SOT23 Dual-Input USB/AC Adapter 1-Cell Li+ Battery Chargers

Transcription

1 19-292; Rev ; 7/3 SOT23 Dual-Input /AC Adapter 1-Cell Li+ General Description The charge a single-cell lithium-ion (Li+) battery from both * and AC adapter sources. They operate with no external FETs or diodes, and accept operating input voltages up to 7V. On-chip thermal limiting simplifies PC board layout and allows optimum charging rate without the thermal limits imposed by worst-case battery and input voltage. When the thermal limits are reached, the chargers do not shut down, but progressively reduce charging current. The MAX1551 includes a POK output to indicate when input power is present. If either charging source is active, POK goes low. The MAX1555 instead features a CHG output to indicate charging status. With connected, but without power, charge current is set to 1mA (max). This allows charging from both powered and unpowered hubs with no port communication required. When power is connected, charging current is set at 28mA (typ). No input-blocking diodes are required to prevent battery drain. The are available in 5-pin thin SOT23 packages and operate over a -4 C to +85 C range. Features Charge from or AC Adapter Automatic Switchover when AC Adapter is Plugged In On-Chip Thermal Limiting Simplifies Board Design Charge Status Indicator 5-Pin Thin SOT23 Package Protected by U.S. Patent #6,57,172 Ordering Information PART TEMP RANGE PIN-PACKAGE MAX1551EZK-T -4 C to +85 C 5 Thin SOT23-5 MAX1555EZK-T -4 C to +85 C 5 Thin SOT23-5 Selector Guide PDAs Wireless Appliances Cell Phones Digital Cameras Applications Pin Configuration PART TOP MARK FEATURES MAX1551EZK ADRT POK Output MAX1555EZK ADRU CHG Output Typical Operating Circuit TOP VIEW AC ADAPTER 3.7V TO 7V BAT TO SYSTEM LOAD 1 5 BAT Li+ GND 2 MAX1551 (MAX1555) 3.7V TO 6V CHARGE CONTROL TO LOGIC RAIL POK (CHG) 3 4 THIN SOT23 MAX1551 (MAX1555) LOGIC CONTROL GND POK (CHG) *Protected by U.S. Patent #6,57,172. Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at , or visit Maxim s website at

2 ABSOLUTE MAXIMUM RATINGS to GND... to +8V to BAT... to +7V BAT, CHG, POK, to GND...-.3V to +7V Continuous Power Dissipation (T A = +7 C) 5-Pin Thin SOT23 (derate 9.1mW/ C above +7 C)...727mW 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 (V = 5V, V =, I BAT =, C BAT = 1µF, T A = C to +85 C, unless otherwise noted.) Operating Temperature Range...-4 C to +85 C Junction Temperature Range...-4 C to +15 C Storage Temperature Range C to +15 C Lead Temperature (soldering, 1s)...+3 C PARAMETER CONDITIONS MIN TYP MAX UNITS Voltage Range (Note 1) V to BAT Voltage Range.1 6. V Undervoltage Lockout Threshold Input rising, 43mV hysteresis, V BAT = 3V (Note 1) V Supply Current ma to BAT On-Resistance V = 3.7V, V BAT = 3.6V 1 2 Ω to BAT Dropout Voltage When charging stops, V BAT = 4V, falling, 2mV hysteresis mv Voltage Range (Note 1) V Undervoltage Threshold Input rising, 43mV hysteresis, V =, V BAT = 3V (Note 1) V Supply Current V = 5V, V = ma to BAT On-Resistance V = 3.7V, V BAT = 3.6V, V = 2 4 Ω to BAT Dropout Voltage BAT When charging stops, V BAT = 4V, falling, 2mV hysteresis, V = mv BAT Regulation Voltage V or V = 5V V Charging Current V BAT = 3.3V, V =, V = 5V ma Charging Current V BAT = 3.3V, V =, V = 5V ma BAT Prequal Threshold V BAT rising, 1mV hysteresis V Prequalification Charging Current V BAT = 2.8V ma BAT Leakage Current V = V =, V BAT = 4.2V 5 µa POK, CHG, AND THERMAL LIMIT CHG Threshold Charge current where CHG goes high, I BAT falling, 5mA hysteresis ma CHG, POK Logic-Low Output I CHG, I POK = 1mA 15 3 mv CHG, POK Leakage Current V CHG, V POK = 6V, T A = +25 C.1 1 µa Thermal-Limit Temperature Charge current reduced by 17mA/ C above this temperature +11 C 2

3 ELECTRICAL CHARACTERISTICS (V = 5V, V =, I BAT =, C BAT = 1µF, T A = -4 C to +85 C, unless otherwise noted.) (Note 2) PARAMETER CONDITIONS MIN MAX UNITS Voltage Range (Note 1) V to BAT Voltage Range.1 6. V Undervoltage Lockout Threshold Input rising, 43mV hysteresis, V BAT = 3V (Note 1) V Supply Current 3 ma to BAT On-Resistance V = 3.7V, V BAT = 3.6V 2 Ω to BAT Dropout Voltage When charging stops, V BAT = 4V, falling, 2mV hysteresis 3 95 mv Voltage Range (Note 1) V Undervoltage Lockout Threshold Input rising, 43mV hysteresis, V =, V BAT = 3V (Note 1) V Supply Current V = 5V, V = 3 ma to BAT On-Resistance V = 3.7V, V BAT = 3.6V, V = 4 Ω to BAT Dropout Voltage BAT When charging stops, V BAT = 4V, falling, 2mV hysteresis, V = 3 95 mv BAT Regulation Voltage V or V = 5V V Charging Current V BAT = 3.3V, V =, V = 5V ma Charging Current V BAT = 3.3V, V =, V = 5V 8 1 ma BAT Prequal Threshold V BAT rising, 1mV hysteresis V Prequalification Charging Current V BAT = 2.8V 2 8 ma BAT Leakage Current V = V =, V BAT = 4.2V 5 µa POK, CHG CHG Threshold Charge current where CHG goes high, I BAT falling, 5mA hysteresis 25 1 ma CHG, POK Logic-Low Output I CHG, I POK = 1mA 3 mv CHG, POK Leakage Current V CHG, V POK = 6V, T A = +25 C 1 µa Note 1: The input undervoltage lockout has 43mV of hysteresis. The charger turns on when an input rises to 3.95V (typ), and turns off when it falls below 3.52V. Note 2: Specifications to -4 C are guaranteed by design, not production tested. 3

4 Typical Operating Characteristics (V = 5V, V =, I BAT =, C BAT = 1µF, T A = +25 C, unless otherwise noted.) CHARGE CURRENT (ma) CHARGE CURRENT vs. VOLTAGE HEADROOM V BAT = 3.8V, V FALLING VOLTAGE HEADROOM (V - V BAT ) (V) MAX1551/55 toc1 CHARGE CURRENT (ma) CHARGE CURRENT vs. VOLTAGE HEADROOM V =, V BAT = 3.8V, V FALLING VOLTAGE HEADROOM (V - V BAT ) (V) MAX1551/55 toc2 CHARGE CURRENT (ma) CHARGE CURRENT vs. BATTERY VOLTAGE BATTERY VOLTAGE (V) MAX1551/55 toc3 CHARGE CURRENT (ma) CHARGE CURRENT vs. BATTERY VOLTAGE BATTERY VOLTAGE (V) MAX1551/55 toc4 CHARGE CURRENT (ma) CHARGE CURRENT vs. AMBIENT TEMPERATURE THERMAL LIMIT ACTIVATED V BAT = 3.8V, V = 5V TEMPERATURE ( C) MAX1551/55 toc5 BATTERY TERMINATION VOLTAGE (V) BATTERY TERMINATION VOLTAGE vs. TEMPERATURE BAT OPEN TEMPERATURE ( C) MAx1551/55 toc6 OFF-BATTERY LEAKAGE CURRENT (µa) OFF-BATTERY LEAKAGE CURRENT vs. INPUT VOLTAGE V =, SWEEPING TO 5V OR V =, SWEEPING TO 5V V BAT = 4.2V OR INPUT VOLTAGE (V) MAX1551/55 toc7 A V V V -TO- TRANSITION WAVEFORM 4ms/div MAX1551/55 toc8 BATTERY CURRENT 2mA/div V 5V/div V POK 2V/div V 5V/div 4

5 PIN NAME FUNCTION Detailed Description The charge a single-cell Li+ battery from both and AC adapter sources, enabling portable users to forgo carrying a wall cube. These devices operate with no external FETs or diodes, and accept operating input voltages up to 7V. An internal thermal control loop simplifies PC board layout and allows optimum charging rate without the thermal limits imposed by worst-case battery and input voltage. When the thermal limits are reached, the chargers do not shut down, but simply reduce charging current by 17mA/ C above a die temperature of +11 C. With connected, but without power, the charge current is set to 1mA (max). This allows charging from both powered and unpowered hubs with no port communication required. When power is connected, charging current is set at 28mA (typ). The do not feature an enable input. Once power is connected to and/or, the charger is on. When input power is removed, battery leakage current is less than 5µA. No input-blocking diodes are required to prevent battery drain. Insert a diode at (the adapter input) if protection from negative voltage inputs (reversed-polarity adapter plugs) is required. Pin Description 1 Port Charger Supply Input. draws up to 1mA to charge the battery. Decouple with a 1µF ceramic capacitor to GND. 2 GND Ground 3 POK CHG Power-OK Active-Low Open-Drain Charger Status Indicator. POK pulls low when either charger source is present (MAX1551 only). Active-Low Open-Drain Charge Status Indicator. CHG pulls low when the battery is charging. CHG goes to a high-impedance state, indicating the battery is fully charged, when the charger is in voltage mode and charge current falls below 5mA. CHG is high impedance when both input sources are low (MAX1555 only). 4 Charger Supply Input for an AC Adapter. draws 28mA to charge the battery. Decouple with a 1µF ceramic capacitor to GND. 5 BAT Battery Connection. Decouple BAT with a 1µF ceramic capacitor to GND. Table 1. and Input Selection to Adapter Power Handoff The can charge from either the input or the input. The battery does not charge from both sources at the same time. The MAX1551/ MAX1555 automatically detect the active input and charge from that. If both power sources are active, the input takes precedence. The switchover between and is detailed in Table 1. MAX1551 Power-OK (POK) The MAX1551 s POK is an active-low, open-drain output that goes low when V or V is above 3.95V. POK can be used as a logic output or can drive an LED. POK indicates the charger is connected to input power and is charging. MAX1555 Charge Status (CHG) The MAX1555 s CHG is an active-low, open-drain charge status indicator. CHG pulls low when the battery is charging (whenever or are powered) and charge current is greater than 5mA. CHG indicates when the battery is fully charged by going high impedance when the charger is in voltage mode and charge current falls below 5mA. Charging does not stop when CHG goes high. CHG is low in precharge mode. V > 7V OR V > 6V V > 3.95V AND V DON T CARE V < 3.52V AND 3.95V < V < 6V V AND V < 3.52V Exceeds operating input range. Not allowed. See the Absolute Maximum Ratings section. 28mA (typ) charging from 1mA (max) charging from Undervoltage lockout (V takes precedence when both inputs are present.) 5

6 Precharge Current The feature a precharge current to protect deeply discharged cells. If V BAT is less than 3V, the device enters precharge mode where charging current is limited to 4mA. Package Thermal Limiting On-chip thermal limiting in the simplifies PC board layout and allows charging rates to be optimized without the limits imposed by worst-case battery and input voltages. The device reduces the power dissipation at BAT to prevent overheating. This allows the board design to be optimized for compact size and typical thermal conditions. When the MAX1551/ MAX1555 thermal limits are reached, the chargers do not shut down, but progressively reduce charging current by 17mA/ C above a die temperature of +11 C. Solder the s GND to a large ground plane to help dissipate power and keep the die temperature below the thermal limit. The charge current of 1mA is unlikely to induce thermal limiting. Bypass Capacitors Use ceramic bypass capacitors at,, and BAT. Mount these capacitors within 1cm of their respective pins. X7R and X5R dielectrics are recommended. TRANSISTOR COUNT: 541 PROCESS: BiCMOS Chip Information Typical Application Circuit AC ADAPTER 3.7V TO 7V C1 1µF BAT Li+ TO SYSTEM LOAD 3.7V TO 6V C2 1µF MAX1551 (MAX1555) CHARGE CONTROL LOGIC CONTROL GND POK (CHG) C3 1µF TO LOGIC RAIL R1 1kΩ INDICATES THAT POWER IS PRESENT (EITHER OR ) 6

7 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 7

8 Package Information (continued) (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to 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. 8 Maxim Integrated Products, 12 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.