FEATURES
n
LTC4098-3.6
USB Compatible Switching
Power Manager/LiFePO
4
Charger
with Overvoltage Protection
DESCRIPTION
The LTC
®
4098-3.6 is a high efficiency USB PowerPath
controller and full-featured LiFePO
4
battery charger. It seam-
lessly manages power distribution from multiple sources
including USB, wall adapter, automotive, Firewire or other
high voltage DC/DC converters, and a LiFePO
4
battery.
The LTC4098-3.6 charge algorithm is optimized for LiFePO
4
by implementing a 1-hour float voltage termination timer
and a 0°C to 60°C NTC-based charge qualification range.
Furthermore, completely discharged batteries are charged
at the full programmed charge current.
The LTC4098-3.6’s switching regulator can automatically
limit its input current for USB compatibility. For automo-
tive and other high voltage applications, the LTC4098-3.6
interfaces with an external switching regulator. Both the
USB input and the auxiliary input controller feature Bat-
Track optimized charging to provide maximum power to
the application and reduced heat in high power density ap-
plications with input supplies from 5V to as high as 38V.
An overvoltage protection circuit guards the LTC4098-3.6
from high voltage damage on the VBUS pin with just two
external components.
The LTC4098-3.6 is available in a 20-lead 3mm
×
4mm
×
0.75mm QFN surface mount package.
L,
LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and
Bat Track and PowerPath are trademarks of Linear Technology Corporation. All other trademarks
are the property of their respective owners.
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Switching Regulator with Bat-Track
TM
Adaptive
Output Control Makes Optimal Use of Limited
Power Available from USB Port to Charge Battery
and Power Application
Charge Control Algorithm Specifically Designed
for LiFePO
4
(Lithium Iron Phosphate)
Overvoltage Protection Guards Against Damage
Bat-Track External Step-Down Switching Regulator
Control Maximizes Efficiency from Automotive,
Firewire and Other High Voltage Input Sources
180mΩ Internal Ideal Diode Plus External Ideal Diode
Controller Seamlessly Provide Low Loss PowerPath
TM
When Input Power Is Limited or Unavailable
Preset 3.6V Charge Voltage with 0.5% Accuracy
Instant-On Operation with Discharged Battery
700mA Maximum Load Current from USB Port
2A Maximum Input Current from Internal Switching
Regulator
1.5A Maximum Charge Current with Thermal Limiting
20-Lead 3mm
×
4mm
×
0.75mm QFN Package
APPLICATIONS
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High Peak Power Battery-Powered Equipment
Backup Applications
High Reliability Handhelds
TYPICAL APPLICATION
High Efficiency USB Compatible LiFePO
4
Battery Charger with Overvoltage Protection
3.3µH
5V/USB
10µF
6.04k
TO µC
3
OVGATE
OVSENS
D0-D2
CLPROG
0.1µF
3.01k
PROG
500
BAT
GND BATSENS
10µF
LTC4098-3.6
V
OUT
V
BUS
SW
POWER DISSIPATION (W)
SYSTEM
LOAD
3.0
2.5
2.0
1.5
1.0
0.5
LiFePO
4
409836 TA01a
Reduced Power Dissipation
vs Linear Battery Charger
LINEAR BATTERY
CHARGER
V
IN
= 5V
PROG = 500
I
CHRG
= 1.1A
10x MODE
ADDITIONAL POWER
AVAILABLE FOR CHARGING
+
SWITCHING
BATTERY
CHARGER
2.85
3.00 3.15 3.30
BATTERY VOLTAGE (V)
3.45
3.60
409836f
0
2.70
409836 TA01b
1
LTC4098-3.6
(Notes 1, 3)
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
TOP VIEW
WALL
ACPR
D2
16 D1
15 D0
21
GND
14 SW
13 V
BUS
12 V
OUT
11 BAT
7
PROG
8
CHRG
9 10
GND
IDGATE
V
C
OVSENS 1
OVGATE 2
CLPROG 3
NTCBIAS 4
NTC 5
BATSENS 6
V
BUS
, WALL (Transient) t < 1ms,
Duty Cycle < 1% .......................................... –0.3V to 7V
V
BUS
, WALL (Static), BAT, BATSENS,
CHRG,
NTC, ................................................. –0.3V to 6V
D0, D1, D2 .........–0.3V to Max (V
BUS
, V
OUT
, BAT) + 0.3V
I
OVSENS
.................................................................±10mA
I
CLPROG
....................................................................3mA
I
PROG
........................................................................2mA
I
CHRG
......................................................................50mA
I
VOUT
, I
SW
, I
BAT
.......................................................2.25A
I
ACPR
......................................................................±5mA
Operating Temperature Range.................. –40°C to 85°C
Junction Temperature ........................................... 125°C
Storage Temperature Range................... –65°C to 125°C
20 19 18 17
UDC PACKAGE
20-LEAD (3mm
×
4mm) PLASTIC QFN
T
JMAX
= 125°C,
θ
JA
= 43°C/W
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH
LTC4098EUDC-3.6#PBF
TAPE AND REEL
LTC4098EUDC-3.6#TRPBF
PART MARKING
LFYR
PACKAGE DESCRIPTION
20-Lead (3mm
×
4mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges.
For more information on lead free part marking, go to:
http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to:
http://www.linear.com/tapeandreel/
The
l
denotes the specifications which apply over the full operating temp-
erature range, otherwise specifications are at T
A
= 25°C (Note 2). V
BUS
= 5V, BAT = 3.3V, R
CLPROG
= 3.01k, unless otherwise noted.
SYMBOL
V
BUS
I
VBUS(LIM)
PARAMETER
Input Supply Voltage
Total Input Current
1x Mode
5x Mode
10x Mode
Low Power Suspend Mode
High Power Suspend Mode
1x Mode
5x Mode
10x Mode
Low Power Suspend Mode
High Power Suspend Mode
1x Mode
5x Mode
10x Mode
Low Power Suspend Mode
High Power Suspend Mode
CONDITIONS
l
l
l
l
l
l
ELECTRICAL CHARACTERISTICS
MIN
4.35
92
445
815
0.32
1.6
TYP
MAX
5.5
UNITS
V
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA
mA/mA
mA/mA
mA/mA
mA/mA
mA/mA
409836f
Input Power Supply
96
473
883
0.39
2.05
6
15
15
0.042
0.042
230
1164
2210
11.6
60
100
500
1000
0.5
2.5
I
VBUSQ
(Note 4)
Input Quiescent Current
h
CLPROG
(Note 4) Ratio of Measured V
BUS
Current to
CLPROG Program Current
2
LTC4098-3.6
The
l
denotes the specifications which apply over the full operating temp-
erature range, otherwise specifications are at T
A
= 25°C (Note 2). V
BUS
= 5V, BAT = 3.3V, R
CLPROG
= 3.01k, unless otherwise noted.
SYMBOL
I
VOUT
PARAMETER
V
OUT
Current Available Before
Discharging Battery
CONDITIONS
1x Mode
5x Mode
10x Mode
Low Power Suspend Mode
High Power Suspend Mode
1x, 5x, 10x Modes
Suspend Modes
Rising Threshold
Falling Threshold
1x, 5x, 10x Modes, 0V < BAT ≤ 3.6V,
I
VOUT
= 0mA, Battery Charger Off
USB Suspend Modes, I
VOUT
= 250µA
f
OSC
R
PMOS
R
NMOS
I
PEAK
R
SUSP
V
WALL
DV
WALL
Switching Frequency
PMOS On-Resistance
NMOS On-Resistance
Peak Inductor Current Clamp
1x Mode
5x Mode
10x Mode
3.95
3.1
3.7
1.96
MIN
TYP
135
659
1231
0.32
2.04
1.188
100
4.30
4.00
BAT + 0.4
3.8
2.25
0.18
0.30
1.2
1.7
3
15
Rising Threshold
Falling Threshold
WALL-BAT Rising Threshold
WALL-BAT Falling Threshold
4.1
4.25
3.2
90
25
BAT + 0.4
100
I
ACPR
= 0mA
I
ACPR
= 0mA
Rising Threshold, R
OVSENS
= 6.04k
Input Below V
OVP
Input Above V
OVP
C
OVGATE
= 1nF
3.582
3.565
980
192
6.10
V
OUT
0
6.35
1.88 • V
OVSENSE
0
2.2
3.6
3.6
1030
206
3.7
3.618
3.635
1080
220
5
6.70
12
4.4
4.35
4.3
3.9
2.65
MAX
UNITS
mA
mA
mA
mA
mA
V
mV
V
V
V
V
MHz
Ω
Ω
A
A
A
Ω
V
V
mV
mV
V
µA
V
V
V
V
V
ms
V
V
mA
mA
µA
ELECTRICAL CHARACTERISTICS
V
CLPROG
V
UVLO
V
OUT
CLPROG Servo Voltage in Current Limit
V
BUS
Undervoltage Lockout
V
OUT
Voltage
Suspend LDO Output Resistance
Absolute WALL Input Threshold
Differential WALL Input Threshold
Regulation Target
WALL Quiescent Current
ACPR
High Voltage
ACPR
Low Voltage
Bat-Track External Switching Regulator Control
0
3.5
50
Overvoltage Protection
V
OVP
V
OVGATE
t
RISE
Battery Charger
V
FLOAT
I
CHG
I
BAT
BAT Regulated Output Voltage
Constant-Current Mode Charge Current
Battery Drain Current
0°C ≤ T
A
≤ 85°C
R
PROG
= 1k, 10x Mode
R
PROG
= 5k, 5x, 10x Modes
V
BUS
> V
UVLO
, PowerPath Switching
Regulator On, Battery Charger Off,
I
VOUT
= 0µA
V
BUS
= 0V, I
VOUT
= 0µA (Ideal Diode
Mode)
V
PROG
h
PROG
V
RECHRG
PROG Pin Servo Voltage
Ratio of I
BAT
to PROG Pin Current
Recharge Battery Threshold Voltage
Threshold Voltage Relative to V
FLOAT
–80
Overvoltage Protection Threshold
OVGATE Output Voltage
OVGATE Time to Reach Regulation
25
1.000
1030
–100
35
µA
V
mA/mA
–120
mV
409836f
3
LTC4098-3.6
The
l
denotes the specifications which apply over the full operating temp-
erature range, otherwise specifications are at T
A
= 25°C (Note 2). V
BUS
= 5V, BAT = 3.3V, R
CLPROG
= 3.01k, unless otherwise noted.
SYMBOL
t
TERM
t
BADBAT
h
C/10
V
CHRG
I
CHRG
R
ON_CHG
T
LIM
NTC
V
COLD
V
HOT
V
DIS
I
NTC
Ideal Diode
V
FWD
R
DROPOUT
I
MAX
V
IL
V
IH
I
PD
Forward Voltage Detection
Internal Diode On-Resistance, Dropout
Diode Current Limit
Input Low Voltage
Input High Voltage
Static Pull-Down Current
V
PIN
= 1V
1.2
2
I
VOUT
= 10mA
I
VOUT
= 200mA
2
0.4
15
0.18
mV
Ω
A
V
V
µA
Cold Temperature Fault Threshold
Voltage
Hot Temperature Fault Threshold
Voltage
NTC Disable Threshold Voltage
NTC Leakage Current
Rising Threshold
Hysteresis
Falling Threshold
Hysteresis
Falling Threshold
Hysteresis
NTC = 5V
75.0
18.4
0.5
–50
76.5
2.9
19.9
1.9
1.3
50
78.0
21.4
2.3
50
%NTCBIAS
%NTCBIAS
%NTCBIAS
%NTCBIAS
%NTCBIAS
mV
nA
PARAMETER
Safety Timer Termination Period
Bad Battery Termination Time
End of Charge Indication Current Ratio
CHRG
Pin Output Low Voltage
CHRG
Pin Input Current
Battery Charger Power FET
On-Resistance (Between V
OUT
and BAT)
Junction Temperature in Constant-
Temperature Mode
CONDITIONS
Timer Starts When BAT = V
FLOAT
BAT < V
TRKL
(Note 5)
I
CHRG
= 5mA
BAT = 4.5V, V
CHRG
= 5V
I
BAT
= 200mA
MIN
0.85
0.43
0.09
TYP
1
0.5
0.1
65
0
0.18
110
MAX
1.15
0.58
0.11
100
1
UNITS
Hour
Hour
mA/mA
mV
µA
Ω
°C
ELECTRICAL CHARACTERISTICS
Logic (D0, D1, D2)
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2:
The LTC4098E-3.6 is tested under pulsed load conditions such
that
T
J
≈
T
A
. The LTC4098E-3.6 is guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the – 40°C to 85°C
operating temperature range are assured by design, characterization and
correlation with statistical process controls.
Note 3:
The LTC4098E-3.6 includes overtemperature protection that is
intended to protect the device during momentary overload conditions.
Junction temperature will exceed 125°C when overtemperature protection
is active. Continuous operation above the specified maximum operating
junction temperature may impair device reliability.
Note 4:
Total input current is:
I
VBUSQ
+ (V
CLPROG
/R
CLPROG
) • (h
CLPROG
+ 1)
Note 5:
h
C/10
is expressed as a fraction of measured full charge current
with a 5k PROG resistor.
409836f
4
LTC4098-3.6
TYPICAL PERFORMANCE CHARACTERISTICS
Ideal Diode V-I Characteristics
1.0
INTERNAL IDEAL DIODE
WITH SUPPLEMENTAL
EXTERNAL VISHAY
Si2333 PMOS
0.25
T
A
= 25°C, unless otherwise noted.
USB Compliant Load Current
Available Before Discharging Battery
750
Ideal Diode Resistance
vs Battery Voltage
0.8
DIODE CURRENT (A)
0.20
DIODE RESISTANCE (Ω)
LOAD CURRENT (mA)
INTERNAL IDEAL
DIODE
700
0.6
INTERNAL IDEAL
DIODE ONLY
0.15
650
0.4
0.2
0.10
0.05
INTERNAL IDEAL DIODE
WITH SUPPLEMENTAL
EXTERNAL VISHAY
Si2333 PMOS
600
V
BUS
= 5V
R
CLPROG
= 3.01k
5x USB SETTING
3.0
3.3
3.6
409836 G03
0
0
0.04
0.12
0.16
0.08
FORWARD VOLTAGE (V)
0.20
409836 G01
0
2.7
3.0
3.6
3.9
3.3
BATTERY VOLTAGE (V)
4.2
409836 G02
550
2.7
BATTERY VOLTAGE (V)
V
OUT
Voltage vs V
OUT
Current
(Battery Charger Disabled)
4.25
BAT = 3.6V
3.75
V
OUT
Voltage vs V
OUT
Current
(Battery Charger Enabled)
600
450
CHARGE CURRENT (mA)
OUTPUT VOLTAGE (V)
3.50
300
150
0
–150
–300
Battery Charge Current vs V
OUT
Current (Battery Charger Enabled)
4.00
OUTPUT VOLTAGE (V)
3.75
BAT = 3.3V
3.25
3.50
3.25
V
BUS
= 5V
5x USB SETTING
0
200
600
400
OUTPUT CURRENT (mA)
800
409836 G04
3.00
3.00
2.75
V
BUS
= 5V
BAT = 3V
R
CLPROG
= 3.01k
R
PROG
= 2k
5x USB SETTING
0
200
600
400
OUTPUT CURRENT (mA)
800
409836 G05
V
BUS
= 5V
BAT = 3V
R
CLPROG
= 3.01k
R
PROG
= 2k
5x USB SETTING
0
200
600
400
OUTPUT CURRENT (mA)
800
409836 G06
USB Compliant Load Current
Available Before Discharging Battery
150
700
600
CHARGE CURRENT (mA)
USB Limited Battery Charge
Current vs Battery Voltage
140
120
CHARGE CURRENT (mA)
100
80
60
40
20
3.3
3.6
409836 G08
USB Limited Battery Charge
Current vs Battery Voltage
LOAD CURRENT (mA)
140
500
400
300
200
100
V
BUS
= 5V
R
PROG
= 1k
R
CLPROG
= 3.01k
5x USB SETTING
3.0
BATTERY VOLTAGE (V)
130
120
V
BUS
= 5V
R
CLPROG
= 3.01k
1x USB SETTING
3.0
3.3
3.6
409836 G07
110
2.7
0
2.7
0
2.7
V
BUS
= 5V
R
PROG
= 1k
R
CLPROG
= 3.01k
1x USB SETTING
3.0
3.3
3.6
409836 G09
BATTERY VOLTAGE (V)
BATTERY VOLTAGE (V)
409836f
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