View MAX8844ZETD_4520944.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-4279; Rev 0; 3/09
EVALUATION KIT AVAILABLE
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output
General Description
The MAX8844Z/MAX8844Y intelligent, stand-alone constant-current, constant-voltage (CCCV), thermally regulated dual input linear chargers are designed for charging a single-cell lithium-ion (Li+) battery. The MAX8844Z/MAX8844Y integrate a current-sense circuit, MOSFET pass element, thermal-regulation circuitry, and eliminate the external reverse-blocking Schottky diode to create the simplest and smallest charging solutions for handheld equipment. The IC controls the charging sequence from the prequalification state through constant current fast-charge, top-off charge, and full-charge indication. Proprietary thermal-regulation circuitry limits the die temperature during fast-charging or when the IC is exposed to high ambient temperatures, allowing maximum charging current without damaging the IC. The MAX8844Z/MAX8844Y achieve high flexibility by providing adjustable fast-charge currents (SETI) and an adjustable top-off current threshold (MIN) through external resistors. The IC features a booting assistant circuit that distinguishes input sources and battery connection and provides an enable signal (ABO, ABO) for system booting. The ICs also integrate two input overvoltage-protected LDO outputs (SAFEOUT, SAFEUSB) for low-voltagerated USB or charger inputs in system, and a battery pack detection circuit (DETBAT) that disables the charger when the battery pack is absent. Other features include an active-low control input (EN), an active-low input power source detection output (POK), and a fully charged top-off threshold detection output (CHG). The MAX8844Z/MAX8844Y automatically select between either the USB or IN source. If both sources are present at the same time, highest priority is given to the IN source. The IN source is selected to ensure the shortest charging time for the system since it is able to deliver the highest current. The MAX8844Z/MAX8844Y accept an input supply range from 4.25V to 28V (IN and USB), but disable charging if the input voltage exceeds +7.5V to protect against unqualified or faulty AC adapters. The ICs operate over the extended temperature range (-40C to +85C) and are available in a compact 14-pin, thermally enhanced, leadfree TDFN 3mm x 3mm package (0.8mm max height).
Features
CCCV, Thermally Regulated Linear One-Cell Li+ Battery Charger No External MOSFET, Reverse Blocking Diode, or Current-Sense Resistor Programmable Fast-Charge Currents (1ARMS max) Programmable Top-Off Current Threshold Input Overvoltage Protected 4.7V Output (SAFEOUT) from IN Input Overvoltage Protected 4.7V Output (SAFEUSB) from USB Proprietary Die Temperature Regulation Control (+115C) 4.25V to 28V Input Voltage Range with Input Overvoltage Protection Above +7.5V Low-Dropout Voltage (300mV at 500mA) Input Power-Source Detection Output (POK), Charge Status Output (CHG), Charge-Enable Input (EN) Output for Autobooting (ABO, MAX8844Z) Output for Autobooting (ABO, MAX8844Y) Tiny 3mm x 3mm, 14-Pin TDFN Package, 0.8mm Height (max)
MAX8844Z/MAX8844Y
Ordering Information
PART MAX8844ZETD+ MAX8844YETD+ PINPACKAGE 14 TDFN-EP* 14 TDFN-EP* TOP MARK AEK AEN ABO ACTIVE STATE Active high Active low
+Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad.
Applications
Cellular and Cordless Phones Smart Phones and PDAs Digital Still Cameras MP3 Players
Bluetooth is a registered trademark of Bluetooth SIG.
Note: All devices are specified over the -40C to +85C operating temperature range.
USB Appliances Charging Cradles and Docks Bluetooth(R) Equipment
Typical Operating Circuit and Pin Configuration appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
ABSOLUTE MAXIMUM RATINGS
IN, USB to GND......................................................-0.3V to +30V ABI, BATT, EN, POK, ABO, ABO, CHG, DETBAT, SETI, MIN, SAFEOUT, SAFEUSB to GND.................................................-0.3V to +6V IN to BATT Continuous Current .........................................1ARMS Continuous Power Dissipation (TA = +70C) 14 TDFN (derate 24.4mW/C above 70C) (multilayer PCB) ....................................................1951.2mW BATT Short-Circuit Duration .......................................Continuous Operating Temperature Range ...........................-40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = 5V or VUSB = 5V, VBATT = 4V, RPOK = 1M to BATT, EN = unconnected, RSETI = 2.8k to GND, VDETBAT = 0V, CBATT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER IN, USB Input Supply Voltage Range Input Supply Operating Voltage Range Overvoltage Lockout Trip Threshold VIN rising, 100mV hysteresis (typ) Constant current charging IIN - IBATT, IBATT = 0A Input Current Constant current charging IIN - IBATT, IBATT = 500mA IC disabled, V EN = 5V VIN = 4V, VBATT = 4.2V BATT, CHG, POK Minimum BATT Bypass Capacitance VBATT Prequalification Threshold Voltage Battery Regulation Voltage Regulator Dropout Voltage (VIN VBATT ) BATT Input Current (Note 2) Current-Sense Amplifier Gain (IBATT to ISETI) VBATT rising, 100mV hysteresis (typ) IBATT = 0A VBATT = 4.1V, IBATT = 425mA VIN = 0 to 4V, VBATT = 4.2V IC disabled IBATT = 500mA TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C 2.3 4.175 4.158 2.2 2.5 4.200 4.200 260 5 3 1120 1120 A/A 10 2.7 4.225 4.242 F V V mV TA = +25C TA = +85C 0 4.25 7.0 7.5 0.25 1 0.23 0.02 0.03 0.50 28 7.00 8.0 0.50 V V V CONDITIONS MIN TYP MAX UNITS
mA
A
2
_______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 5V or VUSB = 5V, VBATT = 4V, RPOK = 1M to BATT, EN = unconnected, RSETI = 2.8k to GND, VDETBAT = 0V, CBATT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER VBATT = 3.5V, RSETI = 2.8k VBATT = 3.5V, RSETI = 14k USB Fast-Charge Current CHG Top-Off Threshold CHG Hysteresis CHG Detection Delay Prequalification Charge Current CHG, POK Output Low Threshold CHG, POK Output High Leakage Current POK Threshold (Note 2) DETBAT, SAFEOUT, SAFEUSB DETBAT Logic Input Low Threshold DETBAT Logic Input High Threshold DETBAT Pullup Resistor Minimum SAFEOUT Bypass Capacitance SAFEOUT Regulated Output SAFEOUT Current Limit Minimum SAFEUSB Bypass Capacitance SAFEUSB Regulated Output SAFEUSB Current Limit EN, ABI, ABO, ABO EN, ABI Internal Pulldown Resistor EN, Logic Input Low Threshold (Note 2) EN, Logic Input High Theshold (Note 2) 4.25V VIN 7V 4.25V VIN 7V 1.3 100 200 400 0.4 k V V ISAFEUSB = 30mA, VUSB = 5V, TA = 0C to +85C 4.5 ISAFEOUT = 30mA, VIN = 5V, TA = 0C to +85C 4.5 DETBAT to VL = 3V 1.3 470 1 4.7 100 1 4.7 100 4.9 4.9 k F V mA F V mA 0.4 V MAX8844Z MAX8844Y IBATT falling, battery is charged, RMIN = 1.75k (Note 3) IBATT rising after top-off is detected, RMIN = 1.75k IBATT falls below top-off threshold Percentage of the fast-charge current, VBATT = 2.2V, TA = 0C to +85C IPOK = 5mA , ICHG = 5mA V POK = 5.5V, V CHG = 5.5V VIN - VBATT TA = +25C TA = +85C VIN rising VIN falling 0.002 40 30 4.0 5 CONDITIONS TA = 0C to +85C TA = -40C to +85C MIN 400 375 74 332 405 TYP 440 440 88 380 450 99 27 6.2 11 10.7 17 0.4 1 MAX 480 505 102 418 495 mA mA mA ms % V A mV mA UNITS
MAX8844Z/MAX8844Y
Fast-Charge Current
_______________________________________________________________________________________
3
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 5V or VUSB = 5V, VBATT = 4V, RPOK = 1M to BATT, EN = unconnected, RSETI = 2.8k to GND, VDETBAT = 0V, CBATT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
ABI Logic Input Low Threshold ABI Logic Input High Threshold ABO Output Low Threshold ABO Output High Threshold ABO Output Low Threshold ABO Output High Threshold THERMAL Die Temperature Regulation Threshold 115 C VBATT = 4V, VIN = 0V VBATT = 4V, VIN = 0V IABO(SINK) = 1mA IABO(SOURCE) = 1mA Open drain, IABO(SINK) = 1mA Open drain, 100k pullup on BATT VBATT 0.4V VBATT 0.4V 0.4 1.3 0.4 0.4 V V V V
Note 1: Specifications are 100% production tested at TA = +25C. Limits over the operating temperature range are guaranteed by design and characterization. Note 2: The IN input supply and USB input supply are interchangeable (VIN = VUSB). See the DC and USB Power Supplies section for further details. Note 3: See the Top-Off Current Threshold Setting section for further details.
Typical Operating Characteristics
(VIN = 5V or VUSB = 5V, VBATT = 4V, R POK = RCHG = 200k to 5V, EN = unconnected, RSETI = 2.8k to GND, RMIN = 1.74k to GND, RDETBAT = 4.7k to GND, CBATT = 2.2F, TA = +25C, unless otherwise noted.
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX8844 toc01
DISABLED MODE SUPPLY CURRENT vs. INPUT VOLTAGE
VEN = 5V 0.5 SUPPLY CURRENT (mA) 0.4 0.3 0.2 0.1 0
MAX8844 toc02
CHARGE CURRENT vs. BATTERY VOLTAGE
700 CHARGE CURRENT (mA) 600 500 400 300 200 100 0 VIN = 0V, VUSB = 5V VIN = 5V, VUSB = 0V
MAX8844 toc03
1.0 0.9 0.8 SUPPLY CURRENT (mA) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 4 8 12 16 20 24 VEN = 0V, IBATT = 0A, VIN RISING
0.6
800
28
0
4
8
12
16
20
24
28
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 BATTERY VOLTAGE (V)
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
4
_______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output
Typical Operating Characteristics (continued)
(VIN = 5V or VUSB = 5V, VBATT = 4V, R POK = RCHG = 200k to 5V, EN = unconnected, RSETI = 2.8k to GND, RMIN = 1.74k to GND, RDETBAT = 4.7k to GND, CBATT = 2.2F, TA = +25C, unless otherwise noted.
CHARGE CURRENT vs. INPUT VOLTAGE
MAX8844 toc04
MAX8844Z/MAX8844Y
CHARGE CURRENT vs. SUPPLY VOLTAGE HEADROOM
MAX8844 toc05
SAFEOUT OUTPUT VOLTAGE vs. INPUT VOLTAGE
4.5 4.0 SAFEOUT VOLTAGE (V) 3.5 3.0 2.5 2.0 1.5 1.0 ISAFEOUT = 1mA
MAX8844 toc06
600 500 CHARGE CURRENT (mA) 400 300 200 100 0 0 4 8 12 16 20 24 VIN = 5V, VUSB = 0V VIN = 0V, VUSB = 5V
600 VIN - VBATT 500 CHARGE CURRENT (mA) 400 300 200 100 0
5.0
VUSB - VBATT
VBATT = 4V VSUPPLY RISING 0 100 200 300 400 500 600
0.5 0 0 4 8 12 16 20 24 28
28
INPUT VOLTAGE (V)
VSUPPLY - VBATT (mV)
INPUT VOLTAGE (V)
SAFEOUT OUTPUT VOLTAGE vs. LOAD CURRENT
MAX8844 toc07
SAFEUSB OUTPUT VOLTAGE vs. USB VOLTAGE
MAX8844 toc08
SAFEUSB OUTPUT VOLTAGE vs. LOAD CURRENT
4.5 4.0 SAFEUSB VOLTAGE (V) 3.5 3.0 2.5 2.0 1.5 1.0 0.5
MAX8844 toc09
5.0 4.5 4.0 SAFEOUT VOLTAGE (V) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 20 40 60 80
6 5 SAFEUSB VOLTAGE (V) 4 3 2 1 0
5.0
0 0 4 8 12 16 20 24 28 0 20 40 60 80 100 USB VOLTAGE (V) LOAD CURRENT (mA)
100
LOAD CURRENT (mA)
STARTUP INTO PRECHARGE
MAX8844 toc10
SHUTDOWN (FAST-CHARGE TO SHUTDOWN)
MAX8844 toc11
IBATT VIN VEN
100mA/div 0 5V/div 0 5V/div 0
IBATT
500mA/div 0
VIN
5V/div 0 5V/div
VEN
0 5V/div
5V/div VPOK 40s/div 0
VPOK 100s/div
0
_______________________________________________________________________________________
5
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
Typical Operating Characteristics (continued)
(VIN = 5V or VUSB = 5V, VBATT = 4V, R POK = RCHG = 200k to 5V, EN = unconnected, RSETI = 2.8k to GND, RMIN = 1.74k to GND, RDETBAT = 4.7k to GND, CBATT = 2.2F, TA = +25C, unless otherwise noted.
BATTERY REGULATION ACCURACY vs. AMBIENT TEMPERATURE
BATTERY REGULATION ACCURACY (%) 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 -40 -15 10 35 60 85 AMBIENT TEMPERATURE (C) 10 1 10 RSETI (k) 100 IBATT = 0A
MAX8844 toc12
FAST-CHARGE CURRENT vs. RSETI
MAX8844 toc13
1.0
10,000
FAST-CHARGE CURRENT (mA)
1000
100
TOP-OFF THRESHOLD CURRENT vs. 1/RMIN (k)
TOP-OFF THRESHOLD CURRENT (mA) 450 400 350 300 250 200 150 100 50 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 1/RMIN (k) TOP-OFF CURRENT FALLING TOP-OFF CURRENT RISING
MAX8844 toc14
CHARGE CURRENT vs. AMBIENT TEMPERATURE
MAX8844 toc15
500
700 600 CHARGE CURRENT (mA) 500 400 300 VBATT = 3.2V 200 100 RSETI = 2.8k 0 -40 -20 0 20 40 60 80 VBATT = 4V
100
AMBIENT TEMPERATURE (C)
AUTOBOOT ENABLED BY ABI SIGNAL (MAX8844Z)
MAX8844 toc16
AUTOBOOT ENABLED BY INPUT VOLTAGE (MAX8844Z)
MAX8844 toc17
5V/div VABI 0 5V/div VIN 0 5V/div 0 5V/div 0 VIN VABI
5V/div 0 5V/div 0 5V/div 0 5V/div 0
VBATT VABO 4s/div
VBATT VABO 20s/div
6
_______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output
Pin Description
PIN MAX8844Z 1 MAX8844Y 1 NAME FUNCTION Input Supply Voltage. IN is the power supply for the SAFEOUT linear regulator and the battery charger. See the DC and USB Power Supplies section. Bypass IN to GND with a 1F or larger ceramic capacitor to improve line noise and input transient rejection. Active-Low, Input Voltage Status Indicator. POK is an open-drain output that asserts low when 2.35V < (VIN or VUSB) < 7V and [(VIN or VUSB) - VBATT] > 40mV. If (VIN or VUSB) > +7.5V or VBATT > (VIN or VUSB), the IC is shut down and POK becomes high impedance. Connect a pullup resistor to the microprocessor's I/O voltage when interfacing with a microprocessor logic input. USB Input Supply Voltage. USB is the power supply for the SAFEUSB linear regulator and the battery charger. See the DC and USB Power Supplies section. Bypass USB to GND with a 1F or larger ceramic capacitor to improve line noise and input transient rejection. Autobooting External Input. See the Autobooting Assistant section and Table 1 for autobooting conditions. ABI is pulled to GND through an internal 200k resistor. Active-High, Autobooting Logic Output. See the Autobooting Assistant section and Table 1 for autobooting conditions. Active-Low, Autobooting Logic Output. See the Autobooting Assistant section and Table 1 for autobooting conditions. Top-Off Current Threshold Programmable Input. IMIN (mA) falling = 126V/RMIN (k) + 27 (mA). Charge-Current Program and Fast-Charge Current Monitor. Output current from SETI is 1120A per ampere of battery charging current. Set the charging current by connecting a resistor (RSETI in Figure 3) from SETI to GND. IFAST-CHARGE = 1250V/RSETI. To configure the MAX8844Z/MAX8844Y as a USB charger, see Figure 5. Battery Pack ID Resistor Detection Input. If DETBAT is pulled low through a pulldown resistor less than 51k, the charger is enabled. If DETBAT is left unconnected, the charger is disabled. Active-Low, Charging Indicator. CHG is an open-drain output that is pulled low once charging begins. CHG is high impedance when the battery current drops below MIN, or when the IC is disabled. Connect a pullup resistor to the microprocessor's I/O voltage when interfacing with a microprocessor logic input. Active-Low, Logic-Level Enable Input. Drive EN high to disable charger. Drive EN low or leave unconnected for normal operation. EN has an internal 200k pulldown resistor. Ground. Connect GND and the exposed pad to a large copper ground plane for maximum power dissipation. Connect GND to the exposed pad directly under the IC. Li+ Battery Connection. Bypass BATT to GND with a 2.2F ceramic capacitor. 4.7V Regulated LDO Output with Input Overvoltage Protection. Bypass SAFEUSB to GND with a 1F or larger ceramic capacitor. SAFEUSB can be used to supply lowvoltage-rated USB systems.
MAX8844Z/MAX8844Y
IN
2
2
POK
3
3
USB
4 5 -- 6
4 -- 5 6
ABI ABO ABO MIN
7
7
SETI
8
8
DETBAT
9
9
CHG
10 11 12 13
10 11 12 13
EN GND BATT SAFEUSB
_______________________________________________________________________________________
7
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
Pin Description (continued)
PIN MAX8844Z 14 MAX8844Y 14 NAME FUNCTION 4.7V Regulated LDO Output with Input Overvoltage Protection. Bypass SAFEOUT to GND with a 1F or larger ceramic capacitor. SAFEOUT can be used to supply lowvoltage-rated charging systems. Exposed Pad. Connect the exposed pad to a large ground plane for maximum power dissipation. Connect GND to the exposed pad directly under the IC.
SAFEOUT
--
--
EP
LINEAR REGULATOR WITH OVP USB
SAFEUSB
LINEAR REGULATOR WITH OVP
SAFEOUT
IN
BATT 4.2V Li+ OUTPUT DRIVER, CURRENT SENSE, AND LOGIC +115C
TEMPERATURE SENSOR
DETBAT
SETI
VREF IMINREF MIN IN/USB*
VREF VI/O
CHG
VIN/VUSB* OVLO BATT
VL REGULATOR
POK
VL VL UVLO DETBAT REFOK REF LOGIC VREF
POK
BATT
ABO (MAX8844Z ONLY)
ABI ABO (MAX8844Y ONLY)
200k
MAX8844Z MAX8844Y
200k *SEE THE DC AND USB POWER SUPPLIES SECTION. GND EP
EN
Figure 1. Functional Diagram
8 _______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output
Detailed Description
The MAX8844Z/MAX8844Y chargers use voltage, current, and thermal-control loops to charge a single Li+ cell and protect the battery (Figure 1). When a Li+ battery with a cell voltage below 2.5V is inserted, the MAX8844Z/MAX8844Y chargers enter a prequalification stage where they precharge that cell with 10% of the user-programmed fast-charge current (Figure 2). The CHG indicator is driven low to indicate entry into the prequalification state. When the battery voltage exceeds 2.5V, the charger soft-starts as it enters the fast-charge stage. The fast-charge current level is programmed through a resistor from SETI to GND. As the battery voltage approaches 4.2V, the battery current is reduced. If the battery current drops to less than the top-off current threshold set by R MIN , the charger enters top-off mode and the CHG indicator goes high impedance, signaling that the battery is fully charged. turns on when VIN 4.25V regardless of EN and is disabled when VIN is greater than the overvoltage threshold (7.5V typ).
MAX8844Z/MAX8844Y
Overvoltage Protected Output (SAFEUSB)
SAFEUSB is a linear regulator that provides an output voltage of 4.7V and can be used to supply low voltage rated USB systems. The SAFEUSB linear regulator turns on when VUSB 4.25V regardless of EN and is disabled when VUSB is greater than the overvoltage threshold (7.5V typ).
Battery Pack Detection Input (DETBAT)
DETBAT is a battery pack ID resistor detector that enables the battery charger if pulled low through a resistor that is less than 51k. If DETBAT is left unconnected or the pulldown resistor is 51k or greater, the battery charger is disabled. The open-drain POK output asserts low when 2.35V (VIN or VUSB) 7V, [(VIN or VUSB) - VBATT] 40mV (typ V IN or V USB rising), and DETBET is pulled low through a resistor that is less than 51k. POK is high
POK Output
Overvoltage-Protected Output (SAFEOUT)
SAFEOUT is a linear regulator that provides an output voltage of 4.7V and can be used to supply low-voltagerated charging systems. The SAFEOUT linear regulator
SHUTDOWN CHARGER = DISABLED CHG = HIGH-Z VBATT < 2.5V (VIN* - VBATT) < 30mV
PRECHARGE 10% OF IFAST-CHARGE CHG = LOW
VIN* < 7.5V, AND (VIN* - VBATT) 40mV, AND IC ENABLED
VIN* > 7V, OR (VIN* - VBATT) < 30mV, OR IC DISABLED
ASYNCHRONOUS FROM ANYWHERE VIN* > 7.5V, OR (VIN* - VBATT) < 30mV, OR THERMAL SHUTDOWN, OR IC DISABLED
VBATT < 2.4V VBATT 2.5V
ANY CHARGING STATE
DIE TEMPERATURE > +115C
CHARGING CURRENT REDUCTION CHARGING CURRENT IS REDUCED AS NECESSARY
DIE TEMPERATURE +115C IBATT > 248V/RMIN (k) - 16mA FAST-CHARGE CONSTANT-CURRENT CHARGE 100% OF IFAST-CHARGE CHG = LOW TOP-OFF 4.2 VOLTAGE REGULATION CHG = HIGH-Z IBATT IMIN FOR 6.2ms (typ) OR LONGER RETURN TO CHARGING STATE
*SEE THE DC AND USB POWER SUPPLIES SECTION.
Figure 2. Charge-State Diagram
_______________________________________________________________________________________
9
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
Table 1. Autobooting Output States
ABI Low High Low Low High BATT Present Present Not present Present Present POK High-Z High-Z Low Low Low CHARGER STATE Shutdown Shutdown CC/CV mode Fast-charge/top-off Fast-charge/top-off ABO (MAX8844Z) Low High High High High ABO (MAX8844Y) High-Z Low High-Z High-Z Low
Note: Present indicates that VBATT 2.0V and Not Present indicates that the battery is not connected.
impedance during shutdown. When interfacing with a microprocessor logic input, a pullup resistor to the microprocessor's I/O voltage may be required. If DETBAT is not used, connect DETBAT to GND for normal operation.
4) is required for ESD protection and noise filtering. If ABI is supplied by a system's internal GPIO, or logic, the RC filter is not required. For the MAX8844Y, the output ABO is only dependent on the state of ABI (Table 1).
Autobooting Assistant
The MAX8844Z/MAX8844Y contain an autobooting assistant circuit that generates an enable signal for system booting (ABO, ABO). For the MAX8844Z, the booting assistant functions as an internal OR gate (Figure 1). The first input is dependent on the input supply voltage (VIN or VUSB) and DETBAT while the second input is an external signal applied to ABI. The first input (POK) is driven high once DETBAT is pulled low through a resistor less than 51k, 2.35V (VIN or VUSB) 7V, and [(VIN or VUSB) - VBATT] 40mV (typ VIN rising). The second input signal (ABI) is driven by an external source (Table 1). ABI enables an autoboot signal when a battery is connected at BATT and is independent of POK. If POK is pulled low, the booting assistant always drives ABO high regardless of ABI. ABI is pulled to GND through an internal 200k resistor. If ABI is supplied from an outside exposed pin, an RC filter (Figure
CHG Charge Indicator Output
CHG is an open-drain output that indicates charge status. Table 2 describes the state of CHG during different stages of operation. CHG is suitable for driving a charge indication LED. If the MAX8844Z/MAX8844Y are used in conjunction with a microprocessor, a pullup resistor to the logic I/O voltage allows CHG to indicate charge status to the microprocessor instead of driving an LED.
Thermal Regulation
The thermal-regulation loop limits the MAX8844Z/ MAX8844Y die temperatures to +115C by reducing the charge current as necessary. This feature not only protects the IC from overheating, but also allows a higher charge current without risking damage to the system.
Table 2. CHG States
EN High Low Low Low Low VIN* X > 7.5V X 4.25V VIN* 7.5V 4.25V VIN* 7.5V 4.25V VIN* 7.5V VBATT X X > VIN* - 30mV < 2.4V 2.5V 4.2V IBATT 0 0 10% of IFAST-CHARGE 100% of IFAST-CHARGE < IMIN CHG High-Z High-Z Low Low High-Z STATE Disabled Shutdown Precharge Fast-charge Top-off
X = Don't care. *VIN and VUSB are interchangeable. See the DC and USB Power Supplies section. I FAST-CHARGE is reduced as necessary to prevent the die temperature from exceeding +115C.
10 ______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output
Charger Enable Input
The MAX8844Z/MAX8844Y contain an active-low logic input (EN) used to enable the chargers. Drive EN low, leave unconnected, or connect to GND to enable the charge-control circuitry. Drive EN high to disable the charger-control circuitry. EN has an internal 200k pulldown resistor.
Top-Off Current Threshold Setting
The top-off current threshold is programmed by an external resistor connected from MIN to GND (RMIN). Use the following equation to determine the top-off current (IMIN): IMIN (falling) = 126V/RMIN (k) + 27mA IMIN (rising) = 248V/RMIN (k) - 16mA where IMIN is in mA and RMIN is in k. Use RMIN 2.2k.
MAX8844Z/MAX8844Y
Soft-Start
The soft-start algorithm activates when entering fastcharge mode. When the prequalification state is complete (V BATT exceeds +2.5V), the charging current ramps up in 250s to the full charging current. This reduces the inrush current demand on the input supply.
Capacitor Selection
Connect a ceramic capacitor from BATT to GND for proper stability. Use a 2.2F ceramic capacitor for most applications. Connect 1F ceramic capacitors from IN to GND and from USB to GND. A larger input capacitor can be used for high charging current to reduce input voltage ripple. Connect 1F ceramic capacitors from SAFEOUT to GND and from SAFEUSB to GND. A larger bypass capacitor for SAFEOUT and SAFEUSB can be used for optimum noise immunity. Ceramic capacitors with X5R or X7R dielectric are highly recommended due to their small size, low ESR, and small temperature coefficients.
Applications Information
Fast-Charge Current Setting
The maximum charging current is programmed by an external resistor connected from SETI to GND (RSETI). Use the following equation to determine the fast-charge current (IFAST-CHARGE): IFAST-CHARGE = 1250V RSETI
where IFAST-CHARGE is in amps and RSETI is in ohms. RSETI must always be 1.25k or higher due to the continuous charging current limit of 1ARMS.
Thermal Considerations
The MAX8844Z/MAX8844Y are available in a thermally enhanced TDFN package with an exposed pad. Connect the exposed pad to a large copper ground plane to provide a thermal contact between the device and the circuit board for increased power dissipation. The exposed pad transfers heat away from the device, allowing the IC to charge the battery with maximum current, while minimizing the increase in die temperature.
Table 3. Input Power-Supply Selection
IN 4.25V VIN 7V 4.25V VIN 7V Not present VIN 7.5V 4.25V VIN 7V USB 4.25V VUSB 7V Not present 4.25V VUSB 7V 4.25V VUSB 7V VUSB 7.5V CHARGER STATE Enabled, selects IN power supply Enabled, selects IN power supply Enabled, selects USB power supply Disabled Enabled
______________________________________________________________________________________
11
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
USB CUSB 1F 4.2V Li+ BATT CBATT 2.2F SYSTEM
AC ADAPTER GND CIN 1F
IN
MAX8844Z
DETBAT SAFEUSB CSAFEUSB 1F
VBUS
ABI
SAFEOUT CSAFEOUT 1F VI/O
VCHG
RCHG 1M ABO SETI RSETI 2.8k MIN RMIN 1.75k GND EP POK EN CHG RPOK 1M GPIO GPIO GPIO
POWER SUPPLY ON
IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8844Y.
Figure 3. AC Adapter Application
DC and USB Power Supplies
The MAX8844Z/MAX8844Y operate from well-regulated DC sources and automatically select between both input power supply connections (Table 3). If both sources are present at the same time, highest priority is given to the IN source. The IN source is selected to ensure the shortest charging time for the system since it is able to deliver the highest current. The USB fastcharge current is fixed at 380mA (MAX8844Z) and 450mA (MAX8844Y). The full charging input voltage range for IN and USB is 4.25V to 7.5V. The device can withstand up to 28V on both inputs, IN and USB, without damage to the IC. If VIN or VUSB is greater than 7.5V, the internal overvoltage-protection circuitry disables charging until the input falls below 7.5V. The power supplies must provide at least 4.25V at the desired peak charging current and stay below 7V when unloaded.
Typical Application Circuits
AC Adapter Application Figure 3 shows the MAX8844Z as a Li+ battery charger with an AC adapter. The MAX8844Z detects the presence of an input supply and DETBET resulting in POK pulled low. Once POK is pulled low, the autobooting assistant drives ABO high and enables the power supplies of the system to boot up. The MAX8844Z begins charging the battery when EN is low or unconnected. By monitoring CHG, the system can detect the top-off threshold and terminate the charge through EN. The MAX8844Z also provides an overvoltage-protected SAFEOUT and SAFEUSB to the system. Factory System Interface Connector Application Figure 4 shows the MAX8844Z as an autoboot assistant with the factory system interface connector. The MAX8844Z detects the ABI input even though there is no input voltage available and drives ABO high to turn
12
______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
USB CUSB 1F
BATT CBATT 2.2F
MAX8844Z
IN 4.2V INTERFACE CONNECTOR GND CIN RABI 1F 10k ABI CABI 1F SAFEOUT CSAFEOUT 1F RCHG 1M ABO SETI RSETI 2.8k MIN RMIN 1.75k GND EP POK EN CHG RPOK 1M GPIO GPIO GPIO VI/O DETBAT SAFEUSB CSAFEUSB 1F
SYSTEM
VBUS
VCHG
POWER SUPPLY ON
IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8844Y.
Figure 4. Factory System Interface Connector Application
on power supplies to boot up the system. The configuration in Figure 4 is used for system development, testing, and calibrations in production or design stage.
USB-Powered Li+ Charger The universal serial bus (USB) provides a high-speed serial communication port as well as power for the remote device. The MAX8844Z can be configured to charge a battery at the highest current possible from the host port. Figure 5 shows the MAX8844Z as a USB battery charger with the default charging current as 380mA. The MAX8844Z also provides an overvoltage protected SAFEUSB to the system. USB Connector and AC Adapter Figure 6 shows the MAX8844Z as a Li+ battery charger with an AC adapter and USB connector. The MAX8844Z detects the presence of input supplies and DETBET resulting in POK pulled low. Once POK is pulled low, the autobooting assistant drives ABO high
and enables the power supplies of the system to boot up. The MAX8844Z begins charging the battery from IN source when EN is low or open. By monitoring CHG, the system can detect the top-off threshold and terminate the charge through the EN pin. The MAX8844Z provides overvoltage protected SAFEOUT and SAFEUSB to the system. Figure 7 shows the timing diagram.
Recommended PCB Layout and Routing
Place all bypass capacitors for IN, USB, BATT, SAFEOUT, and SAFEUSB as close to the device as possible. Connect the battery to BATT as close as possible to the device to provide accurate battery voltage sensing. Provide a large copper ground plane to allow the exposed pad to sink heat away from the device. Make all high-current traces short and wide to minimize voltage drops. A sample layout is available in the MAX8844Z evaluation kit to speed designs.
13
______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
4.2V Li+ USB USB CABLE GND CUSB 1F BATT CBATT 2.2F SYSTEM
MAX8844Z
IN CIN 1F DETBAT SAFEOUT SAFEUSB CSAFEOUT 1F ABI RCHG 1M CHG RPOK 1M POK MIN RMIN 1.75k POWER SUPPLY ON IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8844Y. GND EP EN GPIO GPIO GPIO VI/O
VBUS
ABO SETI RSETI 2.8k
Figure 5. USB Battery Charger
14
______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
4.2V Li+ BATT USB CABLE GND CUSB 1F CBATT 2.2F
USB
MAX8844Z
DETBAT SAFEUSB
SYSTEM
VBUS CSAFEUSB 1F
AC ADAPTER GND CIN 1F
IN SAFEOUT
VCHG CSAFEOUT 1F VI/O
ABI RCHG 1M ABO SETI RSETI 2.8k MIN RMIN 1.75k GND EP POK EN CHG RPOK 1M GPIO GPIO GPIO
POWER SUPPLY ON
IF THE POWER SUPPLY IS ACTIVE-LOW ENABLED, USE THE MAX8844Y.
Figure 6. USB Connector and AC Adapter Application
______________________________________________________________________________________
15
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output MAX8844Z/MAX8844Y
OVP POK VIN
OVP
OVP
OVP
POK VUSB VPOK
VEN
VCHG
VSAFEOUT = 4.7V
VSAFEOUT VSAFEUSB = 4.7V
VSAFEUSB TIME
Figure 7. Timing Diagram
16
______________________________________________________________________________________
28V Dual Input Linear Li+ Battery Chargers with Battery Detection and Overvoltage-Protected Output
Typical Operating Circuit
4.25V TO 28V IN CIN 1F 4.25V TO 28V USB CUSB 1F ABI OFF ON EN MIN RMIN 1.75k DETBAT BATT CBATT 2.2F 4.2V Li+
MAX8844Z/MAX8844Y
MAX8844Z MAX8844Y
SYSTEM SUPPLY
CHG POK (MAX8844Y, ABO) (MAX8844Z, ABO) SAFEOUT CSAFEOUT 1F
SETI RSETI 2.80k
SAFEUSB GND EP CSAFEUSB 1F
Chip Information
PROCESS: BiCMOS
SAFEOUT SAFEUSB
Pin Configuration
DETBAT 8 7 SETI
TOP VIEW
BATT
GND
14
13
12
11
10
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE 14 TDFN-EP (3mm x 3mm) PACKAGE CODE T1433-2 DOCUMENT NO. 21-0137
+ 1 IN
MAX8844Z MAX8844Y
*EXPOSED PAD 2 POK 3 USB 4 ABI 5 ABO/ABO* 6 MIN
TDFN
* = ABO--MAX8844Z, ABO--MAX8844Y
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 17
(c) 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
CHG 9
EN

▲Up To Search▲

Price & Availability of MAX8844ZETD

	To Download MAX8844ZETD Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .