M MCP73828 Single Cell Lithium-Ion Charge Management Controller with Charge Complete Indicator and Temperature Monitor Features Description • Linear Charge Management Controller for Single Lithium-Ion Cells • High Accuracy Preset Voltage Regulation: +1% (max) • Two Preset Voltage Regulation Options: - 4.1V - MCP73828-4.1 - 4.2V - MCP73828-4.2 • Programmable Charge Current • Automatic Cell Preconditioning of Deeply Depleted Cells, Minimizing Heat Dissipation During Initial Charge Cycle • Charge Complete Output CD10 for LED or Microcontroller Interface • Continuous Temperature Monitoring • Automatic Power-Down when Input Power Removed • Temperature Range: -20°C to +85°C • Packaging: 8-Pin MSOP The MCP73828 is a linear charge management controller for use in space-limited, cost sensitive applications. The MCP73828 combines high accuracy constant voltage, controlled current regulation, cell preconditioning, cell temperature monitoring, and charge complete indication in a space saving 8-pin MSOP package. The MCP73828 provides a stand-alone charge management solution. Applications • • • • • • Single Cell Lithium-Ion Battery Chargers Personal Data Assistants Cellular Telephones Hand Held Instruments Cradle Chargers Digital Cameras 500 mA Lithium-Ion Battery Charger 100 mΩ NDS8434 MA2Q705 10 µF 332 Ω 8 100 kΩ 1 4 7 6 VSNS VDRV VIN SHDN VBAT GND CD10 THERM MCP73828 Following the preconditioning phase, the MCP73828 enters the controlled current phase. The MCP73828 allows for design flexibility with a programmable charge current set by an external sense resistor. The charge current is ramped up, based on the cell voltage, from the foldback current to the peak charge current established by the sense resistor. This phase is maintained until the battery reaches the charge-regulation voltage. Then, the MCP73828 enters the final phase, constant voltage. The accuracy of the voltage regulation is better than ±1% over the entire operating temperature range and supply voltage range. The MCP73828-4.1 is preset to a regulation voltage of 4.1V, while the MCP738284.2 is preset to 4.2V. The charge complete output, CD10, indicates when the charge current has diminished to approximately 10% of the peak charge current established by the sense resistor. Typical Application Circuit VIN 5V The MCP73828 charges the battery in three phases: preconditioning, controlled current, and constant voltage. If the battery voltage is below the internal low-voltage threshold, the battery is preconditioned with a foldback current. The preconditioning phase protects the lithium-ion cell and minimizes heat dissipation. Thermistor + Single - Lithium-Ion Cell The MCP73828 operates with an input voltage range from 4.5V to 5.5V. The MCP73828 is fully specified over the ambient temperature range of -20°C to +85°C. Package Type 5 2 3 10 µF MSOP GND 2 THERM 3 CD10 4 2002 Microchip Technology Inc. 8 VIN SHDN 1 MCP73828 7 VSNS 6 VDRV 5 VBAT DS21706A-page 1 SHDN VSNS VIN VIN 0.3V CLAMP CHARGE CURRENT FOLDBACK AMPLIFIER – + 12 kΩ VREF (1.2V) CHARGE CURRENT AMPLIFIER SHUTDOWN, REFERENCE GENERATOR + – Value = 352.5KΩ For MCP73828-4.2 NOTE 1: Value = 340.5KΩ For MCP73828-4.1 37.5 kΩ 112.5 kΩ VREF 1.1 kΩ 500 kΩ 100 kΩ CHARGE CURRENT CONTROL AMPLIFIER – + 113 mV 839 mV VIN 25 mA ITHERM 75 kΩ 75 kΩ 352.5 kΩ (NOTE 1) 21 kΩ 5 kΩ 130 kΩ 140 mV 67 kΩ VREF VOLTAGE CONTROL AMPLIFIER VREF CHARGE COMPLETE COMPARATOR - + THERMISTOR VOLTAGE COMPARATORS V IN 156 kΩ CHARGE COMPLETE AMPLIFIER 140 mV - + - + – – DS21706A-page 2 + + THERM GND VBAT VDRV CD10 MCP73828 Functional Block Diagram 2002 Microchip Technology Inc. MCP73828 1.0 ELECTRICAL CHARACTERISTICS 1.1 Maximum Ratings* PIN FUNCTION TABLE Pin Name 1 SHDN 2 GND Current at CD10 Pin ................................................ +/-30 mA 3 THERM Cell Temperature Monitor Current at VDRV .......................................................... +/-1 mA 4 CD10 Charge Complete Output 5 VBAT Cell Voltage Monitor Input ESD protection on all pins ..................................................≥ 4 kV 6 VDRV Drive Output *Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. 7 VSNS Charge Current Sense Input 8 VIN VIN ...................................................................... -0.3V to 6.0V Description Logic Shutdown Battery Management 0V Reference All inputs and outputs w.r.t. GND ................-0.3 to (VIN+0.3)V Maximum Junction Temperature, TJ.............................. 150°C Storage temperature .....................................-65°C to +150°C Battery Management Input Supply DC CHARACTERISTICS: MCP73828-4.1, MCP73828-4.2 Unless otherwise specified, all limits apply for V IN = [VREG(typ)+1V], RSENSE = 500 mΩ, TA = -20°C to +85°C. Typical values are at +25°C. Refer to Figure 1-1 for test circuit. Sym Min Typ Max Units Supply Voltage Parameter VIN 4.5 — 5.5 V Conditions Supply Current IIN — — 0.7 265 15 560 µA Shutdown, VSHDN = 0V Constant Voltage Mode Regulated Output Voltage VREG 4.059 4.158 4.1 4.2 4.141 4.242 V V MCP73828-4.1 only MCP73828-4.2 only Line Regulation ∆VBAT -10 — 10 mV VIN = 4.5V to 5.5V, IOUT = 75 mA Load Regulation ∆VBAT -1 +0.2 +1 mV IOUT=10 mA to 75 mA ILK — 10 — µA VIN=Floating, VBAT =VREG Gate Drive Current IDRV — 0.08 — — 1 — mA mA Sink, CV Mode Source, CV Mode Gate Drive Minimum Voltage VDRV — 1.6 — V Voltage Regulation (Constant Voltage Mode) Output Reverse Leakage Current External MOSFET Gate Drive Current Regulation (Controlled Current Mode) Current Sense Gain ACS — 100 — dB ∆(VSNS-VDRV) / ∆VBAT Current Limit Threshold VCS 40 53 75 mV (VIN-V SNS) at IOUT K — 0.43 — A/A Current Threshold ITH — 10 — %IOUT(PEAK) Low Output Voltage VOL — — 400 mV ISINK = 10 mA Leakage Current ILK — — 1 µA ISINK=0 mA, VCD10=5.5V Input High Voltage Level VIH 40 — — %VIN Input Low Voltage Level VIL — — 25 %VIN Input Leakage Current ILK — — 1 µA Foldback Current Scale Factor Charge Complete Indicator - CD10 Shutdown Input - SHDN 2002 Microchip Technology Inc. VSHDN = 0V to 5.5V DS21706A-page 3 MCP73828 Unless otherwise specified, all limits apply for V IN = [VREG(typ)+1V], RSENSE = 500 mΩ, TA = -20°C to +85°C. Typical values are at +25°C. Refer to Figure 1-1 for test circuit. Parameter Sym Min Typ Max Units ITHERM 22.5 25.0 27.5 µA VTH — — 113 839 — — mV Conditions Temperature Monitor - THERM Thermistor Bias Current THERM Threshold Voltages Lower Threshold Voltage Upper Threshold Voltage TEMPERATURE SPECIFICATIONS Unless otherwise specified, all limits apply for V IN = 4.5V-5.5V Parameters Sym Min Typ Max Units Specified Temperature Range TA -20 — +85 °C Operating Temperature Range TA -40 — +125 °C Storage Temperature Range TA -65 — +150 °C θJA — 206 — °C/W Conditions Temperature Ranges Package Thermal Resistance Thermal Resistance, 8L-MSOP VIN = 5.1V NDS8434 RSENSE (MCP73828-4.1) Single Layer SEMI G42-88 Standard Board, Natural Convection IOUT VIN = 5.2V (MCP73828-4.2) 22 µF 7 VSNS 8 100 kΩ 100 kΩ 1 4 VOUT 6 VIN VDRV VBAT SHDN CD10 GND THERM 5 22 µF 2 3 10 kΩ MCP73828 FIGURE 1-1: MCP73828 Test Circuit. DS21706A-page 4 2002 Microchip Technology Inc. MCP73828 2.0 TYPICAL PERFORMANCE CHARACTERISTICS Note: The graphs and tables provided following this note are a statistical summary based on a limited number of samples and are provided for informational purposes only. The performance characteristics listed herein are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified operating range (e.g., outside specified power supply range) and therefore outside the warranted range. Note: Unless otherwise indicated, IOUT= 10 mA, Constant Voltage Mode, TA=25°C. Refer to Figure 1-1 for test circuit. 4.205 350 4.204 325 Supply Current (µA) Output Voltage (V) 4.203 4.202 4.201 4.200 4.199 4.198 4.197 300 275 250 225 4.196 4.195 200 0 200 400 600 800 1000 0 200 400 Output Current (mA) FIGURE 2-1: Output Voltage vs. Output Current (MCP73828-4.2). FIGURE 2-4: 800 1000 Supply Current vs. Output Current. 350 4.205 IOUT = 1000 mA IOUT = 1000 mA 4.204 325 Supply Current (µA) 4.203 Output Voltage (V) 600 Output Current (mA) 4.202 4.201 4.200 4.199 4.198 4.197 300 275 250 225 4.196 4.195 200 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 4.5 5.5 4.6 4.7 4.8 Input Voltage (V) FIGURE 2-2: Output Voltage vs. Input Voltage (MCP73828-4.2). 4.205 FIGURE 2-5: 5.0 5.1 5.2 5.3 5.4 5.5 Supply Current vs. Input Voltage. 350 IOUT = 10 mA 4.204 IOUT = 10 mA 325 Supply Current (µA) 4.203 Output Voltage (V) 4.9 Input Voltage (V) 4.202 4.201 4.200 4.199 4.198 4.197 300 275 250 225 4.196 4.195 200 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 4.5 4.6 Input Voltage (V) FIGURE 2-3: Output Voltage vs. Input Voltage (MCP73828-4.2). 2002 Microchip Technology Inc. 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5 Input Voltage (V) FIGURE 2-6: Supply Current vs. Input Voltage. DS21706A-page 5 MCP73828 16 350 VIN = Floating VSHDN = V OUT 14 o 85 C 12 o 25 C 10 o -20 C 8 6 4 325 Supply Current (µA) Ouput Reverse Leakage Current ( µA) Note: Unless otherwise indicated, IOUT= 10 mA, Constant Voltage Mode, TA=25°C. Refer to Figure 1-1 for test circuit. 300 275 250 225 2 200 0 2.0 2.5 3.0 3.5 4.0 -20 4.5 -10 0 10 20 70 80 4.204 o o 25 C 1.0 o -20 C 0.8 0.6 0.4 Output Voltage (V) Output Reverse Leakage Current ( µA) 60 FIGURE 2-10: Supply Current vs. Temperature. 85 C 1.2 4.202 4.200 4.198 4.196 4.194 4.192 0.2 4.190 0.0 2.0 2.5 3.0 3.5 4.0 -20 4.5 -10 0 10 20 30 40 50 60 70 80 o Temperature ( C) Output Voltage (V) FIGURE 2-8: Output Reverse Leakage Current vs. Output Voltage. FIGURE 2-11: Output (MCP73828-4.2). 4.500 4.5 4.000 4.0 3.500 3.5 Output Voltage (V) Output Voltage (V) 50 4.206 VIN = Floating VSHDN = GND 1.4 40 o FIGURE 2-7: Output Reverse Leakage Current vs. Output Voltage. 1.6 30 Temperature ( C) Output Voltage (V) 3.000 2.500 2.000 1.500 1.000 Voltage vs. Temperature 3.0 2.5 2.0 1.5 1.0 0.500 0 20 40 60 80 Output Current (mA) FIGURE 2-9: Current Limit Foldback. DS21706A-page 6 100 120 Power Down Power Up 0.5 0.000 0.0 0 1 2 3 4 5 64 73 8 2 9 1 10 0 Input Voltage (V) FIGURE 2-12: Power-Up / Power-Down. 2002 Microchip Technology Inc. MCP73828 Note: Unless otherwise indicated, IOUT= 10 mA, Constant Voltage Mode, TA=25°C. Refer to Figure 1-1 for test circuit. FIGURE 2-13: Line Transient Response. FIGURE 2-15: Load Transient Response. FIGURE 2-14: Line Transient Response. FIGURE 2-16: Load Transient Response. 2002 Microchip Technology Inc. DS21706A-page 7 MCP73828 3.0 PIN DESCRIPTION The descriptions of the pins are listed in Table 3-1. Pin Name 1 SHDN 2 GND 3 THERM Cell Temperature Monitor 4 CD10 Charge Complete Output 5 VBAT Cell Voltage Monitor Input 6 VDRV Drive Output 7 VSNS Charge Current Sense Input 8 VIN TABLE 3-1: 3.1 Description Logic Shutdown Battery Management 0V Reference Battery Management Input Supply 3.6 Drive Output (VDRV) Direct output drive of an external P-channel MOSFET pass transistor for current and voltage regulation. 3.7 Charge Current Sense Input VSNS) Charge current is sensed via the voltage developed across an external precision sense resistor. The sense resistor must be placed between the supply voltage (VIN) and the source of the external pass transistor. A 50 mΩ sense resistor produces a fast charge current of 1 A, typically. 3.8 Battery Management Input Supply (VIN) A supply voltage of 4.5V to 5.5V is recommended. Bypass to GND with a minimum of 10 µF. Pin Function Table. Logic Shutdown (SHDN) Input to force charge termination, initiate charge, or initiate recharge. 3.2 Battery Management 0V Reference (GND) Connect to negative terminal of battery. 3.3 Cell Temperature Monitor (THERM) Charging is inhibited when the input is outside the upper and lower threshold limits. Connection of a 10 kΩ resistor between THERM and GND disables the function when cell temperature monitoring is not required. 3.4 Charge Complete Output (CD10) Open-drain drive for connection to an LED for charge complete indication. Alternatively, a pull-up resistor can be applied for interfacing to a microcontroller. A low impedance state indicates charging. A high impedance indicates that the charge current has diminished below 10% of the peak charge current. 3.5 Cell Voltage Monitor Input (VBAT) Voltage sense input. Connect to positive terminal of battery. Bypass to GND with a minimum of 10 µF to ensure loop stability when the battery is disconnected. A precision internal resistor divider regulates the final voltage on this pin to VREG. DS21706A-page 8 2002 Microchip Technology Inc. MCP73828 4.0 DEVICE OVERVIEW The MCP73828 is a linear charge management controller. Refer to the functional block diagram on page 2 and the typical application circuit, Figure 6-1. 4.1 Charge Qualification and Preconditioning Upon insertion of a battery or application of an external supply, the MCP73828 automatically performs a series of safety checks to qualify the charge. The SHDN pin must be above the logic high level, and the cell temperature monitor must be within the upper and lower threshold limits. The qualification parameters are continuously monitored. Deviation beyond the limits, automatically suspends the charge cycle. After the qualification parameters have been met, the MCP73828 initiates a charge cycle. The charge complete output, CD10, is pulled low throughout the preconditioning and controlled current phases (see Table 5-1 for charge complete outputs). If the cell voltage is below the preconditioning threshold, 2.4V typically, the MCP73828 preconditions the cell with a scaled back current. The preconditioning current is set to approximately 43% of the fast charge peak current. The preconditioning safely replenishes deeply depleted cells and minimizes heat dissipation in the external pass transistor during the initial charge cycle. 4.2 4.3 Constant Voltage Regulation When the cell voltage reaches the regulation voltage, VREG, constant voltage regulation begins. The MCP73828 monitors the cell voltage at the VOUT pin. This input is tied directly to the positive terminal of the battery. The MCP73828 is offered in two fixed-voltage versions for battery packs with either coke or graphite anodes: 4.1V (MCP73828-4.1) and 4.2V (MCP73828-4.2). 4.4 Charge Cycle Completion The charge cycle can be terminated by a host microcontroller when the charge current has diminished below approximately 10% of the peak output voltage level. The charge complete output will go to a high impedance state signaling when the charge can be terminated. The charge is terminated by pulling the shutdown pin, SHDN, to a logic Low level. Controlled Current Regulation - Fast Charge Preconditioning ends and fast charging begins when the cell voltage exceeds the preconditioning threshold. Fast charge utilizes a foldback current scheme based on the voltage at the VSNS input developed by the drop across an external sense resistor, RSENSE, and the output voltage, VBAT. Fast charge continues until the cell voltage reaches the regulation voltage, VREG. 2002 Microchip Technology Inc. DS21706A-page 9 MCP73828 5.0 DETAILED DESCRIPTION Refer to the typical application circuit, Figure 6-1. 5.1 Analog Circuitry 5.1.1 CELL TEMPERATURE MONITOR (THERM) The cell temperature monitor, THERM, input is used to inhibit charging when the battery temperature exceeds a predetermined temperature range. This temperature range is programmed externally with either a single Thermistor or a resistor/Thermistor network. An example of this type of network is illustrated in Figure 6-1. The MCP73828 internally generates a current source out of the THERM pin (shown in the Functional Block Diagram). The nominal value of the current source (ITHERM) is 25 µA. This current flows through the thermistor network to ground. The factory programmed voltage range of the THERM input (VTH) is 113 mV (typ) to 839 mV (typ). Dependent on the type of Thermistor used and the resistive network, the temperature trip points can be controlled. If the THERM pin is lower that 113 mV or higher than 839 mV the device will shutdown operation. This condition can be corrected by bringing the THERM pin back between these threshold voltages. As an application example, if a 10 kΩ NTC Thermistor with a sensitivity index (b) of 3982 is connected from THERM to ground, the operational temperature range is from –0.5°C to 44.2°C. See Section 6.1.1.6 for more details concerning using the resistive network. Alternatively, a positive temperature coefficient, PTC, thermistor can be utilized. Connect the thermistor from the THERM input to GND. If temperature monitoring is not required, replace the thermistor with a standard 10 kΩ resistor. 5.1.2 CELL VOLTAGE MONITOR INPUT (VBAT) The MCP73828 monitors the cell voltage at the VBAT pin. This input is tied directly to the positive terminal of the battery. The MCP73828 is offered in two fixed-voltage versions for single cells with either coke or graphite anodes: 4.1V (MCP73828-4.1) and 4.2V (MCP73828-4.2). 5.1.3 GATE DRIVE OUTPUT (V DRV) The MCP73828 controls the gate drive to an external P-channel MOSFET, Q1. The P-channel MOSFET is controlled in the linear region, regulating current and voltage supplied to the cell. The drive output is automatically turned off when the input supply falls below the voltage sensed on the VBAT input. CURRENT SENSE INPUT (VSNS) 5.1.4 Fast charge current regulation is maintained by the voltage drop developed across an external sense resistor, RSENSE, applied to the VSNS input pin. The following formula calculates the value for R SENSE: V CS R SENSE = -----------I O UT Where: VCS is the current limit threshold. IOUT is the desired peak fast charge current in amps. The preconditioning current is scaled to approximately 43% of IOUT. 5.1.5 SUPPLY VOLTAGE (VIN) The V IN input is the input supply to the MCP73828. The MCP73828 automatically enters a power-down mode if the voltage on the VIN input falls below the voltage on the VBAT pin. This feature prevents draining the battery pack when the VIN supply is not present. 5.2 Digital Circuitry 5.2.1 SHUTDOWN INPUT (SHDN) The shutdown input pin, SHDN, can be used to terminate a charge anytime during the charge cycle, initiate a charge cycle, or initiate a recharge cycle. Applying a logic High input signal to the SHDN pin, or tying it to the input source, enables the device. Applying a logic Low input signal disables the device and terminates a charge cycle. In shutdown mode, the device’s supply current is reduced to 0.7 µA, typically. 5.2.2 CHARGE COMPLETE OUTPUT (CD10) A charge complete indicator, CD10, provides information on the state of charge. The open-drain output can be used to illuminate an external LED. Optionally, a pull-up resistor can be used on the output for communication with a microcontroller. Table 5-1 summarizes the state of this output during a charge cycle. Charge Cycle State Qualification OFF Preconditioning ON Controlled Current Fast Charge ON Constant Voltage ON Charge Complete OFF Temperature Monitor Invalid OFF Disabled - Sleep mode OFF Battery Disconnected OFF TABLE 5-1: DS21706A-page 10 Mode Charge Complete Output. 2002 Microchip Technology Inc. MCP73828 6.0 APPLICATIONS lowed by constant voltage. Figure 6-1 depicts a typical stand-alone application circuit and Figure 6-2 depicts the accompanying charge profile. The MCP73828 is designed to operate in conjunction with a host microcontroller or in stand-alone applications. The MCP73828 provides the preferred charge algorithm for Lithium-Ion cells, controlled current fol- Q1 RSENSE NDS8434 MA2Q705 IOUT PACK+ 22 kΩ 10 µF 100 mΩ 332 Ω VOLTAGE REGULATED WALL CUBE SHDN GND 100 kΩ RS 1 2 THERM 3 CD10 4 8 MCP73828 7 6 5 10 µF VIN VSNS + VDRV - VBAT RP PACK- RTHERMISTOR TEMP SINGLE CELL LITHIUM-ION BATTERY PACK FIGURE 6-1: Typical Application Circuit. PRECONDITIONING PHASE REGULATION VOLTAGE (VREG) CONTROLLED CURRENT PHASE CONSTANT VOLTAGE PHASE CHARGE VOLTAGE REGULATION CURRENT (IOUT(PEAK)) TRANSITION THRESHOLD PRECONDITION CURRENT CHARGE COMPLETE CURRENT (10% IOUT(PEAK)) CHARGE CURRENT 5V CD10 - CHARGE COMPLETE OUTPUT 0V FIGURE 6-2: Typical Charge Profile. 2002 Microchip Technology Inc. DS21706A-page 11 MCP73828 6.1 Application Circuit Design Due to the low efficiency of linear charging, the most important factors are thermal design and cost, which are a direct function of the input voltage, output current and thermal impedance between the external P-channel pass transistor, Q1, and the ambient cooling air. The worst-case situation is when the output is shorted. In this situation, the P-channel pass transistor has to dissipate the maximum power. A trade-off must be made between the charge current, cost and thermal requirements of the charger. 6.1.1 EXTERNAL PASS TRANSISTOR The external P-channel MOSFET is determined by the gate to source threshold voltage, input voltage, output voltage, and peak fast charge current. The selected Pchannel MOSFET must satisfy the thermal and electrical design requirements. Thermal Considerations The worst case power dissipation in the external pass transistor occurs when the input voltage is at the maximum and the output is shorted. In this case, the power dissipation is: COMPONENT SELECTION Selection of the external components in Figure 6-1 is crucial to the integrity and reliability of the charging system. The following discussion is intended as a guide for the component selection process. 6.1.1.1 6.1.1.2 PowerDissipation = V INMAX × I OU T × K Where: VINMAX is the maximum input voltage SENSE RESISTOR IOUT is the maximum peak fast charge current The preferred fast charge current for Lithium-Ion cells is at the 1C rate with an absolute maximum current at the 2C rate. For example, a 500 mAH battery pack has a preferred fast charge current of 500 mA. Charging at this rate provides the shortest charge cycle times without degradation to the battery pack performance or life. The current sense resistor, RSENSE, is calculated by: V CS R SENSE = -----------I O UT Where: VCS is the current limit threshold voltage IOUT is the desired fast charge current For the 500 mAH battery pack example, a standard value 100 mΩ, 1% resistor provides a typical peak fast charge current of 530 mA and a maximum peak fast charge current of 758 mA. Worst case power dissipation in the sense resistor is: 2 PowerDissipation = 100mΩ × 758mA = 57.5mW A Panasonic ERJ-L1WKF100U 100 mΩ, 1%, 1 W resistor is more than sufficient for this application. A larger value sense resistor will decrease the peak fast charge current and power dissipation in both the sense resistor and external pass transistor, but will increase charge cycle times. Design trade-offs must be considered to minimize space while maintaining the desired performance. K is the foldback current scale factor Power dissipation with a 5V, +/-10% input voltage source, 100 mΩ, 1% sense resistor, and a scale factor of 0.43 is: PowerDissipation = 5.5V × 758mA × 0.43 = 1.8W Utilizing a Fairchild NDS8434 or an International Rectifier IRF7404 mounted on a 1in2 pad of 2 oz. copper, the junction temperature rise is 90°C, approximately. This would allow for a maximum operating ambient temperature of 60°C. By increasing the size of the copper pad, a higher ambient temperature can be realized or a lower value sense resistor could be utilized. Alternatively, different package options can be utilized for more or less power dissipation. Again, design tradeoffs should be considered to minimize size while maintaining the desired performance. Electrical Considerations The gate to source threshold voltage and RDSON of the external P-channel MOSFET must be considered in the design phase. The worst case, VGS provided by the controller occurs when the input voltage is at the minimum and the charge current is at the maximum. The worst case, VGS is: V GS = V DRVMAX – ( V INMIN – I OUT × R SENSE ) Where: VDRVMAX is the maximum sink voltage at the VDRV output DS21706A-page 12 2002 Microchip Technology Inc. MCP73828 VINMIN is the minimum input voltage source IOUT is the maximum peak fast charge current R SENSE is the sense resistor Worst case, VGS with a 5V, +/-10% input voltage source, 100 mΩ, 1% sense resistor, and a maximum sink voltage of 1.6V is: V GS = 1.6V – ( 4.5V – 758mA × 99mΩ ) = – 2.8 V At this worst case VGS, the RDSON of the MOSFET must be low enough as to not impede the performance of the charging system. The maximum allowable RDSON at the worst case VGS is: V INMIN – I PEAK × R SENSE – V BATMAX R D SON = ---------------------------------------------------------------------------------------------I OU T R DSON 4.5V – 758mA × 99mΩ – 4.242V = -------------------------------------------------------------------------------- = 242mΩ 758mA The Fairchild NDS8434 and International Rectifier IRF7404 both satisfy these requirements. 6.1.1.3 EXTERNAL CAPACITORS The MCP73828 is stable with or without a battery load. In order to maintain good AC stability in the constant voltage mode, a minimum capacitance of 10 µF is recommended to bypass the V BAT pin to GND. This capacitance provides compensation when there is no battery load. In addition, the battery and interconnections appear inductive at high frequencies. These elements are in the control feedback loop during constant voltage mode. Therefore, the bypass capacitance may be necessary to compensate for the inductive nature of the battery pack. Virtually any good quality output filter capacitor can be used, independent of the capacitor’s minimum ESR (Effective Series Resistance) value. The actual value of the capacitor and its associated ESR depends on the forward trans conductance, gm, and capacitance of the external pass transistor. A 10 µF tantalum or aluminum electrolytic capacitor at the output is usually sufficient to ensure stability for up to a 1 A output current. 6.1.1.4 REVERSE BLOCKING PROTECTION The optional reverse blocking protection diode depicted in Figure 6-1 provides protection from a faulted or shorted input or from a reversed polarity input source. Without the protection diode, a faulted or shorted input would discharge the battery pack through the body diode of the external pass transistor. 2002 Microchip Technology Inc. If a reverse protection diode is incorporated in the design, it should be chosen to handle the peak fast charge current continuously at the maximum ambient temperature. In addition, the reverse leakage current of the diode should be kept as small as possible. 6.1.1.5 SHUTDOWN INTERFACE In the stand-alone configuration, the shutdown pin is generally tied to the input voltage. The MCP73828 will automatically enter a low power mode when the input voltage is less than the output voltage reducing the battery drain current to 10 µA, typically. By connecting the shutdown pin as depicted in Figure 6-1, the battery drain current may be further reduced. In this application, the battery drain current becomes a function of the reverse leakage current of the reverse protection diode. 6.1.1.6 CELL TEMPERATURE MONITOR As discussed in Section 5.1.1, the MCP73828 can monitor a temperature range for –0.5°C to 44.2°C. This temperature range can be expanded or shifted by placing fixed value resistors in series/parallel combinations with the thermistor (see Figure 6-1). Given that the nominal output current of the THERM pin is 25 µA, the resistor values must satisfy the following equations: R P × R TH ERMISTO R – H R S + -------------------------------------------------------- = 4520Ω ( typ ) R P + R THERMISTOR – H R P × R THERMISTOR – C R S + -------------------------------------------------------- = 33560Ω ( typ ) R P + R THER MISTOR – C Where: RS is the fixed series resistance RP is the fixed parallel resistance RTHERMISTOR-H is the NTC thermistor resistance at the upper temperature of interest RTHERMISTOR-C is the NTC thermistor resistance at the lower temperature of interest. For example, by utilizing a 931 Ω resistor in series with the typical NTC thermistor described previously, the monitored temperature window will shift to 0°C to +50°C, typically. Again, with the same thermistor, a 1 kΩ series resistor and a 140 kΩ parallel resistor will produce a monitored window of -5°C to +50°C, typically. DS21706A-page 13 MCP73828 6.1.1.7 CHARGE COMPLETE INTERFACE The charge complete indicator, CD10, can be utilized to illuminate an LED when the MCP73828 is charging the battery. When the MCP73828 is in constant voltage mode and the charge current has diminished below 10% of IOUT(PEAK), the CD10 pin will transition to a high impedance state. A current limit resistor should be used in series with the LED to establish a nominal LED bias current of 10 mA. The maximum allowable sink current of the CD10 pin is 30 mA. 6.2 PCB Layout Issues For optimum voltage regulation, place the battery pack as close as possible to the device’s V OUT and GND pins. It is recommended to minimize voltage drops along the high current carrying PCB traces. If the PCB layout is used as a heatsink, adding many vias around the external pass transistor can help conduct more heat to the back-plane of the PCB, thus reducing the maximum junction temperature. DS21706A-page 14 2002 Microchip Technology Inc. MCP73828 7.0 PACKAGING INFORMATION 7.1 Package Marking Information Example: 8-Lead MSOP XXXXXX 738281 YWWNNN YWWNNN Legend: Part Number Code MCP73828-4.1VUA 738281 MCP73828-4.2VUA 738282 XX...X Part Number code + temperature range + voltage (two letter code)* Y Year code (last 2 digits of calendar year) WW Week code (week of January 1 is week ‘01’) NNN Alphanumeric traceability code Note: In the event the full Microchip part number cannot be marked on one line, it will be carried over to the next line thus limiting the number of available characters for customer specific information. * Standard OTP marking consists of Microchip part number, year code, week code, and traceability code. 2002 Microchip Technology Inc. DS21706A-page 15 MCP73828 8-Lead Plastic Micro Small Outline Package (MSOP) E E1 D 2 B n 1 α c φ (F) L β Units Number of Pins Pitch Dimension Limits n p Overall Height NOM MAX 8 0.65 .026 A .044 .030 Standoff A1 .002 E .184 Molded Package Width MIN 8 A2 Overall Width MAX NOM Molded Package Thickness § MILLIMETERS* INCHES MIN .034 1.18 .038 0.76 .006 0.05 .193 .200 0.86 0.97 4.67 4.90 .5.08 0.15 E1 .114 .118 .122 2.90 3.00 3.10 Overall Length D .114 .118 .122 2.90 3.00 3.10 Foot Length L .016 .022 .028 0.40 0.55 0.70 Footprint (Reference) .035 .037 .039 0.90 0.95 1.00 Foot Angle F φ 6 0 Lead Thickness c .004 .006 .008 0.10 0.15 0.20 Lead Width B α .010 .012 .016 0.25 0.30 0.40 Mold Draft Angle Top Mold Draft Angle Bottom β 0 6 7 7 7 7 *Controlling Parameter § Significant Characteristic Notes: Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed. 010” (0.254mm) per side. Drawing No. C04-111 DS21706A-page 16 2002 Microchip Technology Inc. MCP73828 ON-LINE SUPPORT Microchip provides on-line support on the Microchip World Wide Web (WWW) site. The web site is used by Microchip as a means to make files and information easily available to customers. To view the site, the user must have access to the Internet and a web browser, such as Netscape or Microsoft Explorer. Files are also available for FTP download from our FTP site. Connecting to the Microchip Internet Web Site Systems Information and Upgrade Hot Line The Systems Information and Upgrade Line provides system users a listing of the latest versions of all of Microchip's development systems software products. Plus, this line provides information on how customers can receive any currently available upgrade kits.The Hot Line Numbers are: 1-800-755-2345 for U.S. and most of Canada, and 1-480-792-7302 for the rest of the world. 013001 The Microchip web site is available by using your favorite Internet browser to attach to: www.microchip.com The file transfer site is available by using an FTP service to connect to: ftp://ftp.microchip.com The web site and file transfer site provide a variety of services. Users may download files for the latest Development Tools, Data Sheets, Application Notes, User's Guides, Articles and Sample Programs. A variety of Microchip specific business information is also available, including listings of Microchip sales offices, distributors and factory representatives. Other data available for consideration is: • Latest Microchip Press Releases • Technical Support Section with Frequently Asked Questions • Design Tips • Device Errata • Job Postings • Microchip Consultant Program Member Listing • Links to other useful web sites related to Microchip Products • Conferences for products, Development Systems, technical information and more • Listing of seminars and events 2002 Microchip Technology Inc. DS21706A-page 17 MCP73828 READER RESPONSE It is our intention to provide you with the best documentation possible to ensure successful use of your Microchip product. If you wish to provide your comments on organization, clarity, subject matter, and ways in which our documentation can better serve you, please FAX your comments to the Technical Publications Manager at (480) 792-4150. Please list the following information, and use this outline to provide us with your comments about this Data Sheet. To: Technical Publications Manager RE: Reader Response Total Pages Sent From: Name Company Address City / State / ZIP / Country Telephone: (_______) _________ - _________ FAX: (______) _________ - _________ Application (optional): Would you like a reply? Device: MCP73828 Y N Literature Number: DS21706A Questions: 1. What are the best features of this document? 2. How does this document meet your hardware and software development needs? 3. Do you find the organization of this data sheet easy to follow? If not, why? 4. What additions to the data sheet do you think would enhance the structure and subject? 5. What deletions from the data sheet could be made without affecting the overall usefulness? 6. Is there any incorrect or misleading information (what and where)? 7. How would you improve this document? 8. How would you improve our software, systems, and silicon products? DS21706A-page 18 2002 Microchip Technology Inc. MCP73828 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. PART NO. -X.X X XX Device Output Voltage Temperature Range Package Device: MCP73828: Linear Charge Management Controller Output Voltage: Examples: a) MCP73828-4.1VUA: Linear Charge Manage- b) MCP73828-4.2VUA: Linear Charge Manage- ment Controller, 4.1V ment Controller, 4.2V c) MCP73828-4.2VUATR: Linear Charge Management Controller, 4.2V, in tape and reel 4.1 = 4.1V 4.2 = 4.2V Temperature Range: V = -20°C to +85°C Package: UA = Plastic Micro Small Outline (MSOP), 8-lead Sales and Support Data Sheets Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following: 1. 2. 3. Your local Microchip sales office The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277 The Microchip Worldwide Site (www.microchip.com) Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using. New Customer Notification System Register on our web site (www.microchip.com/cn) to receive the most current information on our products. 2002 Microchip Technology Inc. DS21706A-page19 MCP73828 NOTES: DS21706A-page 20 2002 Microchip Technology Inc. MCP73828 NOTES: 2002 Microchip Technology Inc. DS21706A-page21 MCP73828 NOTES: DS21706A-page 22 2002 Microchip Technology Inc. Information contained in this publication regarding device applications and the like is intended through suggestion only and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights. Trademarks The Microchip name and logo, the Microchip logo, FilterLab, KEELOQ, MPLAB, PIC, PICmicro, PICMASTER, PICSTART, PRO MATE, SEEVAL and The Embedded Control Solutions Company are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. dsPIC, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC, microID, microPort, Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, MXDEV, PICC, PICDEM, PICDEM.net, rfPIC, Select Mode and Total Endurance are trademarks of Microchip Technology Incorporated in the U.S.A. Serialized Quick Term Programming (SQTP) is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. © 2002, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received QS-9000 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona in July 1999. The Company’s quality system processes and procedures are QS-9000 compliant for its PICmicro ® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs and microperipheral products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001 certified. 2002 Microchip Technology Inc. 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