Linear Technology LT1513-2, LT1513 Datasheet
FEATURES
LT1513/LT1513-2
SEPIC Constant- or
Programmable-Current/
Constant-Voltage Battery Charger
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DESCRIPTION
■
Charger Input Voltage May Be Higher, Equal to or
Lower Than Battery Voltage
■
Charges Any Number of Cells Up to 20V
■
1% Voltage Accuracy for Rechargeable Lithium
Batteries
■
100mV Current Sense Voltage for High Efficiency
(LT1513)
■
0mV Current Sense Voltage for Easy Current
Programming (LT1513-2)
■
Battery Can Be Directly Grounded
■
500kHz Switching Frequency Minimizes
Inductor Size
■
Charging Current Easily Programmable or Shut Down
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APPLICATIONS
■
Charging of NiCd, NiMH, Lead-Acid or Lithium
Rechargeable Cells
■
Precision Current Limited Power Supply
■
Constant-Voltage/Constant-Current Supply
■
Transducer Excitation
■
Universal Input CCFL Driver
The LT®1513 is a 500kHz current mode switching regulator specially configured to create a constant- or programmable-current/constant-voltage battery charger. In addition
to the usual voltage feedback node, it has a current sense
feedback circuit for accurately controlling output current
of a flyback or SEPIC (Single-Ended Primary Inductance
Converter) topology charger. These topologies allow the
current sense circuit to be ground referred and completely
separated from the battery itself, simplifying battery switching and system grounding problems. In addition, these
topologies allow charging even when the input voltage is
lower than the battery voltage. The LT1513 can also drive
a CCFL Royer converter with high efficiency in floating or
grounded mode.
Maximum switch current on the LT1513 is 3A. This allows
battery charging currents up to 2A for a single lithium-ion
cell. Accuracy of 1% in constant-voltage mode is perfect
for lithium battery applications. Charging current can be
easily programmed for all battery types.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION
WALL
ADAPTER
INPUT
CHARGE
SHUTDOWN
C3
+
22µF
25V
SYNC
AND/OR
SHUTDOWN
6
**
LT1513
S/S
GND
TAB4
*
L1A, L1B ARE TWO 10µH WINDINGS ON A
COMMON CORE: COILTRONICS CTX10-4
CERAMIC MARCON THCR40EIE475Z OR TOKIN 1E475ZY5U-C304
†
MBRD340 OR MBRS340T3. MBRD340 HAS 5µA TYPICAL
LEAKAGE, MBRS340T3 50µA TYPICAL
Figure 1. SEPIC Charger with 1.25A Output Current
•
7
V
IN
V
C
13
R5
270Ω
C5
0.1µF
U
L1A*
V
V
I
FB
SW
5
2
FB
C4
0.22µF
R4
39Ω
C2**
4.7µF
†
D1
L1B*
•
R3
0.08Ω
Maximum Charging Current
2.4
2.2
1.25A
R1
C1
+
R2
LT1513 • TA01
22µF
25V
× 2
2.0
1.8
1.6
1.4
1.2
CURRENT (A)
1.0
0.8
0.6
0.4
05
INDUCTOR = 10µH
ACTUAL PROGRAMMED CHARGING CURRENT WILL BE
INDEPENDENT OF INPUT VOLTAGE IF IT DOES NOT
EXCEED VALUES SHOWN
SINGLE Li-Ion CELL
(4.1V)
DOUBLE Li-Ion
CELL (8.2V)
12V
20V
10
INPUT VOLTAGE (V)
20
15
16V
BATTERY
VOLTAGE
25
LT1513 • TA02
30
1
LT1513/LT1513-2
A
W
O
LUTEXI T
S
A
WUW
ARB
U
G
I
S
Supply Voltage ....................................................... 30V
Switch Voltage........................................................ 40V
S/S Pin Voltage....................................................... 30V
FB Pin Voltage (Transient, 10ms) ......................... ±10V
VFB Pin Current .................................................... 10mA
IFB Pin Voltage (Transient, 10ms)......................... ±10V
/
PACKAGE
TAB
IS
GND
7-LEAD PLASTIC DD
WITH PACKAGE SOLDERED TO 0.5INCH
AREA OVER BACKSIDE GROUND PLANE OR INTERNAL
POWER PLANE, θ
> 40°C/W DEPENDING ON MOUNTING TECHNIQUE
O
RDER I FOR ATIO
FRONT VIEW
7
6
5
4
3
2
1
R PACKAGE
T
= 125°C, θ
JMAX
JA
JA
CAN VARY FROM 20°C/W TO
= 30°C/W
2
COPPER
VIN
S/S
V
SW
GND
I
FB
FB
V
C
WU
ORDER PART
NUMBER
LT1513CR
LT1513CR-2
LT1513IR
LT1513IR-2
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Operating Junction Temperature Range
LT1513C............................................... 0°C to 125°C
LT1513I ............................................ –40°C to 125°C
Short Circuit ......................................... 0°C to 150°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
FRONT VIEW
V
IN
S/S
V
SW
GND
I
FB
FB
V
C
LT1513CT7-2
LT1513IT7-2
T
JMAX
T7 PACKAGE
7-LEAD TO-220
= 125°C, θ
7
6
5
4
3
2
1
= 50°C/ W, θJC = 4°C/W
JA
Consult factory for Military grade parts.
LECTRICAL C CHARA TERIST
E
VIN = 5V, VC = 0.6V, VFB = V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
REF
V
IREF
I
FBVOS
g
m
FB Reference Voltage Measured at FB Pin 1.233 1.245 1.257 V
FB Input Current VFB = V
FB Reference Voltage Line Regulation 2.7V ≤ VIN ≤ 25V, VC = 0.8V ● 0.01 0.03 %/V
IFB Reference Voltage (LT1513) Measured at IFB Pin –107 –100 – 93 mV
IFB Input Current V
IFB Reference Voltage Line Regulation 2.7V ≤ VIN ≤ 25V, VC = 0.8V ● 0.01 0.05 %/V
IFB Voltage Offset (LT1513-2) (Note 3) I
IFB Input Current V
VFB Source Current V
Error Amplifier Transconductance ∆IC = ±25µA 1100 1500 1900 µmho
Error Amplifier Source Current VFB = V
Error Amplifier Sink Current VFB = V
, IFB = 0V, VSW and S/S pins open, unless otherwise noted.
REF
ICS
VC = 0.8V ● 1.228 1.245 1.262 V
REF
VFB = 0V, VC = 0.8V ● –110 –100 –90 mV
= V
IFB
VFB
IFB
IREF
(Note 2) ● 10 25 35 µA
IREF
= 60µA (Note 4) ● –7.5 2.5 12.5 mV
= V
IREF
= –10mV, VFB = 1.2V ● – 700 –300 – 100 µA
– 150mV, VC = 1.5V ● 120 200 350 µA
REF
+ 150mV, VC = 1.5V ● 1400 2400 µA
REF
● 600 nA
● – 200 – 10 0 nA
● 700 2300 µmho
300 550 nA
2
LT1513/LT1513-2
LECTRICAL C CHARA TERIST
E
VIN = 5V, VC = 0.6V, VFB = V
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Error Amplifier Clamp Voltage High Clamp, VFB = 1V 1.70 1.95 2.30 V
A
V
f Switching Frequency 2.7V ≤ VIN ≤ 25V 450 500 550 kHz
BV Output Switch Breakdown Voltage 0°C ≤ TJ ≤ 125°C4047V
Error Amplifier Voltage Gain 500 V/V
VC Pin Threshold Duty Cycle = 0% 0.8 1 1.25 V
Maximum Switch Duty Cycle ● 85 95 %
Switch Current Limit Blanking Time 130 260 ns
, IFB = 0V, VSW and S/S pins open, unless otherwise noted.
REF
ICS
Low Clamp, VFB = 1.5V 0.25 0.40 0.52 V
0°C ≤ TJ ≤ 125°C 430 500 580 kHz
T
< 0°C 400 580 kHz
J
T
< 0°C35V
J
V
SAT
I
LIM
∆IIN/∆ISWSupply Current Increase During Switch ON Time 15 25 mA/A
I
Q
The ● denotes specifications which apply over the full operating
temperature range.
Note 1: For duty cycles (DC) between 50% and 85%, minimum
guaranteed switch current is given by I
Output Switch ON Resistance ISW = 2A ● 0.25 0.45 Ω
Switch Current Limit Duty Cycle = 50% ● 3.0 3.8 5.4 A
Control Voltage to Switch Current 4A/V
Transconductance
Minimum Input Voltage ● 2.4 2.7 V
Supply Current 2.7V ≤ VIN ≤ 25V ● 4 5.5 mA
Shutdown Supply Current 2.7V ≤ VIN ≤ 25V, V
Shutdown Threshold 2.7V ≤ VIN ≤ 25V ● 0.6 1.3 2 V
Shutdown Delay ● 51225µs
S/S Pin Input Current 0V ≤ V
Synchronization Frequency Range ● 600 800 kHz
= 1.33 (2.75 – DC).
LIM
Duty Cycle = 80% (Note 1)
≤ 0.6V, TJ ≥ 0°C ● 12 30 µA
TJ < 0°C50µA
≤ 5V ● –10 15 µA
S/S
S/S
Note 2: The I
Note 3: Consult factory for grade selected parts.
Note 4: The I
pin is servoed to its regulating state with VC = 0.8V.
FB
pin is sevoed to regulate FB to 1.245V
FB
● 2.6 3.4 5.0 A
3
LT1513/LT1513-2
TEMPERATURE (°C)
–50
1.8
INPUT VOLTAGE (V)
2.0
2.2
2.4
2.6
050
100
150
LT1513 • G03
2.8
3.0
–25 25
75
125
W
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TYPICAL PERFORMANCE CHARACTERISTICS
Switch Saturation Voltage
vs Switch Current
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
SWITCH SATURATION VOLTAGE (V)
0.1
0
0.8
0.4
0
1.2
SWITCH CURRENT (A)
1.6
100°C
2.0
Negative Feedback Input Current
vs Temperature
0
–10
–20
–30
–40
NEGATIVE FEEDBACK INPUT CURRENT (µA)
–50
–50
–25 25
0
150°C
25°C
–55°C
2.4
2.8
3.2
3.6
LT1513 • G01
50
TEMPERATURE (°C)
Minimum Input Voltage
vs Temperature
4.0
Switch Current Limit
vs Duty Cycle
6
5
4
3
2
SWITCH CURRENT LIMIT (A)
1
0
20 40 60 80
DUTY CYCLE (%)
–55°C
25°C AND
125°C
LT1513 • G02
10010030 50 70 90
Output Charging Characteristics
Showing Constant-Current and
Constant-Voltage Operation
12
CHARGING CURRENT
10
WITH 12V INPUT
8
6
4
BATTERY VOLTAGE (V)
2
125
100
75
150
LT1513 • G06
0
(A) (B)
0.4 0.8 1.2 1.6
CHARGING CURRENT (A)
V
= 12VMAXIMUM AVAILABLE
IN
(A) 8.4V BATTERY
= 0.5A
I
CHRG
(B) 8.4V BATTERY
I
= 1A
CHRG
(C) 4.2V BATTERY
I
= 1.5A
(C)
1513 G07
CHRG
2.00.200.6 1.0 1.4 1.8
4
Minimum Peak-to-Peak
Synchronization Voltage vs Temperature
)
3.0
P-P
2.5
2.0
1.5
1.0
0.5
MINIMUM SYNCHRONIZATION VOLTAGE (V
0
–50
f
= 700kHz
SYNC
050
–25 25
TEMPERATURE (°C)
75
100
125
LT1513 • G04
150
Feedback Input Current
vs Temperature
800
VFB = V
–25
REF
0
50
25
TEMPERATURE (°C)
700
600
500
400
300
200
FEEDBACK INPUT CURRENT (nA)
100
0
–50
75
100
125
LT1513 • G05
150
UUU
PIN FUNCTIONS
V
(Pin 1): The compensation pin is primarily used for
C
frequency compensation, but it can also be used for soft
starting and current limiting. It is the output of the error
amplifier and the input of the current comparator. Peak
switch current increases from 0A to 3.6A as the VC voltage
varies from 1V to 1.9V. Current out of the VC pin is about
200µ A when the pin is externally clamped below the
internal 1.9V clamp level. Loop frequency compensation
is performed with a capacitor or series RC network from
the VC pin
FB (Pin 2): The feedback pin is used for positive output
voltage sensing. The R1/R2 voltage divider connected to
FB defines Li-Ion float voltage at full charge, or acts as a
voltage limiter for NiCd or NiMH applications. FB is the
inverting input to the voltage error amplifier. Input bias
current is typically 300nA, so divider current is normally
set to 100µ A to swamp out any output voltage errors due
to bias current. The noninverting input of this amplifier is
tied internally to a 1.245V reference. The grounded end of
the output voltage divider should be connected directly to
the LT1513 ground pin (avoid ground loops).
I
FB
charging current. It is the input to a current sense amplifier
that controls charging current when the battery voltage is
below a programmed limit. During constant-current
operation, the LT1513 IFB pin regulates at –100mV. Input
resistance of this pin is 5kΩ, so filter resistance (R4,
Figure 1) should be less than 50Ω. The 39Ω, 0.22µ F filter
shown in Figure 1 is used to convert the pulsating current
in the sense resistor to a smooth DC current feedback
signal. The LT1513-2 IFB pin regulates at 0mV to provide
programmable current limit. The current through R5,
Figure 5, is balanced by the current through R4, programming the maximum voltage across R3.
directly to the ground pin
(Pin 3): The current feedback pin is used to sense
(avoid ground loops).
LT1513/LT1513-2
GND (Pin 4): The ground pin is common to both control
circuitry and switch current. VC, FB and S/S signals must
be Kelvin and connected as close as possible to this pin.
The TAB of the R package should also be connected to the
power ground.
V
(Pin 5): The switch pin is the collector of the power
SW
switch, carrying up to 3A of current with fast rise and fall
times. Keep the traces on this pin as short as possible to
minimize radiation and voltage spikes. In particular, the
path in Figure 1 which includes SW to C2, D1, C1 and
around to the LT1513 ground pin should be as short as
possible to minimize voltage spikes at switch turn-off.
S/S (Pin 6): This pin can be used for shutdown and/or
synchronization. It is logic level compatible, but can be
tied to VIN if desired. It defaults to a high ON state when
floated. A logic low state will shut down the charger to a
micropower state. Driving the S/S pin with a continuous
logic signal of 600kHz to 800kHz will synchronize switching frequency to the external signal. Shutdown is avoided
in this mode with an internal timer.
VIN (Pin 7): The input supply pin should be bypassed with
a low ESR capacitor located right next to the IC chip. The
grounded end of the capacitor must be connected directly
to the ground plane to which the TAB is connected.
TAB: The TAB on the surface mount R package is electrically connected to the ground pin, but a low inductance
connection must be made to both the TAB and the pin for
proper circuit operation. See suggested PC layout in
Figure 4.
5
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