Datasheet

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General Description

The MAX8677C is an integrated 1-cell Li+ charger and

Smart Power Selector™ with dual (DC and USB) power

inputs. It can operate with either separate inputs for

USB and AC adapter power*, or from a single input that

accepts both. All power switches for charging and

switching the load between battery and external power

are included on-chip. No external MOSFETs are

required.

The MAX8677C features a Smart Power Selector to

make the best use of limited USB or adapter power.

The battery charge current and input current limit are

independently set up to 1.5A and 2A, respectively.

Input power not used by the system charges the bat-

tery. USB input current can be set to 100mA or 500mA.

Automatic input selection switches the system load

from battery to external power.

Other features include overvoltage protection (OVP),

charge status and fault outputs, power-OK monitors,

charge timer, and battery thermistor monitor.

Additionally, on-chip thermal limiting reduces the battery

charge rate to prevent overheating. The MAX8677C is

available in a 4mm x 4mm, 24-pin TQFN-EP package.

Applications

PDAs, Palmtops, and Wireless Handhelds

Smart Cell Phones

Portable Media/MP3 Players

GPS Navigation

Digital Cameras

Features

o Complete Charger and Smart Power Selector

o No External MOSFETs Required

o Common or Separate USB and Adapter Inputs

o System Operates with Discharged or No Battery

o Automatic Adapter/USB/Battery Switchover

o Load Peaks Over Adapter Rating Are Supported

by Battery

o Input Overvoltage Protection to 16V

o 40mΩ System-to-Battery Switch

o Thermal Regulation Prevents Overheating

o PREQ, CHG, DOK, UOK, and FLT Indicators

o 4.35V (typ) SYS Regulation Voltage

MAX8677C

1.5A Dual-Input USB/AC Adapter Charger

and Smart Power Selector

________________________________________________________________

Maxim Integrated Products

MAX8677C

FLT

UOK

DOK

SYS

CHG

18 17 16 15 14 13

TQFN

(4mm x 4mm x 0.8mm)

3456

PSET

GND

ISET

THM

USUS

TSET

USB

BAT

PEN2

PEN1

CEN

PREQ

Pin Configuration

Ordering Information

ADAPTER

CHARGE AND

SYS LOAD

SWITCH

CHARGE

CURRENT

LOAD

CURRENT

USB

BAT

SYS

GND

BATTERY

SYSTEM

LOAD

MAX8677C

Typical Operating Circuit

19-0781; Rev 0; 4/07

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Denotes a lead-free package.

EP = Exposed paddle.

PART

TEMP RANGE

PIN-

PACKAGE

PKG

CODE

MAX8677CETG+ -40°C to +85°C

24 TQFN-EP**

(4mm x 4mm)

T2444-4

Smart Power Selector is a trademark of Maxim Integrated

Products, Inc.

Protected by U.S. Patent #6,507,172.

Summary of content (21 pages)

PAGE 1
9-0781; Rev 0; 4/07 1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector The MAX8677C is an integrated 1-cell Li+ charger and Smart Power Selector™ with dual (DC and USB) power inputs. It can operate with either separate inputs for USB and AC adapter power*, or from a single input that accepts both. All power switches for charging and switching the load between battery and external power are included on-chip. No external MOSFETs are required.
PAGE 2
MAX8677C 1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector ABSOLUTE MAXIMUM RATINGS DC, PEN1 to GND .................................................-0.3V to +16V USB to GND .............................................................-0.3V to +9V VL to GND ................................................................-0.3V to +4V BAT, SYS, CEN, USUS, PEN2, TSET to GND...........-0.3V to +6V THM, PSET, ISET, CT to GND .........................-0.3V to VL + 0.
PAGE 3
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector (VDC = 5V, THM = CEN = USUS = GND, VBAT = 4V, VPEN1 = VPEN2 = 5V, USB, TSET, PREQ, CHG, DOK, UOK, FLT are unconnected, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS USB-TO-SYS PREREGULATOR USB Operating Range 4.1 USB Standoff Voltage VBAT = VSYS = 0V USB Undervoltage Threshold When V UOK goes low, VUSB rising, 500mV hysteresis 3.
PAGE 4
MAX8677C 1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector ELECTRICAL CHARACTERISTICS (continued) (VDC = 5V, THM = CEN = USUS = GND, VBAT = 4V, VPEN1 = VPEN2 = 5V, USB, TSET, PREQ, CHG, DOK, UOK, FLT are unconnected, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER CONDITIONS MIN TYP MAX UNITS ISET Voltage RISET = 4kΩ, IBAT = 500mA (VISET = 1.5V at full charge current) 0.9 1.0 1.
PAGE 5
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector 0.7 0.6 VUSB RISING VUSB FALLING 0.5 0.4 0.3 0.2 ENTERING OVLO 0.8 0.6 0.4 0.2 0 0 1 2 3 4 5 0 6 7 8 2 3 4 5 6 7 PEN1 = X, PEN2 = 1 0.30 0.25 0.20 0.15 0.10 0.05 0 0 8 1 2 3 4 5 6 7 8 USB VOLTAGE (V) USB VOLTAGE (V) BATTERY LEAKAGE CURRENT vs. BATTERY VOLTAGE (USB DISCONNECTED) BATTERY LEAKAGE CURRENT vs. TEMPERATURE BATTERY LEAKAGE CURRENT vs. BATTERY VOLTAGE (USB CONNECTED) 2.5 2.0 1.5 1.0 3.58 3.56 3.
PAGE 6
Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) 1.0050 1.0025 1.0000 0.9975 0.9950 4.200 MAX8677C toc12 4.40 VBAT = 4V NO SYS LOAD 4.35 4.30 4.195 VSYS (V) 1.0075 BATTERY REGULATION VOLTAGE (V) VUSB = 5V, VBAT = 4V MAX8677C toc11 4.205 MAX8677C toc10 NORMALIZED CHARGE CURRENT 1.0100 SYS OUTPUT VOLTAGE vs. USB VOLTAGE BATTERY REGULATION VOLTAGE vs. TEMPERATURE NORMALIZED CHARGE CURRENT vs. AMBIENT TEMPERATURE (LOW IC POWER DISSIPATION) 4.190 4.25 4.
PAGE 7
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector MAX8677C toc18 1.0 0.6 2.5 2.0 1.5 0.4 0.2 1.0 0.5 0 0 50 100 0.40 IBAT 3.5 VBAT (V) IBAT 3.0 0.30 2.5 0.25 2.0 0.20 1.5 0.15 1.0 0.10 0.5 0.05 0 0 0 20 40 60 80 100 120 140 TIME (min) TIME (min) DC CONNECT WITH USB CONNECTED (RSYS = 25Ω) DC CONNECT WITH NO USB (RSYS = 25Ω) 3.6V IDC VBAT 3.68V CDC CHARGING 2V/div VSYS 3.6V 180 500mA/div 4.35V 3.
PAGE 8
MAX8677C 1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) USB DISCONNECT WITH NO DC (RSYS = 20Ω) USB SUSPEND MAX8677C toc24 VUSB MAX8677C toc25 5V 0V VUSUS 10V/div 475mA IUSB VSYS 3.7V IBAT 5V/div 3V 0V -300mA 500mA IUSB 3.7V VSYS 3.6V 0V VUOK VCHG 500mA/div 0A VCHG 120mA IBAT 1A/div 5V/div 0A 500mA/div 3.
PAGE 9
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector PIN NAME FUNCTION 6 PEN2 USB High/Low Control. PEN2 sets the DC or USB current limit to 100mA (PEN2 low) or 500mA (PEN2 high). PEN2 controls both DC and USB current limits when PEN1 is low. See Table 2. 7 PSET DC Input Current-Limit Set. Connect a resistor to ground to program the DC current limit to 3000/RPSET. 8 VL 9 GND 10 CT 11 ISET Charge Current Set Input.
PAGE 10
MAX8677C 1.
PAGE 11
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector MAX8677C RPU 3X 560kΩ TO VL RPU 560kΩ PREQUAL ADAPTER CDC 4.7μF OFF 1 PREQ 2 DC 3 DC 4 CHARGE ON 5 MAX8677C CEN PEN1 FLT UOK DOK SYS SYS 24 FAULT OUTPUT 23 USB PWR OK 22 DC PWR OK 21 20 TO SYSTEM LOAD CSYS 10μF 560kΩ TO VL 500mA 6 100mA 7 PEN2 PSET CHG BAT 19 18 RPSET 8 CL 0.1μF CT 0.068μF VL BAT 17 USB 16 1-CELL Li+ CBAT 4.7μF USB 9 10 11 GND CT ISET USB 15 12 THM VBUS CUSB 4.
PAGE 12
MAX8677C 1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector 3X 560kΩ TO VL 560kΩ MINI 5-STYLE CONNECTOR VBUS DD+ ID GND PREQUAL 1 2 3 CDC 4.7μF 1 PREQ 2 DC 3 DC 4 5 OFF CHARGE ON 4 HI = DC DC-USB ID LO = USB 5 500mA 6 CEN PEN1 MAX8677C FLT UOK DOK SYS SYS 24 FAULT OUTPUT 23 USB PWR OK 22 DC PWR OK 21 20 560kΩ TO VL 100mA 7 PEN2 PSET CHG BAT 19 8 CL 0.1μF CT 0.
PAGE 13
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector COMPONENT (FIGURES 2, 3) FUNCTION Input filter capacitor 4.7µF ceramic capacitor CL VL filter capacitor 0.1µF ceramic capacitor CSYS SYS output bypass capacitors 10µF ceramic capacitor CBAT Battery bypass capacitor 4.7µF ceramic capacitor CT Charger timing capacitor 0.
PAGE 14
MAX8677C 1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector Input Limiter The input voltage limiter is essentially an LDO regulator. While in dropout, the regulator dissipates a small I2R loss through the 0.2Ω MOSFET (Q1, Figure 4) between DC and SYS. With an AC adapter or USB source connected, the input limiter distributes power from the external power source to the system load and battery charger.
PAGE 15
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector Separate Adapter and USB Connectors When the AC adapter and USB have separate connectors, the adapter output connects to DC and the USB source connects to USB. PEN1 is permanently tied high (to DC or VL). The DC current limit is set by RPSET, while the USB current limit is set by PEN2 and USUS.
PAGE 16
MAX8677C 1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector NOT READY UOK AND DOK = HIGH IMPEDANCE CHG = HIGH IMPEDANCE FLT = HIGH IMPEDANCE PREQ = HIGH IMPEDANCE ICHG = 0mA UOK OR DOK = LOW CEN = 0 RESET TIMER CEN = HI OR REMOVE AND RECONNECT THE INPUT SOURCE(S). ANY STATE TOGGLE CEN OR REMOVE AND RECONNECT THE INPUT SOURCE(S). PREQUAL UOK OR DOK = LOW CHG = LOW FLT = HIGH IMPEDANCE PREQ = LOW 0V ≤ VBATT ≤ 3V ICHG = ICHGMAX/10 VBATT < 2.
PAGE 17
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector MONITORING THE BATTERY CHARGE CURRENT WITH VISET VISET = RISET 2000 x ICHG 1.5 VISET (V) Setting the Charge Current MAX8677C Charge Enable (CEN) When CEN is low, the charger is on. When CEN is high, the charger turns off. CEN does not affect the SYS output.
PAGE 18
MAX8677C 1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector When the MAX8677C is used in conjunction with a µP, connect a pullup resistor between PREQ and the logic I/O voltage to indicate charge status to the µP. Alternatively, PREQ can sink up to 20mA for an LED indicator. Fault Output (FLT) and Charge Timer FLT is an open-drain, active-low output that goes low during a battery fault. The fault state occurs when either the prequal or fast-charge timer expires.
PAGE 19
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector ⎧ ⎛ 1 1 ⎞⎫ RT = R25 × e⎨⎩β⎜⎝ T +273 − 298 ⎟⎠ ⎬⎭ Power Dissipation It is important to ensure that the heat generated by the MAX8677C is dissipated into the PCB. The package’s exposed paddle must be soldered to the PCB with multiple vias tightly packed under the exposed paddle to ensure optimum thermal contact to the ground plane.
PAGE 20
Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.) 24L QFN THIN.EPS MAX8677C 1.
PAGE 21
1.5A Dual-Input USB/AC Adapter Charger and Smart Power Selector Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.