
BAT
for Switch ON V
CC
– 2 V
Current Sense Amplifier CA1 Inputs (Sense, BAT)
Input Bias Current 50 125 µA
Input Common Mode Low 0.25 V
Input Common Mode High V
CC
– 2 V
SPIN Input Current 100 200 µA
Reference
Reference Voltage (Note 3) R
PROG
= 4.93k, Measured at OVP with
VA Supplying I
PROG
and Switch OFF 2.448 2.465 2.477 V
Reference Voltage All Conditions of V
CC
,T
A
0°C 2.441 2.489 V
T
A
< 0°C (Note 4) 2.43 2.489 V
Oscillator
Switching Frequency 180 200 220 kHz
Switching Frequency All Conditions of V
CC
,T
A
0°C 170 200 230 kHz
T
A
< 0°C 160 230 kHz
Maximum Duty Cycle 90 93 %
85 %
Current Amplifier CA2
Transconductance V
C
= 1V, I
VC
= ±1µA 150 250 550 µmho
Maximum V
C
for Switch OFF 0.6 V
I
VC
Current (Out of Pin) V
C
0.6V 100 µA
V
C
< 0.45V 3 mA

LT1769IGN#TRPBF

Mfr. #:
Manufacturer:
Analog Devices / Linear Technology
Description:
Battery Management Const-C/Const-V 2A Bat Chr w/ In C Limin
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
T/T Paypal Visa MoneyGram Western Union