Document
LT1510/LT1510-5 Constant-Voltage/ Constant-Current Battery Charger
FEATURES
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Charges NiCd, NiMH and Lithium-Ion Batteries –– Only One 1/10W Resistor Is Needed to Program Charging Current High Efficiency Current Mode PWM with 1.5A Internal Switch and Sense Resistor 3% Typical Charging Current Accuracy Precision 0.5% Voltage Reference for Voltage Mode Charging or Overvoltage Protection Current Sensing Can Be at Either Terminal of the Battery Low Reverse Battery Drain Current: 3µA Charging Current Soft Start Shutdown Control 500kHz Version Uses Small Inductor
plest, most efficient solution to fast-charge modern rechargeable batteries including lithium-ion (Li-Ion), nickelmetal-hydride (NiMH)* and nickel-cadmium (NiCd)* that require constant-current and/or constant-voltage charging. The internal switch is capable of delivering 1.5A DC current (2A peak current). The 0.1Ω onboard current sense resistor makes the charging current programming very simple. One resistor (or a programming current from a DAC) is required to set the full charging current (1.5A) to within 5% accuracy. The LT1510 with 0.5% reference voltage accuracy meets the critical constant-voltage charging requirement for lithium cells. The LT1510 can charge batteries ranging from 2V to 20V. Ground sensing of current is not required and the battery’s negative terminal can be tied directly to ground. A saturating switch running at 200kHz (500kHz for LT1510-5) gives high charging efficiency 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 adaptor is unplugged. Soft start and shutdown features are also provided. The LT1510 is available in a 16-pin fused lead power SO package with a thermal resistance of 50°C/W, an 8-pin SO and a 16-pin PDIP.
, LTC and LT are registered trademarks of Linear Technology Corporation. * NiCd and NiMH batteries require charge termination circuitry (not shown in Figure 1).
U APPLICATIONS
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Chargers for NiCd, NiMH and Lithium Batteries Step-Down Switching Regulator with Precision Adjustable Current Limit
DESCRIPTION
With switching frequency as high as 500kHz, The LT ®1510 current mode PWM battery charger is the smallest, sim-
TYPICAL APPLICATIONS
C1 0.22µF D1 MBRM120T3 SW VCC D3 MBRM120T3
C1 D1 0.22µF 1N5819 D3 1N5819 SW VCC 11V TO 28V
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CIN* 10µF 1µF 300Ω
BOOST L1** 10µH D2 MMBD914L
PROG
LT1510-5 GND OVP VC 0.1µF
SENSE
BAT
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COUT*** 22µF
NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED * TOKIN OR MARCON CERAMIC SURFACE MOUNT ** COILTRONICS TP3-100, 10µH, 2.2mm HEIGHT (0.8A CHARGING CURRENT) COILTRONICS TP1 SERIES, 10µH, 1.8mm HEIGHT (<0.5A CHARGING CURRENT) *** PANASONIC EEFCD1B220 † OPTIONAL, SEE APPLICATIONS INFORMATION
Figure 1. 500kHz Smallest Li-Ion Cell Phone Charger (0.8A)
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8.2V TO 20V
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+ –
BOOST PROG
CIN* 10µF 1µF 300Ω
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3.83k
6.19k
L1** 33µH
D2 1N914
LT1510 GND OVP SENSE BAT VC 0.1µF
1k
1k
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4.2V Q3† 2N7002 R3 70.6k 0.25% R4 100k 0.25%
1510 F01
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COUT 22µF TANT
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4.2V
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4.2V
Q3† VN2222 R3 240k 0.25% R4 100k 0.25%
1510 F02
NOTE: COMPLETE LITHIUM-ION CHARGER, NO TERMINATION REQUIRED * TOKIN OR MARCON CERAMIC SURFACE MOUNT ** COILTRONICS CTX33-2 † OPTIONAL, SEE APPLICATIONS INFORMATION
Figure 2. Charging Lithium Batteries (Efficiency at 1.3A > 87%)
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LT1510/LT1510-5
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VMAX) ............................................ 30V Switch Voltage with Respect to GND ...................... – 3V Boost Pin Voltage with Respect to VCC ................... 30V Boost Pin Voltage with Respect to GND ................. – 5V VC, PROG, OVP Pin Voltage ...................................... 8V IBAT (Average) ........................................................ 1.5A Switch Current (Peak)............................................... 2A Storage Temperature Range ................. – 65°C to 150°C Operating Ambient Temperature Range Commercial ............................................. 0°C to 70°C Extended Commercial (Note 7) ........... – 40°C to 85°C Industrial (Note 8) .............................. – 40°C to 85°C Operating Junction Temperature Range LT1510C (Note 7) ............................. – 40°C to 125°C LT1510I ............................................ – 40°C to 125°C Lead Temperature (Soldering, 10 sec).................. 300°C
PACKAGE/ORDER INFORMATION
TOP VIEW SW 1 BOOST 2 GND 3 SENSE 4 8 7 6 5 VCC PROG VC BAT **GND SW BOOST GND OVP NC SENSE **GND 1 2 3 4 5 6 7 8 TOP VIEW 16 GND** 15 VCC2 14 VCC1 13 PROG 12 VC 11 NC 10 BAT 9 GND**
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 125°C/ W
ORDER PART NUMBER LT1510CS8 LT1510IS8 S8 PART MARKING 1510 1510I
Consult factory for Military grade parts.
GN PACKAGE (0.015 IN) 16-LEAD PLASTIC SSOP
TJMAX = 125°C, θJA = 75°C/ W ** FOUR CORNER PINS ARE FUSED TO INTERNAL DIE ATTACH PADDLE FOR HEAT SINKING. CONNECT THESE FOUR PINS TO EXPANDED PC LANDS FO.