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4009fd

LTC4009

LTC4009-1/LTC4009-2

Typical applicaTion

FeaTures

applicaTions

DescripTion

High Efficiency,

Multi-Chemistry

Battery Charger

The LTC

4009 is a constant-current/constant-voltage

battery charger controller. It uses a synchronous quasi-

constant frequency PWM control architecture that will

not generate audible noise with ceramic bulk capacitors.

Charge current is set by the combination of external

sense, input and programming resistors. With no built-in

termination, the LTC4009 family charges a wide range of

batteries under external control.

The LTC4009 features a fully adjustable output voltage, while

the LTC4009-1 and LTC4009-2 can be pin-programmed for

lithium-ion/polymer battery packs of 1-, 2-, 3- or 4-series

cells. The LTC4009-1 provides output voltage of 4.1V/cell,

and the LTC4009-2 is a 4.2V/cell version.

The device includes AC adapter input current limiting which

maximizes the charge rate for a fixed input power level. An

external sense resistor programs the input current limit, and

the ICL status pin indicates when the battery charge current

is being reduced as a result of AC adapter current limiting.

The CHRG status pin is active during all charging modes,

including special indication for low charge current.

General Purpose Battery Charger Controller

Efficient 550kHz Synchronous Buck PWM Topology

±0.5% Output Float Voltage Accuracy

Programmable Charge Current: 4% Accuracy

Programmable AC Adapter Current Limit:

3% Accuracy

No Audible Noise with Ceramic Capacitors

Wide Input Voltage Range: 6V to 28V

Wide Output Voltage Range: 2V to 28V

Indicator Outputs for AC Adapter Present, Charging,

C/10 Current Detection and Input Current Limiting

Analog Charge Current Monitor

Micropower Shutdown

Thermally Enhanced 20-Pin 4mm × 4mm × 0.75mm

QFN Package

Notebook Computers

Portable Instruments

Battery Backup Systems

Efficiency at DCIN = 20V

CLP

FROM

ADAPTER

13V TO 20V

CHARGE

CURRENT

MONITOR

0.1µF

5.1k

33mΩ

3.01k

0.1µF

6.8µH

33mΩ

DCIN

0.1µF

2µF

0.1µF

14.3k

1.5k

6.04k

301k

32.8k

26.7k

LTC4009

DCDIV

CHRG

ACP

ICL

SHDN

ITH

PROG

CLN

BOOST

TGATE

INTV

BGATE

TO/FROM

MCU

GND

CSP

CSN

BAT

FBDIV

20µF

POWER TO

SYSTEM

4.7nF

20µF

4009 TA01a

12.3V

Li-Ion

BATTERY

3.01k

CHARGE CURRENT (A)

EFFICIENCY (%)

POWER LOSS (mW)

100

1000

10000

0.5

1.0 1.5 2.0

4009 TA01b

2.5 3.0

EFFICIENCY

POWER LOSS

OUT

= 12.3V

SENSE

= 33mΩ

= 3.01k

PROG

= 26.7k

= SSB44

L = IHLP-2525CZ 6.8µH

L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and

PowerPath and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks

are the property of their respective owners. Protected by U.S. Patents including 5723970.

Summary of content (28 pages)

PAGE 1
LTC4009 LTC4009-1/LTC4009-2 High Efficiency, Multi-Chemistry Battery Charger Description Features n n n n n n n n n n n n General Purpose Battery Charger Controller Efficient 550kHz Synchronous Buck PWM Topology ±0.
PAGE 2
LTC4009 LTC4009-1/LTC4009-2 Absolute Maximum Ratings (Note 1) DCIN, CLP, CLN or SW to GND.................... –0.3V to 30V CLP to CLN.............................................................±0.3V CSP, CSN or BAT to GND............................ –0.3V to 28V CSP to CSN.............................................................±0.3V BOOST to GND............................................ –0.3V to 36V BOOST to SW............................................... –0.
PAGE 3
LTC4009 LTC4009-1/LTC4009-2 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. DCIN = 20V, BAT = 12V, GND = 0V unless otherwise noted. (Note 2) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS Charge Voltage Regulation VTOL VBAT Accuracy (See Test Circuits) LTC4009 C-Grade I-Grade l l –0.5 –0.8 –1.0 0.5 0.8 1.
PAGE 4
LTC4009 LTC4009-1/LTC4009-2 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. DCIN = 20V, BAT = 12V, GND = 0V unless otherwise noted. (Note 2) SYMBOL PARAMETER VIH SHDN Input Voltage High RIN SHDN Pull-Down Resistance CONDITIONS MIN l TYP MAX 1.
PAGE 5
LTC4009 LTC4009-1/LTC4009-2 Test Circuits LTC4009 1.2085V PROG 13 LTC4009-1 LTC4009-2 FROM ICL (CLP = CLN) – – – + FROM ICL (CLP = CLN) EA 1.2085V PROG ITH VFB 10 ITH 11 + 12 TARGET VARIES WITH FVS0,1 LTC1055 – EA BAT 13 12 1.2085V TARGET – – – + + LTC1055 – 0.6V 0.6V 4009 TC02 4009 TC01 Typical Performance Characteristics (TA = 25°C unless otherwise noted. DIN = SSB44, L = IHLP-2525 6.8µH) Efficiency at DCIN = 20V, BAT = 8V 10000 RSENSE = 33mΩ RIN = 3.
PAGE 6
LTC4009 LTC4009-1/LTC4009-2 Typical Performance Characteristics (TA = 25°C unless otherwise noted. DIN = SSB44, L = IHLP-2525 6.8µH) Charge Current Accuracy 2A 1A 12.1V 1A 3A RECONNECT LOAD STATE DISCONNECT 4009 G06 CLP = 20V TIME (1ms/DIV) VOUT = 12.3V CHARGE CURRENT ERROR (%) BATTERY VOLTAGE (500mV/DIV) 5 Charge Current Line Regulation 0.5 RSENSE = 33mΩ RIN = 3.01k 4 DCIN = 24V RPROG = 35.7k 3 2 1 0 DCIN = 12V RPROG = 26.7k –1 –2 0 2 4 6 BAT = 6V RSENSE = 33mΩ RIN = 3.01k 0.
PAGE 7
LTC4009 LTC4009-1/LTC4009-2 Typical Performance Characteristics (TA = 25°C unless otherwise noted. DIN = SSB44, L = IHLP-2525 6.8µH) PWM Frequency vs Charge Current Battery Shutdown Current 25 600 PWM FREQUENCY (kHz) BATTERY CURRENT (µA) BAT = 5V 500 BAT = 12V 400 CLP = 15V RSENSE = 33mΩ RIN = 3.01k 300 200 0 0 0.5 1.0 1.5 2.0 CHARGE CURRENT (A) DC1104 WITH SSB44 INPUT DIODE 15 LTC4009 ALL PINS 10 5 BAT = 14.5V 100 20 2.5 3.
PAGE 8
LTC4009 LTC4009-1/LTC4009-2 Pin Functions FVS0 (Pin 9, LTC4009-1/LTC4009-2): Battery Voltage Select Input (LSB). This pin is one of two pins used on the LTC4009-1 or LTC4009-2 to select one of four preset battery voltages. Selection is done by connecting to either GND or INTVDD. Operating voltage range is GND to INTVDD. CSP (Pin 15): Charge Current Sense Positive Input. Place an external input resistor (RIN, Figure 1) between this pin and the positive side of the charge current sense resistor.
PAGE 9
LTC4009 LTC4009-1/LTC4009-2 Block Diagram 3 2 1 4 8 10 (LTC4009) DCIN BOOST AND OV DETECTION CLP INPUT CURRENT LIMIT CLN ICL CHRG C/10 DETECTION VFB + CSP – CSN CA + – EA + – – – CC R1 TO INTERNAL CIRCUITS PROG BAT BOOST OSCILLATOR TGATE PWM LOGIC CHARGE OVERVOLTAGE 9 FBDIV 5 7 6 DCDIV ACP TO INTERNAL CIRCIUTS 5V REGULATOR SW INTVDD BGATE GND SHUTDOWN CONTROL SHUTDOWN TO INTERNAL CIRCUITS 14 13 1.
PAGE 10
LTC4009 LTC4009-1/LTC4009-2 Block Diagram 2 1 4 8 10 9 11 DCIN BOOST AND OV DETECTION CLP INPUT CURRENT LIMIT CLN ICL CHRG C/10 DETECTION VFB FVS1 FVS0 BAT + CSP – CSN CA OUTPUT VOLTAGE SELECT + CC – EA R1 + – – – 3 (LTC4009-1/LTC4009-2) TO INTERNAL CIRCUITS PROG BOOST OSCILLATOR TGATE OVERVOLTAGE PWM LOGIC TO INTERNAL CIRCIUTS 5V REGULATOR SW INTVDD BGATE GND 5 7 6 DCDIV ACP SHUTDOWN CONTROL SHUTDOWN TO INTERNAL CIRCUITS 14 13 1.
PAGE 11
LTC4009 LTC4009-1/LTC4009-2 Operation Overview The LTC4009 is a synchronous step-down (buck) current mode PWM battery charger controller. The maximum charge current is programmed by the combination of a charge current sense resistor (RSENSE), matched input resistors (RIN, Figure 1), and a programming resistor (RPROG) between the PROG and GND pins.
PAGE 12
LTC4009 LTC4009-1/LTC4009-2 Operation LTC4009 2 11 WATCHDOG TIMER CLP BAT CLOCK OSCILLATOR S SYSTEM POWER TGATE Q PWM LOGIC RD BGATE + + CSP – CSN 19 L1 16 RIN 15 CA CC R1 – PROG FROM ICL VFB RSENSE RIN 14 VSENSE – ICHRG 13 RPROG + – – – EA + CPROG + 10 1.2085V ITH 12 LOOP COMPENSATION 4009 F01 Figure 1. PWM Circuit Diagram Charge Current Monitoring When the LTC4009 is charging, the voltage on the PROG pin varies in direct proportion to the charge current.
PAGE 13
LTC4009 LTC4009-1/LTC4009-2 Operation be used for a variety of purposes in applications. Table 1 summarizes the state of the three indicator outputs as a function of LTC4009 operation. Table 1.
PAGE 14
LTC4009 LTC4009-1/LTC4009-2 Operation PWM Watchdog Timer As input and output conditions vary, the LTC4009 may need to utilize PWM duty cycles approaching 100%. In this case, operating frequency may be reduced well below 550kHz. An internal watchdog timer observes the activity on the TGATE pin. If TGATE is on for more than 40µs, the watchdog activates and forces the bottom NFET on (top NFET off) for about 100ns.
PAGE 15
LTC4009 LTC4009-1/LTC4009-2 Applications Information Programming Charge Current The formula for charge current is: ICHRG = RIN RSENSE  1.2085V  • – 11.67µA  RPROG  The LTC4009 operates best with 3.01k input resistors, although other resistors near this value can be used to accommodate standard sense resistor values. Refer to the subsequent discussion on inductor selection for other considerations that come into play when selecting input resistors RIN.
PAGE 16
LTC4009 LTC4009-1/LTC4009-2 Applications Information BAT LTC4009 95Ω TYPICAL PROG 11 13 FBDIV RMAX 511k RPROG 5V 0V Q1 2N7002 9 CZ R1 LTC4009 + CPROG VFB 10 R2A 4009 F04 R2B* GND (EXPOSED PAD) 21 Figure 4. Programming PWM Current compensation capacitance connected to ITH to maintain stability or prevent large current overshoot during startup. Selecting a higher Q1 PWM frequency (≈10kHz) will reduce the need to change CPROG or other compensation values.
PAGE 17
LTC4009 LTC4009-1/LTC4009-2 Applications Information Programming LTC4009-1/LTC4009-2 Output Voltage The LTC4009-1/LTC4009-2 feature precision internal battery voltage feedback resistor taps configured for common lithium-ion voltages. All that is required to program the desired voltage is proper pin programming of FVS0 and FVS1 as shown in Table 3. CDC 2 FVS1 FVS0 4.1V 4.2V GND GND 8.2V 8.4V GND INTVDD 12.3V 12.6V INTVDD GND 16.4V 16.
PAGE 18
LTC4009 LTC4009-1/LTC4009-2 Applications Information limit value. The second is to make the input current limit value programmable. The overall accuracy of this circuit needs to be better than the power source current tolerance or be margined such that the worse-case error remains under the power source limits. The accuracy of the Figure 7 circuit is a function of the INTVDD, VBE, RCL, RF, R1 and R3 tolerances. To improve accuracy, the tolerance of RF should be changed from 5.1k, 5% to a 2.49k 1% resistor.
PAGE 19
LTC4009 LTC4009-1/LTC4009-2 Applications Information If RPROG is greater than 26.7k, the actual level at which low charge current is detected will be less than C/10. The highest value of RPROG that can be used while reliably indicating low charge current before reaching final VBAT is 30.1k. RPROG can safely be set to values higher than this, but low current indication will be lost. If RPROG is less than 26.7k, low charge current detection occurs at a level higher than C/10.
PAGE 20
LTC4009 LTC4009-1/LTC4009-2 Applications Information Input and Output Capacitors In addition to typical input supply bypassing (0.1µF) on DCIN, the relatively high ESR of aluminum electrolytic capacitors is helpful for reducing ringing when hot plugging the charger to the AC adapter. Refer to LTC Application Note 88 for more information.
PAGE 21
LTC4009 LTC4009-1/LTC4009-2 Applications Information The LTC4009 limits maximum instantaneous peak inductor current during every PWM cycle. To avoid unstable switch waveforms, the ripple current must satisfy: assuming that inductor value could also vary by 25% at IMAX. For I-grade parts, reduce maximum ΔIL to less than 0.4 • IMAX, but only if the IC will actually be used to charge batteries over the wider I-grade temperature range.
PAGE 22
LTC4009 LTC4009-1/LTC4009-2 Applications Information where QG is the rated gate charge of the top external NFET with VGS = 4.5V. The maximum average diode current is then given by: ID = QG • 665kHz To improve efficiency by increasing VGS applied to the top FET, substitute a Schottky diode with low reverse leakage for D1. PWM jitter has been observed in some designs operating at higher VIN/VOUT ratios. This jitter does not substantially affect DC charge current accuracy.
PAGE 23
LTC4009 LTC4009-1/LTC4009-2 Applications Information The LTC4009 uses an improved adaptive TGATE and BGATE drive that is insensitive to MOSFET inertial delays, td(ON/OFF), to avoid overlap conduction losses. Switching characteristics from power MOSFET data sheets apply only to a specific test fixture, so there is no substitute for bench evaluation of external FETs in the target application. In general, MOSFETs with lower inertial delays will yield higher efficiency.
PAGE 24
LTC4009 LTC4009-1/LTC4009-2 Applications Information PCB Layout Considerations To prevent magnetic and electrical field radiation and high frequency resonant problems, proper layout of the components connected to the LTC4009 is essential. Refer to Figure 12. For maximum efficiency, the switch node rise and fall times should be minimized. The following PCB design priority list will help insure proper topology. Layout the PCB using this specific order. 1.
PAGE 25
LTC4009 LTC4009-1/LTC4009-2 Applications Information 10. If possible, place all the parts listed above on the same PCB layer. 11. Copper fills or pours are good for all power connections except as noted above in Rule 3. Copper planes on multiple layers can also be used in parallel. This helps with thermal management and lowers trace inductance, which further improves EMI performance. 12. For best current programming accuracy, provide a Kelvin connection from RSENSE to CSP and CSN.
PAGE 26
LTC4009 LTC4009-1/LTC4009-2 Package Description UF Package 20-Lead Plastic QFN (4mm × 4mm) (Reference LTC DWG # 05-08-1710 Rev A) 0.70 ±0.05 4.50 ± 0.05 3.10 ± 0.05 2.00 REF 2.45 ± 0.05 2.45 ± 0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 ± 0.10 0.75 ± 0.05 R = 0.05 TYP R = 0.115 TYP 19 20 0.40 ± 0.10 PIN 1 TOP MARK (NOTE 6) 4.00 ± 0.10 PIN 1 NOTCH R = 0.20 TYP OR 0.
PAGE 27
LTC4009 LTC4009-1/LTC4009-2 Revision History (Revision history begins at Rev D) REV DATE DESCRIPTION PAGE NUMBER D 3/10 I-Grade Parts Added. Reflected Throughout the Data Sheet 1 to 28 4009fd Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PAGE 28
LTC4009 LTC4009-1/LTC4009-2 Typical Application 12.6V 2 Amp Charger FROM ADAPTER 15V AT 2A C1 0.1µF R 8 3 R2 22.1k 5 R3 2.43k TO/FROM MCU 6 C2 0.1µF R4 6.04k 13 C3 4.7nF R5 26.7k CHRG CLP DCIN CLN DCDIV BOOST 2 C4 0.1µF SHDN GND ITH CSP CSN 20 R15 0Ω* C5 0.1µF D3 D5 C6 2µF R9 3.01k 14 R10 3.01k 10 R6 53.