Datasheet

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LTC4098/LTC4098-1

40981fc

USB Compatible Switching

Power Managers/Li-Ion Chargers

with Overvoltage Protection

The LTC

4098/LTC4098-1 are high efficiency USB Power-

Path controllers and full-featured Li-Ion/Polymer battery

chargers. They seamlessly manage power distribution from

multiple sources including USB, wall adapter, automotive,

Firewire or other high voltage DC/DC converters, and a

Li-Ion/Polymer battery.

The LTC4098/LTC4098-1’s internal switching regulator

automatically limits its input current for USB compatibility.

For automotive and other high voltage applications, the

LTC4098/LTC4098-1 interface with a Linear Technology

external switching regulator to provide a high efficiency

high voltage power path. Both the USB and the optional

high voltage inputs feature Bat-Track optimized charging

to provide maximum power to the application and ease

thermal issues in high power density applications with

input supplies from 5V to as high as 38V.

An overvoltage circuit protects the LTC4098/LTC4098-1

from high voltage damage on the USB/wall adaptor inputs

with an N-channel FET and a resistor.

The LTC4098/LTC4098-1 are 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.

Media Players

GPS

PDAs

Smart Phones

Switching Regulator with Bat-Track™ Adaptive

Output Control Makes Optimal Use of Limited

Power Available from USB Port to Charge Battery

and Power Application

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™

when Input Power is Limited or Unavailable

Preset 4.2V Charge Voltage with 0.5% Accuracy

(4.1V for LTC4098-1)

4.1V Float Voltage (LTC4098-1) Improves Battery Life

and High Temperature Safety Margin

Instant-On Operation with Discharged Battery

700mA Maximum Load Current from USB Port

1.5A Maximum Charge Current with Thermal Limiting

20-Lead 3mm × 4mm × 0.75mm QFN Package

High Efficiency USB/Automotive Battery Charger with Overvoltage Protection

USB Switching Regulator Efficiency

to System Load (P

VOUT

VBUS

)

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

BUS

10μF

0.1μF 3.01k 1k

10μF

3.3μH

6.04k

WALL

INPUT

AUTOMOTIVE,

FIREWIRE, ETC.

INPUT

USB

TO μC

SYSTEM

LOAD

40981 TA01a

CLPROG PROG

LTC4098/LTC4098-1

GND

BATSENS

OVGATE

OVSENS

D0-D2

BAT

OUT

Li-Ion

LT3653

VOUT

(A)

0.01

EFFICIENCY (%)

0.1 1

40981 TA01b

100

BAT = 4.2V

BAT = 3.3V

BUS

= 5V

BAT

= 0mA

10x MODE

Summary of content (32 pages)

PAGE 1
LTC4098/LTC4098-1 USB Compatible Switching Power Managers/Li-Ion Chargers with Overvoltage Protection DESCRIPTION FEATURES n n n n n n n n n n Switching Regulator with Bat-Track™ Adaptive Output Control Makes Optimal Use of Limited Power Available from USB Port to Charge Battery and Power Application 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 Idea
PAGE 2
LTC4098/LTC4098-1 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) VBUS, WALL (Transient) t < 1ms, Duty Cycle < 1% .......................................... –0.3V to 7V VBUS, WALL (Static), BAT, BATSENS, CHRG, NTC, ................................................. –0.3V to 6V D0, D1, D2.........–0.3V to Max (VBUS, VOUT, BAT) + 0.3V IOVSENS ................................................................ ±10mA ICLPROG ....................................................................3mA IPROG ......
PAGE 3
LTC4098/LTC4098-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VBUS = 5V, BAT = 3.8V, RCLPROG = 3.01k, unless otherwise noted. SYMBOL PARAMETER CONDITIONS IVOUT VOUT Current Available Before Discharging Battery 1x Mode, BAT = 3.3V 5x Mode, BAT = 3.3V 10x Mode, BAT = 3.3V Low Power Suspend Mode High Power Suspend Mode MIN TYP 0.26 1.6 135 659 1231 0.32 2.04 MAX UNITS 0.41 2.
PAGE 4
LTC4098/LTC4098-1 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VBUS = 5V, BAT = 3.8V, RCLPROG = 3.01k, unless otherwise noted. SYMBOL PARAMETER VPROG PROG Pin Servo Voltage VPROG,TRKL PROG Pin Servo Voltage in Trickle Charge CONDITIONS MIN BAT < VTRKL TYP MAX UNITS 1.000 V 0.
PAGE 5
LTC4098/LTC4098-1 TYPICAL PERFORMANCE CHARACTERISTICS Ideal Diode Resistance vs Battery Voltage Ideal Diode V-I Characteristics 0.6 INTERNAL IDEAL DIODE ONLY 0.4 0.2 0 800 750 0.20 RESISTANCE (7) CURRENT (A) 0.25 INTERNAL IDEAL DIODE WITH SUPPLEMENTAL EXTERNAL VISHAY Si2333 PMOS 0.8 INTERNAL IDEAL DIODE 0.15 0.10 INTERNAL IDEAL DIODE WITH SUPPLEMENTAL EXTERNAL VISHAY Si2333 PMOS 0.05 0 USB Compliant Load Current Available Before Discharging Battery 0.04 0.12 0.16 0.
PAGE 6
LTC4098/LTC4098-1 TYPICAL PERFORMANCE CHARACTERISTICS Battery Drain Current vs Battery Voltage 30 TA = 25°C unless otherwise noted. 100 IVOUT = 0μA 100 BAT = 3.8V 1x MODE 90 25 RCLPROG = 3.01k RPROG = 1k IVOUT = 0mA 90 LTC4098 5x, 10x MODE 15 10 VBUS = 5V (SUSPEND MODE) 3.0 70 60 3.3 3.6 3.9 BATTERY VOLTAGE (V) 40 0.01 4.2 0.1 OUTPUT CURRENT (A) 2.5 2.0 OUTPUT VOLTAGE (V) 4.0 10 3.0 0 2.5 2 4 3 VBUS VOLTAGE (V) 5 6 SUSPEND LOW 0 0.5 SUSPEND LOW 1.
PAGE 7
LTC4098/LTC4098-1 TYPICAL PERFORMANCE CHARACTERISTICS Oscillator Frequency vs Temperature Low Battery (Instant-On) Output Voltage vs Temperature FREQUENCY (MHz) 3.66 3.64 3.62 2.350 20 2.300 17 2.250 2.200 2.150 –15 35 10 TEMPERATURE (oC) 60 85 2.100 –40 –15 35 10 TEMPERATURE (°C) 60 100 42 39 36 33 30 1x MODE –15 –10 35 TEMPERATURE (°C) 60 60 85 40981 G21 VBUS = 5V BAT = 3.
PAGE 8
LTC4098/LTC4098-1 TYPICAL PERFORMANCE CHARACTERISTICS OVP Protection Waveform TA = 25°C unless otherwise noted. OVP Reconnection Waveform VBUS 5V/DIV VBUS 5V/DIV OVGATE 5V/DIV OVGATE 5V/DIV OVP INPUT VOLTAGE 10V TO 5V STEP 5V/DIV OVP INPUT VOLTAGE 5V TO 10V STEP 5V/DIV 40981 G26 500μs/DIV OVSENS Quiescent Current vs Temperature Rising Overvoltage Threshold vs Temperature 12 OVSENS CONNECTED TO INPUT THROUGH 10 6.04k RESISTOR 6.275 33 31 8 OVGATE (V) 35 6.270 6.
PAGE 9
LTC4098/LTC4098-1 PIN FUNCTIONS OVSENS (Pin 1): Overvoltage Protection Sense Input. OVSENS should be connected through a 6.04k resistor to the input power connector and the drain of an external N-channel MOS pass transistor. When the voltage on this pin exceeds a preset level, the OVGATE pin will be pulled to GND to disable the pass transistor and protect downstream circuitry. If overvoltage protection is not desired, connect OVSENS to GND. OVGATE (Pin 2): Overvoltage Protection Gate Output.
PAGE 10
LTC4098/LTC4098-1 PIN FUNCTIONS VOUT (Pin 12): Output Voltage of the Switching PowerPath Controller and Input Voltage of the Battery Charger. The majority of the portable product should be powered from VOUT. The LTC4098/LTC4098-1 will partition the available power between the external load on VOUT and the internal battery charger. Priority is given to the external load and any extra power is used to charge the battery.
PAGE 11
TO USB OR WALL ADPAPTER T NTC 5 4 3 13 0.1V NTC NTCBIAS 1.188V CLPROG ISWITCH /N ILDO /M VBUS OVGATE + – + – + – 2 + – 1 AVERAGE INPUT CURRENT LIMIT CONTROLLER NTC ENABLE OVERTEMP UNDERTEMP VOUT + – SUSPEND LDO 100mV s2 OVERVOLTAGE PROTECTION – + NTC FAULT OSC 4.6V Q D0 15 D1 16 LOGIC D2 17 NONOVERLAP AND DRIVE LOGIC AVERAGE OUTPUT VOLTAGE LIMIT CONTROLLER PWM R S +– 6V 20 + + – + – OVSENS VC GND 9 3.6V GND 21 +– 0.
PAGE 12
LTC4098/LTC4098-1 OPERATION Introduction The LTC4098/LTC4098-1 are high efficiency power management and Li-Ion charger solutions designed to make optimal use of the power available from a variety of sources, while minimizing power dissipation and easing thermal budgeting constraints. The innovative PowerPath architecture ensures that the application is powered immediately after external voltage is applied, even with a completely dead battery by prioritizing power to the application over the battery.
PAGE 13
FROM USB OR WALL ADAPTER 3 13 2 1 CLPROG VBUS OVGATE 1.188V ISWITCH /N s2 +– PWM AND GATE DRIVE AVERAGE INPUT CURRENT LIMIT CONTROLLER + – OVERVOLTAGE PROTECTION 20 VC 3.6V +– 0.3V CONSTANT-CURRENT CONSTANT-VOLTAGE BATTERY CHARGER VOUT ISENSE SW 18 4.3V WALL 15mV OmV IDEAL DIODE + – Bat-Track HV CONTROL VOUT 3.6V BAT + 0.3V Figure 1.
PAGE 14
LTC4098/LTC4098-1 OPERATION The switching input regulator can also be deactivated (USB suspend).
PAGE 15
LTC4098/LTC4098-1 OPERATION For very low battery voltages, the battery charger acts like a load and, due to limited input power, its current will tend to pull VOUT below the 3.6V instant-on voltage. To prevent VOUT from falling below this level, an undervoltage circuit automatically detects that VOUT is falling and reduces the battery charge current as needed. This reduction ensures that load current and voltage are always prioritized while allowing as much battery charge current as possible.
PAGE 16
LTC4098/LTC4098-1 OPERATION With Bat-Track, battery charger efficiency is approximately: ηTOTAL = ηBUCK • BAT BAT + 0.3V With the same assumptions as above, the total battery charger efficiency is approximately 81%. This example works out to less than 1W of power dissipation, or almost 60% less heat. See the Typical Applications section for complete circuits using the LT3653 and LT3480 with Bat-Track control.
PAGE 17
LTC4098/LTC4098-1 OPERATION MOSFET will be in full conduction. If additional conductance is needed, an external P-channel MOSFET transistor may be added from BAT to VOUT. The IDGATE pin of the LTC4098/LTC4098-1 drives the gate of the external P-channel MOSFET transistor for automatic ideal diode control. The source of the external P-channel MOSFET should be connected to VOUT and the drain should be connected to BAT.
PAGE 18
LTC4098/LTC4098-1 OPERATION Charge Termination The battery charger has a built-in safety timer. Once the voltage on the battery reaches the preprogrammed float voltage of 4.200V for the LTC4098 or 4.100V for the LTC4098-1, the charger will regulate the battery voltage there and the charge current will decrease naturally. Once the charger detects that the battery has reached 4.200V or 4.100V respectively, the 4-hour safety timer is started.
PAGE 19
LTC4098/LTC4098-1 OPERATION To make the CHRG pin easily recognized by both humans and microprocessors, the pin is either a DC signal of ON for charging, OFF for not charging or it is switched at high frequency (35kHz) to indicate the two possible faults. While switching at 35kHz, its duty cycle is modulated at a slow rate that can be recognized by a human. When charging begins, CHRG is pulled low and remains low for the duration of a normal charge cycle.
PAGE 20
LTC4098/LTC4098-1 OPERATION NTC Thermistor Thermal Regulation The battery temperature is measured by placing a negative temperature coefficient (NTC) thermistor close to the battery pack. The NTC circuitry is shown in the Block Diagram. To prevent thermal damage to the LTC4098/LTC4098-1 or surrounding components, an internal thermal feedback loop will automatically decrease the programmed charge current if the die temperature rises to approximately 110°C.
PAGE 21
LTC4098/LTC4098-1 OPERATION POWER ON/ ENABLE CHARGER CLEAR EVENT TIMER ASSERT CHRG LOW NTC OUT OF RANGE YES INHIBIT CHARGING NO PAUSE EVENT TIMER BAT < 2.85V BATTERY STATE BAT > VFLOAT – E 2.
PAGE 22
LTC4098/LTC4098-1 APPLICATIONS INFORMATION CLPROG Resistor and Capacitor Choosing the Inductor As described in the Bat-Track Input Current Limited Step Down Switching Regulator section, the resistor on the CLPROG pin determines the average input current limit in each of the six current limit modes. The input current will be comprised of two components, the current that is used to drive VOUT and the quiescent current of the switching regulator.
PAGE 23
LTC4098/LTC4098-1 APPLICATIONS INFORMATION is used in the compensation of the switching regulator. At least 10μF with low ESR are required on VOUT. Additional capacitance will improve load transient performance and stability. Multilayer ceramic chip capacitors typically have exceptional ESR performance. MLCCs combined with a tight board layout and an unbroken ground plane will yield very good performance and low EMI emissions.
PAGE 24
LTC4098/LTC4098-1 APPLICATIONS INFORMATION Reverse Voltage Protection The LTC4098/LTC4098-1 can also be easily protected against the application of reverse voltage, as shown in Figure 8. D1 and R1 are necessary to limit the maximum VGS seen by MP1 during positive overvoltage events. D1’s breakdown voltage must be safely below MP1’s BVGS. The circuit shown in Figure 8 offers forward voltage protection up to MN1’s BVDSS and reverse voltage protection up to MP1’s BVDSS.
PAGE 25
LTC4098/LTC4098-1 APPLICATIONS INFORMATION By using a bias resistor, RNOM, different in value from R25, the hot and cold trip points can be moved in either direction. The temperature span will change somewhat due to the nonlinear behavior of the thermistor. The following equations can be used to easily calculate a new value for the bias resistor: RNOM = rHOT • R25 0.536 RNOM = rCOLD • R25 3.25 From the Vishay curve 1 R-T characteristics, rHOT is 0.2488 at 60°C.
PAGE 26
LTC4098/LTC4098-1 APPLICATIONS INFORMATION USB Inrush Limiting The USB specification allows at most 10μF of downstream capacitance to be hot-plugged into a USB hub. In most LTC4098/LTC4098-1 applications, 10μF should be enough to provide adequate filtering on VBUS. If more capacitance is required, the OVP circuit will provide adequate soft-connect time to prevent excessive inrush currents. An additional 22μF on the VBUS pin will generally contribute less than 100mA to the hot-plug inrush current.
PAGE 27
LTC4098/LTC4098-1 APPLICATIONS INFORMATION Battery Charger Stability Considerations The LTC4098/LTC4098-1’s battery charger contains both a constant-voltage and a constant-current control loop. The constant-voltage loop is stable without any compensation when a battery is connected with low impedance leads. Excessive lead length, however, may add enough series inductance to require a bypass capacitor of at least 1μF from BAT to GND.
PAGE 28
LTC4098/LTC4098-1 TYPICAL APPLICATIONS High Efficiency USB/2A Automotive Battery Charger with Overvoltage Protection and Low Battery Start-Up C6 0.47μF 2 4 AUTOMOTIVE, FIREWIRE, ETC. VIN R11 150k 5 C1 C7 4.7μF 68nF R10 40.2k BOOST 3 SW LT3480 RUN/SS 10 PG RT VC 7 R9 R8 499k 100k D3 GND 8 FB SYNC BD 11 9 L2 10μH 1 C4 22μF 6 M1 L1 3.3μH 20 M3 USB 13 R3 6.
PAGE 29
LTC4098/LTC4098-1 TYPICAL APPLICATIONS USB/Automotive Switching Battery Charger with Automatic Current Limiting on Both Inputs 7 1 AUTOMOTIVE, FIREWIRE, ETC. C1 4.7μF VIN R1 27.4k ILIM 6 GND VC 13 C3 10μF 0805 2 R6 6.04k TO μC 1 3 15-17 8 TO μC 4 M1: ON SEMICONDUCTOR NTLJS4114N R3: VISHAY-DALE NTHS0603N011-N1003F 3 R2 100k 5 VBUS 2 L2 3.
PAGE 30
LTC4098/LTC4098-1 PACKAGE DESCRIPTION UDC Package 20-Lead Plastic QFN (3mm × 4mm) (Reference LTC DWG # 05-08-1742 Rev Ø) 0.70 ±0.05 3.50 ± 0.05 2.10 ± 0.05 1.50 REF 2.65 ± 0.05 1.65 ± 0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 2.50 REF 3.10 ± 0.05 4.50 ± 0.05 RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 3.00 ± 0.10 0.75 ± 0.05 1.50 REF 19 R = 0.05 TYP PIN 1 NOTCH R = 0.20 OR 0.25 × 45° CHAMFER 20 0.40 ± 0.10 1 PIN 1 TOP MARK (NOTE 6) 4.00 ± 0.10 2 2.
PAGE 31
LTC4098/LTC4098-1 REVISION HISTORY (Revision history begins at Rev C) REV DATE DESCRIPTION PAGE NUMBER C 6/10 Removal of PDC package information from the data sheet. 1 to 32 UDC Package added to the data sheet. 1 to 32 LTC4098EPDC designated Obsolete in the Order Information section. 2 40981fc Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 32
LTC4098/LTC4098-1 TYPICAL APPLICATION High Efficiency USB Automotive Battery Charger with Overvoltage Protection and Low Battery Start-Up 1 AUTOMOTIVE, FIREWIRE, ETC. C1 4.7μF 50V VIN BOOST SW 4 R2 27.4k USB C3 10μF 0805 2 R4 6.04k TO μC 1 3 15-17 8 TO μC 4 M1: VISHAY-SILICONIX Si2333DS M2: ON SEMICONDUCTOR NTLJS4114N R6: VISHAY-DALE NTHS0603N011-N1003F R5 100k 5 R6 T 100k L1 4.7μH D2 6 GND 13 C2 0.