ACT8828 Active-Semi Rev 3, 24-Sep-09 Six Channel ActivePathTM Power Management IC FEATURES GENERAL DESCRIPTION • ActivePathTM Li+ Charger with System Power The patent-pending ACT8828 is a complete, cost effective, highly-efficient ActivePMUTM power management solution that is ideal for a wide range of high performance portable handheld applications such as personal navigation devices (PNDs). This device integrates the ActivePath complete battery charging and management system with four power supply channels. Selection • Four Integrated Regulators: − 1.3A High Efficiency Step-Down DC/DC − 1.0A High Efficiency Step-Down DC/DC − 0.55A High Efficiency Step-Down DC/DC − 30V Step-Up DC/DC for up to 7s × 3p WLEDs • • • • I2CTM Serial Interface Minimal External Components The ActivePath architecture automatically selects the best available input supply for the system. If the external input source is not present or the system load current is more than the input source can provide, the ActivePath supplies additional current from the battery to the system. The charger is a complete, thermallyregulated, stand-alone single-cell linear Li+ charger that incorporates an internal power MOSFET. Compatible with USB or AC-Adapter Charging 5×5mm, Thin-QFN (TQFN55-40) Package − Only 0.75mm Height − RoHS Compliant APPLICATIONS REG1, REG2, and REG3 are three independent, fixed-frequency, current-mode step-down DC/DC converters that output 1.3A, 1.0A, and 0.55A, respectively. REG4 is a fixed-frequency, step-up DC/DC converter that safely and efficiently biases strings of up to 7 white-LEDs (up to a total of 21 LEDs) for display backlight applications. Finally, an I2C serial interface provides programmability for the DC/DC converters. • Personal Navigation Devices • Portable Media Players • Smart Phones The ACT8828 is available in a tiny 5mm × 5mm 40pin Thin-QFN package that is just 0.75mm thin. SYSTEM BLOCK DIAGRAM CHG_IN CHGLEV DCCC ISET ACIN nSTAT Li+ Battery Programmable Up to 1A VSYS ActivePathTM & Single-Cell Li+ Battery Charger REG1 Step-Down DC/DC REG2 Step-Down DC/DC nPBIN nIRQ nRSTO REG3 Step-Down DC/DC SCL SDA ON1 System Control REG4 Step-Up DC/DC ON2 ON3 ON4 ACT8828 PMU VSEL Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. Active -1- OUT1 Adjustable, or 0.8V to 4.4V Up to 1.3A OUT2 Adjustable, or 0.8V to 4.4V Up to 1.0A OUT3 Adjustable, or 0.8V to 4.4V Up to 0.55A OUT4 Up to 30V 7s x 3p WLEDs TM www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TABLE OF CONTENTS GENERAL INFORMATION ..........................................................................................P. 01 Functional Block Diagram ...................................................................................................... p. 03 Ordering Information .............................................................................................................. p. 04 Pin Configuration .................................................................................................................... p. 04 Pin Descriptions ..................................................................................................................... p. 05 Absolute Maximum Ratings.................................................................................................... p. 07 SYSTEM MANAGEMENT ...........................................................................................P. 08 Register Descriptions ............................................................................................................. p. 08 I2C Interface Electrical Characteristics ................................................................................... p. 09 Electrical Characteristics ........................................................................................................ p. 10 Register Descriptions ............................................................................................................. p. 11 Typical Performance Characteristics...................................................................................... p. 12 Functional Description ............................................................................................................ p. 13 STEP-DOWN DC/DC CONVERTERS ..........................................................................P. 17 Electrical Characteristics ........................................................................................................ p. 17 Typical Performance Characteristics...................................................................................... p. 20 Register Descriptions ............................................................................................................. p. 22 Functional Description ............................................................................................................ p. 28 STEP-UP DC/DC CONVERTERS ................................................................................P. 31 Electrical Characteristics ........................................................................................................ p. 31 Typical Performance Characteristics...................................................................................... p. 32 Register Descriptions ............................................................................................................. p. 33 Functional Description ............................................................................................................ p. 35 ActivePathTM CHARGER .............................................................................................P. 37 Electrical Characteristics ........................................................................................................ p. 37 Typical Performance Characteristics...................................................................................... p. 39 Functional Description ............................................................................................................ p. 41 PACKAGE INFORMATION ..........................................................................................P. 49 Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. -2- www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 FUNCTIONAL BLOCK DIAGRAM (Optional) AC Adaptor USB Active-Semi BODY SWITCH CHG_IN Up to 12V ACT8828 VSYS System Supply BODY SWITCH ACIN BAT Li+ Battery DCCC VSYS 100µA ActivePath Control + TH CURRENT SENSE nSTAT VOLTAGE SENSE PRECONDITION CHARGE STATUS Charge Control ISET THERMAL REGULATION 2.9V 110°C VSYS BTR CHGLEV OUT1 VP1 To VSYS nRSTO REG1 SW1 VSYS nPBIN OUT1 OUT1 GP1 PUSH BUTTON OUT1 VP2 nIRQ To VSYS REG2 SW2 OUT2 OUT2 GP2 SCL VP3 SDA System Control ON2 OUT3 OUT3 ON3 GP3 ON4 SW4 OVP4 REG4 VSEL REFBP Reference To VSYS SW3 REG3 ON1 FB4 To VSYS OUT4 7s x 3p WLEDs GP4 GA EP Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. -3- www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 ORDERING INFORMATION PART NUMBER VOUT1/VSTBY1 VOUT2/VSTBY2 VOUT3/VSTBY3 CONTROL SEQUENCE ACT8828QJ1D2-T 1.2V/1.2V 1.9V/1.9V 3.3V/3.3V Sequence A ACT8828QJ250-T 3.3V/3.3V 1.85V/1.85V 1.25V/1.25V Sequence B ACT8828QJ3B9-T 1.2V/1.2V 1.8V/1.8V 3.3V/3.3V Sequence C PACKAGING DETAILS PACKAGE PINS TEMPERATURE RANGE PACKING ACT8828QJ###-T TQFN55-40 40 -40°C to +85°C TAPE & REEL : All Active-Semi components are RoHS Compliant and with Pb-free plating unless specified differently. The term Pb-free means semiconductor products that are in compliance with current RoHS (Restriction of Hazardous Substances) standards. : To select VSTBYx as a output regulation voltage of REGx, tie VSEL to VSYS or a logic high. : Refer to the Control Sequence section for more information. PIN CONFIGURATION TOP VIEW GP4 SW4 nSTAT ON2 GA REFBP ON4 nRSTO nIRQ CHGLEV TH OVP4 DCCC FB4 BTR VP3 ACIN SW3 Active-Semi BAT BAT GP3 OUT3 ACT8828 VSYS nPBIN VSYS SDA CHG_IN SCL EP ISET ON3 OUT1 VP1 SW1 GP1 GP2 SW2 VP2 OUT2 ON1 VSEL Thin - QFN (TQFN55-40) Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. -4- www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 PIN DESCRIPTIONS PIN NAME DESCRIPTION 1 TH Temperature Sensing Input. Connect to battery thermistor. TH is pulled up with a 100µA current internally. See the Battery Temperature Monitoring section for more information. 2 DCCC Dynamic Charging Current Control. Connect a resistor to set the dynamic charging current control point. A internal 100µA current source sets up a voltage that is used to compare with VSYS and dynamically scale the charging current to maintain VSYS regulation. See the Dynamic Charge Current Control section for more information. 3 BTR Safety Timer Program Pin. The resistance between this pin and GA determines the timers timeout values. See the Charging Safety Timers section for more information. 4 ACIN AC Adaptor Detect. Detects presence of a wall adaptor and automatically adjusts the charge current to the maximum charge current level. Do not leave ACIN floating. 5, 6 BAT Battery Charger Output. Connect this pin directly to the battery anode (+ terminal) 7, 8 VSYS 9 CHG_IN Power Input for the Battery Charger. Bypass CHG_IN to GA with a capacitor placed as close to the IC as possible. The battery charger are automatically enabled when a valid voltage is present on CHG_IN. 10 ISET Charge Current Set. Program the maximum charge current by connecting a resistor (RISET) between ISET and GA. See the Charger Current Programming section for more information. 11 VSEL Step-Down DC/DCs Output Voltage Selection. Drive to logic low to select default output voltage. Drive to logic high to select secondary output voltage. See the Output Voltage Selection Pin section for more information. 12 ON1 Independent Enable Control Input for REG1. Drive ON1 to VSYS or to a logic high for normal operation, drive to GA or a logic low to disable REG1. Do not leave ON1 floating. 13 OUT2 Output Feedback Sense for REG2. Connect this pin directly to the output node to connect the internal feedback network to the output voltage. 14 VP2 Power Input for REG2. Bypass to GP2 with a high quality ceramic capacitor placed as close as possible to the IC. 15 SW2 Switching Node Output for REG2. Connect this pin to the switching end of the inductor. 16 GP2 Power Ground for REG2. Connect GA, GP1, GP2, GP3, and GP4 together at a single point as close to the IC as possible. 17 GP1 Power Ground for REG1. Connect GA, GP1, GP2, GP3, and GP4 together at a single point as close to the IC as possible. 18 SW1 Switching Node Output for REG1. Connect this pin to the switching end of the inductor. 19 VP1 Power Input for REG1. Bypass to GP1 with a high quality ceramic capacitor placed as close as possible to the IC. 20 OUT1 Output Feedback Sense for REG1. Connect this pin directly to the output node to connect the internal feedback network to the output voltage. 21 ON3 Enable Control Input for REG3. Drive ON3 to a logic high for normal operation, drive to GA or a logic low to disable REG3. Do not leave ON3 floating. 22 SCL Clock Input for I2C Serial Interface. 23 SDA Data Input for I2C Serial Interface. Data is read on the rising edge of SCL. System Output Pin. Bypass to GA with a 10µF or larger ceramic capacitor. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. -5- www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 PIN DESCRIPTIONS CONT’D PIN NAME DESCRIPTION 24 nPBIN Master Enable Input. Drive nPBIN to GA through a 100kΩ resistor to enable the IC, drive nPBIN directly to GA to assert a Hard-Reset condition. Refer to the System Startup & Shutdown section for more information. nPBIN is internally pulled up to VSYS through a 50kΩ resistor. 25 OUT3 Output Feedback Sense for REG3. Connect this pin directly to the output node to connect the internal feedback network to the output voltage. 26 GP3 Power Ground for REG3. Connect GA, GP1, GP2, GP3, and GP4 together at a single point as close to the IC as possible. 27 SW3 Switching Node Output for REG3. Connect this pin to the switching end of the inductor. 28 VP3 Power Input for REG3. Bypass to GP3 with a high quality ceramic capacitor placed as close as possible to the IC. 29 FB4 Feedback Sense for REG4. Connect this pin to the LED string current sense resistor to sense the LED current. 30 OVP4 31 GP4 Power Ground for REG4. Connect GP4 directly to a power ground plane. Connect GA, GP1, GP2, GP3, and GP4 together at a single point as close to the IC as possible. 32 SW4 Switching Node Output for REG4. Connect this pin to the switching end of the inductor. Over-Voltage Protection Input for REG4. Connect this pin to the output node through a 10kΩ resistor to sense and prevent over-voltage conditions. 33 nSTAT Active-Low Open-Drain Charger Status Output. nSTAT has a 5mA (typ) current limit, allowing it to directly drive an indicator LED without additional external components. To generate a logic-level output, connect nSTAT to an appropriate supply voltage (typically VSYS) through a 10kΩ or greater pull-up resistor. See the Charge Status Indication section for more information. 34 ON2 Independent Enable Control Input for REG2. Drive ON2 to a logic high for normal operation, drive to GA or a logic low to disable REG2. Do not leave ON2 floating. 35 GA 36 REFBP 37 ON4 Independent Enable Control Input for REG4. Drive ON4 to a logic high for normal operation, drive to GA or a logic low to disable REG4. Do not leave ON4 floating. 38 nRSTO Open-Drain Reset Output. nRSTO asserts low whenever REG1 is out of regulation, and remains low for 260ms (typ) after REG1 reaches regulation. 39 nIRQ Analog Ground. Connect GA directly to a quiet ground node. Connect GA, GP1, GP2, GP3, and GP4 together at a single point as close to the IC as possible. Reference Noise Bypass. Connect a 0.01µF ceramic capacitor from REFBP to GA. This pin is discharged to GA in shutdown. Open-Drain Interrupt Output. nIRQ asserts any time nPBIN is asserted or an unmasked fault condition exists. When asserted by nPBIN, nIRQ automatically de-asserts when nPBIN is released. When asserted by an unmasked fault condition, nIRQ remains asserted until the ACT8828 is polled by the microprocessor. See the nIRQ Output section for more information. Charging State Select Input. 40 CHGLEV EP EP When ACIN = 0 charge current is internally set; Drive CHGLEV to a logic-high for high-current USB charging mode (maximum charge current is 500mA), drive CHGLEV to a logic-low for lowcurrent USB charging mode (maximum charge current is 100mA). When ACIN = 1 charge current is externally set by RISET; Drive CHGLEV to a logic-high to for high -current charging mode (ICHG = K x 1000/RISET(mA) where K = 640), drive CHGLEV to a logic-low for low-current charging mode (ICHG = K x 500/RISET(mA) where K = 640). Do not leave CHGLEV floating. Exposed Pad. Must be soldered to ground on the PCB. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. -6- www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 ABSOLUTE MAXIMUM RATINGS PARAMETER VALUE UNIT CHG_IN to GA t < 1ms and duty cycle <1% Steady State -0.3 to +18 -0.3 to +14 V V BAT, VSYS to GA -0.3 to +6 V VP1 to GP1, VP2 to GP2, VP3 to GP3 -0.3 to +6 V SW1, OUT1 to GP1 -0.3 to (VVP1 +0.3) V SW2, OUT2 to GP2 -0.3 to (VVP2 +0.3) V SW3, OUT3 to GP3 -0.3 to (VVP3 +0.3) V ON1, ON2, ON3, ON4, ISET, ACIN, BTR, nPBIN, VSEL, nSTAT, DCCC, CHGLEV, TH, SCL, SDA, REFBP, nIRQ, nRSTO to GA -0.3 to +6 V SW4, OVP4 to GP4 -0.3 to +30 V Operating Ambient Temperature -40 to 85 °C Maximum Junction Temperature 125 °C Maximum Power Dissipation TQFN55-40 (Thermal Resistance θJA = 30oC/W) 2.7 W -65 to 150 °C 300 °C Storage Temperature Lead Temperature (Soldering, 10 sec) : Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. -7- www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT REGISTER DESCRIPTIONS Table 1: Global Register Map OUTPUT ADDRESS DATA (DEFAULT VALUE) HEX A7 A6 A5 A4 A3 A2 A1 A0 D7 D6 D5 D4 D3 D2 D1 D0 MSTR 06h 0 0 0 0 0 1 1 0 R R R 0 R R 1 R REG1 10h 0 0 0 1 0 0 0 0 R R V V V V V V REG1 11h 0 0 0 1 0 0 0 1 R R R R R R R R REG1 12h 0 0 0 1 0 0 1 0 R R R R R 0 R 1 REG1 13h 0 0 0 1 0 0 1 1 R V V V V V V V REG2 20h 0 0 1 0 0 0 0 0 R R V V V V V V REG2 21h 0 0 1 0 0 0 0 1 R R R R R R R R REG2 22h 0 0 1 0 0 0 1 0 R R R R R 0 R 1 REG2 23h 0 0 1 0 0 0 1 1 R V V V V V V V REG3 30h 0 0 1 1 0 0 0 0 R R V V V V V V REG3 31h 0 0 1 1 0 0 0 1 R R R R R R R R REG3 32h 0 0 1 1 0 0 1 0 R R R R R 0 R 1 REG3 33h 0 0 1 1 0 0 1 1 R V V V V V V V REG4 40h 0 1 0 0 0 0 0 0 R R R R R R R R REG4 41h 0 1 0 0 0 0 0 1 R R R R R R R R REG4 42h 0 1 0 0 0 0 1 0 R R R R R 0 R 1 REG4 43h 0 1 0 0 0 0 1 1 R R V V V V V V KEY: R: Read-Only bits. No Default Assigned. V: Default Values Depend on Voltage Option. Default Values May Vary. Note: Addresses other than those specified in Table 1 may be used for factory settings. Do not access any registers other than those specified in Table 1. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. -8- www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT I2C INTERFACE ELECTRICAL CHARACTERISTICS (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS MIN SCL, SDA Low Input Voltage VVSYS = 2.6V to 5.5V, TA = -40ºC to 85ºC SCL, SDA High Input Voltage VVSYS = 2.6V to 5.5V, TA = -40ºC to 85ºC 0.35 1.55 SCL, SDA Leakage Current SDA Low Output Voltage TYP MAX UNIT IOL = 5mA V V 1 µA 0.3 V SCL Clock Period, tSCL 2.5 µs SDA Data In Setup Time to SCL High, tSU 100 ns SDA Data Out Hold Time after SCL Low, tHD 300 ns Start Condition 100 ns SDA Data High Hold Time after Clock High, tSP Stop Condition 100 ns SDA Data Low Setup Time to SCL Low, tST Figure 1: I2C Serial Bus Timing tSCL SCL tST tSU SDA IN tSP tHD SDA OUT Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. -9- www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT ELECTRICAL CHARACTERISTICS (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS Input Voltage Range MIN TYP 2.6 5.5 V 2.7 V VSYS Rising UVLO Hysteresis VSYS Falling 100 mV ONx = VSYS, Not charging 100 µA ONx = VSYS, Charging 2 mA ONx = GA, Not Charging 5 µA VSYS Shutdown Current 2.5 UNIT UVLO Threshold Voltage VSYS Supply Current 2.35 MAX Voltage Reference 1.24 1.25 1.26 V Oscillator Frequency 1.35 1.6 1.85 MHz Logic High Input Voltage ON1, ON2, ON3, ON4, VSEL, CHGLEV Logic Low Input Voltage ON1, ON2, ON3, ON4, VSEL, CHGLEV Leakage Current ON1, ON2, ON3, ON4, VSEL, nIRQ, nRSTO Low Level Output Voltage nIRQ, nRSTO. Sinking 10mA nRSTO Delay 1.4 V 0.4 V 1 µA 0.3 V 260 ms Thermal Shutdown Temperature Temperature rising 160 °C Thermal Shutdown Hysteresis Temperature decreasing 20 °C nPBIN Enable/Disable Threshold R = 100kΩ 0.4 V nPBIN Hard-Reset Threshold R < 100kΩ 0.4 V nPBIN Internal Pull-up Resistance Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. 50 - 10 - kΩ www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 2: Control Register Map DATA ADDRESS 06h D7 D6 D5 D4 D3 D2 D1 D0 R R R W/E R R nPBMASK PBSTAT R: Read-Only bits. Default Values May Vary. W/E: Write-Exact bits. Read/Write bits which must be written exactly as specified in Table 1. Table 3: Control Register Bit Descriptions ADDRESS NAME BIT ACCESS FUNCTION 06h PBSTAT [0] R Push Button Status 06h nPBMASK [1] R/W Push Button Interrupt Mask Option 06h [3:2] R READ ONLY 06h [4] W/E WRITE-EXACT 06h [7:5] R READ ONLY Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 11 - DESCRIPTION 0 De-assert 1 Asserted 0 Masked 1 Not Mask www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT TYPICAL PERFORMANCE CHARACTERISTICS (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) Oscillator Frequency vs. Temperature ACT8828-001 1.71 Frequency (MHz) 1.68 1.65 1.62 1.59 1.56 1.53 1.50 -40 -20 0 20 40 60 85 Temperature (°C) VSYS Current vs. Temperature Supply Current (µA) ACT8828-002 26 ON1 = ON2 = ON3 = ON4 = GA VVSYS = 4.2V 24 VVSYS = 3.6V VVSYS = 3.2V 22 20 -40 -20 0 20 40 60 85 Temperature (°C) Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 12 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT FUNCTIONAL DESCRIPTION General Description The ACT8828 offers a wide array of system management functions that allow it to be configured for optimal performance in a wide range of applications. I2C Serial Interface At the core of the ACT8828’s flexible architecture is an I2C interface that permits optional programming capability to enhance overall system performance. To ensure compatibility with a wide range of system processors, the ACT8828 uses standard I2C commands; I2C write-byte commands are used to program the ACT8828, and I2C read-byte commands are used to read the ACT8828’s internal registers. The ACT8828 always operates as a slave device, and is addressed using a 7-bit slave address followed by an eighth bit, which indicates whether the transaction is a read-operation or a write-operation, [1011010x]. SDA is a bi-directional data line and SCL is a clock input. The master initiates a transaction by issuing a START condition, defined by SDA transitioning from high to low while SCL is high. Data is transferred in 8-bit packets, beginning with the MSB, and is clocked-in on the rising edge of SCL. Each packet of data is followed by an “Acknowledge” (ACK) bit, used to confirm that the data was transmitted successfully. For more information regarding the I2C 2-wire serial interface, go to the NXP website: http://www.nxp.com nPBIN Input ACT8828's nPBIN pin is a dual-function pin, combining system enable/disable control with a hardware reset function. Refering to Figure 2, the two pin functions are obtained by asserting this pin low, either through a direct connection or through a 100kΩ resistor, as described below. Figure 2: nPBIN Input In most applications, nPBIN will be driven through a 100kΩ resistor. When driven in this way, nPBIN initiates system startup or shutdown, as described in the System Startup and Shutdown section. When a hardware-reset function is desired, nPBIN may also be driven directly to GA. In this case, nRSTO is immediately asserted low and remains low until nPBIN is de-asserted and the reset timeout period expires. This provides a hardware-reset function, allowing the system to be manually reset if the system processor locks up. Although a typical application will use momentary switches to drive nPBIN, as shown in Figure 2, nPBIN may also be driven by other sources, such as a GPIO or other logic output. Enable/Disable Inputs (ON1, ON2, ON3, and ON4) The ACT8828 provides three manual enable/disable inputs, ON1, ON2, ON3, and ON4, which enable and disable REG1, REG2, REG3, and REG4 respectively. Once the system is enabled, the system will remain enabled until all of ON1, ON2, ON3, and ON4 have been de-asserted. See the System Startup and Shutdown section for more information. Power-On Reset Output nRSTO is an open-drain output which asserts low upon startup or when nPBIN is driven directly to GA, and remains asserted low until the 260msec (default) power-on reset timer has expired. Connect a 10kΩ or greater pull-up resistor from nRSTO to an appropriate voltage supply. nIRQ Output nIRQ is an open-drain output that asserts low any time startup or an unmasked fault condition exists. When asserted, nIRQ remains low until the microprocessor polls the ACT8828's I2C interface. The ACT8828 supports a variety of other fault conditions, which may each be optionally unmasked via the I2C interface. For more information about the available fault conditions, refer to the appropriate sections of this datasheet. Connect a pull-up resistor from nIRQ to an appropriate voltage supply. nIRQ is typically used to drive the interrupt input of the system processor, and is useful in a variety of software-controlled enable/disable control routines. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 13 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT FUNCTIONAL DESCRIPTION CONT’D Thermal Shutdown The ACT8828 integrates thermal shutdown protection circuitry to prevent damage resulting from excessive thermal stress, as may be encountered under fault conditions. This circuitry disables all regulators if the ACT8828 die temperature exceeds 160°C, and prevents the regulators from being enabled until the IC temperature drops by 20°C (typ). Control Sequence Sequence A The ACT8828QJ1## features a flexible enable architecture that allows it to support a variety of push-button enable/disable schemes. Although other startup routines are possible, a typical startup and shutdown process proceeds as shown in Figure 3. System startup is initiated whenever the following conditions occurs: 1) nPBIN is pushed low via 100kΩ resistance, When condition exists, the ACT8828QJ1## begins its system startup procedure by enabling REG1. When REG1 reaches regulation, REG2 and REG3 are enable, and nRSTO is asserted low, holding the microprocessor in reset for a user selectable reset period of 260ms. If VOUT1 is within 6% of its regulation voltage when the reset timer expires, the nRSTO is de-asserted, and the microprocessor can begin its power-up sequence. Once the power-up routine is successfully completed, the system remains enabled after the push-button is released as long as the microprocessor asserts any one of ON1, ON2, ON3, or ON4. ON1, ON2, ON3, or ON4 enable REG1, REG2, REG3 and REG4 separately, but any one of them can enable ACT8828QJ1##. This start-up procedure requires that the pushbutton be held until the microprocessor assumes control (by asserting any one of ON1, ON2, ON3, and ON4), providing protection against inadvertent momentary assertions of the pushbutton. If desired, longer “push-and-hold” times can be easily implemented by simply adding an additional time delay before asserting ON1, ON2, ON3, or ON4. If the microprocessor is unable to complete its power-up routine successfully before the user lets go of the push-button, the ACT8828QJ1## automatically shuts itself down. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. This start-up procedure requires that the pushbutton be held until the microprocessor assumes control (by asserting any one of ON1, ON2, ON3, and ON4), providing protection against inadvertent momentary assertions of the pushbutton. If desired, longer “push-and-hold” times can be easily implemented by simply adding an additional time delay before asserting ON1, ON2, ON3, or ON4. If the microprocessor is unable to complete its power-up routine successfully before the user lets go of the push-button, the ACT8828QJ1## automatically shuts itself down. Once a successful power-up routine is completed, a shutdown process may be initiated by asserting nPBIN a second time, typically as the result of pressing the push-button. Although the shutdown process is completely software-controlled, a typical shutdown sequence proceeds as follows: The second assertion of nPBIN asserts nPBIN and interrupts the microprocessor, which then initiates an interrupt service routine to reveal that nPBIN has been asserted. The microprocessor disables each regulator according to the sequencing requirements of the system, then the system will finally be disabled when ON1, ON2, ON3, and ON4 have been de-asserted. Figure 3: Sequence A First Push Button Assert Power-Hold Release Button Second Push System Button Shutdown nPBIN System Enable OUT1 94% of VOUT1 ~100ms Enable Qualification OUT2, OUT3 OUT4 ON1, ON2, ON3, ON4 260ms nRSTO nIRQ Sequence B The ACT8828QJ2## features a flexible enable architecture that allows it to support a variety of push-button enable/disable schemes. Although other startup routines are possible, a typical startup - 14 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT FUNCTIONAL DESCRIPTION CONT’D and shutdown process proceeds as shown in Figure 4. System startup is initiated whenever the following conditions occurs: 1) nPBIN is pushed low via 100kΩ resistance, When condition exists, the ACT8828QJ2## begins its system startup procedure by enabling REG1, REG2 and REG3. When REG1 reaches regulation, nRSTO is asserted low, holding the microprocessor in reset for a user selectable reset period of 260ms. If VOUT1 is within 6% of its regulation voltage when the reset timer expires, the nRSTO is de-asserted, and the microprocessor can begin its power-up sequence. Once the power-up routine is successfully completed, the system remains enabled after the push-button is released as long as the microprocessor asserts any one of ON1, ON2, ON3, or ON4. ON1, ON2, ON3, or ON4 enable REG1, REG2, REG3 and REG4 separately, but any one of them can enable ACT8828QJ2##. This start-up procedure requires that the pushbutton be held until the microprocessor assumes control (by asserting any one of ON1, ON2, ON3, and ON4), providing protection against inadvertent momentary assertions of the pushbutton. If desired, longer “push-and-hold” times can be easily implemented by simply adding an additional time delay before asserting ON1, ON2, ON3, or ON4. If the microprocessor is unable to complete its power-up routine successfully before the user lets go of the push-button, the ACT8828QJ2## automatically shuts itself down. This start-up procedure requires that the pushbutton be held until the microprocessor assumes control (by asserting any one of ON1, ON2, ON3, and ON4), providing protection against inadvertent momentary assertions of the pushbutton. If desired, longer “push-and-hold” times can be easily implemented by simply adding an additional time delay before asserting ON1, ON2, ON3, or ON4. If the microprocessor is unable to complete its power-up routine successfully before the user lets go of the push-button, the ACT8828QJ2## automatically shuts itself down. Once a successful power-up routine is completed, a shutdown process may be initiated by asserting nPBIN a second time, typically as the result of pressing the push-button. Although the shutdown process is completely software-controlled, a typical Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. shutdown sequence proceeds as follows: The second assertion of nPBIN asserts nPBIN and interrupts the microprocessor, which then initiates an interrupt service routine to reveal that nPBIN has been asserted. The microprocessor disables each regulator according to the sequencing requirements of the system, then the system will finally be disabled when ON1, ON2, ON3, and ON4 have been de-asserted. Sequence C The ACT8828QJ3## features a flexible enable architecture that allows it to support a variety of push-button enable/disable schemes. Although other startup routines are possible, a typical startup and shutdown process proceeds as shown in Figure 5. System startup is initiated whenever the following conditions occurs: 1) A valid input voltage is present at VIN, or 2) nPBIN is pushed low via 100kΩ resistance, When any of these conditions exists, the ACT8828QJ3## begins its system startup procedure by enabling REG1. When REG1 reaches regulation, nRSTO is asserted low, holding the microprocessor in reset for a user selectable reset period of 260ms. If VOUT1 is within 6% of its regulation voltage when the reset timer expires, the nRSTO is de-asserted, and the microprocessor can begin its power-up sequence. Once the power-up routine is successfully completed, the system remains enabled after the push-button is released as long as the microprocessor asserts any one of ON1, ON2, ON3, or ON4. ON1, ON2, ON3, or ON4 enable REG1, REG2, REG3 and REG4 separately, but any one of them can enable ACT8828QJ3##. This start-up procedure requires that the pushbutton be held or a valid input voltage be present at VIN until the microprocessor assumes control (by asserting any one of ON1, ON2, ON3, and ON4), providing protection against inadvertent momentary assertions of the pushbutton. If desired, longer “push-and-hold” times can be easily implemented by simply adding an additional time delay before asserting ON1, ON2, ON3, or ON4. If the microprocessor is unable to complete its powerup routine successfully before the user lets go of the push-button or un-plug the charger adapter, the ACT8828QJ3## automatically shuts itself down. - 15 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 SYSTEM MANAGEMENT FUNCTIONAL DESCRIPTION CONT’D Once a successful power-up routine is completed, a shutdown process may be initiated by asserting nPBIN a second time, typically as the result of pressing the push-button. Although the shutdown process is completely software-controlled, a typical shutdown sequence proceeds as follows: The second assertion of nPBIN asserts nPBIN and interrupts the microprocessor, which then initiates an interrupt service routine to reveal that nPBIN has been asserted. If there is no input to the charger, then the microprocessor disables each regulator according to the sequencing requirements of the system, the microprocessor disables each regulator according to the sequencing requirements of the system, then the system will finally be disabled when ON1, ON2, ON3, and ON4 have been deasserted. Figure 4: Figure 5: Sequence B Sequence C First Push Button Assert Power-Hold Release Button nPBIN Assert Power-Hold Release Button Second Push System Button Shutdown CHG_IN OR nPBIN OUT1, OUT2, OUT3 OUT1 ON1, ON2, ON3, ON4 94% of VOUT1 ~100ms Enable Qualification OUT2, OUT3 OUT4 Reset Time Enable First Push Button Second Push System Button Shutdown ON1, ON2, ON3, ON4 OUT4 260ms Reset Time Enable nRSTO 260ms nRSRO nIRQ nIRQ Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 16 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS ELECTRICAL CHARACTERISTICS (REG1) (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS VP1 Operating Voltage Range MIN 2.9 VP1 UVLO Threshold Input Voltage Rising VP1 UVLO Hysteresis Input Voltage Falling 2.7 Output Voltage Regulation Accuracy REG1 is disabled, VVP1 = 4.2V UNIT 5.5 V 2.9 V mV 130 200 µA 0.1 1 µA VNOM1 < 1.5V, IOUT1 = 10mA -2.1% VNOM1 +2.1% VNOM1 ≥ 1.5V, IOUT1 = 10mA -1.5% VNOM1 +1.5% Line Regulation VVP1 = Max(VNOM1 + 1V, 3.2V) to 5.5V Load Regulation IOUT1 = 10mA to 1.3A Current Limit Oscillator Frequency 2.8 MAX 85 Standby Supply Current Shutdown Supply Current TYP VOUT1 ≥ 20% of VNOM1 V 0.15 %/V 0.0017 %/mA 1.4 1.8 A 1.35 1.6 1.85 MHz VOUT1 = 0V 540 PMOS On-Resistance ISW1 = -100mA 0.16 0.24 Ω NMOS On-Resistance ISW1 = 100mA 0.16 0.24 Ω SW1 Leakage Current VVP1 = 5.5V, VSW1 = 5.5V or 0V 1 µA kHz Power Good Threshold 94 %VNOM1 Minimum On-Time 60 ns : VNOM1 refers to the nominal output voltage level for VOUT1 as defined by the Ordering Information section. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 17 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS ELECTRICAL CHARACTERISTICS (REG2) (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS VP2 Operating Voltage Range MIN 2.9 VP2 UVLO Threshold Input Voltage Rising VP2 UVLO Hysteresis Input Voltage Falling 2.7 Output Voltage Regulation Accuracy REG2 Disabled, VVP2 = 4.2V UNIT 5.5 V 2.9 V mV 130 200 µA 0.1 1 µA VNOM2 < 1.5V, IOUT2 = 10mA -2.1% VNOM2 +2.1% VNOM2 ≥ 1.5V, IOUT2 = 10mA -1.5% VNOM2 +1.5% Line Regulation VVP2 = Max(VNOM2 + 1V, 3.2V) to 5.5V Load Regulation IOUT2 = 10mA to 1.0A Current Limit Oscillator Frequency 2.8 MAX 85 Standby Supply Current Shutdown Supply Current TYP VOUT2 ≥ 20% of VNOM2 V 0.15 %/V 0.0017 %/mA 1.15 1.45 A 1.35 1.6 1.85 MHz VOUT2 = 0V 540 PMOS On-Resistance ISW2 = -100mA 0.25 0.38 Ω NMOS On-Resistance ISW2 = 100mA 0.17 0.26 Ω SW2 Leakage Current VVP2 = 5.5V, VSW2 = 5.5V or 0V 1 µA kHz Power Good Threshold 94 %VNOM2 Minimum On-Time 60 ns : VNOM2 refers to the nominal output voltage level for VOUT2 as defined by the Ordering Information section. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 18 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS ELECTRICAL CHARACTERISTICS (REG3) (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS VP3 Operating Voltage Range MIN 2.9 VP3 UVLO Threshold Input Voltage Rising VP3 UVLO Hysteresis Input Voltage Falling 2.7 Output Voltage Regulation Accuracy REG3 Disabled, VVP3 = 4.2V UNIT 5.5 V 2.9 V mV 130 200 µA 0.1 1 µA VNOM3 < 1.5V, IOUT3 = 10mA -2.1% VNOM3 +2.1% VNOM3 ≥ 1.5V, IOUT3 = 10mA -1.5% VNOM3 +1.5% Line Regulation VVP3 = Max(VNOM3 + 1V, 3.2V) to 5.5V Load Regulation IOUT3 = 10mA to 550mA Current Limit Oscillator Frequency 2.8 MAX 85 Standby Supply Current Shutdown Supply Current TYP VOUT3 ≥ 20% of VNOM3 V 0.15 %/V 0.0017 %/mA 0.55 0.7 A 1.35 1.6 1.85 MHz VOUT3 = 0V 540 PMOS On-Resistance ISW3 = -100mA 0.46 0.69 Ω NMOS On-Resistance ISW3 = 100mA 0.3 0.45 Ω SW3 Leakage Current VVP3 = 5.5V, VSW3 = 5.5V or 0V 1 µA kHz Power Good Threshold 94 %VNOM3 Minimum On-Time 60 ns : VNOM3 refers to the nominal output voltage level for VOUT3 as defined by the Ordering Information section. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 19 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS TYPICAL PERFORMANCE CHARACTERISTICS (ACT8828QJ16C, VVP1 = VVP2 = 3.6V, L = 3.3µH, CVP1 = CVP2 = 4.7μF, COUT1 = 22μF, COUT2 = 10μF, TA = 25°C, unless otherwise specified.) REG2 Efficiency vs. Load Current REG1 Efficiency vs. Load Current VVSYS = 4.2V 60 REG2 Efficiency (%) REG1 Efficiency (%) VVSYS = 5.2V VVSYS = 4.6V 40 20 VVSYS = 3.6V 90 VVSYS = 5.2V 80 VVSYS = 4.6V VVSYS = 4.2V 70 60 VOUT1 = 3.3V VOUT2 = 1.2V 0 50 200 20 2 1 2000 10 OUT1 Regulation Voltage vs. Temperature 1.808 1.804 OUT2 Regulation Voltage (V) IOUT1 = 35mA 1.800 1.796 1.792 1.788 -40 -20 0 20 40 60 85 3.315 IOUT2 = 35mA 3.312 3.309 3.306 3.303 3.300 3.297 3.294 3.291 3.288 3.285 3.282 -40 -20 Temperature (°C) REG1 RDSON vs. VP1 Input Voltage 40 60 85 ACT8828-008 ACT8828-007 0.5 REG2 RDSON (mΩ) NMOS 0.12 20 REG2 RDSON vs. VP2 Input Voltage PMOS 0.14 0 Temperature (°C) 0.18 0.16 ACT8828-006 OUT1 Regulation Voltage (V) OUT2 Regulation Voltage vs. Temperature 3.318 ACT8828-005 1.812 1000 100 Load Current (mA) Load Current (mA) REG1 RDSON (mΩ) ACT8828-004 VVSYS = 3.6V 80 100 ACT8828-003 100 0.10 0.08 0.06 0.04 0.4 0.3 PMOS 0.2 NMOS 0.1 0.02 0 3.0 0 3.5 4.0 4.5 5.0 5.5 3.0 6.0 ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. 4.0 4.5 5.0 5.5 6.0 VP2 Input Voltage (V) VP1 Input Voltage (V) Innovative PowerTM 3.5 - 20 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (ACT8828QJ16C, VVP3 = 3.6V, L = 3.3µH, CVP3 = 4.7μF, COUT3 = 10μF, TA = 25°C, unless otherwise specified.) REG3 Efficiency vs. Load Current REG3 Efficiency (%) VOUT3 = 1.2V VVSYS = 3.6V 80 VVSYS = 4.6V 60 VVSYS = 4.2V ACT8828-009 100 40 20 0 10 1 100 1000 Load Current (mA) OUT3 Regulation Voltage vs. Temperature OUT3 Regulation Voltage (V) ACT8828-010 1.212 IOUT3 = 35mA 1.208 1.204 1.200 1.196 1.192 1.188 -40 -20 0 20 40 60 85 Temperature (°C) REG3 RDSON vs. VP3 Input Voltage REG3 RDSON (mΩ) 0.45 0.40 PMOS ACT8828-011 0.50 0.35 0.30 0.25 NMOS 0.20 0.15 0.1 3.0 3.5 4.0 4.5 5.0 5.5 6.0 VP3 Input Voltage (V) Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 21 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 4: REG1 Control Register Map DATA ADDRESS D7 D6 D5 D4 10h R R 11h R R R R 12h R R R R 13h R VRANGE D3 D2 D1 D0 R R R R R nFLTMSK OK ON VSET1 VSET0 R: Read-Only bits. Default Values May Vary. Table 5: REG1 Control Register Bit Descriptions ADDRESS NAME BIT ACCESS FUNCTION DESCRIPTION 10h VSET1 [5:0] R/W REG1 Standby Output Voltage Selection See Table 6 10h [7:6] R READ ONLY 11h [7:0] R READ ONLY 12h ON [0] R/W REG1 Enable 12h OK [1] R REG1 Power-OK 12h nFLTMSK [2] R/W REG1 Output Voltage Fault Mask Option [7:3] R 12h REG1 Disable 1 REG1 Enable 0 Output is not OK 1 Output is OK 0 Masked 1 Not Mask READ ONLY 13h VSET0 [5:0] R/W REG1 Output Voltage Selection 13h VRANGE [6] R/W REG1 Voltage Range [7] R 13h 0 Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. See Table 6 0 Min VOUT = 0.8V 1 Min VOUT = 1.25V READ ONLY - 22 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS CONT’D Table 6: REG1/VSETx[ ] Output Voltage Setting REG1/VSETx[5:4] REG1/VSETx[3:0] REG1/VRANGE[ ] = [0] REG1/VRANGE[ ] = [1] 00 01 10 11 00 01 10 11 0000 Adjustable 1.025 1.425 1.825 Adjustable 2.050 2.850 3.650 0001 0.800 1.050 1.450 1.850 1.300 2.100 2.900 3.700 0010 0.800 1.075 1.480 1.875 1.350 2.150 2.950 3.750 0011 0.800 1.100 1.500 1.900 1.400 2.200 3.000 3.800 0100 0.800 1.125 1.525 1.925 1.450 2.250 3.050 3.850 0101 0.800 1.150 1.550 1.950 1.500 2.300 3.100 3.900 0110 0.800 1.175 1.575 1.975 1.550 2.350 3.150 3.950 0111 0.800 1.200 1.600 2.000 1.600 2.400 3.200 4.000 1000 0.825 1.225 1.625 2.025 1.650 2.450 3.250 4.050 1001 0.850 1.250 1.650 2.050 1.700 2.500 3.300 4.100 1010 0.875 1.275 1.675 2.075 1.750 2.550 3.350 4.150 1011 0.900 1.300 1.700 2.100 1.800 2.600 3.400 4.200 1100 0.925 1.325 1.725 2.125 1.850 2.650 3.450 4.250 1101 0.950 1.350 1.750 2.150 1.900 2.700 3.500 4.300 1110 0.975 1.375 1.775 2.175 1.950 2.750 3.550 4.350 1111 1.000 1.400 1.800 2.200 2.000 2.800 3.600 4.400 : Refer to Output Voltage Programming section for more information. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 23 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 7: REG2 Control Register Map DATA ADDRESS D7 D6 D5 D4 20h R R 21h R R R R 22h R R R R 23h R VRANGE D3 D2 D1 D0 R R R R R nFLTMSK OK ON VSET1 VSET0 R: Read-Only bits. Default Values May Vary. Table 8: REG2 Control Register Bit Descriptions ADDRESS NAME BIT ACCESS FUNCTION DESCRIPTION 20h VSET1 [5:0] R/W REG2 Standby Output Voltage Selection See Table 9 20h [7:6] R READ ONLY 21h [7:0] R READ ONLY 22h ON [0] R/W REG2 Enable 22h OK [1] R REG2 Power-OK 22h nFLTMSK [2] R/W REG2 Output Voltage Fault Mask Option [7:3] R 22h REG2 Disable 1 REG2 Enable 0 Output is not OK 1 Output is OK 0 Masked 1 Not Mask READ ONLY 23h VSET0 [5:0] R/W REG2 Output Voltage Selection 23h VRANGE [6] R/W REG2 Voltage Range [7] R 23h 0 Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. See Table 9 0 Min VOUT = 0.8V 1 Min VOUT = 1.25V READ ONLY - 24 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS CONT’D Table 9: REG2/VSETx[ ] Output Voltage Setting REG2/VSETx[5:4] REG2/VSETx[3:0] REG2/VRANGE[ ] = [0] REG2/VRANGE[ ] = [1] 00 01 10 11 00 01 10 11 0000 Adjustable 1.025 1.425 1.825 Adjustable 2.050 2.850 3.650 0001 0.800 1.050 1.450 1.850 1.300 2.100 2.900 3.700 0010 0.800 1.075 1.480 1.875 1.350 2.150 2.950 3.750 0011 0.800 1.100 1.500 1.900 1.400 2.200 3.000 3.800 0100 0.800 1.125 1.525 1.925 1.450 2.250 3.050 3.850 0101 0.800 1.150 1.550 1.950 1.500 2.300 3.100 3.900 0110 0.800 1.175 1.575 1.975 1.550 2.350 3.150 3.950 0111 0.800 1.200 1.600 2.000 1.600 2.400 3.200 4.000 1000 0.825 1.225 1.625 2.025 1.650 2.450 3.250 4.050 1001 0.850 1.250 1.650 2.050 1.700 2.500 3.300 4.100 1010 0.875 1.275 1.675 2.075 1.750 2.550 3.350 4.150 1011 0.900 1.300 1.700 2.100 1.800 2.600 3.400 4.200 1100 0.925 1.325 1.725 2.125 1.850 2.650 3.450 4.250 1101 0.950 1.350 1.750 2.150 1.900 2.700 3.500 4.300 1110 0.975 1.375 1.775 2.175 1.950 2.750 3.550 4.350 1111 1.000 1.400 1.800 2.200 2.000 2.800 3.600 4.400 : Refer to Output Voltage Programming section for more information. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 25 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 10: REG3 Control Register Map DATA ADDRESS D7 D6 D5 D4 30h R R 31h R R R R 32h R R R R 33h R VRANGE D3 D2 D1 D0 R R R R R nFLTMSK OK ON VSET1 VSET0 R: Read-Only bits. Default Values May Vary. W/E: Write-Exact bits. Read/Write bits which must be written exactly as specified in Table 1 Table 11: REG3 Control Register Bit Descriptions ADDRESS NAME BIT ACCESS FUNCTION DESCRIPTION 30h VSET1 [5:0] R/W REG3 Standby Output Voltage Selection See Table 12 30h [7:6] R READ ONLY 31h [7:0] R READ ONLY 32h ON [0] R/W REG3 Enable 32h OK [1] R REG3 Power-OK 32h nFLTMSK [2] R/W REG3 Output Voltage Fault Mask Option [7:3] R 32h REG3 Disable 1 REG3 Enable 0 Output is not OK 1 Output is OK 0 Masked 1 Not Mask READ ONLY 33h VSET0 [5:0] R/W REG3 Output Voltage Selection 33h VRANGE [6] R/W REG3 Voltage Range [7] R 33h 0 Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. See Table 12 0 Min VOUT = 0.8V 1 Min VOUT = 1.25V READ ONLY - 26 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS CONT’D Table 12: REG3/VSETx[ ] Output Voltage Setting REG3/VSETx[5:4] REG3/VSETx[3:0] REG3/VRANGE[ ] = [0] REG3/VRANGE[ ] = [1] 00 01 10 11 00 01 10 11 0000 Adjustable 1.025 1.425 1.825 Adjustable 2.050 2.850 3.650 0001 0.800 1.050 1.450 1.850 1.300 2.100 2.900 3.700 0010 0.800 1.075 1.480 1.875 1.350 2.150 2.950 3.750 0011 0.800 1.100 1.500 1.900 1.400 2.200 3.000 3.800 0100 0.800 1.125 1.525 1.925 1.450 2.250 3.050 3.850 0101 0.800 1.150 1.550 1.950 1.500 2.300 3.100 3.900 0110 0.800 1.175 1.575 1.975 1.550 2.350 3.150 3.950 0111 0.800 1.200 1.600 2.000 1.600 2.400 3.200 4.000 1000 0.825 1.225 1.625 2.025 1.650 2.450 3.250 4.050 1001 0.850 1.250 1.650 2.050 1.700 2.500 3.300 4.100 1010 0.875 1.275 1.675 2.075 1.750 2.550 3.350 4.150 1011 0.900 1.300 1.700 2.100 1.800 2.600 3.400 4.200 1100 0.925 1.325 1.725 2.125 1.850 2.650 3.450 4.250 1101 0.950 1.350 1.750 2.150 1.900 2.700 3.500 4.300 1110 0.975 1.375 1.775 2.175 1.950 2.750 3.550 4.350 1111 1.000 1.400 1.800 2.200 2.000 2.800 3.600 4.400 : Refer to Output Voltage Programming section for more information. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 27 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS FUNCTIONAL DESCRIPTION General Description REG1, REG2, and REG3 are fixed-frequency, current-mode, synchronous PWM step-down converters that are capable of supplying up to 1.3A, 1.0A, and 0.55A of output current, respectively. These regulators operate with a fixed frequency of 1.6MHz, minimizing noise in sensitive applications and allowing the use of small external components, and achieve peak efficiencies of up to 97%. Each step-down DC/DC is available with a variety of standard and custom output voltages, which may be software-controlled by systems requiring advanced power management functions, via the I2C interface. Buck Regulator PFM/PWM Operating Modes The buck converters offer PFM/PWM operating modes to maximize efficiency under both light and full load conditions. The device will automatically transition from fixed frequency PWM mode to PFM mode when the output current is approximately 100mA. In PFM mode, the device maintains output voltage regulation by adjusting the switching frequency. The device transitions into fixed frequency PWM mode when the output current reaches approximately 100mA. 100% Duty Cycle Operation REG1, REG2 and REG3 are each capable of operating at up to 100% duty cycle. During 100% duty-cycle operation, the high-side power MOSFET is held on continuously, providing a direct connection from the input to the output (through the inductor), ensuring the lowest possible dropout voltage in battery powered applications. Synchronous Rectification REG1, REG2 and REG3 each feature integrated channel synchronous rectifiers, maximizing efficiency and minimizing the total solution size and cost by eliminating the need for external rectifiers. input. Refer to the System Startup and Shutdown section for more information about this function. Each regulator is enabled when the following conditions are met: 1) ONx is asserted high to enable REGx, 2) REGx/ONx[ ] is set to 1 when ONx is high In addition REG1, REG2, or REG3 may be enable when nPBIN is pushed low via 100kΩ resistance. It depends on sequence is set. See the Control Sequence section for more information. When none of these conditions are true, REG1, REG2 and REG3 are disabled, and each regulator’s quiescent supply current drops to less than 1μA. Power-OK REG1, REG2 and REG3 each feature a variety of status bits that can be read by the system microprocessor. If any output falls below its powerOK threshold, typically 6% below the programmed regulation voltage, REGx/OK[ ] is cleared to 0. Soft-Start REG1, REG2 and REG3 each include matched soft-start circuitry. When enabled, the output voltages track the internal 80μs soft-start ramp and both power up in a monotonic manner that is independent of loading on either output. This circuitry ensures that each output powers up in a controlled manner, greatly simplifying power sequencing design considerations. Compensation REG1, REG2 and REG3 utilize current-mode control and a proprietary internal compensation scheme to simultaneously simplify external component selection and optimize transient performance over their full operating range. No compensation design is required; simply follow a few simple guide lines described below when choosing external components. Input Capacitor Selection Enabling and Disabling REG1, REG2 and REG3 REG1, REG2, and REG3 are typically enabled and disabled using the ACT8828's closed-loop enable/disable control scheme, including the nPBIN Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. The input capacitor reduces peak currents and noise induced upon the voltage source. A 4.7μF ceramic capacitor for each of REG1, REG2 and REG3 is recommended for most applications. - 28 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS FUNCTIONAL DESCRIPTION CONT’D Programming with Adjustable Option Output Capacitor Selection For most applications, 22μF ceramic output capacitors are recommended for REG1 and 10μF ceramic output capacitors are recommended for REG2, REG3. Although the these regulators were designed to take advantage of the benefits of ceramic capacitors, namely small size and very-low ESR, low-ESR tantalum capacitors can provide acceptable results as well. Figure 6 shows the feedback network necessary to set the output voltage when using the adjustable output voltage option. Select components as follows: Set RFB2 = 51kΩ, then calculate RFB1 using the following equation: Inductor Selection Where VFBx is 0.625V when REGx × VRANGE[ ] = 0 and 1.25V when REGx × VRANGE[ ] = 1 REG1, REG2 and REG3 utilize current-mode control and a proprietary internal compensation scheme to simultaneously simplify external component selection and optimize transient performance over their full operating range. ⎞ ⎛V R FB 1 = R FB 2 ⎜⎜ OUTx − 1 ⎟⎟ ⎠ ⎝ V FBx Figure 6: Output Voltage Programming OUTx The REG1, REG2 and REG3 of these devices was optimized for operation with and 3.3μH inductor, although inductors in the 2.2μH to 4.7μH range can be used. Choose an inductor with a low DC-resistance, and avoid inductor saturation by choosing inductors with DC ratings that exceed the maximum output current of the application by at least 30%. Output Voltage Programming By default, REG1, REG2 and REG3 each power up and regulate to their default output voltage, as defined in the Ordering Information section. Once the system is enabled, each regulator’s output voltage may be modified through either the I2C interface or the Voltage Selection (VSEL) pin. 2 Programming via the I C Interface Following startup, REG1, REG2, and REG3 may be independently programmed to different values by writing to the REGx/VSETx[_] and REGx/VRANGE[_] registers via the I2C interface. To program each regulator, first select the desired output voltage range via the REGx/VRANGE[ ] bit. Each regulator supports two overlapping ranges; set REGx/VRANGE[_] to 0 for voltages below 2.245V, set REGx/VRANGE[_] to 1 for voltages above 1.25V. Once the desired range has been selected, program the output to a voltage within that range by setting the REGx/VSETx bits. For more information about the output voltage setting options, refer to Tables 4, 7, and 10, for REG1, REG2, and REG3, respectively. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. (1) CFF ACT8828 RFB1 FBx RFB2 Finally choose CFF using the following equation: C FF = 2.2 × 10 −6 R FB1 (2) Where RFB1 = 47kΩ, use 47pF. When using Adjustable Option, OUTx pins works as FBx function. Output Voltage Selection Pin (VSEL) ACT8828's VSEL pin provides a simple means of alternating between two preset output voltage settings, such as may be needed for dynamic voltage selection (DVS). The operation of this pin is as follows: when VSEL is driven to GA or a logic low, the output voltages of REG1, REG2, and REG3 are each defined by their VSET0[ ] register. when VSEL is driven to VSYS or a logic high, the output voltages of REG1, REG2, and REG3 are each defined by their VSET1[ ] register. By default, each regulator's VSET0[ ] and VSET1[ ] registers are both programmed to the same voltage, as defined in the Ordering Information section. As a result, toggling VSET under default conditions has no affect. However, by re-programming one or more regulator's VSET0[ ] and/or VSET1[ ] registers, one can easily toggle these regulators' output voltages - 29 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-DOWN DC/DC CONVERTERS FUNCTIONAL DESCRIPTION CONT’D between two sets of voltages, such as to implement 'normal' and 'standby' modes in a system utilizing the ACT8828 to implement an advanced power management architecture. PCB Layout Considerations High switching frequencies and large peak currents make PC board layout an important part of stepdown DC/DC converter design. A good design minimizes excessive EMI on the feedback paths and voltage gradients in the ground plane, both of which can result in instability or regulation errors. Step-down DC/DCs exhibit discontinuous input current, so the input capacitors should be placed as close as possible to the IC, and avoiding the use of vias if possible. The inductor, input filter capacitor, and output filter capacitor should be connected as close together as possible, with short, direct, and wide traces. The ground nodes for each regulator’s power loop should be connected at a single point in a star-ground configuration, and this point should be connected to the backside ground plane with multiple vias. The output node for each regulator should be connected to its corresponding OUTx pin through the shortest possible route, while keeping sufficient distance from switching nodes to prevent noise injection. Finally, the exposed pad should be directly connected to the backside ground plane using multiple vias to achieve low electrical and thermal resistance. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 30 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-UP DC/DC CONVERTER ELECTRICAL CHARACTERISTICS (REG4) (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER CONDITIONS Input Voltage Range MIN TYP 2.9 2.7 UNIT 6 V 2.9 V Input UVLO Threshold Voltage Rising Input UVLO Hysteresis Voltage Falling 100 Quiescent Supply Current Not Switching 75 150 µA 0.1 1 µA 255 275 mV Supply Current in Shutdown FB4 Feedback Voltage 235 FB4 Input Current 2.8 MAX mV 50 nA Switching Frequency 1.35 1.6 1.85 MHz Maximum Duty Cycle 87 92 % Switch Current Limit Duty = 75% 800 mA Switch On-Resistance ISW4 = 100mA 0.45 Ω Switch Leakage Current VSW4 = 30V, VVSYS = 3.6V, ON4 = GA Over Voltage Protection Threshold Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. 10 28.5 - 31 - µA V www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-UP DC/DC CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (ACT8828QJ16C, TA = 25°C, unless otherwise specified.) REG4 Efficiency vs. Output Current 800 REG4 RDSON (mΩ) Efficiency (%) 6 LEDs ACT8828-013 4 LEDs 90 REG4 RDSON vs. VSYS Voltage 900 ACT8828-012 100 80 70 60 700 600 500 400 300 50 1 5 9 13 17 21 25 200 2.5 29 31 Output Current (mA) 3.0 3.5 REG4 Over-Voltage Protection 4.5 5.0 5.5 REG4 Startup Waveform ACT8828-015 ACT8828-014 CH1 4.0 VSYS Voltage (V) CH1 0V REG4/ON4[ ] = 1 CH2 0V REG4/ON4[ ] = 0 CH1: VOUT4, 10V/div CH2: VFB4, 200mV/div TIME: 2ms/div Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. CH1: VOUT4, 10V/div TIME: 100µs/div - 32 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-UP DC/DC CONVERTER REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 13: REG4 Control Register Map DATA ADDRESS D7 D6 D5 D4 D3 D2 D1 D0 40h R R R R R R R R 41h R R R R R R R R 42h R R R R R W/E OK ON 43h R R VSET R: Read-Only bits. Default Values May Vary. W/E: Write-Exact bits. Read/Write bits which must be written exactly as specified in Table 1. Table 14: REG4 Control Register Bit Descriptions ADDRESS NAME BIT ACCESS FUNCTION DESCRIPTION 40h [7:0] R READ ONLY 41h [7:0] R READ ONLY 0 REG4 Disable 1 REG4 Enable 0 Output is not OK 1 Output is OK 42h ON [0] R/W REG4 Enable 42h OK [1] R REG4 Power-OK 42h [2] W/E WRITE-EXACT 42h [7:3] R READ ONLY [5:0] R/W [7:6] R 43h 43h VSET REG4 Output Voltage Selection Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. See Table 15 READ ONLY - 33 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-UP DC/DC CONVERTER REGISTER DESCRIPTIONS CONT’D Table 15: REG4/VSET[ ] Over Voltage Threshold Setting REG4/VSET[4:3] REG4/VSET [2:0] VSET[5] = 1 VSET[5] = 0 00 01 10 11 00 01 10 11 000 5.00 7.00 9.00 11.00 13.00 17.00 21.00 25.00 001 5.25 7.25 9.25 11.25 13.50 17.50 21.50 25.50 010 5.50 7.50 9.50 11.50 14.00 18.00 22.00 26.00 011 5.75 7.75 9.75 11.75 14.50 18.50 22.50 26.50 100 6.00 8.00 10.00 12.00 15.00 19.00 23.00 27.00 101 6.25 8.25 10.25 12.25 15.50 19.50 23.50 27.50 110 6.50 8.50 10.50 12.50 16.00 20.00 24.00 28.00 111 6.75 8.75 10.75 12.75 16.50 20.50 24.50 28.50 Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 34 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-UP DC/DC CONVERTER FUNCTIONAL DESCRIPTION General Description REG4 is a highly efficient step-up DC/DC converter that employs a fixed frequency, current-mode, PWM architecture. This regulator is optimized for white-LED bias applications consisting of up to seven white-LEDs. Enabling and Disabling REG4 REG1 is typically enabled and disabled using the ACT8828's closed-loop enable/disable control scheme, including the nPBIN input. Refer to the System Startup and Shutdown section for more information about this function. Each regulator is enabled when the following conditions are met: 1) nPBIN is pushed low via 100kΩ resistance, Compensation and Stability REG4 utilizes current-mode control and an internal compensation network to optimize transient performance, ease compensation, and improve stability over a wide range of operating conditions. REG4 is a flexible regulator, and its external components can be chosen to achieve the smallest possible footprint or to achieve the highest possible efficiency. Inductor Selection REG4 was designed to provide excellent performance across a wide range of applications, but was optimized for operation with inductors in the 10µH to 22µH range, although larger inductor values of up to 68µH can be used to achieve the highest possible efficiency. 2) ON4 is asserted high to enable REG4, Optimizing for Smallest Footprint 3) REG4/ON4[ ] is set to 1 when ON4 is high REG4 is capable of operating with very low inductor values in order to achieve the smallest possible footprint. When solution size is of primary concern, best results are achieved when using an inductor that ensures discontinuous conduction mode (DCM) operation over the full load current range. When none of these conditions are true, REG4 is disabled, and each regulator’s quiescent supply current drops to less than 1μA. As with all non-synchronous step-up DC/DC converters, REG4’s application circuit produces a DC current path between the input and the output in shutdown mode. Although the forward drop of the WLEDs makes this leakage current very small in most applications, it is important to consider the effect that this may have in your application particularly when using fewer than three WLEDs. Over-Voltage Protection REG4 features internal over-voltage protection (OVP) circuitry which protects the system from LED open-circuit fault conditions. If the voltage at OV ever reaches the over-voltage threshold, REG4 will regulate the top of the LED strong to the OVP threshold voltage. By default, the ACT8828’s OVP threshold is set at 28.5V, although it may be programmed to a lower value by writing to the REG4/VSET[ ] register. Power-OK Bit REG4 features a Power-OK status bit that can be read by the system microprocessor via the I2C interface. If the voltage at OV is greater than the OVP threshold, REG4/OK[ ] will clear to 0. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. Optimizing for Highest Efficiency REG4 achieves excellent efficiency in applications that demand the longest possible battery life. When efficiency is the primary design consideration, best results are achieved when using an inductor that results in continuous conduction mode (CCM) operation and achieves very small inductor ripple current. Output Capacitor Selection REG4 was designed to operate with output capacitors ranging from 0.47µF to 10µF, providing design flexibility. A 1µF output capacitor is suitable for most applications, although larger output capacitors may be used to minimize output voltage ripple, if needed. Ceramic capacitors are recommended for most applications. Rectifier Selection REG4 requires a Schottky diode to rectify the inductor current. Select a low forward voltage drop Schottky diode with a forward current (IF) rating that is sufficient to support the maximum switch current and a sufficient peak repetitive reverse voltage (VRRM) to support the output voltage. - 35 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 STEP-UP DC/DC CONVERTER FUNCTIONAL DESCRIPTION CONT’D Setting the LED Bias Current The LED bias current is set by a resistor connected from FB4 and ground, and the regulator is satisfied when the LED current is sufficient to generate 250mV across this resistor. Once the bias current is programmed, the LED current can be adjusted using the ACT8828’s Direct-PWM feature. REG4 is also compatible with a variety of well-known LED dimming circuits, such as with a DC control voltage and a filtered PWM signal. PCB Layout Considerations High switching frequencies and large peak currents make PC board layout a very important part of the design. Good design minimizes excessive EMI on the feedback paths and voltage gradients in the ground plane, both of which can result in instability or regulation errors. Step-Up DC/DCs exhibit continuous input current, so there is some amount of flexibility in placing vias in the input capacitor circuit. The inductor, input filter capacitor, rectifier, and output filter capacitor should be connected as close together as possible, with short, direct, and wide traces. Connect the ground nodes together in a star configuration, with a direct connection to the exposed pad. Finally, the exposed pad should be directly connected to the backside ground plane using multiple vias to achieve low electrical and thermal resistance. Note that since the LED string is a low, DC-current path, it does not generally require special layout consideration. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 36 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER ELECTRICAL CHARACTERISTICS (VCHG_IN = 5V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 12 V 4.0 V ActivePath CHG_IN Operating Voltage Range 4.35 CHG_IN UVLO Threshold CHG_IN Voltage Rising CHG_IN UVLO Hysteresis CHG_IN Voltage Falling 0.8 V CHG_IN OVP Threshold CHG_IN Voltage Rising 6.8 V CHG_IN OVP Hysteresis CHG_IN Voltage Falling 350 mV VCHG_IN < VUVLO 20 µA CHG_IN Supply Current CHG_IN to VSYS On-Resistance CHG_IN to VSYS Current Limit VCHG_IN < VBAT + 120mV , VCHG_IN > VUVLO 3.6 50 3.8 120 200 µA VCHG_IN > VBAT + 120mV , VCHG_IN > VUVLO Charger disabled, ISYS = 0mA 1.8 IVSYS = 100mA 0.4 0.6 Ω A mA ACIN = VSYS 1.5 2 3 ACIN = GA, CHGLEV = GA 85 95 105 ACIN = GA, CHGLEV = VSYS 400 450 500 mA VSYS AND DCCC REGULATION VSYS Regulated Voltage IVSYS = 10mA 4.4 4.6 4.8 V DCCC Pull-Up Current VCHG_IN > VBAT + 120mV, Hysteresis = 50mV 92 100 108 µA nSTAT Sink current VnSTAT = 2V 3 5 7 mA nSTAT Output Low Voltage InSTAT = 1mA 0.4 V nSTAT Leakage Current VnSTAT = 4.2V 1 µA nSTAT OUTPUT ACIN AND CHGLEV INPUTS CHGLEV Logic High Input Voltage 1.4 V CHGLEV Logic Low Input Voltage CHGLEV Leakage Current VCHGLEV = 4.2V ACIN Logic High Input Voltage V 1 µA 1.4 V ACIN Logic Low Input Voltage ACIN Leakage Current 0.4 VACIN = 4.2V 0.4 V 1 µA TEMPERATURE SENSE COMPARATOR TH Pull-Up Current VCHG_IN > VBAT + 120mV, Hysteresis = 50mV 92 100 108 µA VTH Upper Temperature Voltage Threshold (VTHH) Hot Detect NTC Thermistor 0.485 0.500 0.525 V VTH Lower Temperature Voltage Threshold (VTHL) Cold Detect NTC Thermistor 2.47 2.52 2.57 V VTH Hysteresis Upper and Lower Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. 30 - 37 - mV www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM CHARGER TYP MAX UNIT ActivePath ELECTRICAL CHARACTERISTICS CONT’D (VCHG_IN = 5V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS MIN CHARGER BAT Reverse Leakage Current VCHG_IN = 0V, VBAT = 4.2V, IVSYS = 0mA BAT to VSYS On-Resistance ISET Pin Voltage Battery Regulation Voltage Charge Current mΩ Precondition 0.12 TA = -20°C to 70°C 4.179 TA = -40°C to 85°C 4.170 4.2 V 4.221 4.230 ACIN = VSYS, CHGLEV = VSYS -10% ISET1 +10% ACIN = VSYS, CHGLEV = GA -16% 50%ISET +16% VBAT = 3.5V ACIN = GA, CHGLEV = VSYS -10% Smallest (450mA or +10% ISET) -10% Smallest (90mA or ISET) ACIN = VSYS, CHGLEV = VSYS 12%ISET ACIN = VSYS, CHGLEV = GA 12%ISET VBAT = 2.5V ACIN = GA, CHGLEV = VSYS 12%ISET VBAT Voltage Rising End-of-Charge Current Threshold VBAT = 4.2V 2.75 mA +10% mA 2.85 2.95 100 -10% 10%ISET +10% ACIN = VSYS, CHGLEV = GA -10% 10%ISET +10% ACIN = GA, CHGLEV = VSYS -10% 5%ISET +10% ACIN = GA, CHGLEV = GA -10% 5%ISET +10% 150 170 190 BTR Scale Factor V mV ACIN = VSYS, CHGLEV = VSYS VVSYS - VBAT, VBAT Falling V Smallest (90mA or 12%ISET) Precondition Threshold Hysteresis VBAT Voltage Falling Charge Restart Threshold 80 1.02 ACIN = GA, CHGLEV = GA Precondition Threshold Voltage µA Fast Charge ACIN = GA, CHGLEV = GA Precondition Charge Current 5 mA mV 0.24 s/Ω Precondition Safety Timer RBTR = 47kΩ, tPRCHG = 0.24 × RBTR(Ω)/180(min) 1 hr Fast Charge Safety Timer RBTR = 47kΩ, tCHG = 0.24 × RBTR(Ω)/60(min) 3 hr THERMAL REGULATION Thermal Regulation Threshold 100 145 °C : ISET = 640 x (1V/RISET) Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 38 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER TYPICAL PERFORMANCE CHARACTERISTICS (VCHG_IN = 5V, TA = 25°C, unless otherwise specified.) SYS Output Voltage vs. DC Voltage SYS Voltage vs. SYS Current 4.6 4.15 SYS Voltage (V) SYS Voltage (V) 4.7 4.5 4.4 4.3 4.2 No Load ACIN = 1 CHGLEV = 1 ISYS = 10mA 4.1 ACT8828-017 4.25 ACT8828-016 4.8 4.05 3.95 3.85 VBAT = 4.2V 3.75 4.0 0 2 4 6 8 10 12 14 0 1000 CHG_IN Voltage (V) Charger Current vs. Battery Voltage Charger Current vs. Battery Voltage (USB Mode) Charger Current (mA) Charger Current (mA) 450 VBAT Falling VBAT Rising 20 CHG_IN = 5V ISYS = 0 mA 100mA USB 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Battery Voltage Falling 400 350 Battery Voltage Rising 300 250 200 150 100 CHG_IN = 5V ISYS = 0mA 500mA USB 50 0 0.0 4.5 0.5 1.0 2.5 3.0 3.5 4.0 4.5 Battery Voltage Falling Fast Charger Current (mA) ISYS = 0mA 800 Battery Voltage Rising 600 400 200 0 ACT8828-021 1200 ACT8828-020 Charger Current (mA) 2.0 Fast Charge Current vs. Ambient Temperature Charger Current vs. Battery Voltage (AC Mode) 1000 1.5 Battery Voltage (V) Battery Voltage (V) 1200 ACT8828-019 500 ACT8828-018 80 40 3000 SYS Current (mA) 100 60 2000 1000 ACIN, CHGLEV = 11 800 ACIN, CHGLEV = 10 600 400 ACIN, CHGLEV = 01 200 ACIN, CHGLEV = 00 0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 -40 4.5 ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. 0 20 40 60 80 100 120 140 Ambient Temperature (°C) Battery Voltage (V) Innovative PowerTM -20 - 39 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (VCHG_IN = 5V, TA = 25°C, unless otherwise specified.) VAC Applied, CHGLEV = HIGH VAC Applied, CHGLEV = LOW CH2 ACT8828-023 ACT8828-022 CH1 CH1 CH2 CH3 CH3 100mA 450mA CH4 CH4 CH1: VUSB, 2.00V/div CH2: VCHG_IN, 2.00V/div CH3: IBAT, 500mA/div CH4: VVAC, 2.00V/div TIME: 400µs/div CH1: VUSB, 2.00V/div CH2: VCHG_IN, 2.00V/div CH3: IBAT, 500mA/div CH4: VVAC, 2.00V/div TIME: 400µs/div VAC Removed, CHGLEV = LOW VAC Removed, CHGLEV = HIGH CH2 ACT8828-025 ACT8828-024 CH1 CH1 CH2 CH3 CH3 100mA 450mA CH4 CH4 CH1: VUSB, 2.00V/div CH2: VCHG_IN, 2.00V/div CH3: IBAT, 500mA/div CH4: VVAC, 2.00V/div TIME: 400µs/div CH1: VUSB, 2.00V/div CH2: VCHG_IN, 2.00V/div CH3: IBAT, 500mA/div CH4: VVAC, 2.00V/div TIME: 400µs/div Battery Leakage Current vs. Battery Voltage Battery Leakage Current (µA) ACT8828-026 10 8 6 4 2 0 0 1 2 3 No CHG_IN CHGLEV = 0 4 5 Battery Voltage (V) Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 40 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER FUNCTIONAL DESCRIPTION System Configuration Optimization General Description The ACT8828 incorporates Active-Semi's patentpending ActivePath architecture. ActivePath is a complete battery-charging and system powermanagement solution for portable hand-held equipment. This circuitry performs a variety of advanced battery-management functions, including automatic selection of the best available input supply, current-management to ensure system power availability, and a complete, high-accuracy (±0.5%), thermally regulated, full-featured singlecell linear Li+ charger with an integrated 12V power MOSFET. ActivePath Architecture Active-semi's patent-pending ActivePath architecture performs three important functions: 1) Input Protection, 2) System Configuration Optimization, and ActivePath circuitry automatically detects the state of the input supply, the battery, and the system, and automatically reconfigures itself to optimize the power system. If the input supply is present, ActivePath powers the system in parallel with charging the battery, so that system power and charge current can be independently managed to satisfy all system power requirements. This allows the battery to charge as quickly as possible, while ensuring that the total system current does not exceed the capability of the input supply. If the input supply is not present, however, then ActivePath automatically configures the system to draw power from the battery. Finally, if the input is present and the system current requirement exceeds the capability of the input supply, such as under momentary peak-power consumption conditions, ActivePath automatically configures itself for maximum power capability by drawing system power from both the battery and the input supply. 3) Battery-Management Battery Management Input Protection At the input of the ACT8828's ActivePath circuit is an internal, low-dropout linear regulator (LDO) that regulates the system voltage (VSYS). This LDO features a 12V power MOSFET, allowing the ActivePath system to withstand input voltages of up to 12V, and additionally includes a variety of other protection features, including current limit protection and input over-voltage protection. The ActivePath circuitry provides a very simple means of implementing a solution that safely operates within the current-capability limitations of a USB port while taking advantage of the high outputcurrent capability of an AC adapter, when available. ActivePath limits the total current drawn from the input supply to a value set by the ACIN input; when ACIN is driven to a logic-low ActivePath operates in “USB Mode” and limits the current to either 500mA (when CHGLEV is driven to a logic-high) or to 100mA (when CHGLEV is driven to a logic-low), and when ACIN is driven to a logic-high ActivePath operates in “AC-Mode” and limits the input current to 2A. In either case, ActivePath's DCCC circuitry, described below, allows the input overload protection to be adjusted to accommodate a wide range of input supplies. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. ActivePath includes a full-featured battery charger for single-cell Li-based batteries. This charger is a full-featured, intelligent, linear-mode, single-cell charger for Lithium-based cells, and was designed specifically to provide a complete charging solution with minimum system design effort. The core of the ActivePath's charger is a CC/CV (Constant-Current/Constant-Voltage), linear-mode charge controller. This controller incorporates current and voltage sense circuitry, an internal 80mΩ power MOSFET, a full-featured statemachine that implements charge control and safety features, and circuitry that eliminates the reverseblocking diode required by conventional charger designs. This charger also features thermal-regulation circuitry that protects it against excessive junction temperature, allowing the fastest possible charging times, as well as proprietary input protection circuitry that makes the charger robust against input voltage transients that can damage other chargers. The charge termination voltage is highly accurate (±0.5%), and features a selection of charge safety timeout periods that protect the system from operation with damaged cells. Other features include pin-programmable fast-charge current and - 41 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER FUNCTIONAL DESCRIPTION CONT’D current-limited nSTAT outputs that can directly drive LED indicators or provide a logic-level status signal to the host microprocessor. Dynamic Charge Current Control (DCCC) The ACT8828's ActivePath charger features Dynamic Charge Current Control (DCCC) circuitry, which continuously monitors the input supply and prevents input overload conditions by dynamically adjusting the charge current to keep the input voltage from dropping below the DCCC voltage threshold. When ACIN is driven to a logic-low, the circuitry operates in “USB-Mode”, which maximum charge current setting of CHGLEV is driven to a logic-high, or CHGLEV is driven to a logic-low. The ACT8828's charge current summarized in the table below: ACIN CHGLEV Where RDCCC is the value of the external resistor, and IDCCC is the value of the current sourced from DCCC, typically 100μA. The ACT8828's ActivePath charger features a flexible charge current-programming scheme that combines the convenience of internal charge current programming with the flexibility of resistor based charge current programming. Current limits and charge current programming are managed as a function of the ACIN and CHGLEV pins, in combination with RISET, the resistance connected to the ISET pin. ACIN and CHGLEV Inputs ACIN is a logic input that configures the current-limit of ActivePath's linear regulator as well as that of the battery charger. ACIN features a precise 1.25V logic threshold, so that the input voltage detection threshold may be adjusted with a simple resistive voltage divider. This input also allows a simple, lowcost dual-input charger switch to be implemented with just a few, low-cost components. When ACIN is driven to a logic high, the ActivePath operates in “AC-Mode” and the charger charges at the current programmed by RISET, ICHG = 1V/RISET × KISET (3) where KISET = 640 when CHGLEV is driven to a logic high, and K = 320 when CHGLEV is driven to a logic low. are ACIN and CHGLEV Inputs Table CHARGE CURRENT ICHG (mA) PRECONDITION CHARGE CURRENT ICHG (mA) 0 0 90mA or 12% ISET (Smallest one) 90mA or 12%ISET (Smallest one) 0 1 450mA or ISET (Smallest one) 12% × ISET 1 0 50% × ISET 12% × ISET 1 1 ISET 12% × ISET (2) Charger Current Programming settings Table 16: By default, the DCCC voltage threshold is set to 4.4V, but it may also be programmed by connecting a resistor from DCCC to GA, where the resistor has value given by the following equation: VDCCC = 2 × (IDCCC × RDCCC) ActivePath enforces a 500mA, if 100mA, if Note that the actual charging current may be limited to a current that is lower than the programmed fast charge current due to the ACT8828’s internal thermal regulation loop. See the Thermal Regulation and Protection section for more information. Battery Temperature Monitoring The ACT8828 continuously monitors the temperature of the battery pack by sensing the resistance of its thermistor, and suspends charging if the temperature of the battery pack exceeds the safety limits. In a typical application, shown in Figure 7, the TH pin is connected to the battery pack's thermistor input. The ACT8828 injects a 100µA current out of the TH pin into the thermistor, so that the thermistor resistance is monitored by comparing the voltage at TH to the internal VTHH and VTHL thresholds of 0.5V and 2.5V, respectively. When VTH > VTHL or VTH < VTHH charging and the charge timers are suspended. When VTH returns to the normal range, charging and the charge timers resume. The net resistance from TH to G required to cross the threshold is given by: 100µA × RNOM × kHOT = 0.5V → RNOM × kHOT = 5kΩ 100µA × RNOM × kCOLD = 2.5V → RNOM × kCOLD = 25kΩ Innovative Power TM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 42 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER FUNCTIONAL DESCRIPTION CONT’D where RNOM is the nominal thermistor resistance at room temperature, and kHOT and kCOLD are the ratios of the thermistor's resistance at the desired hot and cold thresholds, respectively. Figure 7: RNOM = 5kΩ/kHOT, and Simple Configuration RNOM = 25kΩ/kCOLD where kHOT and kCOLD for a given thermistor can be found on its characteristic tables. ACT8828 100µA + VTHH – + Li+ Battery Pack TH + – requirements with very little design effort, but also provides flexibility when additional control over a design is required. Initial thermistor selection is accomplished by choosing one that best meets the following requirements: NTC VTHL – Taking a 0°C to 40°C application using a "curve 2" NTC for this example, from the characteristic tables one finds that kHOT and kCOLD are 0.5758 and 2.816, respectively, and the RNOM that most closely satisfies these requirements is therefore around 8.8kΩ. Selecting 10kΩ as the nearest standard value, calculate kCOLD and kHOT as: kCOLD = VTHL/(ITH × RNOM) = 2.5V/(100µA × 10kΩ) = 2.5 Design Procedure When designing with thermistors it is important to keep in mind that their nonlinear behavior typically allows one to directly control no more than one threshold at a time. As a result, the design procedure can change depending on which threshold is most critical for a given application. Most application requirements can be solved using one of three cases, kHOT = VTHH/(ITH × RNOM) = 0.5V/(100µA × 10kΩ) = 0.5 Identifying these values on the curve 2 characteristic tables indicates that the resulting operating temperature range is 2°C to 44°C, vs. the design goal of 0°C to 40°C. This example demonstrates that one can satisfy common operating temperature ranges with very little design effort. Fix VTHH 1) Simple solution 2) Fix VTHH, accept the resulting VTHL 3) Fix VTHL, accept the resulting VTHH The ACT8828 was designed to achieve an operating temperature range that is suitable for most applications with very little design effort. The simple solution is often found to provide reasonable results and should always be used first, then the design procedure may proceed to one of the other solutions if necessary. In each design example, we refer to the Vishay NTHS series of NTCs, and more specifically those which follow a "curve 2" characteristic. For more information on these NTCs, as well as access to the resistance/temperature characteristic tables referred to in the example, please refer to the Vishay website at http://www.vishay.com/thermistors. Simple Solution The ACT8828 was designed to accommodate most Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. For demonstration purposes, supposing that we had selected the next closest standard thermistor value of 6.8kΩ in the example above, we would have obtained the following results: kCOLD = VTHL/(ITH × RNOM) = 2.5V/(100µA × 6.8kΩ) = 3.67 kHOT = VTHH/(ITH × RNOM) = 0.5V/(100µA × 6.8kΩ) = 0.74 which, according to the characteristic tables would have resulted in an operating temperature range of -6°C to 33°C vs. the design goal of 0°C to 40°C. In this case, one can add resistance in series with the thermistor to shift the range upwards, using the following equation: (VTHH/ITH) = kHOT(@40°C) × RNOM + R R = (VTHH/ITH) - kHOT(@40°C) × RNOM R = (2.5V/100µA) - 0.5758 × 6.8kΩ Finally, R = 5kΩ - 3.9kΩ = 1.1kΩ - 43 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER FUNCTIONAL DESCRIPTION CONT’D This result shows that adding 1.1kΩ in series with the thermistor sets the net resistance from TH to G to be 0.5V at 40°C, satisfying VTHH at the correct temperature. Adding this resistance, however, also impacts the lower temperature limit as follows: parallel with ITH. The desired resistance can be found using the following equation: VTHL/ITH = kCOLD(@TC) × RNOM + R R = (VCHG_IN - VTHL)/(VTHL/(kCOLD(@0°C) × RNOM) - ITH) kCOLD(@TC) = (VTHL/ITH) - R)/RNOM R = (5V - 2.5V)/(2.5V/(2.816 × 6.8kΩ) - 100µA) Finally, R = 82kΩ kCOLD(@TC) = (25kΩ - 1.1kΩ)/6.8kΩ = 3.51 Adding 82kΩ in parallel with the current source increases the net current flowing into the thermistor, thus increasing the voltage at TH. Adding this resistance, however, also impacts the upper temperature limit: Reviewing the characteristic curves, the lower threshold is found to move to -5°C, a change of only 1°C. As a result, the system satisfies the upper threshold of 40°C with an operating temperature range of -5°C to 40°C, vs. our design target of 0°C to 40°C. It is informative to highlight that due to the NTC behavior of the thermistor, the relative impact on the lower threshold is significantly smaller than the impact on the upper threshold. Fix VTHL (ITH + (VCHG_IN - VTHL)/R) × kCOLD(@0°C) × RNOM = VTHL Rearranging yields VTHH = (ITH + (VCHG_IN - VTHH)/R) × kHOT(@40°C) × RNOM Rearranging yields, kHOT(@TC) = VTHH/(RNOM × (ITH + (VCHG_IN - VTHH)/R)) kHOT(@TC) = 0.5V/(6.8kΩ × (100µA + (5V - 0.5V)/82kΩ)) = 0.4748 Following the same example as above, the "unadjusted" results yield an operating temperature range of -6°C to 33°C vs. the design goal of 0°C to 40°C. In applications that favor VTHL over VTHH, however, one can control the voltage present at TH at low temperatures by connecting a resistor in Reviewing the characteristic curves, the upper threshold is found to move to 45°C, a change of about 14°C. Adding the parallel resistance has allowed us to achieve our desired lower threshold of 0°C with an operating temperature range of 0°C to 45°C, vs. our design target of 0°C to 40°C. Figure 8: Figure 9: Fix VTHH Configuration Fix VTHL Configuration ACT8828 ACT8828 + + VTHH – TH R Li+ Battery Pack + NTC VTHL VTHH – + – CHG_IN 100µA 100µA – ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. Li+ Battery Pack TH + – Innovative PowerTM + R - 44 - NTC VTHL – www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER FUNCTIONAL DESCRIPTION CONT’D Thermal Regulation Table 17: The ACT8828's ActivePath charger features an internal thermal regulation loop that reduces the charging current as necessary to ensure that the die temperature does not rise beyond the thermal regulation threshold of 110°C. This feature protects the against excessive junction temperature and makes the device more accommodating to aggressive thermal designs. Note, however, that attention to good thermal designs is required to achieve the fastest possible charge time by maximizing charge current. Charging Status Indication Table In order to account for the reduced charge current resulting from operation in thermal regulation mode, the charge timeout periods are extended proportionally to the reduction in charge current. Charging Safety Timers The ACT8828 features a safety timer that is programmable via an external resistor (RBTR) connected from BTR to GA. The timeout period is calculated as a function of this resistor by the following equation: tCHG = KBTR × RBTR, where KBTR = 0.24s/Ω. If the timeout period expires prior to charge termination, the charger is disabled and the nSTAT pin signal a fault condition. If the ACT8828 detects that the charger remains in precondition for longer than the precondition time out period (which determined as tCHG/3), the ACT8828 turns off the charger and generate a FAULT to ensure prevent charging a bad cell. Charging Status Indication The ACT8828 provides one charge-status output, nSTAT which indicates charge status as defined in Table 17. nSTAT is open-drain output with internal 5mA current limits, which sinks current when asserted and are high-Z otherwise, and is capable of directly driving LED without the need of currentlimiting resistor or other external circuitry. To drive an LED, simply connect the LED between nSTAT pin and an appropriate supply (typically VSYS). For a logic level indication, simply connect a resistor from nSTAT to a appropriate voltage supply. Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. STATE nSTAT Charging ON Discharging OFF Charging Complete OFF Input Floating OFF Fault OFF Input Supply Detection The ACT8828's ActivePath charger is capable of withstanding voltages of up to 12V, protecting the system from fault conditions such as input voltage transients or application of an incorrect input supply. Although the ACT8828 can withstand a wide range of input voltages, valid input voltages for charging must be greater than the under-voltage lockout voltage (UVLO) and the over-voltage protection (OVP) thresholds, as described below. Under Voltage Lock Output (UVLO) Whenever the input voltage applied to CHG_IN falls below 3.8V (typ), an input under-voltage condition is detected and the charger is disabled. Once an input under-voltage condition is detected, the input must exceed the under-voltage threshold by at least 800mV for charging to resume. Over Voltage Protection (OVP) If the charger detects that the voltage applied to CHG_IN exceeds 6.8V (typ), an over-voltage condition is detected and the charger is disabled. Once an input over-voltage condition is detected, the input must fall below the OVP threshold by at least 400mV for charging to resume. Reverse Leakage Current The ACT8828's ActivePath charger includes internal circuitry that eliminates the need for blocking diodes, reducing solution size and cost as well as dropout voltage relative to conventional battery chargers. When the voltage at CHG_IN falls below VBAT, the charger automatically reconfigures its power switch to minimize current drain from the battery - 45 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER Figure 10: Typical Li+ Charge Profile and ACT8828 Charge States VSET RECHARGE ISET Current Voltage VPRECHARGE 12% ISET STATE A B C D E B A: PRECONDITION State B: FAST-CHARGE State C: TOP-OFF State D: SLEEP State E: DISCHARGE State Figure 11: Charger State Diagram ANY STATE BATTERY REMOVED OR VCHG_IN < VBAT + 120mV OR VCHG_IN < UVLO SUSPEND BATTERY REPLACED AND VCHG_IN > VBAT + 120mV AND VCHG_IN > UVLO T > TPRECONDITION AND VBAT < 2.85V TIMEOUT-FAULT PRECONDITION VBAT > 2.85V T > TNORMAL AND VBAT < VTERM FAST-CHARGE VBAT = VTERM TOP-OFF IBAT < ITERM IBAT > ITERM DELAY SLEEP VBAT < VTERM – 170mV Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 46 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER FUNCTIONAL DESCRIPTION CONT’D End of Charge State Charger State-Machine PRECONDITION State A new charging cycle begins with the PRECONDITION state, and operation continues in this state until VBAT exceeds the Precondition Threshold Voltage of 2.85V (typ). When operating in PRECONDITION state, the cell is charged at a reduced current, 12% of the programmed maximum fast-charge constant current, ISET. Once VBAT reaches the Precondition Threshold Voltage the state machine jumps to the NORMAL state. If VBAT does not reach the Precondition Threshold Voltage before the Precondition Timeout period tPRECONDITION expires, then a damaged cell is detected and the state machine jumps to the TIMEOUT-FAULT State. For the Precondition Timeout period, see the Charging Safety Timers section for more information. FAST CHARGE State Normal state is made up of two operating modes, fast charge Constant-Current (CC) and ConstantVoltage (CV). In CC mode, the ACT8828 charges at the current programmed by RISET (see the Current Limits and Charge Current Programming section for more information). During a normal charge cycle fast-charge continues in CC mode until VBAT reaches the charge termination voltage (VTERM), at which point the ACT8828 charges in CV mode. Charging continues in CV mode until the charge current drops to 10% (ACIN = 1) or 5% (ACIN = 0) of the programmed maximum charge current, at which point the state machine jumps to the TOPOFF state. If VBAT does not proceed out of the NORMAL state before the Normal Timeout period (TNORMAL) expires, then a damaged cell is detected and the state machine jumps to the TIMEOUTFAULT State. See the Charging Safety Times section for more information. In the End-of-Charge (EOC) state, the ACT8828 presents a high-impedance to the battery, allowing the cell to “relax” and minimizes battery leakage current. The ACT8828 continues to monitor the cell voltage, however, so that it can re-initiate charging cycles as necessary to ensure that the cell remains fully charged. SUSPEND State The ACT8828 features an user-selectable suspendcharge mode, which disables the charger but keeps other circuiting functional. The charger can be put into suspend mode by driving EN to logic low. Upon exiting the SUSPEND State, the charge timer is reset and the state machine jumps to PRECONDITION state. SLEEP State In SLEEP mode the ACT8828 presents a highimpedance to the battery, allowing the cell to “relax” and minimizes battery leakage current. The ACT8828 continues to monitor the cell voltage, however, so that it can re-initiate charging as necessary to ensure that the cell remains fully charged. Under normal operation, the state machine initiates a new charging cycle by jumping to the FAST-CHARGE state when VBAT drops below the Charge Termination Threshold. CHG_IN Bypass Capacitor Selection TOP-OFF State CHG_IN is the power input for the ACT8828 battery charger. The battery charger is automatically enabled whenever a valid voltage is present on CHG_IN. In most applications, CHG_IN is connected to either a wall adapter or USB port. Under normal operation, the input of the charger will often be “hot-plugged” directly to a powered USB or wall adapter cable, and supply voltage ringing and overshoot may appear at the CHG_IN pin. In the TOP-OFF state, the cell is charged in constant-voltage (CV) mode. Charge current decreases as charging continues. During a normal charging cycle charging proceeds until the charge current decreases below the End-Of-Charge (EOC) threshold, defined as 10% of ISET (ACIN = 1) or 5% of ISET (ACIN = 0) . When this happens, the state machine terminates the charge cycle and jumps to the SLEEP state. In most applications a high quality capacitor connected from CHG_IN to GA, placed as close as possible to the IC, is sufficient to absorb the energy. Wall-adapter powered applications provide flexibility in input capacitor selection, but the USB specification presents limitations to input capacitance selection. In order to meet both the USB 2.0 and USB OTG (On The Go) specifications while avoiding USB supply under-voltage conditions Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 47 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 TM ActivePath CHARGER FUNCTIONAL DESCRIPTION CONT’D resulting from the current limit slew rate (100mA/µS) limitations of the USB bus, the CHG_IN bypass capacitance value must to be between 4.7µF and 10µF for the ACT8828. Ceramic capacitors are often preferred for bypassing applications due to their small size and good surge current ratings, but care must be taken in applications that can encounter hot plug conditions as their very low ESR, in combination with the inductance of the cable, can create a highQ filter that induces excessive ringing at the CHG_IN pin. This ringing can couple to the output and be mistaken as loop instability, or the ringing may be large enough to damage the input itself. Although the CHG_IN pin is designed for maximum robustness and an absolute maximum voltage rating of 14V for transients, attention must be given to bypass techniques to ensure safe operation. As a result, design of the CHG_IN bypass must take care to “de-Q” the filter. This can be accomplished by connecting a 1Ω resistor in series with a ceramic capacitor (as shown in Figure 12), or by using a tantalum or electrolytic capacitor to utilize it’s higher ESR to dampen the ringing. For additional protection in extreme situations, Zener diodes with 12V clamp voltages may also be used. In any case, it is always critical to evaluate voltage transients at the ACT8828 CHG_IN pin with an oscilloscope to ensure safe operation. Figure 12: CHG_IN Bypass Options for USB or Wall Adaptor Supplies Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 48 - www.active-semi.com Copyright © 2009 Active-Semi, Inc. ACT8828 Active-Semi Rev 3, 24-Sep-09 PACKAGE OUTLINE AND DIMENSIONS PACKAGE OUTLINE TQFN55-40 PACKAGE OUTLINE AND DIMENSIONS D D/2 SYMBOL A E/2 A1 E A L MAX MIN MAX 0.700 0.800 0.028 0.031 0.200 REF 0.008 REF 0.050 0.000 0.002 b 0.150 0.250 0.006 0.010 D 4.900 5.100 0.193 0.201 E 4.900 5.100 0.193 0.201 D2 3.450 3.750 0.136 0.148 E2 3.450 3.750 0.136 0.148 R b MIN 0.000 L D2 DIMENSION IN INCHES A2 e A2 A1 DIMENSION IN MILLIMETERS 0.400 BSC 0.300 0.500 0.300 0.016 BSC 0.012 0.020 0.012 e E2 R Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. Users should evaluate each product to make sure that it is suitable for their applications. Active-Semi products are not intended or authorized for use as critical components in life-support devices or systems. Active-Semi, Inc. does not assume any liability arising out of the use of any product or circuit described in this datasheet, nor does it convey any patent license. Active-Semi and its logo are trademarks of Active-Semi, Inc. For more information on this and other products, contact [email protected] or visit http://www.active-semi.com. For other inquiries, please send to: 2728 Orchard Parkway, San Jose, CA 95134-2012, USA Innovative PowerTM ActivePMUTM and ActivePathTM are trademarks of Active-Semi. I2CTM is a trademark of Philips Electronics. - 49 - www.active-semi.com Copyright © 2009 Active-Semi, Inc.