ACT8712 Rev0, 25-Feb-08 Advanced Product Information―All Information Subject to Change Four Channel Integrated Power Management IC for Handheld Portable Equipment FEATURES GENERAL DESCRIPTION • Multiple Patents Pending • Li+ Battery Charger with Integrated MOSFET The patent-pending ACT8712 is a complete, cost effective, highly efficient ActivePMUTM power management solution that is ideal for a wide range of portable handheld equipment. This device integrates two PWM step-down DC/DC converters, one PWM step-up DC/DC converter with over-voltage protection (OVP) and a full-featured linear-mode Li+ battery charger into a single, thin, space-saving package. An I2C Serial Interface provides programmability for the DC/DC converters and battery charger. − Programmable Charge Current up to 1A − ON/OFF Control and Status Indication • Three Integrated Regulators − 550mA Step-Down DC/DC − 750mA Step-Down DC/DC − Step-Up DC/DC with OVP for WLED Bias • I2CTM Compatible Serial Interface − Programmable Output Voltages − Configurable Operating Modes REG1 and REG2 are fixed-frequency, current-mode PWM step-down DC/DC converters that are optimized for high efficiency and are capable of supplying up to 550mA and 750mA, respectively. REG3 is a fixed-frequency PWM step-up converter that safely and efficiently biases a string of up to seven white-LEDs for backlighting. The battery charger incorporates an internal power MOSFET for constant-current/constant-voltage, thermally regulated charging of a single-cell Li+ battery. All DC/DC converters’ output voltage are programmable and controllable via the I2C interface. • Minimal External Components • 4x4mm, Thin-QFN (TQFN44-24) Package − Only 0.75mm Height − RoHS Compliant APPLICATIONS • Portable Devices and PDAs • Digital Media Players The ACT8712 is available in a tiny 4mm x 4mm 24-pin Thin-QFN package that is just 0.75mm thin. • Battery Operated Devices • GPS Receivers, etc. SYSTEM BLOCK DIAGRAM VIN CHGLEV nSTAT nMSTR nIRQ nRSTO SCL SDA ON1 ON2 Battery Programmable Up to 1A Single-Cell Li+ Battery Charger REG1 Step-Down DC/DC System Control REG2 Step-Down DC/DC REG3 ACT8712 PMU Active Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. OUT1 1.1V to 4.4V Up to 550mA Step-Up DC/DC TM -1- OUT2 1.1V to 4.4V Up to 750mA Pb-free OUT3 WLED Bias www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 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 Electrical Characteristics .................................................................................................... p. 09 I2C Interface Electrical Characteristics ............................................................................... p. 10 Typical Performance Characteristics ................................................................................. p. 11 Functional Description ....................................................................................................... p. 12 STEP-DOWN DC/DC CONVERTERS ...................................................................... P. 14 Electrical Characteristics ................................................................................................... p. 14 Register Descriptions ......................................................................................................... p. 15 Typical Performance Characteristics ................................................................................. p. 20 Functional Description ....................................................................................................... p. 21 WLED BIAS DC/DC CONVERTER ......................................................................... P. 23 Electrical Characteristics .................................................................................................... p. 23 Register Descriptions ......................................................................................................... p. 24 Typical Performance Characteristics ................................................................................. p. 26 Functional Description ....................................................................................................... p. 27 SINGLE-CELL Li+ BATTERY CHARGER ............................................................... P. 29 Electrical Characteristics .................................................................................................... p. 29 Register Descriptions ......................................................................................................... p. 30 Typical Performance Characteristics ................................................................................. p. 32 Functional Description ....................................................................................................... p. 33 PACKAGE INFORMATION ...................................................................................... P. 36 Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. -2- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 FUNCTIONAL BLOCK DIAGRAM VSYS BODY AND VSYS CONTROL AC Adaptor or USB ACT8712 VIN 4.3V to 6V BAT Li+ Battery + CURRENT SENSE VINUVLO nSTAT 4.0V VOLTAGE SENSE CHARGE STATUS OUT2 Charge Control CHGLEV FLOAT PRECONDITION 2.9V THERMAL REGULATION 110°C VP1 To Battery SCL Serial Interface SDA REG1 OUT2 nRSTO SW1 OUT1 OUT1 GP12 VP2 To Battery VSYS REG2 nMSTR PUSH BUTTON OUT2 SW2 OUT2 OUT2 GP12 nIRQ System Control SW3 ON1 OVP3 REG3 ON2 GA Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. To Battery OUT3 -3- FB3 GP3 www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 ORDERING INFORMATIONcd PART NUMBER VOUT1 VOUT2 PACKAGE PINS TEMPERATURE RANGE ACT8712QLCHA-T 1.2V 3.3V TQFN44-24 24 -40°C to +85°C ACT8712QLEHA-T 1.8V 3.3V TQFN44-24 24 -40°C to +85°C OUTPUT VOLTAGE CODES C D E F G H 1.2V 1.5V 1.8V 2.5V 3.0V 3.3V c: Output voltage options detailed in this table represent standard voltage options, and are available for samples or production orders. Additional output voltage options, as detailed in the Output Voltage Codes table, are available for production subject to minimum order quantities. Contact Active-Semi for more information regarding semi-custom output voltage combinations. d: 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. PIN CONFIGURATION TOP VIEW BAT CHGLEV nSTAT SW3 GP3 OVP3 24 23 22 21 20 19 VIN 1 18 FB3 SCL 2 17 GA SDA 3 16 VSYS nIRQ 4 nMSTR 5 nRSTO 6 15 ON1 ACT8712 14 ON2 EP 10 11 12 GP12 SW2 VP2 9 SW1 OUT1 8 VP1 7 13 OUT2 Thin - QFN (TQFN44-24) Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. -4- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 PIN DESCRIPTIONS PIN NAME DESCRIPTION 1 VIN Power Input for the Battery Charger. Bypass VIN to GA with a capacitor placed as close to the IC as possible. The battery charger and both step-down DC/DCs (REG1 and REG2) are automatically enabled when a valid voltage is present on VIN. 2 SCL Clock Input for I2C Serial Interface. Data is read on the rising edge of the clock. 3 SDA Data Input for I2C Serial Interface. Data is read on the rising edge of the clock. 4 nIRQ Open-Drain Push-Button Status Output. nIRQ is an open-drain output which sinks current when nMSTR is asserted. 5 nMSTR Master Enable Input. Drive nMSTR to GA or to a logic low to enable IC. 6 nRSTO Open-Drain Reset Output. nRSTO asserts low for the reset timeout period of 300ms whenever the IC is enabled. 7 OUT1 Output Feedback Sense for REG1. Connect this pin directly to the output node to connect the internal feedback network to the output voltage. 8 VP1 Power Input for REG1. Bypass to GP12 with a high quality ceramic capacitor placed as close as possible to the IC. 9 SW1 Switching Node Output for REG1. Connect this pin to the switching end of the inductor. 10 GP12 Power Ground for REG1 and REG2. Connect GA, GP12, and GP3 together at a single point as close to the IC as possible. 11 SW2 Switching Node Output for REG2. Connect this pin to the switching end of the inductor. 12 VP2 Power Input for REG2. Bypass to GP12 with a high quality ceramic capacitor placed as close as possible to the IC. 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 ON2 Enable Control Input for REG3. ON2 is functional only when ON1 is driven high, nMSTR is driven low, or when a valid supply voltage is present on VIN. Drive ON2 to VSYS or to a logic high for normal operation, drive to GA or a logic low to disable REG3. 15 ON1 Enable Control Input for REG1 and REG2. Drive ON1 to VSYS or to a logic high for normal operation, drive to GA or to a logic low to disable REG1 and REG2. 16 VSYS Power Bypass for System Management Circuitry. Bypass to GA with a high quality ceramic capacitor placed as close as possible to the IC. VSYS is internally connected to the higher voltage of either VVIN or VBAT. Do not load VSYS with more than 100µA. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. -5- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 PIN DESCRIPTIONS CONT’D PIN NAME DESCRIPTION 17 GA Analog Ground. Connect GA directly to a quiet ground node. Connect GA, GP12, and GP3 together at a single point as close to the IC as possible. 18 FB3 Feedback Sense for REG3. Connect this pin to the LED string current sense resistor to sense the LED current. 19 OVP3 Over-Voltage Protection Input for REG3. Connect this pin directly to the output node to sense and prevent over-voltage conditions. 20 GP3 Power Ground for REG3. Connect GP3 directly to a power ground plane. Connect GA, GP12, and GP3 together at a single point as close to the IC as possible. 21 SW3 Switching Node Output for REG3. Connect this pin to the switching end of the inductor. 22 nSTAT Active-Low Open-Drain Charger Status Output. nSTAT sinks current whenever the charger is charging the battery, and is high-Z otherwise. nSTAT has a 6mA (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 OUT2) through a 10kΩ or greater pull-up resistor. 23 CHGLEV Tri-State Charging State Select Input. When ISET1[ ] = [0000], drive CHGLEV to VSYS or to a logic high for high-current charging mode (maximum charge current of 500mA), and drive to GA or a logic low for low-current charging mode (maximum charge current of 100mA). Allow CHGLEV to float (|ICHGLEV| < 2µA) to disable the charger. 24 BAT Battery Charger Output. Connect this pin directly to the battery anode (+ terminal) to sense the battery voltage. EP EP Exposed Pad. Must be soldered to ground on PCB. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. -6- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 ABSOLUTE MAXIMUM RATINGSc PARAMETER VALUE UNIT VP1, SW1, VP2, SW2 to GP12, VSYS, OUT1, OUT2, FB3, BAT, CHGLEV, nSTAT, ON1, ON2, nRSTO, nMSTR, nIRQ, SCL, SDA to GA -0.3 to +6 V OVP3, SW3 to GP3 -0.3 to +30 V SW1 to VP1, SW2 to VP2 -6 to +0.3 V VIN to GA t <1ms and duty cycle <1% Steady State -0.3 to +7 -0.3 to +6 V V -0.3 to +0.3 V 1.8 W -40 to 85 °C Junction Temperature 125 °C Storage Temperature -55 to 150 °C 300 °C GP12, GP3 to GA RMS Power Dissipation (TA = 70°C) Operating Temperature Range Lead Temperature (Soldering, 10 sec) c: 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 Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. -7- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 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 CHGR 08h 0 0 0 0 1 0 0 0 0 0 0 0 R R R R CHGR 09h 0 0 0 0 1 0 0 1 0 1 R R R R R R CHGR 0Ah 0 0 0 0 1 0 1 0 0 0 0 0 R R R R CHGR 0Bh 0 0 0 0 1 0 1 1 R R R R 0 0 R 0 REG1 10h 0 0 0 1 0 0 0 0 R V V V V V V V REG1 11h 0 0 0 1 0 0 0 1 R R R R R R R 0 REG1 12h 0 0 0 1 0 0 1 0 0 0 R R R R R R REG1 13h 0 0 0 1 0 0 1 1 R R R 0 R 0 R 1 REG2 20h 0 0 1 0 0 0 0 0 R V V V V V V V REG2 21h 0 0 1 0 0 0 0 1 R R R R R R R 0 REG2 22h 0 0 1 0 0 0 1 0 0 1 R R R R R R REG2 23h 0 0 1 0 0 0 1 1 R R R 0 R 0 R 1 REG3 30h 0 0 1 1 0 0 0 0 R R 1 1 1 1 1 1 REG3 31h 0 0 1 1 0 0 0 1 R R R R R R R 0 REG3 32h 0 0 1 1 0 0 1 0 0 0 0 0 0 0 0 0 REG3 33h 0 0 1 1 0 0 1 1 0 0 0 R R 0 R 0 KEY: R: Read-Only bit. 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 Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. -8- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SYSTEM MANAGEMENT ELECTRICAL CHARACTERISTICS (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS VSYS Operating Voltage Range MIN 2.6 VSYS UVLO Threshold VSYS Voltage Rising VSYS UVLO Hysteresis VSYS Voltage Falling 2.25 VSYS Output Resistance Oscillator Frequency VSYS Supply Current TYP 1.35 ON1 = ON2 = GA, CHGLEV = floating nMSTR Internal Pull-Up Resistance 250 2.4 MAX UNIT 5.5 V 2.55 V 80 mV 10 Ω 1.6 1.85 MHz 1.5 µA 500 kΩ Logic High Input Voltage ON1, ON2, nMSTR Logic Low Input Voltage ON1, ON2, nMSTR 0.4 V Logic Low Output Voltage nIRQ, nRSTO, ISINK = 5mA 0.3 V Leakage Current nIRQ, nRSTO, VnIRQ = VnRSTO = 4.2V 1 µA 360 ms nRSTO Delay 1.4 240 V 300 Thermal Shutdown Temperature Temperature Rising 160 °C Thermal Shutdown Hysteresis Temperature Falling 20 °C Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. -9- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SYSTEM MANAGEMENT I2C INTERFACE ELECTRICAL CHARACTERISTICS (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS MIN SCL, SDA Low Input Voltage SCL, SDA High Input Voltage TYP MAX UNIT 0.4 V 1.4 SCL, SDA Leakage Current SDA Low Output Voltage IOL = 5mA SCL Clock Period, tSCL fSCL clock freq = 400kHz V 1 µA 0.3 V 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 Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 10 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SYSTEM MANAGEMENT TYPICAL PERFORMANCE CHARACTERISTICS (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) Oscillator Frequency vs. Temperature ON1 = ON2 = GA Supply Current (µA) 1.65 ACT8712-002 1.68 Frequency (MHz) VSYS Current vs. Temperature 3 ACT8712-001 1.71 1.62 1.59 1.56 VVSYS = 4.2V 2 VVSYS = 3.6V VVSYS = 3.2V 1 1.53 1.50 -40 -20 0 20 40 60 0 -40 85 Temperature (°C) 20 40 60 85 Shutdown Sequence ACT8712-004 ACT8712-003 CH2 0 Temperature (°C) Startup Sequence CH1 -20 CH1 CH2 CH3 CH3 CH4 CH4 CH1: VnMSTR, 5V/div CH2: VnRSTO, 2V/div CH3: VON1, 5V/div CH4: VOUT1, 2V/div CH1: VnMSTR, 5V/div CH2: VnRSTO, 2V/div CH3: VON1, 5V/div CH4: VOUT1, 2V/div TIME: 100ms/div Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 11 - TIME: 100ms/div www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SYSTEM MANAGEMENT FUNCTIONAL DESCRIPTION General Description The ACT8712 offers an array of system management functions that allow it to provide optimal performance in a wide range of applications. I2C Serial Interface At the core of the ACT8712’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 ACT8712 uses standard I2C commands; I2C write-byte commands are used to program the ACT8712, and I2C read-byte commands are used to read the ACT8712’s internal registers. The ACT8712 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, [1010 011x]. 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 Automatic Enable Due to Valid VIN Supply The ACT8712 battery charger and step-down DC/DC converters (REG1 and REG2) are automatically enabled when a valid input supply is applied to VIN. Automatically enabling these functions simplifies system design and eliminates the need for external input supply-detection circuitry. Manual Enable Due to Asserting nMSTR Low System startup is initiated when the user presses the push-button, asserting nMSTR low. When this occurs, both REG1 and REG2 are enabled and nRSTO is asserted low to hold the microprocessor in RESET for 260ms. nRSTO goes high-Z upon expiration of the reset timer, de-asserting the processor’s reset input and allowing the microprocessor to initiate its power up sequence. Once the powerup routine is successfully completed, the microprocessor must assert ON1 so that the ACT8712 remains enabled after the push-button is released by the user. Upon completion of the start-up sequence the processor assumes control of the power system and all further operation is software-controlled. Manual Enable Due to Asserting ON1 High The ACT8712 is compatible with applications that do not utilize it’s push-button control function, and may be enabled by simply driving ON1 to a logichigh. In this case, the signal driving ON1 controls enable/disable timing, although software-controlled enable/disable sequences are still supported if the processor assumes control of the power system once the startup sequence is completed. System Startup and Shutdown The ACT8712 features a flexible control architecture that supports a variety of software-controlled enable/disable functions that make it a simple yet flexible and highly configurable solution. The ACT8712 is automatically enabled when any of the following conditions exists: 1) A valid supply voltage is present at VIN, 2) nMSTR is asserted low, or 3) ON1 is asserted high. If any of these conditions is true, the ACT8712 enables REG1 and REG2, powering up the system processor so that the startup and shutdown sequences may be controlled via software. Each of these startup conditions are described in detail below. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. Shutdown Sequence Once a successful power-up routine is completed, the system processor controls the operation of the power system, including the system shutdown timing and sequence. The ACT8712 asserts nIRQ low when nMSTR is asserted low, providing a simple means of alerting the system processor when the user wishes to shut the system down. Asserting nIRQ interrupts the system processor, initiating an interrupt service routine in the processor which will reveal that the user pressed the push-button. The microprocessor may validate the input, such as by ensuring that the push-button is asserted for a minimum amount of time, then initiates a softwarecontrolled power-down routine, the final step of which is to de-assert the ON1 input, disabling REG1 and REG2 and shutting the system down. - 12 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SYSTEM MANAGEMENT nMSTR Enable Input In most applications, connect nMSTR to an active low, momentary push-button switch to utilize the ACT8712’s closed-loop enable/disable functionality. If a momentary-on switch is not used, drive nMSTR to GA or to a logic low to initiate a startup sequence. Enable/Disable Inputs (ON1 and ON2) The ACT8712 provides two manual enable/disable inputs, ON1 and ON2. ON1 is the master enable input. When driven high, ON1 enables REG1 and REG2. ON2 is the enable input for REG3. ON2 is used to enable REG3 when any of the following conditions exists: 1) A valid supply voltage is present at VIN, 2) nMSTR is asserted low, or 3) ON1 is asserted high. Power-On Reset Output The ACT8712 integrates a 260ms power-on reset generator, reducing system size and cost. nRSTO is an open-drain output. Connect a 10kΩ or greater pull-up resistor from nRSTO to an appropriate voltage supply, typically OUT2. nRSTO asserts low upon startup and remains low until the reset-timeout period expires, at which point nRSTO goes high-Z. nIRQ Output The ACT8712 provides an active-low, open-drain push-button status output that sinks current when nMSTR is driven to a logic-low. 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. Thermal Shutdown The ACT8712 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 ACT8712 die temperature exceeds 160°C, and prevents the regulators from being enabled until the IC temperature drops by 20°C (typ). Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 13 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS ELECTRICAL CHARACTERISTICS (VVP1 = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS VP1 Operating Voltage Range MIN 3.1 VP1 UVLO Threshold Input Voltage Rising VP1 UVLO Hysteresis Input Voltage Falling 2.9 Output Voltage Regulation Accuracy ON1 = GA, VVP1 = 4.2V 0.1 c VNOM1 < 1.3V, IOUT1 = 10mA -2.4% VNOM1 VNOM1 ≥ 1.3V, IOUT1 = 10mA -1.2% VNOM1 VVP1 = Max(VNOM1 + 1V, 3.2V) to 5.5V Load Regulation IOUT1 = 10mA to 550mA Current Limit VOUT1 ≥ 20% of VNOM1 UNIT 5.5 V 3.1 V mV 130 Line Regulation Oscillator Frequency 3 MAX 80 Standby Supply Current Shutdown Supply Current TYP 200 µA 1 µA +1.8% +1.8% V 0.15 %/V 0.0017 %/mA 0.65 0.85 A 1.35 1.6 1.85 MHz VOUT1 = 0V 530 kHz PMOS On-Resistance ISW1 = -100mA 0.35 0.60 Ω NMOS On-Resistance ISW1 = 100mA 0.23 0.40 Ω SW1 Leakage Current VVP1 = 5.5V, VSW1 = 5.5V or 0V 1 µA Power Good Threshold 94 %VNOM1 Minimum On-Time 70 ns c: VNOM1 refers to the nominal output voltage level for VOUT1 as defined by the Ordering Information section. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 14 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 2: REG1 Control Register Map ADDRESS DATA D7 D6 D5 D4 10h R VRANGE 11h R R R R 12h W/E W/E R 13h R R R D3 D2 D1 D0 R R R MODE R R R R R W/E R W/E OK W/E 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 3: REG1 Control Register Bit Descriptions ADDRESS NAME BIT ACCESS FUNCTION DESCRIPTION 10h VSET [5:0] R/W REG1 Output Voltage Selection See Table 4 10h VRANGE [6] R/W REG1 Reference Voltage Selection [7] R [0] R/W 11h [7:1] R READ ONLY 12h [5:0] R READ ONLY 12h [7:6] W/E WRITE-EXACT 13h [0] W/E WRITE-EXACT [1] R 13h [2] W/E WRITE-EXACT 13h [3] R READ ONLY 13h [4] W/E WRITE-EXACT 13h [7:5] R READ ONLY 10h 11h 13h MODE OK Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. 0 Min VOUT = 1.1V 1 Min VOUT = 1.25V READ ONLY Mode Selection REG1 Power-OK - 15 - 0 PFM/PWM 1 Forced PWM 0 Output is not OK 1 Output is OK www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS CONT’D Table 4: REG1/VSET[ ] Output Voltage Setting REG1/VSET[5:4] REG1/VSET [3:0] REG1/VRANGE = [0] REG1/VRANGE = [1] 00 01 10 11 00 01 10 11 0000 N/A N/A 1.455 1.860 1.250 2.050 2.850 3.650 0001 N/A N/A 1.480 1.890 1.300 2.100 2.900 3.700 0010 N/A 1.100 1.505 1.915 1.350 2.150 2.950 3.750 0011 N/A 1.125 1.530 1.940 1.400 2.200 3.000 3.800 0100 N/A 1.150 1.555 1.965 1.450 2.250 3.050 3.850 0101 N/A 1.175 1.585 1.990 1.500 2.300 3.100 3.900 0110 N/A 1.200 1.610 2.015 1.550 2.350 3.150 3.950 0111 N/A 1.225 1.635 2.040 1.600 2.400 3.200 4.000 1000 N/A 1.255 1.660 2.065 1.650 2.450 3.250 4.050 1001 N/A 1.280 1.685 2.090 1.700 2.500 3.300 4.100 1010 N/A 1.305 1.710 2.115 1.750 2.550 3.350 4.150 1011 N/A 1.330 1.735 2.140 1.800 2.600 3.400 4.200 1100 N/A 1.355 1.760 2.165 1.850 2.650 3.450 4.250 1101 N/A 1.380 1.785 2.190 1.900 2.700 3.500 4.300 1110 N/A 1.405 1.810 2.200 1.950 2.750 3.550 4.350 1111 N/A 1.430 1.835 2.245 2.000 2.800 3.600 4.400 (N/A): Not Available Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 16 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS ELECTRICAL CHARACTERISTICS (VVP2 = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS VP2 Operating Voltage Range MIN 3.1 VP2 UVLO Threshold Input Voltage Rising VP2 UVLO Hysteresis Input Voltage Falling 2.9 Output Voltage Regulation Accuracy ON1 = GA, VVP2 = 4.2V UNIT 5.5 V 3.1 V mV 130 200 µA 0.1 1 µA VNOM2 < 1.3V, IOUT2 = 10mA -2.4% VNOM2c +1.8% VNOM2 ≥ 1.3V, IOUT2 = 10mA -1.2% VNOM2 +1.8% Line Regulation VVP2 = Max(VNOM2 + 1V, 3.2V) to 5.5V Load Regulation IOUT2 = 10mA to 750mA Current Limit Oscillator Frequency 3 MAX 80 Standby Supply Current Shutdown Supply Current TYP VOUT2 ≥ 20% of VNOM2 V 0.15 %/V 0.0017 %/mA 0.85 1.1 A 1.35 1.6 1.85 MHz VOUT2 = 0V 530 kHz PMOS On-Resistance ISW2 = -100mA 0.28 0.50 Ω NMOS On-Resistance ISW2 = 100mA 0.20 0.35 Ω SW2 Leakage Current VVP2 = 5.5V, VSW2 = 5.5V or 0V 1 µA Power Good Threshold 94 %VNOM2 Minimum On-Time 70 ns c: VNOM2 refers to the nominal output voltage level for VOUT2 as defined by the Ordering Information section. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 17 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 5: REG2 Control Register Map ADDRESS DATA D7 D6 D5 D4 20h R VRANGE 21h R R R R 22h W/E W/E R 23h R R R D3 D2 D1 D0 R R R MODE R R R R R W/E R W/E OK W/E 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 6: REG2 Control Register Bit Descriptions ADDRESS NAME BIT ACCESS FUNCTION DESCRIPTION 20h VSET [5:0] R/W REG2 Output Voltage Selection See Table 7 20h VRANGE [6] R/W REG2 Reference Voltage Selection [7] R [0] R/W 21h [7:1] R READ ONLY 22h [5:0] R READ ONLY 22h [7:6] W/E WRITE-EXACT 23h [0] W/E WRITE-EXACT [1] R 23h [2] W/E WRITE-EXACT 23h [3] R READ ONLY 23h [4] W/E WRITE-EXACT 23h [7:5] R READ ONLY 20h 21h 23h MODE OK Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. 0 Min VOUT = 1.1V 1 Min VOUT = 1.25V READ ONLY Mode Selection REG2 Power-OK - 18 - 0 PFM/PWM 1 Forced PWM 0 Output is not OK 1 Output is OK www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS REGISTER DESCRIPTIONS CONT’D Table 7: REG2/VSET[ ] Output Voltage Setting REG2/VSET[5:4] REG2/VSET [3:0] REG2/VRANGE = [0] REG2/VRANGE = [1] 00 01 10 11 00 01 10 11 0000 N/A N/A 1.455 1.860 1.250 2.050 2.850 3.650 0001 N/A N/A 1.480 1.890 1.300 2.100 2.900 3.700 0010 N/A 1.100 1.505 1.915 1.350 2.150 2.950 3.750 0011 N/A 1.125 1.530 1.940 1.400 2.200 3.000 3.800 0100 N/A 1.150 1.555 1.965 1.450 2.250 3.050 3.850 0101 N/A 1.175 1.585 1.990 1.500 2.300 3.100 3.900 0110 N/A 1.200 1.610 2.015 1.550 2.350 3.150 3.950 0111 N/A 1.225 1.635 2.040 1.600 2.400 3.200 4.000 1000 N/A 1.255 1.660 2.065 1.650 2.450 3.250 4.050 1001 N/A 1.280 1.685 2.090 1.700 2.500 3.300 4.100 1010 N/A 1.305 1.710 2.115 1.750 2.550 3.350 4.150 1011 N/A 1.330 1.735 2.140 1.800 2.600 3.400 4.200 1100 N/A 1.355 1.760 2.165 1.850 2.650 3.450 4.250 1101 N/A 1.380 1.785 2.190 1.900 2.700 3.500 4.300 1110 N/A 1.405 1.810 2.200 1.950 2.750 3.550 4.350 1111 N/A 1.430 1.835 2.245 2.000 2.800 3.600 4.400 (N/A): Not Available Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 19 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS TYPICAL PERFORMANCE CHARACTERISTICS (ACT8712QLEHA, VVP1 = VVP2 = 3.6V, L = 3.3µH, CVP1 = CVP2 = 2.2µF, COUT1 = COUT2 = 10µF, TA = 25°C, unless otherwise specified.) REG1 Efficiency vs. Load Current Efficiency (%) 85 4.2V 80 VOUT2 = 3.0V 90 Efficiency (%) 3.6V 90 ACT8712-006 VOUT1 = 1.8V REG2 Efficiency vs. Load Current 100 ACT8712-005 95 75 70 65 60 4.2V 3.6V 80 70 60 55 50 50 1 10 1 1000 100 10 Output Current (mA) OUT1 Regulation Voltage OUT2 Voltage Accuracy (%) OUT1 Voltage Accuracy (%) 0.222 0.0 -0.222 -0.444 IOUT2 = 35mA 0.363 0.181 0.0 -0.181 -0.363 -0.545 -20 0 20 40 60 -40 85 -20 Temperature (°C) REG1 MOSFET Resistance 450 400 PMOS 350 RDSON (mΩ) RDSON (mΩ) 60 85 REG2 MOSFET Resistance NMOS 250 200 40 150 100 ACT8712-010 PMOS 350 300 20 500 ACT8712-009 550 500 450 400 0 Temperature (°C) 600 300 250 NMOS 200 150 100 50 50 0 3.0 ACT8712-008 IOUT1 = 35mA 0.444 -0.666 -40 1000 OUT2 Regulation Voltage 0.545 ACT8712-007 0.666 100 Output Current (mA) 0 3.5 4.0 4.5 5.0 5.5 3 VP1 Voltage (V) Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. 3.5 4.0 4.5 5.0 5.5 VP2 Voltage (V) - 20 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS FUNCTIONAL DESCRIPTION General Description Programming the Output Voltage REG1 and REG2 are fixed-frequency, currentmode, synchronous PWM step down converters that achieve peak efficiencies of up to 97%. REG1 is capable of supplying up to 550mA of output current, while REG2 supports up to 750mA. These regulators operate with a fixed frequency of 1.6MHz, minimizing noise in sensitive applications and allowing the use of small external components. REG1 and REG2 are available with a variety of standard and custom output voltages, as described in the Ordering Information section of this datasheet. REG1 and REG2 also take advantage of the I2C interface, and may be software-controlled in systems that require advanced power management functions. By default, REG1 and REG2 each power up and regulate to their default output voltage. Once the system is enabled, each regulator’s output voltage may be independently programmed to a different value, typically in order to reduce the power consumption of a microprocessor in standby mode. Program the output voltages via the I2C serial interface by writing to the REGx/VSETx[ ] and REGx/VRANGE[ ] registers. 100% Duty Cycle Operation Both REG1 and REG2 are 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 batterypowered applications. Synchronous Rectification REG1 and REG2 both feature integrated n-channel synchronous rectifiers, maximizing efficiency and minimizing the total solution size and cost by eliminating the need for external rectifiers. Enabling and Disabling REG1 and REG2 Enable/disable functionality is typically implemented as part of a controlled enable/disable scheme utilizing nMSTR and other system control features of the ACT8712. REG1 and REG2 are automatically enabled whenever any of the following conditions are met: 1) A valid input voltage is present at VIN, 2) nMSTR is driven low, or 3) ON1 is asserted high. When none of these conditions are true, REG1 and REG2 are disabled, and each regulator's quiescent supply current drops to less than 1µA. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. Programmable Operating Mode By default, REG1 and REG2 operate in fixedfrequency PWM mode at medium to heavy loads, then transition to a proprietary power-saving mode at light loads in order to save power. In applications where low noise is critical, force fixed-frequency PWM operation across the entire load current range, at the expense of light-load efficiency, by setting the REGx/MODE[ ] bit to [1]. Power-OK REG1 and REG2 each feature a variety of status bits that can be read by the system microprocessor. If either output voltage is lower than the power-OK threshold, typically 6% below the programmed regulation voltage, REGx/OK[ ] will clear to 0. Soft-Start REG1 and REG2 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 both outputs power up in a controlled manner, greatly simplifying power sequencing design considerations. Compensation REG1 and REG2 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 guidelines described below when choosing external components. - 21 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 STEP-DOWN DC/DC CONVERTERS Input Capacitor Selection PCB Layout Considerations The input capacitor reduces peak currents and noise induced upon the voltage source. A 2.2µF ceramic capacitor for each of REG1 and REG2 is recommended for most applications. 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. Stepdown 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. Output Capacitor Selection For most applications, 10µF ceramic output capacitors are recommended for both REG1 and REG2. 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. Inductor Selection REG1 and REG2 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. These devices were optimized for operation with 3.3µH inductors, 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%. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 22 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 WLED BIAS DC/DC CONVERTER ELECTRICAL CHARACTERISTICS (VVSYS = 3.6V, TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS c Input Voltage Range MIN TYP 2 5.5 V 3.1 V VSYS Voltage Rising UVLO Voltage Hysteresis VSYS Voltage Falling 80 ON2 = VIN, VFB3 = 0.3V 75 150 µA ON2 = GA, ILOAD = 0mA 0.1 1 µA 255 275 mV FB3 Feedback Voltage 235 FB3 Input Current 3 UNIT UVLO Voltage Threshold Supply Current 2.9 MAX mV 50 Oscillator Frequency 1.35 Minimum On-Time Maximum Duty Cycle Switch Current Limit Duty = 83%, L = 22µH, COUT3 = 4.7µF Switch On-Resistance ISW3 = 100mA Switch Leakage Current VSW3 = 30V, ON2 = GA Over-Voltage Threshold REG3/VSET[ ] = [111111] 1.6 nA 1.85 MHz 100 ns 87 92 % 500 750 mA 0.67 27.5 28.5 1.1 Ω 10 µA 29.5 V c: As long as VSYS is within the VSYS operating range, this spec refers to the voltage range of the input that the inductor is connected to. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 23 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 WLED BIAS DC/DC CONVERTER REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 8: REG3 Control Register Map ADDRESS DATA D7 D6 D5 D4 30h R R 31h R R R R 32h W/E W/E W/E 33h W/E W/E W/E D3 D2 D1 D0 R R R W/E W/E W/E W/E W/E W/E R R W/E OK ON 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 9: REG3 Control Register Bit Descriptions ADDRESS NAME BIT ACCESS FUNCTION DESCRIPTION 30h VSET [5:0] R/W REG3 Over Voltage Threshold Selection See Table 10 30h [7:6] R READ ONLY 31h [0] W/E WRITE-EXACT 31h [7:1] R READ ONLY 32h [7:0] W/E WRITE-EXACT 0 REG3 Disable 1 REG3 Enable 0 Output is not OK 1 Output is OK 33h ON [0] R/W REG3 Enable 33h OK [1] R REG3 Power-OK 33h [2] W/E WRITE-EXACT 33h [4:3] R READ ONLY 33h [7:5] W/E WRITE-EXACT Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 24 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 WLED BIAS DC/DC CONVERTER REGISTER DESCRIPTIONS CONT’D Table 10: REG3/VSET[ ] Output Voltage Setting REG3/VSET[4:3] REG3/VSET [2:0] REG3/VSET[5] = [0] REG3/VSET[5] = [1] 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 Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 25 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 WLED BIAS DC/DC CONVERTER TYPICAL PERFORMANCE CHARACTERISTICS (ACT8712QLEHA, VVSYS = 3.6V, L = 22µH, CVP1 = CVP2 = 2.2µF, COUT = 2.2µF, TA = 25°C, unless otherwise specified.) REG3 Efficiency vs. Output Current PWM Output Current Adjustment Efficiency (%) 90 6 LEDs Normalized Output Current (%) 4 LEDs 80 70 60 50 1 5 9 13 17 21 25 ON2 PWM Frequency = 1kHz 90 80 70 60 50 40 30 20 10 0 0 31 10 20 30 40 50 60 70 80 Output Current (mA) ON2 Duty Cycle (%) REG3 RDSON REG3 Over-Voltage Protection 800 700 90 100 ACT8712-014 ACT8712-013 900 RDSON (mΩ) 100 ACT8712-012 ACT8712-011 100 CH1 600 500 400 CH2 300 0V 200 2.5 3.0 3.5 4.0 4.5 5.0 5.5 CH1: VOUT3, 10V/div CH2: VFB3, 200mV/div TIME: 2ms/div VSYS Voltage (V) REG3 Startup Waveform ACT8712-015 CH1 0V CH2 0V CH1: VOUT3, 10V/div CH2: VON2, 1V/div TIME: 100µs/div Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 26 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 WLED BIAS DC/DC CONVERTER FUNCTIONAL DESCRIPTION General Description Power-OK Bit REG3 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. REG3 feature a variety of status bits that can be read by the system microprocessor. If the voltage at OV is greater than the OVP threshold, REG3/OK[ ] will clear to 0. Enabling and Disabling REG3 REG3 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. REG3 is a flexible regulator, and its external components can be chosen to achieve the smallest possible footprint or to achieve the highest possible efficiency. Enable/disable control of REG3 is done through a combination of the ACT8712’s system control circuitry, the ON2 pin, and the REG3/ON[ ] bit. REG3 may be enabled when at least one of the following conditions exists: 1) A valid supply voltage is present at VIN 2) nMSTR is asserted low, or 3) ON1 is asserted high. When any of these conditions exist, REG3 may be enabled by either of the following conditions: 1) ON2 is asserted high, or 2) REG3/ON[ ] is set to [1]. When disabled, REG3's quiescent supply current drops to just 1µA. As with all non-synchronous step-up DC/DC converters, REG3'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 REG3 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, REG3 will regulate the top of the LED strong to the OVP threshold voltage. By default, the ACT8712's OVP threshold is set at 28.5V, although it may be programmed to a lower value by writing to the REG3/VSET[ ] register. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. Compensation and Stability Inductor Selection REG3 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. Optimizing for Smallest Footprint REG3 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. Optimizing for Highest Efficiency REG3 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 REG3 was designed to operate with output capacitors ranging from 0.47µF to 10µF, providing design flexibility. A 1µF output capacitor is suitable for most - 27 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 WLED BIAS DC/DC CONVERTER applications, although larger output capacitors may be used to minimize output voltage ripple, if needed. Ceramic capacitors are recommended for most applications. Rectifier Selection REG3 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. put 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. Setting the LED Bias Current The LED bias current is set by a resistor connected from FB3 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 ACT8712’s Direct-PWM feature. REG3 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 out- Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 28 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SINGLE-CELL Li+ BATTERY CHARGER (CHGR) ELECTRICAL CHARACTERISTICS (VVIN = 5V, VBAT = 3.6V, ISET[ ] = [0101], TA = 25°C, unless otherwise specified.) PARAMETER TEST CONDITIONS VIN Operating Voltage Range MIN TYP 4.3 VIN UVLO Threshold VVIN Voltage Rising VIN UVLO Hysteresis VVIN Voltage Falling 3.75 V 4.25 V mV 300 500 TA = 25°C 4.179 4.200 4.221 VVIN = 4.5V to 5.5V, TA = 0°C to 85°C 4.158 4.200 4.242 Line Regulation VVIN = 4.5V to 5.5V, IBAT = 10mA Load Regulation IBAT = 50mA to 500mA VBAT = 4V, CHGLEV = GA Charge Current 6 500 On-Resistance Battery Termination Voltage 4 MAX UNIT mΩ V 0.2 %/V 0.001 %/mA 90 100 mA VBAT = 4V, CHGLEV = VSYS 400 450 500 mA Precondition Charge Current VBAT = 2.7V, CHGLEV = VSYS or GA 30 45 60 mA Precondition Threshold Voltage VBAT Voltage Rising 2.75 2.9 3.05 V Precondition Threshold Hysteresis VBAT Voltage Falling End-of-Charge Current Threshold VBAT = 4.2V, CHGLEV = VSYS 150 31 End-of-Charge Delay Charge Restart Threshold VSET[ ] -VBAT, VBAT falling Thermal Regulation Threshold BAT Reverse Leakage Current 47 200 mV 110 °C VVIN < UVLO Voltage 50 SLEEP, SUSPEND, or TIMER-FAULT state 200 PRECONDITION, FAST-CHARGE, or TOPOFF state 700 Precondition Timeout Period TIMOSET[ ] = [01] 90 nSTAT Sink current VnSTAT = 2V nSTAT Output Low Voltage nSTAT Leakage Current CHGLEV Logic Low Input Voltage µA µA min mA InSTAT = 1mA 0.4 V VnSTAT = 6V 1 µA 0.4 V 2 µA ICHGLEV ≤ -15µA CHGLEV Tri-state Current Threshold -2 ICHGLEV ≥ 15µA 1.4 8 2 12 c CHGLEV Logic High Input Voltage mA min 0.4 4 63 4 VBAT = 4.2V, VIN = GA or BAT VIN Supply Current mV V c: Charger is suspended when CHGLEV pin current is within this range Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 29 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SINGLE-CELL Li+ BATTERY CHARGER (CHGR) REGISTER DESCRIPTIONS Note: See Table 1 for default register settings. Table 11: Battery Charger (CHGR) Control Register Map ADDRESS DATA D7 D6 08h D4 D3 D2 D1 D0 R R R R TIMOFLT TEMPFLT CHGRSTAT VINPOK R R R R W/E ICHGSET CHGROK SUSCHG ISET1 09h TIMOSET R 0Ah 0Bh D5 BATFLT ISET2 R R R R 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 12: Battery Charger (CHGR) Control Register Bit Descriptions ADDRESS NAME 08h BIT ACCESS [3:0] R FUNCTION READ ONLY 08h ISET1 [7:4] R/W ISET1 Charger Current Selection 09h VINPOK [0] R Input Supply Power-OK 09h CHGRSTAT [1] R Charging Status 09h TEMPFLT [2] R Temperature Status 09h TIMOFLT [3] R Timeout Fault 09h BATFLT [4] R Battery Removed Fault [5] R 09h 09h TIMOSET 0Ah 0Ah ISET2 [7:6] R/W [3:0] R [7:4] R/W Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. DESCRIPTION See Tables 13 and 14 0 Input Power is not OK 1 Input Power is OK 0 Not Charging 1 Charging 0 Temperature Fault 1 No Timeout Fault 0 No Timeout Fault 1 Timeout Fault 0 Battery Not Removed 1 Battery Removed READ ONLY Charge Timeout Select 00 60mins 01 90mins 10 120mins 11 No Timeout READ ONLY ISET2 Charger Current Selection - 30 - See Tables 13 and 14 www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SINGLE-CELL Li+ BATTERY CHARGER (CHGR) REGISTER DESCRIPTIONS CONT’D Table 12: Battery Charger (CHGR) Control Register Bit Descriptions (Cont’d) ADDRESS NAME BIT ACCESS FUNCTION DESCRIPTION 0Bh SUSCHG [0] R/W Suspend Charging 0Bh CHGROK [1] R Charge Status 0Bh ICHGSET [2] R/W Charge Current Selectionc 0Bh [3] W/E WRITE-EXACT 0Bh [7:4] R READ ONLY 0 Charging Enable 1 Charging Disable 0 Charging Error Occurred 1 Charging OK 0 90mA 1 450mA c: ICHGSET only has affect when CHGLEV = 0 and ISET2[3:0] = [0000] Table 13: Table 14: Charge Current Setting for CHGLEV = 0 Charge Current Setting for CHGLEV = 1 CHGLEV = 0 ISET1[3:0] ISET2[3:0] CURRENT(mA) ISET1[3:0] 90 if ICHGSET = 0 0000 450 450 if ICHGSET = 1 0001 300 0001 300 0010 350 0010 350 0011 400 0011 400 0100 450 0100 450 0101 500 0101 500 0110 550 0110 550 0111 0111 600 1000 1000 650 1001 700 1001 700 1010 750 1010 750 1011 800 1011 800 1100 850 1100 850 1101 900 1101 900 1110 950 1110 950 1111 1000 1111 1000 0000 Any Value CHGLEV = 1 Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 31 - ISET2[3:0] Any Value CURRENT(mA) 600 650 www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SINGLE-CELL Li+ BATTERY CHARGER (CHGR) TYPICAL PERFORMANCE CHARACTERISTICS (ACT8712QLEHA, VVIN = 5V, TA = 25°C, unless otherwise specified.) Trickle-Charge Threshold Charge Termination Voltage 4.206 4.204 Trickle-Charge Threshold (V) VBAT Voltage Accuracy (V) 4.208 4.202 4.200 4.198 4.196 4.194 4.192 4.190 0 2.9 VBAT RISING 2.8 VBAT FALLING 2.7 2.6 2.5 10 20 30 40 50 60 70 0 10 20 SUSPEND Mode Battery Current VIN FLOATING VVIN = 5V 1 LOGIC HIGH INPUT 3 FLOATING INPUT 0 -3 LOGIC LOW INPUT -6 0 20 30 40 50 60 70 -20 -40 0 Temperature (°C) MOSFET Resistance Max. Charge Current (mA) RDSON (mΩ) 150 100 50 0 40 50 60 ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. 1000 CHGLEV = VSYS 800 CHARGE CURRENT LIMITED BY THERMAL CONTROL CIRCUITRY 600 400 CHGLEV = GA 200 0 -40 70 Temperature (°C) Innovative Products. Active Solutions. 85 ACT8712-021 200 30 60 1100 ACT8712-020 250 20 40 Maximum Charge Current 300 10 20 Temperature (°C) 350 0 70 CHGLEV Drive Current Threshold CHGLEV Drive Current (µA) BAT Current (µA) VIN = GA 10 60 ACT8712-019 4 0 50 6 ACT8712-018 5 2 40 30 Temperature (°C) Temperature (°C) 3 ACT8712-017 3.0 ACT8712-016 4.210 -25 5 35 65 95 125 Temperature (°C) - 32 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SINGLE-CELL Li+ BATTERY CHARGER (CHGR) FUNCTIONAL DESCRIPTION General Description Charger Status The ACT8712's internal battery charger is a fullfeatured, intelligent, linear-mode, single-cell charger for Lithium-based cells. This charger provides a complete selection of advanced functions and requires minimum system design effort. During normal operation, the processor can read the status of the input supply by reading CHGR/VINPOK[ ], which is set to [1] when the following conditions are true: The core of the charger is a CC/CV (Constant- Current/Constant-Voltage), linear-mode charge controller with a highly-accurate charge termination threshold. This controller incorporates current and voltage sense circuitry, an internal power MOSFET, a fullfeatured state-machine that implements charge control and safety features, and circuitry that eliminates the reverse-blocking diode required by conventional charger designs. The ACT8712’s 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. CC/CV Regulation Loop At the core of the ACT8712's battery charger is a CC/CV regulation loop, which regulates either current or voltage as necessary to ensure fast and safe charging of the battery. In a normal charge cycle, this loop regulates the charge current to the programmed charge current level and continues charging at this current until the battery cell voltage reaches the charge termination voltage. Once the cell reaches the Charge-Termination Threshold Voltage, the CV loop takes over and charge current is allowed to decrease as necessary to keep the cell voltage at the charge termination voltage. Charger Enable/Disable 1) The voltage at VIN is greater than the voltage at BAT, and 2) The voltage at VIN is greater than the VIN UVLO threshold. Alternatively, the processor can read the status of the charger by reading the CHGR/CHGROK[ ] bit, which is set to [1] when the following conditions are true: 1) The voltage at VIN is greater than the voltage at BAT, and 2) The voltage at VIN is greater than the VIN UVLO threshold, and 3) No fault has occurred. Finally, the status of a charge cycle can be determine by reading the CHGR/CHGSTAT[ ] bit or by evaluating the state of the nSTAT output. nSTAT is an open-drain output that has an internal 8mA current limit, and is capable of directly driving LEDs for a visual charge-status indication without the need of current-limiting resistors or other external circuitry. To drive an LED, simply connect the LED between an appropriate supply, typically VIN, and nSTAT. When a logic-level charge status indicator is desired, simply connect a pull-up resistor of 10kΩ or more from nSTAT to OUT2 or another suitable supply. CHGR/CHGSTAT[ ] is set to [1] and nSTAT sinks current when any of the following conditions are true: When a valid input voltage is applied to VIN, the battery charger is automatically enabled in order to simplify system design and eliminate the need for external input supply detection circuitry. 1) The charger is operating in the PRECONDITION state, or Once the charger is enabled, a charge cycle automatically begins unless CHGLEV is floating, CHGR/SUSCHG[ ] is set to [1], or a fault condition has occurred. 3) The charger is operating in the TOP-OFF state. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. 2) The charger is operating in the FAST-CHARGE state, or When none of these conditions are true, CHGR/CHGSTAT[ ] is cleared to [0] and nSTAT goes into a high-Z state. - 33 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SINGLE-CELL Li+ BATTERY CHARGER (CHGR) Input Capacitor Selection VIN is the power input pin for the ACT8712 battery charger. The battery charger is automatically enabled whenever a valid voltage is present on VIN. In most applications, VIN is connected to either a wall adapter or a USB port. Under normal operation, the input of the charger will often be “hotplugged” directly to a powered USB or a wall adapter cable, and supply voltage ringing and overshoot may appear at the VIN pin and can potentially be large enough to damage the charger input. In most applications, a capacitor connected from VIN to GA, placed as close as possible to the IC, is sufficient to absorb the energy. The VIN pin is designed for enhanced robustness and has an absolute maximum transient voltage rating of +7V, and attention must be given to bypass techniques to ensure operation within this limit. Charge Current Programming Charge current programming is performed using a combination of the ACT8712’s CHGR/ISET1[ ] and CHGR/ISET2[e] registers and the multifunction CHGLEV input. The multi-function CHGLEV input provides charge-current selection between the current setting defined by CHGR/ISET1[ ] and the current setting programmed by CHGR/ISET2[ ], as well as a charge suspend function. Drive CHGLEV to a logic-low to select the current programmed by CHGR/ISET1[ ]. In order to reduce the number of GPIOs required to interface with the ACT8712, the CHGR/ICHGSET[ ] bit may be used instead of the CHGLEV pin to achieve identical functionality. By default, the ACT8712’s CHGR/ISET1[ ] and CHGR/ISET2[ ] registers are programmed to provide a charge current of 90mA when CHGLEV is driven low, and 450mA when CHGLEV is driven high, so that the ACT8712 is compatible with system that utilize lower-current input supplies, such as a USB port. To achieve a different charge current, program the CHGR/ISET1[ ] and/or CHGR/ISET2[ ] registers accordingly. Charge Safety Timer The ACT8712 features a programmable charge safety timer that is utilized during operation in the PRECONDITION state. The safety timer has a default timeout period of 60 minutes, although it may be programmed to either 90 minutes or 120 minutes by writing to the CHGR/TIMOSET[ ] register. This register also provides a timer-disable function, for Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. applications that do not require a charge safety timer function. Thermal Regulation The ACT8712 features an internal thermal feedback loop that reduces the charging current as necessary to ensure that the die temperature does not exceed the thermal regulation threshold of 110°C. This feature protects the ACT8712 against excessive junction temperature and makes the ACT8712 more accommodating of aggressive thermal designs without risk of damage. Note, however, that attention to good thermal design is required to achieve the shortest possible charge time. Charge Status Bits The ACT8712 charger provides a variety of readonly charge status bits that can be read by the host processor as needed to make intelligent power management decisions. Five charge status bits are available: Input Voltage Status The CHGR/VINPOK[ ] bit is set to [1] when a valid input supply is connected to VIN. A valid input supply is defined as one that : 1) is greater than the voltage at BAT, and 2) is greater than the VIN UVLO threshold. Charger Status There are two bits available that describe the current status of the charger itself. The CHGR/CHGSTAT[ ] bit is set to [1] when the charger is actively charging the battery, and is cleared to [0] when a charge cycle terminates or is suspended. The CHGR/CHGROK[ ] bit is set to [1] when TBD, and is cleared otherwise. Timeout Fault The CHGR/TIMOFLT[ ] bit is set to [1] when a timeout fault occurs, and remains cleared otherwise. Once set to [1], it is automatically cleared to [0] when TBD. Battery Removed Fault The CHGR/BATFLT[ ] bit is set to [1] when there is no battery connected, and remains cleared otherwise. - 34 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 SINGLE-CELL Li+ BATTERY CHARGER (CHGR) SLEEP State Reverse Leakage Current The ACT8712 includes internal circuitry that eliminates the need for series blocking diodes, reducing solution size and cost as well as dropout voltage relative to conventional battery chargers. When the input supply is removed, when VVIN goes below its under-voltage-lockout (UVLO) voltage, or when VVIN drops below VBAT, the ACT8712 automatically goes into SUSPEND mode and reconfigures its power switch to minimize current drain from the battery. Charger State Machine PRECONDITION State A new charging cycle begins in the PRECONDITION state. In this state, the cell is charged at a reduced current of either 45mA or 10% of the selected maximum fast-charge current, whichever is greater. During a normal charge cycle, charging continues at this rate until VBAT reaches the Precondition Threshold Voltage, at which point the state machine jumps to the FAST-CHARGE state. If VBAT does not reach the Precondition Threshold Voltage before the Precondition Charge Timeout period expires, then a damaged cell is detected and the state machine jumps to the TIMEOUT-FAULT state. FAST-CHARGE State In the FAST-CHARGE state the charger operates in Constant-Current (CC) mode and charges the cell at the programmed charge current. During a normal charge cycle, constant-current charging continues until VBAT reaches the charge termination voltage, at which point the state machine jumps to the TOPOFF state. TOP-OFF State In the TOP-OFF state the cell is charged in Constant-Voltage (CV) mode with the charge current limited by the internal chemistry of the cell, decreasing as the cell charges. A normal charging cycle continues until the charge current decreases to below the End-Of-Charge (EOC) threshold. In order to improve immunity to conditions that can result in false-EOC detection, the charging continues until the EOC condition persists for 4 consecutive minutes. Once this condition is met, the charge cycle is terminated and the state machine jumps to the SLEEP state. Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. In the SLEEP state the ACT8712 presents a highimpedance to the battery, allowing the cell to “relax” and minimizing battery leakage current. The ACT8712 continues to monitor the cell voltage, however, so that it can reinitiate a charging cycle as necessary to ensure that the cell remains fully charged. Charge Restart After a charge cycle successfully terminates, the ACT8712 jumps to its SLEEP state to minimize battery drain, but continues to actively monitor the cell voltage. A new charging cycle begins when the cell voltage has dropped by 200mV (typ), keeping the cell fully charged. This charge restart process minimizes cycle-life degradation of the cell by allowing it to “relax” between charges, while ensuring that the cell remains fully-charged while connected to a power source. SUSPEND State When in the SUSPEND state, the charger is disabled and the charger presents a high-impedance to the battery, but the charge-control circuitry remains functional. When exiting the SUSPEND state, the charge timer is reset and the state machine jumps to the PRECONDITION state. TIMEOUT-FAULT State When a TIMEOUT-FAULT occurs, charging is suspended, CHGR/TIMOFLT[ ] is set to [1], and the charger presents a high-impedance to the battery. To maximize safety, there is no direct path to resume charging from the TIMEOUT-FAULT state. A new charging cycle may only be initiated if the state machine first jumps to the SUSPEND state then each of the conditions necessary to enter the PRECONDITION state are satisfied. - 35 - www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT8712 Rev0, 25-Feb-08 PACKAGE INFORMATION PACKAGE OUTLINE TQFN44-24 PACKAGE OUTLINE AND DIMENSIONS D D/2 SYMBOL E/2 E PIN #1 INDEX AREA DIMENSION IN MILLIMETERS DIMENSION IN INCHES MIN MAX MIN MAX A 0.700 0.800 0.028 0.031 A1 0.000 0.050 0.000 0.002 A3 0.200 REF 0.008 REF D/2 x E/2 A A3 A1 0.180 0.300 0.007 0.012 D 3.850 4.150 0.152 0.163 E 3.850 4.150 0.152 0.163 D2 2.500 2.800 0.098 0.110 E2 2.500 2.800 0.098 0.110 e D2 L b b L R e K 0.500 BSC 0.350 0.450 0.200 TYP 0.200 --- 0.020 BSC 0.014 0.018 0.008 TYP 0.008 --- E2 PIN #1 INDEX AREA D/2 x E/2 K 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 lifesupport 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: 1270 Oakmead Parkway, Suite 310, Sunnyvale, California 94085-4044, USA Innovative Products. Active Solutions. ActivePMUTM is a trademark of Active-Semi. I2CTM is a trademark of Philips Electronics. - 36 - www.active-semi.com Copyright © 2008 Active-Semi, Inc.