Datasheet

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LTC4088

4088fb

Typical applicaTion

FeaTures DescripTion

High Efﬁciency Battery

Charger/USB Power Manager

The LTC

4088 is a high efficiency USB PowerPath™

controller and Li-Ion/Polymer battery charger. It includes

a synchronous switching input regulator, a full-featured

battery charger and an ideal diode. Designed specifically

for USB applications, the LTC4088’s switching regulator

automatically limits its input current to either 100mA,

500mA or 1A for wall-powered applications via logic

control.

The switching input stage provides power to V

OUT

where

power sharing between the application circuit and the

battery charger is managed. Unlike linear PowerPath

controllers, the LTC4088’s switching input stage can use

nearly all of the 0.5W or 2.5W available from the USB port

with minimal power dissipation. This feature allows the

LTC4088 to provide more power to the application and

eases thermal issues in space-constrained applications.

An ideal diode ensures that system power is available

from the battery when the input current limit is reached

or if the USB or wall supply is removed.

The LTC4088 is available in the low profile 14-lead 4mm

× 3mm × 0.75mm DFN surface mount package.

L, LT , LT C , LT M , Linear Technology and the Linear logo are registered trademarks and

PowerPath, Bat-Track and ThinSOT are trademarks of Linear Technology Corporation. All other

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

6522118.

applicaTions

Switching Regulator Makes Optimal Use of Limited

Power Available from USB Port to Charge Battery

and Power Application

180mΩ Internal Ideal Diode Plus Optional External

Ideal Diode Controller Seamlessly Provides Low

Loss Power Path When Input Power is Limited or

Unavailable

Full Featured Li-Ion/Polymer Battery Charger

BUS

Operating Range: 4.25V to 5.5V (7V Absolute

Maximum—Transient)

1.2A Maximum Input Current Limit

1.5A Maximum Charge Current with Thermal Limiting

Bat-Track™ Adaptive Output Control

Slew Control Reduces Switching EMI

Low Profile (0.75mm) 14-Lead 4mm × 3mm DFN

Package

Media Players

Digital Cameras

GPS

PDAs

Smart Phones

High Efficiency Battery Charger/USB Power Manager

Switching Regulator Efficiency to

System Load (P

OUT

BUS

)

BUS

OUT

10µF

WALL

USB

0.1µF

1µF

3.3V

10µF

SYSTEM

LOAD

2.94k

499Ω

8.2Ω

4088 TA01a

CLPROG PROG

LTC4088

C/X GND

3.3µH

NTC

CHRG

LDO3V3

GATE

BAT

Li-Ion

OUT

(A)

0.01

EFFICIENCY (%)

0.1 1

4088 TA01b

100

BAT = 4.2V

BAT = 3.3V

BUS

= 5V

BAT

= 0mA

10x MODE

Summary of content (24 pages)

PAGE 1
LTC4088 High Efficiency Battery Charger/USB Power Manager Description Features n n n n n n n n n Switching Regulator Makes Optimal Use of Limited Power Available from USB Port to Charge Battery and Power Application 180mΩ Internal Ideal Diode Plus Optional External Ideal Diode Controller Seamlessly Provides Low Loss Power Path When Input Power is Limited or Unavailable Full Featured Li-Ion/Polymer Battery Charger VBUS Operating Range: 4.25V to 5.5V (7V Absolute Maximum—Transient) 1.
PAGE 2
LTC4088 Absolute Maximum Ratings Pin Configuration (Note 1) TOP VIEW VBUS (Transient) t < 1ms, Duty Cycle < 1%... –0.3V to 7V VBUS (Static), BAT, CHRG, NTC, D0, D1, D2........................................................... –0.3V to 6V ICLPROG.....................................................................3mA IPROG, IC/X.................................................................2mA ILDO3V3....................................................................30mA ICHRG.........................
PAGE 3
LTC4088 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 = 2.94k, unless otherwise noted. SYMBOL PARAMETER CONDITIONS IOUT 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 1.6 135 672 1251 0.32 2.04 MAX UNITS 0.41 2.
PAGE 4
LTC4088 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 = 2.94k, unless otherwise noted. SYMBOL PARAMETER CONDITIONS RON_CHG Battery Charger Power FET On-Resistance (Between VOUT and BAT) IBAT = 200mA TLIM Junction Temperature in Constant Temperature Mode MIN TYP MAX UNITS 0.
PAGE 5
LTC4088 Typical Performance Characteristics Ideal Diode Resistance vs Battery Voltage Ideal Diode V-I Characteristics 0.20 INTERNAL IDEAL DIODE ONLY 0.2 0.15 0.10 INTERNAL IDEAL DIODE WITH SUPPLEMENTAL EXTERNAL VISHAY Si2333 PMOS 0.05 VBUS = 0V VBUS = 5V 0.04 0.12 0.16 0.08 FORWARD VOLTAGE (V) 0 0 2.7 0.20 3.0 3.6 3.9 3.3 BATTERY VOLTAGE (V) 4088 G01 150 600 125 CHARGE CURRENT (mA) CHARGE CURRENT (mA) 700 400 300 200 5x USB SETTING, BATTERY CHARGER SET FOR 1A 0 3.0 3.3 3.6 3.9 2.
PAGE 6
LTC4088 Typical Performance Characteristics VBUS Current vs Output Current in Suspend 5.0 2.5 5x MODE 2.0 VBUS CURRENT (mA) OUTPUT VOLTAGE (V) 4.5 4.0 3.5 1x MODE 3.0 2.5 0.5 5x MODE 1.5 1.0 0.5 VBUS = 5V VBAT = 3.3V RCLPROG = 2.94k 0 3.4 VBUS = 5V VBAT = 3.3V RCLPROG = 2.94k OUTPUT VOLTAGE (V) Output Voltage vs Output Current in Suspend TA = 25°C, unless otherwise noted. VBAT = 3.9V, 4.2V 1.5 2 1 OUTPUT CURRENT (mA) 0 2.5 0.5 1.5 2 1 OUTPUT LOAD CURRENT (mA) 0 VBAT = 3V VBAT = 3.
PAGE 7
LTC4088 Typical Performance Characteristics CHRG Pin Current vs Voltage (Pull-Down State) CHRG PIN CURRENT (mA) 100 TA = 25°C, unless otherwise noted. 3.3V LDO Transient Response (5mA to 15mA) VBUS = 5V VBAT = 3.8V Suspend LDO Transient Response (500µA to 1mA) 80 ILDO3V3 5mA/DIV IOUT 500µA/DIV 60 0mA 0mA 40 VLDO3V3 20mV/DIV AC COUPLED VOUT 20mV/DIV AC-COUPLED 20 0 VBAT = 3.
PAGE 8
LTC4088 Pin Functions CHRG (Pin 7): Open-Drain Charge Status Output. The CHRG pin indicates the status of the battery charger. Four possible states are represented by CHRG: charging, not charging (or float charge current less than programmed end of charge indication current), unresponsive battery and battery temperature out of range. CHRG is modulated at 35kHz and switches between a low and a high duty cycle for easy recognition by either humans or microprocessors.
PAGE 9
T NTC 1 2 0.1V NTC VBUS 1.188V CLPROG + – + – + – + – ISWITCH/N ILDO/M + – NTC ENABLE OVERTEMP UNDERTEMP AVERAGE INPUT CURRENT LIMIT CONTROLLER SUSPEND LDO 100mV NTC FAULT OSC 4.6V – + Q D0 13 D1 14 LOGIC AVERAGE OUTPUT VOLTAGE LIMIT CONTROLLER PWM R S 4 D2 NONOVERLAP AND DRIVE LOGIC 3.6V GND 15 +– 0.3V 1V 6 PROG IBAT/1031 CONSTANT CURRENT CONSTANT VOLTAGE BATTERY CHARGER + – VBUS 5 C/X BAD CELL NTC IBAT/1031 100mV 15mV 0V PWM + – ALWAYS ON 3.
PAGE 10
LTC4088 Operation Introduction Input Current Limited Step Down Switching Regulator The LTC4088 includes a PowerPath controller, battery charger, internal ideal diode, optional external ideal diode controller, SUSPEND LDO and an always-on 3.3V LDO. Designed specifically for USB applications, the PowerPath controller incorporates a precision average input current limited step-down switching regulator to make maximum use of the allowable USB power.
PAGE 11
LTC4088 Operation The current at CLPROG is a precise fraction of the VBUS current. When a programming resistor and an averaging capacitor are connected from CLPROG to GND, the voltage on CLPROG represents the average input current of the switching regulator. As the input current approaches the programmed limit, CLPROG reaches 1.188V and power delivered by the switching regulator is held constant.
PAGE 12
LTC4088 Operation Ideal Diode from BAT to VOUT The LTC4088 has an internal ideal diode as well as a controller for an optional external ideal diode. Both the internal and the external ideal diodes are always on and will respond quickly whenever VOUT drops below BAT. If the load current increases beyond the power allowed from the switching regulator, additional power will be pulled from the battery via the ideal diodes.
PAGE 13
LTC4088 Operation Battery Charger The LTC4088 includes a constant-current/constant-voltage battery charger with automatic recharge, automatic termination by safety timer, low voltage trickle charging, bad cell detection and thermistor sensor input for out of temperature charge pausing. When a battery charge cycle begins, the battery charger first determines if the battery is deeply discharged. If the battery voltage is below VTRKL, typically 2.
PAGE 14
LTC4088 Operation microprocessor. An open-drain output, the CHRG pin can drive an indicator LED through a current limiting resistor for human interfacing or simply a pull-up resistor for microprocessor interfacing. 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.
PAGE 15
LTC4088 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 IC 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 16
LTC4088 Applications Information CLPROG Resistor and Capacitor As described in the Step-Down Input 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. To ensure that the USB specification is strictly met, both components of input current should be considered.
PAGE 17
LTC4088 Applications Information Table 3. Recommended Inductors for the LTC4088 INDUCTOR TYPE L (µH) MAX IDC MAX DCR (A) (Ω) LPS4018 3.3 2.2 0.08 3.9 × 3.9 × 1.7 Coilcraft www.coilcraft.com D53LC DB318C 3.3 3.3 2.26 1.55 0.034 0.070 5×5×3 3.8 × 3.8 × 1.8 Toko www.toko.com WE-TPC Type M1 3.3 1.95 0.065 4.8 × 4.8 × 1.8 Wurth Elektronik www.we-online.com CDRH6D12 CDRH6D38 3.3 3.3 2.2 3.5 0.0625 0.020 6.7 × 6.7 × 1.5 7×7×4 Sumida www.sumida.
PAGE 18
LTC4088 Applications Information power to charge the battery as quickly as possible, and with minimal power dissipation within the charger. Alternate NTC Thermistors and Biasing The LTC4088 provides temperature qualified charging if a grounded thermistor and a bias resistor are connected to NTC.
PAGE 19
LTC4088 Applications Information From the Vishay Curve 1 R-T characteristics, rHOT is 0.2488 at 60°C. Using the above equation, RNOM should be set to 46.4k. With this value of RNOM, the cold trip point is about 16°C. Notice that the span is now 44°C rather than the previous 40°C. This is due to the decrease in “temperature gain” of the thermistor as absolute temperature increases.
PAGE 20
LTC4088 Applications Information Voltage overshoot on VBUS may sometimes be observed when connecting the LTC4088 to a lab power supply. This overshoot is caused by long leads from the power supply to VBUS. Twisting the wires together from the supply to VBUS can greatly reduce the parasitic inductance of these long leads, and keep the voltage at VBUS to safe levels. USB cables are generally manufactured with the power leads in close proximity, and thus fairly low parasitic inductance.
PAGE 21
LTC4088 Typical Applications High Efficiency Battery Charger/USB Power Manager with NTC Qualified Charging and Reverse Input Protection L1 3.3µH WALL M2 USB VBUS R1 100k D0 D1 D2 CHRG µC C1 10µF 0805 LOAD VOUT SW LDO3V3 GATE LTC4088 M1 C3 10µF 0805 BAT NTC CLPROG T R2 100k C2 0.1µF 0603 R5 8.2Ω PROG C/X GND R3 2.
PAGE 22
LTC4088 Package Description Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. DEPackage Package DE 14-Lead Plastic DFN (4mm (4mm ×× 3mm) 14-Lead Plastic DFN 3mm) (ReferenceLTC LTCDWG DWG ## 05-08-1708 05-08-1708 Rev (Reference Rev B) B) 0.70 ±0.05 3.30 ±0.05 3.60 ±0.05 2.20 ±0.05 1.70 ±0.05 PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 3.00 REF RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 4.00 ±0.
PAGE 23
LTC4088 Revision History (Revision history begins at Rev B) REV DATE DESCRIPTION B 05/12 Clarified thermistor part number. PAGE NUMBER 18, 21 4088fb 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 24
LTC4088 Related Parts PART NUMBER DESCRIPTION COMMENTS LTC4057 Lithium-Ion Linear Battery Charger Up to 800mA Charge Current, Thermal Regulation, ThinSOT™ Package LTC4058 Standalone 950mA Lithium-Ion Charger in DFN C/10 Charge Termination, Battery Kelvin Sensing, ±7% Charge Accuracy LTC4065/LTC4065A 750mA Linear Lithium-Ion Battery Charger 2mm × 2mm DFN Package, Thermal Regulation, Standalone Operation LTC4411/LTC4412 Low Loss Single PowerPath Controllers in ThinSOT Automatic Switching Between