LP3972 Power Management Unit for Advanced Application Processors General Description ■ 100 mV (typ) dropout The LP3972 is a multi-function, programmable Power Management Unit, designed especially for advanced application processors. The LP3972 is optimized for low power handheld applications and provides 6 low dropout, low noise linear regulators, three DC/DC magnetic buck regulators, a back-up battery charger and two GPIO’s. A high speed serial interface is included to program individual regulator output voltages as well as on/off control. Features Key Specifications Buck Regulators ■ Programmable VOUT from 0.725 to 3.3V ■ Up to 95% efficiency ■ Up to 1.6A output current ■ ±3% output voltage accuracy requiring DVM (Dynamic Voltage Management) ■ Three buck regulators for powering high current processor functions or I/O's ■ 6 LDO's for powering RTC, peripherals, and I/O's ■ Backup battery charger with automatic switch for lithium■ ■ ■ ■ ■ ■ manganese coin cell batteries and Super capacitors I2C compatible high speed serial interface Software control of regulator functions and settings Precision internal reference Thermal overload protection Current overload protection Tiny 40-pin 5x5 mm LLP package Applications LDO’s ■ Programmable VOUT of 1.0V–3.3V ■ ±3% output voltage accuracy ■ 150/300/400 mA output currents — LDO RTC 30 mA — LDO 1 300 mA — LDO 2 150 mA — LDO 3 150 mA — LDO 4 150 mA — LDO 5 400 mA © 2008 National Semiconductor Corporation ■ Compatible with advanced applications processors ■ ■ ■ ■ ■ 202076 PDA phones Smart phones Personal Media Players Digital cameras Application processors — Marvell PXA — Freescale — Samsung www.national.com LP3972 Power Management Unit for Advanced Application Processors January 11, 2008 LP3972 Simplified Application Circuit 20207601 www.national.com 2 LP3972 20207628 — The I2C lines are pulled up via a I/O source — VINLDO4, 5 can either be powered from main battery source, or by a buck regulator or VIN. 3 www.national.com LP3972 Connection Diagrams and Package Mark Information 40-Pin Leadless Leadframe Package NS Package Number SQF40A 20207602 Note: Circle marks pin 1 position. Package Mark 20207604 Top View Note: The actual physical placement of the package marking will vary from part to part. (*) UZTTYY format: 'U' — wafer fab code; 'Z' — assembly code; 'XY' 2 digit date code; 'TT' — die run code. See http://www.national.com/quality/marking_convertion.html for more information on marking information. www.national.com 4 LP3972 Ordering Information Voltage Option Order Number Package Type NSC Package Drawing Package Marking 40 lead LLP SQF040A Voltage A514 LP3972SQ-A514 Voltage A514 LP3972SQXA514 72-A514 40 lead LLP Voltage A413 LP3972SQ-A413 40 lead LLP Voltage A413 LP3972SQXA413 40 lead LLP Voltage E514 LP3972SQ-E514 40 lead LLP Voltage E514 LP3972SQXE514 40 lead LLP Voltage I514 LP3972SQ-I514 40 lead LLP SQF040A 72-I514 1000 tape & reel Voltage I514 LP3972SQX-I514 40 lead LLP SQF040A 72-I514 4500 tape & reel SQF040A Supplied As 1000 tape & reel 4500 tape & reel 72-A514 SQF040A 72-A413 SQF040A 1000 tape & reel 4500 tape & reel 72-A413 SQF040A 72-E514 SQF040A 1000 tape & reel 4500 tape & reel 72-E514 20207605 Default VOUT Coding Z Default VOUT 0 1.3 1 1.8 2 2.5 3 2.8 4 3.0 5 3.3 6 1.0 7 1.4 8 1.2 9 1.25 5 www.national.com LP3972 Pin Descriptions Pin # Name I/O Type Description 1 PWR_ON I D This is an active HI push button input which can be used to signal PWR_ON and PWR_OFF events to the CPU by controlling the ext_wakup [pin4] and select contents of register 8H'88 2 nTEST_JIG I D This is an active LOW input signal used for detecting an external HW event. The response is seen in the ext_wakup [pin4] and select contents of register 8H'88 3 SPARE I D This is an input signal used for detecting a external HW event. The response is seen in the ext_wakup [pin4] and select contents of register 8H'88. The polarity on this pin is assignable 4 EXT_WAKEUP O D This pin generates a single 10mS pulse output to CPU in response to input from pin[s] 1, 2, and 3. Flags CPU to interrogate register 8H'88 5 FB1 I A Buck1 input feedback terminal 6 VIN I PWR Battery Input (Internal circuitry and LDO1-3 power input) 7 VOUT LDO1 O PWR LDO1 output 8 VOUT LDO2 O PWR LDO2 output 9 nRSTI I D Active low Reset pin. Signal used to reset the IC (by default is pulled high internally). Typically a push button reset. 10 GND1 G G Ground 11 VREF O A Bypass Cap. for the high internal impedance reference. 12 VOUT LDO3 O PWR LDO3 output 13 VOUT LDO4 O PWR LDO4 output 14 VIN LDO4 I PWR Power input to LDO4, this can be connected to either from a 1.8V supply to main Battery supply. 15 VIN BUBATT I PWR Back Up Battery input supply. 16 VOUT LDO_RTC O PWR LDO_RTC output supply to the RTC of the application processor. 17 nBATT_FLT O D Main Battery fault output, indicates the main battery is low (discharged) or the dc source has been removed from the system. This gives the processor an indicator that the power will shut down. During this time the processor will operate from the back up coin cell. 18 PGND2 G G 19 SW2 O PWR Buck2 switcher output 20 VIN Buck2 I PWR Battery input power to Buck2 21 SDA I/O D I2C Data (Bidirectional) 22 SCL I D I2C Clock 23 FB2 I A Buck2 input feedback terminal 24 nRSTO O D Reset output from the PMIC to the processor 25 VOUT LDO5 O PWR LDO5 output 26 VIN LDO5 I PWR Power input to LDO5, this can be connected to VIN or to a separate 1.8V supply. 27 VDDA I PWR Analog Power for VREF, BIAS 28 FB3 I A Buck3 Feedback 29 GPIO1 / nCHG_EN I/O D General Purpose I/O / Ext. backup battery charger enable pin. This pin enables the main battery / DC source power to charge the backup battery. This pin toggled via the application processor. By grounding this pin the DC source continuously charges the backup battery 30 GPIO2 I/O D General Purpose I/O 31 VIN Buck3 I PWR Battery input power to Buck3 32 SW3 O PWR Buck3 switcher output 33 PGND3 G G www.national.com Buck2 NMOS Power Ground Buck3 NMOS Power Ground 6 LP3972 Pin # Name I/O Type Description 34 BGND1,2,3 G G Bucks 1, 2 and 3 analog Ground 35 SYNC I D Frequency Synchronization: Connection to an external clock signal PLL to synchronize the PMIC internal oscillator. 36 SYS_EN I D Input Digital enable pin for the high voltage power domain supplies. Output from the Monahans processor. 37 PWR_EN I D Digital enable pin for the Low Voltage domain supplies. Output signal from the Monahans processor 38 PGND1 G G Buck1 NMOS Power Ground 39 SW1 O PWR Buck1 Switcher output 40 VIN Buck1 I PWR Battery input power to Buck1 A: Analog Pin D: Digital Pin G: Ground Pin P: Power Pin I: Input Pin I/O: Input/Output Pin O: Output Pin Note: In this document active low logic items are prefixed with a lowercase “n” 7 www.national.com LP3972 Maximum Lead Temp (Soldering) ESD Rating (Note 5) Human Body Model Machine Model Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. All Inputs GND to GND SLUG Junction Temperature (TJ-MAX) Storage Temperature Power Dissipation (TA = 70°C) (Note 3) Junction-to-Ambient Thermal Resistance θJA (Note 3) −0.3V to +6.5V ±0.3V 150°C −65°C to +150°C 260°C 2 kV 200V Operating Ratings VIN LDO 4,5 VEN Junction Temperature (TJ) Operating Temperature (TA) Maximum Power Dissipation (TA = 70°C) (Notes 3, 4) 3.2W 25°C/W 2.7V to 5.5V 1.74 to (VIN −40°C to +125°C −40°C to +85°C 2.2W General Electrical Characteristics Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, −40°C to +125°C. (Notes 2, 6) Symbol Parameter Conditions VIN, VDDA, VIN Buck1, 2 and 3 Battery Voltage VINLDO4, VINLDO5 Power Supply for LDO 4 and 5 TSD Thermal Shutdown (Note 14) Min Typ Max Units 2.7 3.6 5.5 V 3.6 5.5 V 1.74 Temperature 160 Hysteresis 20 **No input supply should be higher then VDDA Supply Specifications (Notes 2, 5) VOUT (Volts) Supply IMAX Maximum Current Range Resolution (V) (mV) LDO_RTC 2.8V N/A 30 mA dc source 10 mA backup source LDO1 (VCC_MVT) 1.7 to 2.0 25 300 LDO2 1.8 to 3.3 100 150 LDO3 1.8 to 3.3 100 150 LDO4 1.0 to 3.3 50-600 150 LDO5 (VCC_SRAM) 0.850 to 1.5 25 400 BUCK 1 (VCC_APPS) 0.725 to 1.5 25 1600 BUCK 2 0.8 to 3.3 50-600 1600 BUCK 3 0.8 to 3.3 50-600 1600 www.national.com 8 Current (mA) °C Version Enable LP3972 Default Voltage Option (Notes 2, 5) LP3972SQ-A514 LP3972SQ-A413 Version A Version A — 2.8 — 2.8 LDO1 SYS_EN 1.8 SYS_EN 1.8 LDO2 SYS_EN 1.8D SYS_EN 1.8D LDO3 SYS_EN 3D SYS_EN 3D LDO4 SYS_EN 3D SYS_EN 2.8D LDO5 PWR_EN 1.4 PWR_EN 1.4 BUCK1 PWR_EN 1.4 PWR_EN 1.4 BUCK2 SYS_EN 3.3 SYS_EN 3 BUCK3 SYS_EN 1.8 SYS_EN 1.8 LDO_RTC Version Enable LP3972SQ-E514 LP3972SQ-I514 Version E Version I — 2.8 — LDO1 SYS_EN 1.8 SYS_EN 1.8 LDO2 SYS_EN 1.8E SYS_EN 1.8E LDO3 SYS_EN 3D SYS_EN 3E LDO4 SYS_EN 3D SYS_EN 3E LDO5 PWR_EN 1.4 PWR_EN 1.4 BUCK1 PWR_EN 1.4 PWR_EN 1.4 BUCK2 SYS_EN 3.3 SYS_EN 3.3 BUCK3 SYS_EN 1.8 SYS_EN 1.8 LDO_RTC 2.8 Note : E = Regulator is ENABLED during startup D = Regulator is DISABLED during startup 9 www.national.com LP3972 LDO RTC Unless otherwise noted, VIN = 3.6V, CIN = 1.0 μF, COUT = 0.47 µF, COUT (VRTC) = 1.0 μF ceramic. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, −40°C to +125°C. (Notes 2, 6, 7) and (Note 10) Symbol Parameter Conditions Min Typ Max Units 2.632 2.8 2.968 V VIN = (VOUT nom + 1.0V) to 5.5V (Note 11) Load Current = 1 mA 0.15 %/V From Main Battery Load Current = 1 mA to 30 mA 0.05 From Backup Battery VIN = 3.0V Load Current = 1 mA to 10 mA 0.5 VOUT Accuracy Output Voltage Accuracy VIN Connected, Load Current = 1 mA ΔVOUT Line Regulation Load Regulation ISC Short Circuit Current Limit From Main Battery VIN = VOUT +0.3V to 5.5V 100 From Backup Battery 30 VIN - VOUT Dropout Voltage Load Current = 10 mA IQ_Max Maximum Quiescent Current IOUT = 0 mA TP1 %/mA mA 375 mV 30 μA RTC LDO Input Switched from Main VIN Falling Battery to Backup Battery 2.9 V TP2 RTC LDO Input Switched from Backup Battery to Main Battery VIN Rising 3.0 V CO Output Capacitor Capacitance for Stability 1.0 μF ESR www.national.com 0.7 5 10 500 mΩ Unless otherwise noted, VIN = 3.6V, CIN = 1.0 μF, COUT = 0.47 µF, COUT (VRTC) = 1.0 μF ceramic. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, −40°C to +125°C. (Notes 2, 6, 7, 10, 11, 15) and (Note 16). Symbol Parameter Conditions Max Units 3 % VIN =3.1V to 5.0V, (Note 11) Load Current = 1 mA 0.15 %/V Load Regulation VIN = 3.6V, Load Current = 1 mA to IMAX 0.011 %/mA Short Circuit Current Limit LDO1–4, VOUT = 0V 400 LDO5, VOUT = 0V 500 VOUT Accuracy Output Voltage Accuracy (Default VOUT) Load Current = 1 mA ΔVOUT Line Regulation ISC Min Typ −3 VIN - VOUT Dropout Voltage Load Current = 50 mA (Note 7) PSRR Power Supply Ripple Rejection f = 10 kHz, Load Current = IMAX 45 IQ Quiescent Current “On” IOUT = 0 mA 40 Quiescent Current “On” IOUT = IMAX Quiescent Current “Off” EN is de-asserted 0.03 TON Turn On Time Start up from Shut-down 300 COUT Output Capacitor Capacitance for Stability mA mV 150 dB 60 0.33 0.47 0.68 1.0 µA μsec 0°C ≤ TJ ≤ 125°C −40°C ≤ TJ ≤ 125°C ESR µF 5 500 mΩ LDO Dropout Voltage vs. Load Current Collect Data For All LDO’s Dropout Voltage vs. Load Current Change in Output Voltage vs. Load Current 20207629 20207630 11 www.national.com LP3972 LDO 1 to 5 LP3972 LDO1 Line Regulation VOUT = 1.8 volts VIN 3 to 4 volts Load = 100 mA LDO1 Load Transient VIN = 4.1 volts VOUT = 1.8 volts no-load-100 mA 20207631 20207632 Enable Start-up time (LDO1) LDO1 channel 2 LDO4 Channel 1 Sys_enable from 0 volts Load = 100mA 20207633 www.national.com 12 Unless otherwise noted, VIN = 3.6V, CIN = 10 μF, COUT = 10 μF, LOUT = 2.2 μH ceramic. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, −40°C to +125°C. (Notes 2, 6, 12) and (Note 13). Symbol Parameter Conditions VOUT Output Voltage Accuracy Default VOUT Eff Efficiency Load Current = 500 mA ISHDN Shutdown Supply Current EN is de-asserted Sync Mode Clock Frequency Synchronized from 13 MHz System Clock fOSC Internal Oscillator Frequency IPEAK Peak Switching Current Limit IQ Quiescent Current “On” Min Typ −3 Max Units +3 % 95 % μA 0.1 10.4 13 15.6 MHz 2.0 2.1 No Load PFM Mode 21 No Load PWM Mode 200 MHz 2.4 A μA RDSON (P) Pin-Pin Resistance PFET 240 RDSON (N) Pin-Pin Resistance NFET TON Turn On Time Start up from Shut-down CIN Input Capacitor Capacitance for Stability 8 µF CO Output Capacitor Capacitance for Stability 8 µF mΩ 200 mΩ 500 μsec Buck 1 Output Efficiency vs. Load Current Varied from 1mA to 1.5 Amps VIN = 3, 3.5 volts VOUT = 1.4 volts Forced PWM VIN = 4.0-4.5 volts VOUT = 1.4 volts Forced PWM 20207634 20207635 13 www.national.com LP3972 Buck Converters SW1, SW2, SW3 LP3972 VIN = 3, 3.5 volts VOUT = 1.4 volts Forced PWM Line Transient Response VIN = 3 – 3.6 V, VOUT = 1.2 V, 250 mA load 20207637 20207636 Load Transient 3.6 VIN, 3.3 VOUT, 0 – 100 mA load Mode Change Load transients 20 mA to 560 mA VOUT = 1.4 volts [PFM to PWM] VIN = 4.1 volts 20207638 20207639 Startup Startup into PWM Mode 980 mA [channel 2] VOUT = 1.4 volts VIN = 4.1 volts 20207638 www.national.com 14 Unless otherwise noted, VIN = VBATT = 3.6V. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, −40°C to +125°C. (Notes 2, 6) and (Note 8). Symbol Parameter Conditions VIN Operational Voltage Range Voltage at VIN IOUT Backup Battery Charging Current VIN = 3.6V, Backup_Bat = 2.5V, Backup Battery Charger Enabled (Note 8) VOUT Charger Termination Voltage VIN = 5.0V Backup Battery Charger Enabled. Programmable PSRR Min Typ 3.3 Max Units 5.5 V 190 μA 3.1 V Backup Battery Charger Short Circuit Backup_Bat = 0V, Backup Battery Current Charger Enabled 9 mA Power Supply Ripple Rejection Ratio IOUT ≤ 50 μA, VOUT = 3.15V 15 dB 2.91 VOUT + 0.4 ≤ VBATT = VIN ≤ 5.0V f < 10 kHz IQ Quiescent Current IOUT < 50 μA 25 μA COUT Output Capacitance 0 μA ≤ IOUT ≤ 100 μA 0.1 μF Output Capacitor ESR 5 LP3972 Battery Switch Operation 500 mΩ continued the battery switch will disconnect the input of the RTC_LDO from the main battery and connect to the backup battery. • The main battery voltage at which the RTC LDO is switched over from main to backup battery is 2.8V typically. • There is a hysteric voltage in this switch operation so; the RTC LDO will not be reconnected to main battery until main battery voltage is greater than 3.1V typically. • The system designer may wish to disable the battery switch when only a main battery is used. This is accomplished by setting the “no back up battery bit” in the control register 8h’0B bit 7 NBUB. With this bit set to “1”, the above described switching will not occur, that is the RTC LDO will remain connected to the main battery even as it is discharged below the 2.9V threshold. The Backup battery input should also be connected to main battery. The LP3972 has provisions for two battery connections, the main battery Vbat and Backup Battery The function of the battery switch is to connect power to the RTC LDO from the appropriate battery, depending on conditions described below: • If only the backup battery is applied, the switch will automatically connect the RTC LDO power to this battery. • If only the main battery is applied, the switch will automatically connect the RTC LDO power to this battery • If both batteries are applied, and the main battery is sufficiently charged (Vbat > 3.1V), the switch will automatically connect the RTC LDO power to the main battery. • As the main battery is discharged a separate circuit called nBATT_FLT will warn the system. Then if no action is taken to restore the charge on the main battery, and discharging is 15 www.national.com LP3972 Back-Up Charger Electrical Characteristics LP3972 Logic Inputs and Outputs DC Operating Conditions (Note 2) Logic Inputs (SYS_EN, PWR_EN, SYNC, nRSTI, PWR_ON, nTEST_JIG, SPARE and GPI's) Symbol Parameter VIL Low Level Input Voltage VIH High Level Input Voltage ILEAK Input Leakage Current Conditions Min Max Units 0.5 V V VRTC −0.5V −1 +1 µA Min Max Units 0.5 V Logic Outputs (nRSTO, EXT_WAKEUP and GPO's) Symbol Parameter Conditions VOL Output Low Level Load = +0.2 mA = IOL Max VOH Output High Level Load = −0.1 mA = IOL Max ILEAK Output Leakage Current VON = VIN V VRTC −0.5V +5 µA Logic Output (nBATT_FLT) Symbol Parameter Conditions nBATT_FLT Threshold Voltage Programmable via Serial Interface Default = 2.8V VOL Output Low Level Load = +0.4 mA = IOL Max VOH Output High Level Load = −0.2 mA = IOH Max ILEAK Input Leakage Current www.national.com Min Typ Max Units 2.4 2.8 3.4 V 0.5 V V VRTC −0.5V +5 16 μA Unless otherwise noted, VIN = 3.6V. Typical values and limits appearing in normal type apply for TJ = 25°C. Limits appearing in boldface type apply over the entire junction temperature range for operation, −40°C to +125°C. (Notes 2, 6) and (Note 9) Max Units VIL Symbol Low Level Input Voltage Parameter (Note 14) Conditions −0.5 Min Typ 0.3 VRTC V VIH High Level Input Voltage (Note 14) 0.7 VRTC VRTC VOL Low Level Output Voltage (Note 14) 0 0.2 VTRC IOL Low Level Output Current VOL = 0.4V (Note 14) FCLK Clock Frequency (Note 14) tBF Bus-Free Time Between Start and Stop (Note 14) 1.3 μs tHOLD Hold Time Repeated Start Condition (Note 14) 0.6 μs tCLKLP CLK Low Period (Note 14) 1.3 μs tCLKHP CLK High Period (Note 14) 0.6 μs tSU Set Up Time Repeated Start Condition (Note 14) 0.6 μs tDATAHLD Data Hold Time (Note 14) 0 μs tCLKSU Data Set Up Time (Note 14) 100 ns TSU Set Up Time for Start Condition (Note 14) 0.6 μs TTRANS Maximum Pulse Width of Spikes that Must (Note 14) be Suppressed by the Input Filter of Both DATA & CLK Signals 3.0 mA 400 kHz 50 ns Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics tables. Note 2: All voltages are with respect to the potential at the GND pin. Note 3: In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 125°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA x PD-MAX). Note 4: Junction-to-ambient thermal resistance (θJA) is taken from a thermal modeling result, performed under the conditions and guidelines set forth in the JEDEC standard JESD51–7. The test board is a 4-layer FR-4 board measuring 102 mm x 76 mm x 1.6 mm with a 2x1 array of thermal vias. The ground plane on the board is 50 mm x 50 mm. Thickness of copper layers are 36 µm/1.8 µm/18 µm/36 µm (1.5 oz/1 oz/1 oz/1.5 oz). Ambient temperature in simulation is 22° C, still air. Power dissipation is 1W. Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists, special care must be paid to thermal dissipation issues in board design. The value of θJA of this product can vary significantly, depending on PCB material, layout, and environmental conditions. In applications where high maximum power dissipation exists (high VIN, high IOUT), special care must be paid to thermal dissipation issues. For more information on these topics, please refer to Application Note 1187: Leadless Leadframe Package (LLP) and the Power Efficiency and Power Dissipation section of this datasheet. Note 5: The Human body model is a 100 pF capacitor discharged through a 1.5 k ??? resistor into each pin. (MIL-STD-883 3015.7) The machine model is a 200 pF capacitor discharged directly into each pin. (EAIJ) Note 6: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (bold typeface). All room temperature limits are production tested, guaranteed through statistical analysis or guaranteed by design. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). Note 7: Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value. Note 8: Back-up battery charge current is programmable via the I2C compatible interface. Refer to the Application Section for more information. Note 9: The I2C signals behave like open-drain outputs and require an external pull-up resistor on the system module in the 2 kΩ to 20 kΩ range. Note 10: LDO_RTC voltage can track LDO3 voltage. LP3972 has a tracking function (nIO_TRACK). When enabled, LDO_RTC voltage will track LDO3 voltage within 200mV down to 2.8V when LDO3 is enabled Note 11: VIN minimum for line regulation values is 2.7V for LDOs 1–3 and 1.8V for LDOs 4 and 5. Condition does not apply to input voltages below the minimum input operating voltage. Note 12: The input voltage range recommended for ideal applications performance for the specified output voltages is given below: VIN = 2.7V to 5.5V for 0.80V < VOUT < 1.8V VIN = (VOUT+ 1V) to 5.5V for 1.8V ≤ VOUT ≤ 3.3V Note 13: Test condition: for VOUT less than 2.7V, VIN = 3.6V; for VOUT greater than or equal to 2.7V, VIN = VOUT+ 1V. Note 14: This electrical specification is guaranteed by design. Note 15: An increase in the load current results in a slight decrease in the output voltage and vice versa. Note 16: Dropout voltage is the input-to-output voltage difference at which the output voltage is 100 mV below its nominal value. This specification does not apply for input voltages below 2.7V for LDOs 1–3 and 1.8V for LDOs 4 and 5. 17 www.national.com LP3972 I2C Compatible Serial Interface Electrical Specifications (SDA and SCL) LP3972 next cycle is initiated by the clock turning off the NFET and turning on the PFET. Buck Converter Operation DEVICE INFORMATION The LP3972 includes three high efficiency step down DC-DC switching buck converters. Using a voltage mode architecture with synchronous rectification, the buck converters have the ability to deliver up to 1600 mA depending on the input voltage, output voltage, ambient temperature and the inductor chosen. There are three modes of operation depending on the current required - PWM, PFM, and shutdown. The device operates in PWM mode at load currents of approximately 100 mA or higher, having voltage tolerance of ±3% with 95% efficiency or better. Lighter load currents cause the device to automatically switch into PFM for reduced current consumption. Shutdown mode turns off the device, offering the lowest current consumption (IQ, SHUTDOWN = 0.01 µA typ). Additional features include soft-start, under voltage protection, current overload protection, and thermal shutdown protection. The part uses an internal reference voltage of 0.5V. It is recommended to keep the part in shutdown until the input voltage is 2.7V or higher. 20207611 FIGURE 1. Typical PWM Operation Internal Synchronous Rectification While in PWM mode, the converters uses an internal NFET as a synchronous rectifier to reduce rectifier forward voltage drop and associated power loss. Synchronous rectification provides a significant improvement in efficiency whenever the output voltage is relatively low compared to the voltage drop across an ordinary rectifier diode. CIRCUIT OPERATION The buck converter operates as follows. During the first portion of each switching cycle, the control block turns on the internal PFET switch. This allows current to flow from the input through the inductor to the output filter capacitor and load. The inductor limits the current to a ramp with a slope of (VIN– VOUT)/L, by storing energy in a magnetic field. During the second portion of each cycle, the controller turns the PFET switch off, blocking current flow from the input, and then turns the NFET synchronous rectifier on. The inductor draws current from ground through the NFET to the output filter capacitor and load, which ramps the inductor current down with a slope of –VOUT/L. The output filter stores charge when the inductor current is high, and releases it when inductor current is low, smoothing the voltage across the load. The output voltage is regulated by modulating the PFET switch on time to control the average current sent to the load. The effect is identical to sending a duty-cycle modulated rectangular wave formed by the switch and synchronous rectifier at the SW pin to a low-pass filter formed by the inductor and output filter capacitor. The output voltage is equal to the average voltage at the SW pin. Current Limiting A current limit feature allows the converters to protect itself and external components during overload conditions. PWM mode implements current limiting using an internal comparator that trips at 2.0 A (typ). If the output is shorted to ground the device enters a timed current limit mode where the NFET is turned on for a longer duration until the inductor current falls below a low threshold, ensuring inductor current has more time to decay, thereby preventing runaway. PFM OPERATION At very light loads, the converter enters PFM mode and operates with reduced switching frequency and supply current to maintain high efficiency. The part will automatically transition into PFM mode when either of two conditions occurs for a duration of 32 or more clock cycles: A: The inductor current becomes discontinuous. B: The peak PMOS switch current drops below the IMODE level, (Typically IMODE < 30 mA + VIN/42Ω). PWM OPERATION During PWM operation the converter operates as a voltage mode controller with input voltage feed forward. This allows the converter to achieve good load and line regulation. The DC gain of the power stage is proportional to the input voltage. To eliminate this dependence, feed forward inversely proportional to the input voltage is introduced. While in PWM (Pulse Width Modulation) mode, the output voltage is regulated by switching at a constant frequency and then modulating the energy per cycle to control power to the load. At the beginning of each clock cycle the PFET switch is turned on and the inductor current ramps up until the comparator trips and the control logic turns off the switch. The current limit comparator can also turn off the switch in case the current limit of the PFET is exceeded. Then the NFET switch is turned on and the inductor current ramps down. The www.national.com 18 20207612 FIGURE 2. Typical PFM Operation During PFM operation, the converter positions the output voltage slightly higher than the nominal output voltage during PWM operation, allowing additional headroom for voltage drop during a load transient from light to heavy load. The PFM comparators sense the output voltage via the feedback pin and control the switching of the output FETs such that the output voltage ramps between <0.6% and <1.7% above the nominal PWM output voltage. If the output voltage is below 20207613 FIGURE 3. Operation in PFM Mode and Transfer to PWM Mode SHUTDOWN MODE During shutdown the PFET switch, reference, control and bias circuitry of the converters are turned off. The NFET switch will be open in shutdown to discharge the output. When the converter is enabled, EN, soft start is activated. It is recommended to disable the converter during the system power up and undervoltage conditions when the supply is less than 2.7V. SOFT START The buck converter has a soft-start circuit that limits in-rush current during start-up. During start-up the switch current limit is increased in steps. Soft start is activated only if EN goes from logic low to logic high after VIN reaches 2.7V. Soft start is implemented by increasing switch current limit in steps of 213 mA, 425 mA, 850 mA and 1700 mA (typ. Switch current limit). The start-up time thereby depends on the output capacitor and load current demanded at start-up. Typical start- 19 www.national.com LP3972 the “high” PFM comparator threshold, the PMOS power switch is turned on. It remains on until the output voltage reaches the ‘high’ PFM threshold or the peak current exceeds the IPFM level set for PFM mode. The typical peak current in PFM mode is: IPFM = 112 mA + VIN/27Ω. Once the PMOS power switch is turned off, the NMOS power switch is turned on until the inductor current ramps to zero. When the NMOS zero-current condition is detected, the NMOS power switch is turned off. If the output voltage is below the ‘high’ PFM comparator threshold (see Figure 3), the PMOS switch is again turned on and the cycle is repeated until the output reaches the desired level. Once the output reaches the ‘high’ PFM threshold, the NMOS switch is turned on briefly to ramp the inductor current to zero and then both output switches are turned off and the part enters an extremely low power mode. Quiescent supply current during this ‘sleep’ mode is 21 μA (typ), which allows the part to achieve high efficiencies under extremely light load conditions. When the output drops below the ‘low’ PFM threshold, the cycle repeats to restore the output voltage (average voltage in PFM mode) to <1.15% above the nominal PWM output voltage. If the load current should increase during PFM mode (see Figure 3) causing the output voltage to fall below the ‘low2’ PFM threshold, the part will automatically transition into fixed-frequency PWM mode. Typically when VIN = 3.6V the part transitions from PWM to PFM mode at 100 mA output current . LP3972 up times with 10 μF output capacitor and 1000 mA load current is 390 μs and with 1 mA load current its 295 μs. switching frequency, FC, is one parameter that system designers want to be as low as practical to reduce interference to the environment and subsystems within their products. The LP3972 has a user selectable function on chip, wherein a noise reduction technique known as “spread spectrum” can be employed to ease customer’s design and production issues. The principle behind spread spectrum is to modulate the switching frequency slightly and slowly, and spread the signal frequency over a broader bandwidth. Thus, its power spectral density becomes attenuated, and the associated interference electro-magnetic energy is reduced. The clock used to modulate the LP3972 buck regulator can be used as a spread spectrum clock via 2 I2C control register (System Control Register 1 (SCR1) 8h’80) bits bk_ssen, and slomod. With this feature enabled, the intense energy of the clock frequency can be spread across a small band of frequencies in the neighborhood of the center frequency. The results in a reduction of the peak energy! The LP3972 spread spectrum clock uses a triangular modulation profile with equal rise and fall slopes. The modulation has the following characteristics: • The center frequency: FC = 2 MHz, and • The modulating frequency, fM = 6.8 kHz or 12 kHz. • Peak frequency deviation: Δ_f = ±100 kHz (or ±5%) • Modulation index β = Δ_f/fM = 14.7 or 8.3 LDO - LOW DROP OUT OPERATION The LP3672 can operate at 100% duty cycle (no switching; PMOS switch completely on) for low drop out support of the output voltage. In this way the output voltage will be controlled down to the lowest possible input voltage. When the device operates near 100% duty cycle, output voltage ripple is approximately 25 mV. The minimum input voltage needed to support the output voltage is VIN, MIN = ILOAD * (RDSON, PFET + RINDUCTOR) + VOUT • ILOAD Load Current • RDSON, PFET Drain to source resistance of PFET switch in the triode region • RINDUCTOR Inductor resistance SPREAD SPECTRUM FEATURE Periodic switching in the buck regulator is inherently a noisier function block compared to an LDO. It can be challenging in some critical applications to comply with stringent regulatory standards or simply to minimize interference to sensitive circuits in space limited portable systems. The regulator’s switching frequency and harmonics can cause “noise” in the signal spectrum. The magnitude of this noise is measured by its power spectral density. The power spectral density of the Switching Energy RBW = 300 Hz 20207641 www.national.com 20 LP3972 I2C Compatible Interface I2C DATA VALIDITY The data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, state of the data line can only be changed when CLK is LOW. 20207614 I2C START and STOP CONDITIONS START and STOP bits classify the beginning and the end of the I2C session. START condition is defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. STOP condition is defined as the SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C master always generates START and STOP bits. The I2C bus is considered to be busy after START condition and free after STOP condition. During data transmission, I2C master can generate repeated START conditions. First START and repeated START conditions are equivalent, function-wise. TRANSFERRING DATA Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) being transferred first. The number of bytes that can be transmitted per transfer is unrestricted. Each byte of data has to be followed by an acknowledge bit. The acknowledge related clock pulse is generated by the master. The transmitter releases the SDA line (HIGH) during the acknowledge clock pulse. The receiver must pull down the SDA line during the 9th clock pulse, signifying an acknowledge. A receiver which has been addressed must generate an acknowledge after each byte has been received. After the START condition, a chip address is sent by the I2C master. This address is seven bits long followed by an eighth bit which is a data direction bit (R/W). The LP3972 address is 34h. For the eighth bit, a “0” indicates a WRITE and a “1” indicates a READ. The second byte selects the register to which the data will be written. The third byte contains data to write to the selected register. 20207615 I2C CHIP ADDRESS - 7h'34 MSB ADR6 Bit7 ADR5 Bit6 ADR4 Bit5 ADR3 Bit4 ADR2 Bit3 ADR1 Bit2 ADR0 Bit1 R/W Bit0 0 1 1 0 1 0 0 R/W 21 www.national.com LP3972 Write Cycle Write cycle 20207616 Read Cycle When a READ function is to be accomplished, a WRITE function must precede the READ function as follows. Read Cycle 20207617 w = write (SDA = “0”) r = read (SDA = “1”) ack = acknowledge (SDA pulled down by either master or slave) rs = repeated start id = 34h (Chip Address) I2C DVM Timing for VCC_APPS (Buck1) 20207618 www.national.com 22 Device Address, LP3972 MULTI-BYTE I2C COMMAND SEQUENCE To correctly function with the Monahan’s Power Management I2C the LP3972’s I2C serial interface shall support Random register Multi-byte command sequencing: During a multi-byte write the Master sends the Start command followed by the Device address, which is sent only once, followed by the 8 Bit register address, then 8-bits of data. The I2C slave must then accept the next random register address followed by 8 bits of data and continue this process until the master sends a valid stop condition. A Typical Multi-byte random register transfer is outlined below: Register A Address, Ach, Register A Data, Ach Register M Address, Ach, Register M Data, Ach Register X Address, Ach, Register X Data, Ach Register Z Address, Ach, Register Z Data, Ach, Stop Note: the PMIC is not required to see the I2C device address for each transaction. A, M, X, and Z are Random numbers. 20207642 been sent. Address incrimination may be required for non XScale applications. User can define whether multi-byte (default) to random address or address incrimination will be used. INCREMENTAL REGISTER I2C COMMAND SEQUENCE The LP3972 supports address increment (burst mode). When you have defined register address n data bytes can be sent and register address is incremented after each data byte has 20207643 23 www.national.com LP3972 LP3972 CONTROL REGISTER Register Address Register Name Read/Write 8h’07 SCR R/W System Control Register Register Description 8h’10 OVER1 R/W Output Voltage Enable Register 1 8h’11 OVSR1 R Output Voltage Status Register 1 8h’12 OVER2 R/W Output Voltage Enable Register 2 8h’13 OVSR2 R Output Voltage Status Register 2 8h’20 VCC1 R/W Voltage Change Control Register 1 8h’23 ADTV1 R/W BUCK1 Target Voltage 1 Register 8h’24 ADTV2 R/W BUCK1 DVM Target Voltage 2 Register 8h’25 AVRC R/W VCC_APPS Voltage Ramp Control 8h’26 CDTC1 W Dummy Register 8h’27 CDTC2 W Dummy Register 8h’29 SDTV1 R/W LDO5 Target Voltage 1 8h’2A SDTV2 R/W LDO5 Target Voltage 2 8h’32 MDTV1 R/W LDO1 Target Voltage 1 Register 8h’33 MDTV2 R/W LDO1 Voltage 2 Register 8h’39 L2VCR R/W LDO2 Voltage Control Registers 8h’3A L34VCR R/W LDO3 & LDO4 Voltage Control Registers 8h’80 SCR1 R/W System Control Register 1 8h’81 SCR2 R/W System Control Register 2 8h’82 OEN3 R/W Output Voltage Enable Register 3 8h’83 OSR3 R/W Output Voltage Status Register 3 8h’84 LOER4 R/W Output Voltage Enable Register 3 8h’85 B2TV R/W VCC_Buck2 Target Voltage 8h’86 B3TV R/W VCC_Buck3 Target Voltage 8h’87 B32RC R/W Buck 32 Voltage Ramp Control 8h’88 ISRA R 8h’89 BCCR R/W Interrupt Status Register A 8h’8E II1RR R Internal 1 Revision Register 8h’8F II2RR R Internal 2 Revision Register Backup Battery Charger Control Register SERIAL INTERFACE REGISTER SELECTION CODES (Bold face voltages are default values) System Control Status Register Register is an 8 bit register which specifies the control bits for the PMIC clocks. This register works in conjunction with the SYNC pin where an external clock PLL buffer operating at 13 MHz is synchronized with the oscillators of the buck converters. System Control Register (SCR) 8h’07 Bit 7 6 5 Designation 4 3 2 1 Reserved Reset Value 0 0 0 0 0 CLK_SCL 0 0 0 System Control Register (SCR) 8h’07 Definitions Bit Access Name 7-1 — — 0 R/W CLK_SCL www.national.com Description Reserved External Clock Select 0 = Internal Oscillator clock for Buck Converters 1 = External 13 MHz Oscillator clock for Buck Converters 24 0 LP3972 OUTPUT VOLTAGE ENABLE REGISTER 1 This register enables or disables the low voltage supplies LDO1 and Buck1. See details below. Output Voltage Enable Register 1 (OVER1) 8h’10 Bit 7 6 0 0 Designation 5 4 3 0 0 Reserved Reset Value 0 2 1 0 S_EN Reserved A_EN 1 0 1 Output Voltage Enable Register 1 (OVER1) 8h’10 Definitions Bit Access Name Description 7-3 — — Reserved 2 R/W S_EN VCC_SRAM (LDO5) Supply Output Enabled 0 = VCC_SRAM (LDO5) Supply Output Disabled 1 = VCC_SRAM (LDO5) Supply Output Enabled 1 — — Reserved 0 R/W A_EN VCC_APPS (Buck1) Supply Output Enabled 0 = VCC_APPS (BUCK1) Supply Output Disabled 1 = VCC_APPS (BUCK1) Supply Output Enabled OUTPUT VOLTAGE STATUS REGISTER This 8 bit register is used to indicate the status of the low voltage supplies. By polling each of the specify supplies is within its specified operating range. Output Voltage Status Register 1 (OVSR1) 8h’11 Bit 7 6 Designation LP_OK Reset Value 0 5 4 3 Reserved 0 0 0 0 2 1 0 S_OK Reserved A_OK 0 0 0 Output Voltage Status Register 1 (OVSR1) 8h’11 Definitions Bit Access Name Description 7 R LP_OK Low Voltage Supply Output Voltage Status 0 - VCC_APPS (Buck1) & VCC_SRAM (LDO5) output voltage < 90% of selected value 1 - VCC_APPS (Buck1) & VCC_SRAM (LDO5) output voltage > 90% of selected value 6:3 — — 2 R S_OK 1 — — 0 R A_OK Reserved VCC_SRAM Supply Output Voltage Status 0 - VCC_SRAM (LDO5) output voltage < 90% of selected value 1 - VCC_SRAM (LDO5) output voltage > 90% of selected value Reserved VCC_APPS Supply output Voltage Status 0 - VCC_APPS(BUCK1) output voltage < 90% of selected value 1 - VCC_APPS(BUCK1) output voltage > 90% of selected value 25 www.national.com LP3972 OUTPUT VOLTAGE ENABLE REGISTER 2 This 8 bit output register enables and disables the output voltages on the LDO 2,3,4 supplies. Output Voltage Enable Register 2 (OVER2) 8h’12 Bit 7 Designation 6 5 Reserved Reset Value 0 0 4** 3** 2** LDO4_EN LDO3_EN LDO2_EN 0 0 0 0 1 0 Reserved 0 0 Note: ** denotes one time factory programmable EPROM registers for default values Output Voltage Enable Register 2 (OVER2) 8h’12 Definitions Bit Access Name 7 — — Description Reserved 6 — — Reserved Reserved 5 — — 4 R/W LDO4_EN LDO_4 Output Voltage Enable 0 = LDO4 Supply Output Disabled, Default 1 = LDO4 Supply Output Enabled 3 R/W LDO3_EN LDO_3 Output Voltage Enable 0 = LDO3 Supply Output Disabled, Default 1 = LDO3 Supply Output Enabled 2 R/W LDO2_EN LDO_2 Output Voltage Enable 0 = LDO2 Supply Output Disabled, Default 1 = LDO2 Supply Output Enabled 1 — — Reserved 0 — — Reserved OUTPUT VOLTAGE ENABLE REGISTER 2 Output Voltage Status Register 2 (OVSR2) 8h’13 7 6 5 4 3 2 1 0 Designation Bit LDO_OK N/A N/A LDO4_OK LDO3_OK LDO2_OK N/A N/A Reset Value 0 0 0 0 0 0 0 0 Output Voltage Status Register 2 (OVSR2) 8h’13 Definitions Bit Access Name 7 R LDO_OK 6 — — Reserved 5 — — Reserved 4 R LDO4_OK LDO_4 Output Voltage Status 0 - (VCC_LDO4) output voltage < 90% of selected value 1 - (VCC_LDO4) output voltage > 90% of selected value 3 R LDO3_OK LDO_3 Output Voltage Status 0 - (VCC_LDO3) output voltage < 90% of selected value 1 - (VCC_LDO3) output voltage > 90% of selected value 2 R LDO2_OK LDO_2 Output Voltage Status 0 - (VCC_LDO2) output voltage < 90% of selected value 1 - (VCC_LDO2) output voltage > 90% of selected value 1 — — Reserved 0 — — Reserved www.national.com Description LDO 2-4 Supply Output Voltage Status 0 - (LDO 2-4) output voltage < 90% of selected value 1 - (LDO 2-4) output voltage > 90% of selected value 26 LP3972 DVM VOLTAGE CHANGE CONTROL REGISTER 1 DVM Voltage Change Control Register 1 (VCC1) 8h’20 Bit 7 6 5 4 Designation MVS MGO SVS SGO Reset Value 0 0 0 0 3 2 Reserved 0 0 1 0 AVS AGO 0 0 DVM Voltage Change Control Register 1 (VCC1) 8h’20 Definitions Bit Access Name Description 7 R/W MVS VCC_MVT (LDO1) Voltage Select 0 - Change VCC_MVT Output Voltage to MDVT1 1 - Change VCC_MVT Output Voltage to MDVT2 6 R/W MGO Start VCC_MVT (LDO1) Voltage Change 0 - Hold VCC_MVT Output Voltage at current Level 1 - Ramp VCC_MVT Output Voltage as selected by MVS 5 R/W SVS VCC_SRAM (LDO5) Voltage Select 0 - Change VCC_SRAM Output Voltage to SDTV1 1 - Change VCC_SRAM Output Voltage to SDTV2 4 R/W SGO Start VCC_SRAM (LDO5) Voltage Change 0 - Hold VCC_SRAM Output Voltage at current Level 1 - Change VCC_SRAM Output Voltage as selected by SVS 3:2 — — 1 R/W AVS VCC_APPS (Buck 1) Voltage Select 0 - Ramp VCC_APPS Output Voltage to ADVT1 1 - Ramp VCC_APPS Output Voltage to ADVT2 0 R/W AGO Start VCC_APPS(Buck1) Voltage Change 0 - Hold VCC_APPS Output Voltage at current Level 1 - Ramp VCC_APPS Output Voltage as selected by AVS Reserved 27 www.national.com LP3972 BUCK1 (VCC_APPS) VOLTAGE 1 Buck1 (VCC_APPS) Target Voltage 1 Register (ADTV1) 8h’23 Bit 7 Designation 6 5 4** 0 0 3** Reserved Reset Value 0 0 2** 1** 0** Buck 1 Output Voltage (B1OV1) 1 0 1 1 Note: ** denotes one time factory programmable Buck1 (VCC_APPS) Target Voltage 1 Register (ADTV1) 8h’23 Definitions Bit Access Name 7:5 — — 4:0 R/W B1OV1 www.national.com Description Reserved Data Code 5h’0 5h’1 5h’2 5h’3 5h’4 5h’5 5h’6 5h’7 5h’8 5h’9 5h’A 5h’B 5h’C 5h’D 5h’E 5h’F 28 Output Voltage 0.725 0.750 0.775 0.800 0.825 0.850 0.875 0.900 0.925 0.950 0.975 1.000 1.025 1.050 1.075 1.100 Data Code 5h’10 5h’11 5h’12 5h’13 5h’14 5h’15 5h’16 5h’17 5h’18 5h’19 5h’1A 5h’1B 5h’1C 5h’1D 5h’1E 5h’1F Output Voltage 1.125 1.150 1.175 1.200 1.225 1.250 1.275 1.300 1.325 1.350 1.375 1.400 1.425 1.450 1.475 1.500 LP3972 BUCK1 (VCC_APPS) TARGET VOLTAGE 2 REGISTER Buck1 (VCC_APPS) Target Voltage 2 Register (ADTV2) 8h’24 Bit 7 Designation 6 5 4 0 0 3 Reserved Reset Value 0 0 2 1 0 Buck 1 Output Voltage (B1OV2) 1 0 1 1 Buck1 (VCC_APPS) Target Voltage 2 Register (ADTV2) 8h’24 Definitions Bit Access Name 7:5 — — 4:0 R/W B1OV2 Description Reserved Data Code 5h’0 5h’1 5h’2 5h’3 5h’4 5h’5 5h’6 5h’7 5h’8 5h’9 5h’A 5h’B 5h’C 5h’D 5h’E 5h’F 29 Output Voltage 0.725 0.750 0.775 0.800 0.825 0.850 0.875 0.900 0.925 0.950 0.975 1.000 1.025 1.050 1.075 1.100 Data Code 5h’10 5h’11 5h’12 5h’13 5h’14 5h’15 5h’16 5h’17 5h’18 5h’19 5h’1A 5h’1B 5h’1C 5h’1D 5h’1E 5h’1F Output Voltage 1.125 1.150 1.175 1.200 1.225 1.250 1.275 1.300 1.325 1.350 1.375 1.400 1.425 1.450 1.475 1.500 www.national.com LP3972 BUCK1 (VCC_APPS) VOLTAGE RAMP CONTROL REGISTER Buck1 (VCC_APPS) Voltage Ramp Control Register (AVRC) 8h’25 Bit 7 Designation 6 5 4 3 0 0 1 Reserved Reset Value 0 0 2 1 0 1 0 Ramp Rate (B1RR) 0 Buck 1 (VCC_APPS) Voltage Ramp Control Register (AVRC) 8h’25 Definitions Bit Access Name 7:5 — — Description Reserved DVM Ramp Speed 4:0 www.national.com R/W Data Code 5h’0 5h’1 5h’2 5h’3 5h’4 5h’5 5h’6 5h’7 5h’8 5h’9 5h’A 4h’B-4h’1F B1RR 30 Ramp Rate (mV/uS) Instant 1 2 3 4 5 6 7 8 9 10 Reserved LP3972 VCC_COMM TARGET VOLTAGE 1 DUMMY REGISTER (CDTV1) VCC_COMM Target Voltage 1 Dummy Register (CDTV1) 8h’26 Write Only Bit 7 6 Designation 5 4 3 0 0 0 4 3 Reserved Reset Value 0 Note: CDTV1 must be writable by an I 2C 0 2 1 0 0 0 0 2 1 0 0 0 Output Voltage controller. This is a dummy register VCC_COMM TARGET VOLTAGE 2 DUMMY REGISTER (CDTV2) VCC_COMM Target Voltage 2 Dummy Register (CDTV2) 8h’27 Write Only Bit 7 6 Designation 5 Reserved Reset Value 0 Note: CDTV2 must be writable by an I 2C 0 Output Voltage 0 0 0 0 controller. This is a dummy register and can not be read. This is a variable voltage supply to the internal SRAM of the Application processor. LDO 5 (VCC_SRAM) TARGET VOLTAGE 1 REGISTER LDO 5 (VCC_SRAM) Target Voltage 1 Register (SDTV1) 8H'29 Bit 7 Designation 6 5 4** 3** Reserved Reset Value 0 0 2** 1** 0** LDO 5 Output Voltage (L5OV) 0 0 1 0 1 1 Note: ** denotes one time factory programmable EPROM registers for default values LDO 5 (VCC_SRAM) Target Voltage 1 Register (SDTV1) 8h’29 Definitions Bit Access Name 7:5 — — 4:0 R/W B1OV Description Reserved Data Code 5h’0 5h’1 5h’2 5h’3 5h’4 5h’5 5h’6 5h’7 5h’8 5h’9 5h’A 5h’B 5h’C 5h’D 5h’E 5h’F 31 Output Voltage — — — — — 0.850 0.875 0.900 0.925 0.950 0.975 1.000 1.025 1.050 1.075 1.100 Data Code 5h’10 5h’11 5h’12 5h’13 5h’14 5h’15 5h’16 5h’17 5h’18 5h’19 5h’1A 5h’1B 5h’1C 5h’1D 5h’1E 5h’1F Output Voltage 1.125 1.150 1.175 1.200 1.225 1.250 1.275 1.300 1.325 1.350 1.375 1.400 1.425 1.450 1.475 1.500 www.national.com LP3972 LDO 5 (VCC_SRAM) TARGET VOLTAGE 2 REGISTER LDO 5 (VCC_SRAM) Target Voltage 2 Register (SDTV2) 8h’2A Bit 7 Designation 6 5 4 3 0 0 1 Reserved Reset Value 0 0 2 1 0 LDO 5 Output Voltage (L5OV) 0 1 1 LDO 5 (VCC_SRAM) Target Voltage 2 Register (SDTV2) 8h’2A Definitions Bit Access Name 7:5 — — 4:0 R/W B1OV Description Reserved Data Code 5h’0 5h’1 5h’2 5h’3 5h’4 5h’5 5h’6 5h’7 5h’8 5h’9 5h’A 5h’B 5h’C 5h’D 5h’E 5h’F Output Voltage — — — — — 0.850 0.875 0.900 0.925 0.950 0.975 1.000 1.025 1.050 1.075 1.100 Data Code 5h’10 5h’11 5h’12 5h’13 5h’14 5h’15 5h’16 5h’17 5h’18 5h’19 5h’1A 5h’1B 5h’1C 5h’1D 5h’1E 5h’1F Output Voltage 1.125 1.150 1.175 1.200 1.225 1.250 1.275 1.300 1.325 1.350 1.375 1.400 1.425 1.450 1.475 1.500 VCC_MVT is low tolerance regulated power supply for the application processor ring oscillator and logic for communicating to the LP3972. VCC_MVT is enabled when SYS_EN is asserted and disabled when SYS_EN is deasserted. www.national.com 32 LP3972 LDO 1 (VCC_MVT) TARGET VOLTAGE 1 REGISTER (MDTV1) LDO 1 (VCC_MVT) Target Voltage 1 Register (MDTV1) 8h’32 Bit 7 6 Designation 5 4** 3** 0 0 0 Reserved Reset Value 0 0 2** 1** 0** 0 0 Output Voltage (OV) 1 Note: ** denotes one time factory programmable EPROM registers for default values LDO 1 (VCC_MVT) Target Voltage 1 Register (MDTV1) 8h’32 Definitions Bit Access Name 7:5 — — 4:0 R/W L1OV Description Reserved Data Code 5h’0 5h’1 5h’2 5h’3 5h’4 5h’5 5h’6 5h’7 5h’8 5h’9 5h’A 5h’B 5h’C 5h’D-5h’F 33 Output Voltage 1.700 1.725 1.750 1.775 1.800 1.825 1.850 1.875 1.900 1.925 1.950 1.975 2.000 Reserved Notes: www.national.com LP3972 LDO 1 (VCC_MVT) TARGET VOLTAGE 2 REGISTER LDO 1 (VCC_MVT) Target Voltage 2 Register (MDTV2) 8h’33 Bit 7 6 Designation 5 4 3 0 0 1 Reserved Reset Value 0 0 2 1 0 1 1 Output Voltage (OV) 0 LDO 1 (VCC_MVT) Target Voltage 2 Register (MDTV2) 8h’33 Definitions Bit Access Name 7:5 — — 4:0 R/W L1OV www.national.com Description Reserved Data Code 5h’0 5h’1 5h’2 5h’3 5h’4 5h’5 5h’6 5h’7 5h’8 5h’9 5h’A 5h’B 5h’C 5h’D-5h’F 34 Output Voltage 1.700 1.725 1.750 1.775 1.800 1.825 1.850 1.875 1.900 1.925 1.950 1.975 2.000 Reserved Notes: LP3972 LDO2 VOLTAGE CONTROL REGISTER (L12VCR) LDO2 Voltage Control Register (L12VCR) 8h’39 Bit 7** 6** Designation 5** 4** 3 0 0 LDO 2 Output Voltage (L2OV) Reset Value 0 0 0 2 1 0 Reserved 0 0 0 Note: ** denotes one time factory programmable EPROM registers for default values LDO2 Voltage Control Register (L12VCR) 8h’39 Definitions Bit Access Name 7:4 R/W L2OV Data Code 4h’0 4h’1 4h’2 4h’3 4h’4 4h’5 4h’6 4h’7 4h’8 4h’9 4h’A 4h’B 4h’C 4h’D 4h’E 4h’F Description 3:0 — — Reserved 35 Output Voltage 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 Notes: Default www.national.com LP3972 LDO4 – LDO3 VOLTAGE CONTROL REGISTER (L34VCR) LDO4 – LDO3 Voltage Control Register (L34VCR) 8h’3A Bit 7** Designation 6** 5** 4** 3** 0 0 LDO 4 Output Voltage (L4OV) Reset Value 0 0 2** 1** LDO 3 Output Voltage (L3OV) 0 0 0 Note: ** denotes one time factory programmable EPROM registers for default values LDO4 – LDO3 Voltage Control Register (L34VCR) 8h’3A Definitions Bit Access Name 7:4 R/W L4OV Description Data Code 4h’0 4h’1 4h’2 4h’3 4h’4 4h’5 4h’6 4h’7 4h’8 4h’9 4h’A 4h’B 4h’C 4h’D 4h’E 4h’F Output Voltage 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 1.40 1.50 1.80 1.90 2.50 2.80 3.00 3.30 Notes: Default 3:0 www.national.com R/W L3OV 0** Data Code 4h’0 4h’1 4h’2 4h’3 4h’4 4h’5 4h’6 4h’7 4h’8 4h’9 4h’A 4h’B 4h’C 4h’D 4h’E 4h’F 36 Output Voltage 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 Notes: Default 0 LP3972 NSC DEFINED CONTROL AND STATUS REGISTERS SYSTEM CONTROL REGISTER 1 (SCR1) System Control Register 1 (SCR1) 8h’80 Bit 7** 6** Designation BPSEN Reset Value 0 5** SENDL 1 0 4 3 2 1 0 FPWM3 FPWM2 FPWM1 BK_SLOMOD BK_SSEN 0 0 0 0 0 Note: ** denotes one time factory programmable EPROM registers for default values System Control Register 1 (SCR1) 8h’80 Definitions Bit Access Name Description 7 R/W BPSEN Bypass System enable safety Lock. Prevents activation of PWR_EN when SYS_EN is low. 0 = PWR_EN “AND” with SYS_EN signal, Default 1 = PWR_EN independent of SYS_EN Delay time for High Voltage Power Domains LDO2, LDO3, LDO4, Buck2, and Buck3 after activation of SYS_EN. VCC_LDO1 has no delay. Data Code Delay mS Notes: 2h’0 0.0 2h’1 0.5 2h’2 1.0 Default 2h’3 1.4 6:5 R/W SENDL 4 R/W FPWM3 Buck 3 PWM/PFM Mode select 0 - Auto Switch between PFM and PWM operation 1 - PWM Mode Only will not switch to PFM 3 R/W FPWM2 Buck 2 PWM/PFM Mode select 0 - Auto Switch between PFM and PWM operation 1 - PWM Mode Only will not switch to PFM 2 R/W FPWM1 Buck 1 PWM/PFM Mode select 0 - Auto Switch between PFM and PWM operation 1 - PWM Mode Only will not switch to PFM 1 R BK_SLOMOD 0 R BK_SSEN Buck Spread Spectrum Modulation Buck 1-3 0 = 10 kHz triangular wave spread spectrum modulation 1 = 2 kHz triangular wave spread spectrum modulation Spread spectrum function Buck 1-3 0 = SS Output Disabled 1 = SS Output Enabled 37 www.national.com LP3972 SYSTEM CONTROL REGISTER 2 (SCR2) System Control Register 2 (SCR2) 8h’81 Bit Designation 7 6 5** 4 BBCS SHBU BPTR WUP3 1 0 1 1 3 2 1 0 1 GPIO2 0 0 GPIO1 0 Note: ** denotes one time factory programmable EPROM registers for default values System Control Register 2 (SCR2) 8h’81 Definitions Bit Access Name 7 R/W BBCS 6 R/W SHBU 5 R/W BPTR Bypass RTC_LDO Output Voltage to LDO 3 Output Voltage Tracking 0 - RTC-LDO 3 Tracking enabled 1 - RTC-LDO 3 Tracking disabled, Default 4 R/W WUP3 Spare Wakeup control input 0 - Active High 1 - Active Low 3:2 R/W GPIO2 Configure direction and output sense of GPIO2 Pin Data Code GPIO2 2h’00 Hi-Z 2h’01 Output Low 2h’02 Input 2h’03 Output high 1:0 R/W GPIO1 Configure direction and output sense of GPIO1 Pin Data Code GPIO1 2h’00 Hi-Z 2h’01 Output Low 2h’02 Input 2h’03 Output high www.national.com Description Sets GPIO1 as control input for Back Up battery charger 0 - Back Up battery Charger GPIO Disabled 1 - Back Up battery Charger GPIO Pin Enabled Shut down Back up battery to prevent battery drain during shipping 0 = Back up Battery Enabled 1 = Back up battery Disabled 38 Bit 7 Designation 6 5 Reserved Reset Value 0 0 0 4** 3 2** 1 0** B3EN ENFLAG B2EN Reserved L1EN 1 0 1 0 1 Note: ** denotes one time factory programmable EPROM registers for default values OUTPUT ENABLE 3 REGISTER (OEN3) 8H’82 DEFINITIONS Bit Access Name 7:5 — — 4 R/W B3EN 3 R/W ENFLAG 2 R/W B2EN 1 — — 0 R/W L1EN Description Reserved VCC_Buck3 Supply Output Enabled 0 = VCC_Buck3 Supply Output Disabled 1 = VCC_Buck3 Supply Output Enabled, Default Enable for Temperature Flags (BCT) 0 = Temperature Flag Disabled 1 = Temperature Flag Enabled VCC_Buck2 Supply Output Enabled 0 = VCC_Buck2 Supply Output Disabled 1 = VCC_Buck2 Supply Output Enabled, Default Reserved LDO_1 (MVT)Output Voltage Enable 0 = LDO1 Supply Output Disabled 1 = LDO1 Supply Output Enabled, Default STATUS REGISTER 3 (OSR3) 8H’83 7 6 5 4 3 2 1 0 Designation Bit BT_OK B3_OK B2_OK LDO1_OK Reserved BCT2 BCT1 BCT0 Reset Value 0 0 0 0 0 0 0 0 STATUS REGISTER 3 (OSR3) DEFINITIONS 8H’83 Bit Access Name 7 R BT_OK Buck 2-3 Supply Output Voltage Status 0 - (Buck 1-3) output voltage < 90% Default value 1 - (Buck 1-3) output voltage > 90% Default value Description 6 R B3_OK Buck 3 Supply Output Voltage Status 0 - (Buck 3) output voltage < 90% Default value 1 - (Buck 3) output voltage > 90% Default value 5 R B2_OK Buck 2 Supply Output Voltage Status 0 - (Buck 2) output voltage < 90% Default value 1 - (Buck 2) output voltage > 90% Default value 4 R LDO1_OK 3 — — LDO_1 Output Voltage Status 0 - (VCC_LDO1) output voltage < 90% of selected value 1 - (VCC_LDO1) output voltage > 90% of selected value Reserved 39 www.national.com LP3972 OUTPUT ENABLE 3 REGISTER (OEN3) 8H’82 LP3972 Bit Access Name 2:0 R BCT www.national.com Description Binary coded thermal management flag status register Temperature Ascending °C Data Code 40 000 60 001 80 010 100 011 120 100 140 101 160 110 Reserved 111 40 7 6* 5* 4* 3* 2* 1* 0* Designation Bit Reserved B3ENC B2ENC B1ENC L5EC L4EC L3EC L2EC Reset Value 0 1 1 0 0 1 1 1 Note: ** denotes one time factory programmable EPROM registers for default values LOGIC OUTPUT ENABLE REGISTER (LOER) DEFINITIONS 8H’84 Bit Access Name Description 7 — — 6 R/W B3ENC Connects Buck 3 enable to SYS_EN or PWR_EN Logic Control pin 0 - Buck 3 enable connected to PWR_EN 1 - Buck 3 enable connected to SYS_EN, Default 5 R/W B2ENC Connects Buck 2 enable to SYS_EN or PWR_EN Logic Control pin 0 - Buck 2 enable connected to PWR_EN 1 - Buck 2 enable connected to SYS_EN, Default 4 R/W B1ENC Connects Buck 1 enable to SYS_EN or PWR_EN Logic Control pin 0 - Buck 1 enable connected to PWR_EN, Default 1 - Buck 1 enable connected to SYS_EN 3 R/W L5EC Connects LDO5 enable to SYS_EN or PWR_EN Logic Control pin 0 - LDO 5 enable connected to PWR_EN, Default 1 - LDO 5 enable connected to SYS_EN 2 R/W L4EC Connects LDO4 enable to SYS_EN or PWR_EN Logic Control pin 0 - LDO 4 enable connected to PWR_EN 1 - LDO 4 enable connected to SYS_EN, Default 1 R/W L3EC Connects LDO3 enable to SYS_EN or PWR_EN Logic Control pin 0 - LDO 3 enable connected to PWR_EN 1 - LDO 3 enable connected to SYS_EN, Default 0 R/W L2EC Connects LDO2 enable to SYS_EN or PWR_EN Logic Control pin 0 - LDO 2 enable connected to PWR_EN 1 - LDO 2 enable connected to SYS_EN, Default Reserved 41 www.national.com LP3972 LOGIC OUTPUT ENABLE REGISTER (LOER) 8H’84 LP3972 VCC_BUCK 2 TARGET VOLTAGE REGISTER (B2TV) 8H’85 Bit 7 Designation 6 5 4** 3** Reserved Reset Value 0 0 2** 1** 0** Buck 2 Output Voltage (B2OV) 0 1 1 0 0 1 Note: ** denotes one time factory programmable EPROM registers for default values VCC_BUCK 2 TARGET VOLTAGE REGISTER (B2TV) 8H’85 DEFINITIONS Bit Access 7:5 — 4:0 R/W Name Description Reserved B2OV Output Voltage Data Code 5h’01 5h’02 5h’03 5h’04 5h’05 5h’06 5h’07 5h’08 5h’09 5h’0A 5h’0B 5h’0C (V) 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 Data Code 5h’0D 5h’0E 5h’0F 5h’10 5h’11 5h’12 5h’13 5h’14 5h’15 5h’16 5h’17 5h’18 5h’19 (V) 1.40 1.45 1.50 1.55 1.60 1.65 1.70 1.80 1.90 2.50 2.80 3.00 3.30 BUCK 3 TARGET VOLTAGE REGISTER (B3TV) 8H’86 Bit 7 Designation 6 5 4** 3** Reserved Reset Value 0 0 2** 1** 0** Buck 3 Output Voltage (B3OV) 0 1 0 1 0 0 Note: ** denotes one time factory programmable EPROM registers for default values BUCK 3 TARGET VOLTAGE REGISTER (B3TV) 8H’86 DEFINITIONS Bit Access 7:5 — 4:0 R/W www.national.com Name Description Reserved B3OV Output Voltage Data Code 5h’01 5h’02 5h’03 5h’04 5h’05 5h’06 5h’07 5h’08 5h’09 5h’0A 5h’0B 5h’0C 42 (V) 0.80 0.85 0.90 0.95 1.00 1.05 1.10 1.15 1.20 1.25 1.30 1.35 Data Code 5h’0D 5h’0E 5h’0F 5h’11 5h’12 5h’13 5h’14 5h’15 5h’16 5h’17 5h’18 5h’19 (V) 1.40 1.45 1.50 1.60 1.65 1.70 1.80 1.90 2.50 2.80 3.00 3.30 Default LP3972 VCC_BUCK 3:2 VOLTAGE RAMP CONTROL REGISTER (B32RC) VCC_Buck 3:2 Voltage Ramp Control Register (B32RC) 8h’87 Bit 7 Designation 6 5 4 3 0 1 Ramp Rate (B3RR) Reset Value 1 0 2 1 0 Ramp Rate (B2RR) 1 0 1 0 Buck 3:2 Voltage Ramp Control Register (B3RC) 8h’87 Definitions Bit Access Name 7:4 R/W B3RR Data Code 4h’0 4h’1 4h’2 4h’3 4h’4 4h’5 4h’6 4h’7 4h’8 4h’9 4h’A Description Ramp Rate mV/µS Instant 1 2 3 4 5 6 7 8 9 10 3:0 R/W B2RR Data Code 4h’0 4h’1 4h’2 4h’3 4h’4 4h’5 4h’6 4h’7 4h’8 4h’9 4h’A Ramp Rate mV/µS Instant 1 2 3 4 5 6 7 8 9 10 43 www.national.com LP3972 INTERRUPT STATUS REGISTER ISRA This register specifies the status bits for the interrupts generated by the PMIC. Thermal warning of the IC, GPIO1, GPIO2, PWR_ON pin, TEST_JIG factory programmable on signal, and the SPARE pin. Interrupt Status Register ISRA 8h’88 7 6 5 4 3 2 1 0 Designation Bit Reserved T125 GPI2 GPI1 WUP3 WUP2 WUPT WUPS Reset Value 0 0 0 0 0 0 0 0 Interrupt Status Register ISRA 8h’88 Definitions Bit Access Name 7 — — 6 R T125 Status bit for thermal warning PMIC T>125C 0 = PMIC Temp. < 125°C 1 = PMIC Temp. > 125°C 5 R GPI2 Status bit for the input read in from GPIO 2 when set as Input 0 = GPI2 Logic Low 1 = GPI2 Logic High 4 R GPI1 Status bit for the input read in from GPIO 1 when set as Input 0 = GPI1 Logic Low 1 = GPI1 Logic High 3 R WUP3 PWR_ON Pin long pulse Wake Up Status 0 = No wake up event 1 = Long pulse wake up event 2 R WUP2 PWR_ON Pin Short pulse Wake Up Status 0 = No wake up event 1 = Short pulse wake up event 1 R WUPT TEST_JIG Pin Wake Up Status 0 = No wake up event 1 = Wake up event 0 R WUPS SPARE Pin Wake Up Status 0 = No wake up event 1 = Wake up event www.national.com Description Reserved 44 LP3972 BACKUP BATTERY CHARGER CONTROL REGISTER (BCCR) This register specifies the status of the main battery supply. NBUB bit Backup Battery Charger Control Register (BCCR) 8h’89 7** 6 Designation Bit NBUB CNBFL 5** Reset Value 0 0 4** 3** 2 nBFLT 0 1 BUCEN 1 0 0 IBUC 0 0 1 Note: ** denotes one time factory programmable EPROM registers for default values Backup Battery Charger Control Register (BCCR) 8h’89 Definitions Bit Access Name Description 7 R/W NBUB No back-up battery default setting. Logic will not allow switch over to back-up battery. 0 = Back up Battery Enabled, Default 1 = Back up Battery Disabled 6 R/W CNBFL Control for nBATT_FLT output signal 0 = nBATT_FLT Enabled 1 = nBATT_FLT Disabled nBATT_FLT monitors the battery voltage and can be set to the Assert voltages listed below. 5:3 2 R/W R/W BFLT BUCEN Data Code 3h’01 3h’02 3h’03 3h’04 3h’05 Asserted 2.6 2.8 3.0 3.2 3.4 De-Asserted 2.8 3.0 3.2 3.4 3.6 Note: Default Enables backup battery charger 0 = Back up Battery Charger Disabled 1 = Back up Battery Charger Enabled Charger current setting for back-up battery 1:0 R/W IBUC Data Code 2h’00 2h’01 2h’02 2h’03 45 BU Charger I (µA) 260 190 325 390 Note: Default www.national.com LP3972 MARVELL PXA INTERNAL 1 REVISION REGISTER (II1RR) 8H’8E Bit 7 6 5 4 Designation 3 2 1 0 0 0 0 0 3 2 1 0 0 0 0 0 II1RR Reset Value 0 0 0 0 MARVELL PXA INTERNAL 1 REVISION REGISTER (II1RR) 8H’8E DEFINITIONS Bit Access Name 7:0 R II1RR Description Intel internal usage register for revision information. MARVELL PXA INTERNAL 2 REVISION REGISTER (II2RR) 8H’8F Bit 7 6 5 4 Designation II2RR Reset Value 0 0 0 0 MARVELL PXA INTERNAL 2 REVISION REGISTER (II2RR) 8H’8F DEFINITIONS Bit Access Name 7:0 R II2RR Description Intel internal usage register for revision information. REGISTER PROGRAMMING EXAMPLES Example 1) Start of Day Sequence PMIC Register Address PMIC Register Name Register Data 8h’23 ADTVI 00011011 Sets the SOD VCC_APPS voltage 8h’29 SDTV1 00011011 Sets the SOD VCC_SRAM voltage 8h’10 OVER1 00000111 Enables VCC_SRAM and VCC_APPS to their programmed values. Description SODl Multi-byte random register transfer is outlined below: 20207644 www.national.com 46 LP3972 Device Address, Register A Address, Ach, Register A Data, Ach Register M Address, Ach, Register M Data, Ach Register X Address, Ach, Register X Data, Ach Register Z Address, Ach, Register Z Data, Ach, Stop Example 2) Voltage change Sequence PMIC Register Address PMIC Register Name Register Data Description 8h’24 ADTV2 00010111 Sets the VCC_APPS target voltage 2 to 1.3 V 8h’2A SDTV2 00001111 Sets the VCC_SRAM target voltage 2 to 1.1 V 8h’20 VCC1 00110011 Enable VCC_SRAM and VCC_APPS to change to their programmed target values. I2C DATA EXCHANGE BETWEEN MASTER AND SLAVE DEVICE 20207645 47 www.national.com LP3972 LP3972 Controls DIGITAL INTERFACE CONTROL SIGNALS Signal Definition Active State Signal Direction SYS_EN High Voltage Power Enable High Input PWR_EN Low Voltage Power Enable High Input SCL Serial Bus Clock Line Clock Input SDA Serial Bus Data Line nRSTI Forces an unconditional hardware reset Low Input nRSTO Forces an unconditional hardware reset Low Output nBATT_FLT Main Battery removed or discharged indicator Low Output PWR_ON Wakeup Input to CPU High Input nTEST_JIG Wakeup Input to CPU Low Input SPARE Wakeup Input to CPU High/Low Input EXT_WAKEUP Wake-Up Output for application processor High Output GPIO1 / nCHG_EN General Purpose I/O /External Back-up Battery Charger enable — Bidirectional /Input GPIO2 General Purpose I/O — Bidirectional POWER DOMAIN ENABLES PMU Output HW Enable LDO_RTC — LDO 1 (VCC_MVT) SYS_EN LDO2 SYS_EN LDO3 SYS_EN Bidirectional SW Enable PMU Output SW Enable — PWR_EN S_EN LDO1_EN Buck1 (VCC_APPS) PWR_EN A_EN LDO2_EN BUCK2 SYS_EN B2_EN LDO3_EN BUCK3 SYS_EN B3_EN LDO4 SYS_EN LDO4_EN POWER DOMAINS SEQUENCING (DELAY) By default SYS_EN must be on to have PWR_EN enable but this feature can be switched off by register bit BP_SYS. By default SYS_EN enables LDO1 always first and after a typical of 1 ms delay others. Also when SYS_EN is set off the LDO1 will go off last. This function can be switched off or delay can be changed by DELAY bits via serial interface as seen on table below. 8h’80 Bit 5:4 DELAY bits ‘00’ ‘01’ ‘10’ ‘11’ Delay, ms 0 0.5 1.0 1.5 www.national.com HW Enable LDO5 (VCC_SRAM) LDO_RTC TRACKING (nIO_TRACK) LP3972 has a tracking function (nIO_TRACK). When enabled, LDO_RTC voltage will track LDO3 voltage within 200 mV down to 2.8V when LDO3 is enabled. This function can be switched on/off by nIO_TRACK register bit BPTR. POWER SUPPLY ENABLE SYS_EN and PWR_EN can be changed by programmable register bits. 48 WAKEUP register bits Reason for WAKEUP WUP0 SPARE WUP1 TEST_JIG WUP2 PWR_ON short pulse WUP3 PWR_ON long pulse TSD_EW TSD Early Warning INTERNAL THERMAL SHUTDOWN PROCEDURE Thermal shutdown is build to generate early warning (typ. 125°C) which triggers the EXT_WAKEUP for the processor acknowledge. When a thermal shutdown triggers (typ. 160° C) the PMU will reset the system until the device cools down. BATTERY SWITCH AND BACK UP BATTERY CHARGER When Back-Up battery is connected but the main battery has been removed or its supply voltage too low, LP3972 uses Back-Up Battery for generating LDO_RTC voltage. When Main Battery is available the battery fet switches over to the main battery for LDO_RTC voltage. When Main battery voltage is too low or removed nBATT_FLT is asserted. If no back up battery exists, the battery switch to back up can be switched off by nBU_BAT_EN bit. User can set the battery fault determination voltage and battery charger current via I2C compatible interface. Enabling of back up battery charger can be done via serial interface (nBAT_CHG_EN) or external charger enable pin (nCHG_EN). Pin 29 is set as external charger enable input by default. 20207619 49 www.national.com LP3972 WAKE-UP FUNCTIONALITY (PWR_ON, nTEST_JIG, SPARE AND EXT_WAKEUP) Three input pins can be used to assert wakeup output for 10 ms for application processor notification to wakeup. SPARE Input can be programmed through I2C compatible interface to be active low or high (SPARE bit, Default is active low ‘1’). A reason for wakeup event can be read through I2C compatible interface also. Additionally wakeup inputs have 30 ms debounce filtering. Furthermore PWR_ON have distinguishing between short and long (∼1s) pulses (push button input). LP3972 also has an internal Thermal Shutdown early warning that generates a wakeup to the system also. This is generated usually at 125°C. LP3972 input, output or hi-Z mode. Inputs value can be read via serial interface (GPI1,2 bits). The pin 29 functionality needs to be set to GPIO by serial interface register bit nEXTCHGEN. (GPIO/CHG) GENERAL PURPOSE I/O FUNCTIONALITY (GPIO1 AND GPIO2) LP3972 has 2 general purpose I/Os for system control. I2C compatible interface will be used for setting any of the pins to Controls Port Function Reg batmonchg Function GPIO<1> GPIO<1> Nextchgen_sel bucen GPIO1 Gpin 1 X X 1 0 Input = 0 0 Enabled X X 1 0 Input = 1 0 Not Enabled 0 1 0 1 X X X X X 1 X 0 0 0 X HiZ 1 0 0 X Input (dig)-> Input 0 1 0 X Output = 0 0 1 1 0 X Output = 1 0 Factory fm disabled Enabled GPIO<1> GPIO<1> GPIO_tstiob GPIO2 gpin2 0 0 1 HiZ 0 1 0 1 Input (dig)-> input 0 1 1 Output = 0 0 1 1 1 Output = 1 0 The LP3972 has provision for two battery connections, the main battery Vbat and Backup Battery (See Applications Schematic Diagrams 1 & 2 of the LP3972 Data Sheet). The function of the battery switch is to connect power to the RTC LDO from the appropriate battery, depending on conditions described below: • If only the backup battery is applied, the switch will automatically connect the RTC LDO power to this battery. • If only the main battery is applied, the switch will automatically connect the RTC LDO power to this battery. • If both batteries are applied, and the main battery is sufficiently charged (VBAT > 3.1V), the switch will automatically connect the RTC LDO power to the main battery. • As the main battery is discharged by use, the user will be warned by a separate circuit called nBATT_FLT. Then if no action is taken to restore the charge on the main battery, and discharging is continued the battery switch will protect the RTC LDO by disconnecting from the main battery and connecting to the backup battery. www.national.com • — The main battery voltage at which the RTC LDO is switched from main to backup battery is 2.9V typically. — There is a hysterisis voltage in this switch operation so, the RTC LDO will not be reconnected to main battery until main battery voltage is greater than 3.1V typically. Additionally, the user may wish to disable the battery switch, such as, in the case when only a main battery is used. This is accomplished by setting the “no back up battery bit” in the control register 8h’89 bit 7 NBUB. With this bit set to “1”, the above described switching will not occur, that is the RTC LDO will remain connected to the main battery even as it is discharged below the 2.9 Volt threshold. REGULATED VOLTAGES OK All the power domains have own register bit (X_OK) that processor can read via serial interface to be sure that enabled powers are OK (regulating). Note that these read only bits are only valid when regulators are settled (avoid reading these bits during voltage change or power up). 50 THERMAL WARNING 2 of 6 low power comparators, each consumes less than 1 µA, are always enabled to operate the “T=125°C warning flag with hysteresis. This allows continuous monitoring of a thermal-warning flag feature with very low power consumption. LP3972 THERMAL FLAGS FUNCTIONAL DIAGRAM, DATA FROM INITIAL SILICON The following functions are extra features from the thermal shutdown circuit: 20207646 51 www.national.com LP3972 temperature range and resolution of these flags, might also be refined/redefined. THERMAL MANAGEMENT Application: There is a mode wherein all 6 comparators (flags) can be turned on via the “enallflags” control register bit. This mode allows the user to interrogate the device or system temperature under the set operating conditions. Thus, the rate of temperature change can also be estimated. The system may then negotiate for speed and power trade off, or deploy cooling maneuvers to optimize system performance. The “enallflags” bit needs enabled only when the “bct<2:0> bits are read to conserve power. Note: The thermal management flags have been verified functional. Presently these registers are accessible by factory only. If there is a demand for this function, the relevant register controls may be shifted into the user programmable bank; the LP3972 Application Note - LP3972 Reset Sequence 6. The LP3972 enables the high-voltage power supplies. — LDO1 power for VCC_MVT (Power for internal logic and I/O Blocks), BG (Bandgap reference voltage), OSC13M (13 MHz oscillator voltage) and PLL enabled first, followed by others if delay is on. 7. Countdown timer expires; the Applications processor asserts PWR_EN to enable the low-voltage power supplies. The processor starts the countdown timer set to 125 mS period. 8. The Applications processor asserts PWR_EN (ext. pin or I2C), the LP3972 enables the low-voltage regulators. 9. Countdown timer expires; If enabled power domains are OK (I2C read) the power up sequence continues by enabling the processors 13 MHz oscillator and PLL’s. 10. The Applications processor begins the execution of code. INITIAL COLD START POWER ON SEQUENCE 1. The Back up battery is connected to the PMU, power is applied to the back-up battery pin, the RTC_LDO turns on and supplies a stable output voltage to the VCC_BATT pin of the Applications processor (initiating the power-on reset event) with nRSTO asserted from the LP3972 to the processor. 2. nRSTO de-asserts after a minimum of 50 mS. 3. The Applications processor waits for the de-assertion of nBATT_FLT to indicate system power (VIN) is available. 4. After system power (VIN) is applied, the LP3972 deasserts nBATT_FLT. Note that BOTH nRSTO and nBATT_FLT need to be de-asserted before SYS_EN is enabled. The sequence of the two signals is independent of each other. 5. The Applications processor asserts SYS_EN, the LP3972 enables the system high-voltage power supplies. The Applications processor starts its countdown timer set to 125 mS. 20207622 * Note that BOTH nRSTO and nBATT_FLT need to be de-asserted before SYS_EN is enabled. The sequence of the two signals is independent of each other and can occur is either order. www.national.com 52 Symbol Description t1 Delay from VCC_RTC assertion to nRSTO de-assertion Min t2 Delay from nBATT_FLT de-assertion to nRSTI assertion 100 µS t3 Delay from nRST de-assertion to SYS_EN assertion 10 mS t4 Delay from SYS_EN assertion to PWR_EN assertion 125 mS t5 Delay from PWR_EN assertion to nRSTO de-assertion 125 mS HARDWARE RESET SEQUENCE Hardware reset initiates when the nRSTI signal is asserted (low). Upon assertion of nRST the processor enters hardware RESET SEQUENCE 1. nRSTI is asserted. 2. nRSTO is asserted and will de-asserts after a minimum of 50 mS 3. The Applications processor waits for the de-assertion of nBATT_FLT to indicate system power (VIN) is available. 4. After system power (VIN) is turned on, the LP3972 deasserts nBATT_FLT. 5. The Applications processor asserts SYS_EN, the LP3972 enables the system high-voltage power supplies. The Applications processor starts its countdown timer. Typ 50 Max Units mS reset state. The LP3972 holds the nRST low long enough (50 ms typ.) to allow the processor time to initiate the reset state. 6. The LP3972 enables the high-voltage power supplies. 7. Countdown timer expires; the Applications processor asserts PWR_EN to enable the low-voltage power supplies. The processor starts the countdown timer. 8. The Applications processor asserts PWR_EN, the LP3972 enables the low-voltage regulators. 9. Countdown timer expires; If enabled power domains are OK (I2C read) the power up sequence continues by enabling the processors 13 MHz oscillator and PLL’s. 10. The Applications processor begins the execution of code. 53 www.national.com LP3972 POWER-ON TIMING LP3972 the capacitor parameters, to ensure that the specification is met within the application. The capacitance can vary with DC bias conditions as well as temperature and frequency of operation. Capacitor values will also show some decrease over time due to aging. The capacitor parameters are also dependant on the particular case size, with smaller sizes giving poorer performance figures in general. As an example, Figure 4 shows a typical graph comparing different capacitor case sizes in a Capacitance vs. DC Bias plot. As shown in the graph, increasing the DC Bias condition can result in the capacitance value falling below the minimum value given in the recommended capacitor specifications table. Note that the graph shows the capacitance out of spec for the 0402 case size capacitor at higher bias voltages. It is therefore recommended that the capacitor manufacturers’ specifications for the nominal value capacitor are consulted for all conditions, as some capacitor sizes (e.g. 0402) may not be suitable in the actual application. Application Hints LDO CONSIDERATIONS External Capacitors The LP3972’s regulators require external capacitors for regulator stability. These are specifically designed for portable applications requiring minimum board space and smallest components. These capacitors must be correctly selected for good performance. Input Capacitor An input capacitor is required for stability. It is recommended that a 1.0 µF capacitor be connected between the LDO input pin and ground (this capacitance value may be increased without limit). This capacitor must be located a distance of not more than 1 cm from the input pin and returned to a clean analogue ground. Any good quality ceramic, tantalum, or film capacitor may be used at the input. Important: Tantalum capacitors can suffer catastrophic failures due to surge current when connected to a low impedance source of power (like a battery or a very large capacitor). If a tantalum capacitor is used at the input, it must be guaranteed by the manufacturer to have a surge current rating sufficient for the application. There are no requirements for the ESR (Equivalent Series Resistance) on the input capacitor, but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the capacitance will remain approximately 1.0 µF over the entire operating temperature range. Output Capacitor The LDO’s are designed specifically to work with very small ceramic output capacitors. A 1.0 μF ceramic capacitor (temperature types Z5U, Y5V or X7R) with ESR between 5 mΩ to 500 mΩ, are suitable in the application circuit. For this device the output capacitor should be connected between the VOUT pin and ground. It is also possible to use tantalum or film capacitors at the device output, COUT (or VOUT), but these are not as attractive for reasons of size and cost (see the section Capacitor Characteristics). The output capacitor must meet the requirement for the minimum value of capacitance and also have an ESR value that is within the range 5 mΩ to 500 mΩ for stability. 20207623 FIGURE 4. Graph Showing a Typical Variation in Capacitance vs. DC Bias The ceramic capacitor’s capacitance can vary with temperature. The capacitor type X7R, which operates over a temperature range of −55°C to +125°C, will only vary the capacitance to within ±15%. The capacitor type X5R has a similar tolerance over a reduced temperature range of −55°C to +85°C. Many large value ceramic capacitors, larger than 1 µF are manufactured with Z5U or Y5V temperature characteristics. Their capacitance can drop by more than 50% as the temperature varies from 25°C to 85°C. Therefore X7R is recommended over Z5U and Y5V in applications where the ambient temperature will change significantly above or below 25°C. Tantalum capacitors are less desirable than ceramic for use as output capacitors because they are more expensive when comparing equivalent capacitance and voltage ratings in the 0.47 µF to 4.7 µF range. Another important consideration is that tantalum capacitors have higher ESR values than equivalent size ceramics. This means that while it may be possible to find a tantalum capacitor with an ESR value within the stable range, it would have to be larger in capacitance (which means bigger and more costly) than a ceramic capacitor with the same ESR value. It should also be noted that the ESR of a typical tantalum will increase about 2:1 as the temperature goes from 25°C down to –40°C, so some guard band must be allowed. No-Load Stability The LDO’s will remain stable and in regulation with no external load. This is an important consideration in some circuits, for example CMOS RAM keep-alive applications. Capacitor Characteristics The LDO’s are designed to work with ceramic capacitors on the output to take advantage of the benefits they offer. For capacitance values in the range of 0.47 µF to 4.7 µF, ceramic capacitors are the smallest, least expensive and have the lowest ESR values, thus making them best for eliminating high frequency noise. The ESR of a typical 1.0 µF ceramic capacitor is in the range of 20 mΩ to 40 mΩ, which easily meets the ESR requirement for stability for the LDO’s. For both input and output capacitors, careful interpretation of the capacitor specification is required to ensure correct device operation. The capacitor value can change greatly, depending on the operating conditions and capacitor type. In particular, the output capacitor selection should take account of all www.national.com 54 Inductor Selection There are two main considerations when choosing an inductor; the inductor should not saturate, and the inductor current ripple is small enough to achieve the desired output voltage ripple. Different saturation current rating specs are followed by different manufacturers so attention must be given to details. Saturation current ratings are typically specified at 25°C so ratings at max ambient temperature of application should be requested from manufacturer. There are two methods to choose the inductor saturation current rating. Input Capacitor Selection A ceramic input capacitor of 10 μF, 6.3V is sufficient for most applications. Place the input capacitor as close as possible to the VIN pin of the device. A larger value may be used for improved input voltage filtering. Use X7R or X5R types, do not use Y5V. DC bias characteristics of ceramic capacitors must be considered when selecting case sizes like 0805 and 0603. The input filter capacitor supplies current to the PFET switch of the converter in the first half of each cycle and reduces voltage ripple imposed on the input power source. A ceramic capacitor’s low ESR provides the best noise filtering of the input voltage spikes due to this rapidly changing current. Select a capacitor with sufficient ripple current rating. The input current ripple can be calculated as: Method 1 The saturation current is greater than the sum of the maximum load current and the worst case average to peak inductor current. This can be written as • IRIPPLE: Average to peak inductor current • IOUTMAX: Maximum load current (1500 mA) • VIN: Maximum input voltage in application • L: Min inductor value including worst case tolerances (30% drop can be considered for method 1) • f: Minimum switching frequency (1.6 MHz) • VOUT: Output voltage Method 2 A more conservative and recommended approach is to choose an inductor that has saturation current rating greater than the max current limit of TBD mA. The worst case is when VIN = 2 * VOUT TABLE 1. Suggested Inductors and Their Suppliers Model Vendor FDSE0312-2R2M Toko Dimensions LxWxH (mm) 3.0 x 3.0 x 1.2 D.C.R (Typ) 160 mΩ DO1608C-222 Coilcraft 6.6 x 4.5 x 1.8 80 mΩ Voltage peak-to-peak ripple due to ESR can be expressed as follows Output Capacitor Selection Use a 10 μF, 6.3V ceramic capacitor. Use X7R or X5R types, do not use Y5V. DC bias characteristics of ceramic capacitors must be considered when selecting case sizes like 0805 and 0603. DC bias characteristics vary from manufacturer to manufacturer and dc bias curves should be requested from them as part of the capacitor selection process. The output filter capacitor smooths out current flow from the inductor to the load, helps maintain a steady output voltage during transient load changes and reduces output voltage ripple. These capacitors must be selected with sufficient capacitance and sufficiently low ESR to perform these functions. The output voltage ripple is caused by the charging and discharging of the output capacitor and also due to its ESR and can be calculated as: VPP-ESR = (2 * IRIPPLE) * RESR Because these two components are out of phase the rms value can be used to get an approximate value of peak-to-peak ripple. Voltage peak-to-peak ripple, root mean squared can be expressed as follows Note that the output voltage ripple is dependent on the inductor current ripple and the equivalent series resistance of the output capacitor (RESR). The RESR is frequency dependent (as well as temperature dependent); make sure the value used for calculations is at the switching frequency of the part. 55 www.national.com LP3972 A 2.2 μH inductor with a saturation current rating of at least TBD mA is recommended for most applications. The inductor’s resistance should be less than 0.3Ω for a good efficiency. Table 1 lists suggested inductors and suppliers. For low-cost applications, an unshielded bobbin inductor could be considered. For noise critical applications, a toroidal or shielded bobbin inductor should be used. A good practice is to lay out the board with overlapping footprints of both types for design flexibility. This allows substitution of a low-noise shielded inductor, in the event that noise from low-cost bobbin models is unacceptable. BUCK CONSIDERATIONS LP3972 TABLE 2. Suggested Capacitor and Their Suppliers Model Type Vendor Voltage Case Size Inch (mm) GRM21BR60J106K Ceramic, X5R Murata 6.3V 0805 (2012) JMK212BJ106K Ceramic, X5R Taiyo-Yuden 6.3V 0805 (2012) C2012X5R0J106K Ceramic, X5R TDK 6.3V 0805 (2012) www.national.com 56 (s) that are expected to perform under these extreme corner conditions. (Schottky diodes are recommended to reduce the output ripple, if system requirements include this shaded area of operation. VIN > 1.5V and ILOAD > 1.24) 20207647 57 www.national.com LP3972 Buck Output Ripple Management If VIN and ILOAD increase, the output ripple associated with the Buck Regulators also increases. The figure below shows the safe operating area. To ensure operation in the area of concern it is recommended that the system designer circumvents the output ripple issues to install schottky diodes on the Bucks LP3972 Board Layout Considerations PC board layout is an important part of DC-DC converter design. Poor board layout can disrupt the performance of a DCDC converter and surrounding circuitry by contributing to EMI, ground bounce, and resistive voltage loss in the traces. These can send erroneous signals to the DC-DC converter IC, resulting in poor regulation or instability. Good layout for the converters can be implemented by following a few simple design rules. 1. Place the converters, inductor and filter capacitors close together and make the traces short. The traces between these components carry relatively high switching currents and act as antennas. Following this rule reduces radiated noise. Special care must be given to place the input filter capacitor very close to the VIN and GND pin. 2. Arrange the components so that the switching current loops curl in the same direction. During the first half of each cycle, current flows from the input filter capacitor through the converter and inductor to the output filter capacitor and back through ground, forming a current loop. In the second half of each cycle, current is pulled up from ground through the converter by the inductor to the output filter capacitor and then back through ground forming a second current loop. Routing these loops so the current curls in the same direction prevents magnetic field reversal between the two half-cycles and reduces radiated noise. 3. Connect the ground pins of the converter and filter capacitors together using generous component-side www.national.com 4. 5. 6. 58 copper fill as a pseudo-ground plane. Then, connect this to the ground-plane (if one is used) with several vias. This reduces ground-plane noise by preventing the switching currents from circulating through the ground plane. It also reduces ground bounce at the converter by giving it a low-impedance ground connection. Use wide traces between the power components and for power connections to the DC-DC converter circuit. This reduces voltage errors caused by resistive losses across the traces. Route noise sensitive traces, such as the voltage feedback path, away from noisy traces between the power components. The voltage feedback trace must remain close to the converter circuit and should be direct but should be routed opposite to noisy components. This reduces EMI radiated onto the DC-DC converter’s own voltage feedback trace. A good approach is to route the feedback trace on another layer and to have a ground plane between the top layer and layer on which the feedback trace is routed. In the same manner for the adjustable part it is desired to have the feedback dividers on the bottom layer. Place noise sensitive circuitry, such as radio RF blocks, away from the DC-DC converter, CMOS digital blocks and other noisy circuitry. Interference with noisesensitive circuitry in the system can be reduced through distance. LP3972 Physical Dimensions inches (millimeters) unless otherwise noted 40-Pin Leadless Leadframe Package NS Package Number SQF40A 59 www.national.com LP3972 Power Management Unit for Advanced Application Processors Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH www.national.com/webench Audio www.national.com/audio Analog University www.national.com/AU Clock Conditioners www.national.com/timing App Notes www.national.com/appnotes Data Converters www.national.com/adc Distributors www.national.com/contacts Displays www.national.com/displays Green Compliance www.national.com/quality/green Ethernet www.national.com/ethernet Packaging www.national.com/packaging Interface www.national.com/interface Quality and Reliability www.national.com/quality LVDS www.national.com/lvds Reference Designs www.national.com/refdesigns Power Management www.national.com/power Feedback www.national.com/feedback Switching Regulators www.national.com/switchers LDOs www.national.com/ldo LED Lighting www.national.com/led PowerWise www.national.com/powerwise Serial Digital Interface (SDI) www.national.com/sdi Temperature Sensors www.national.com/tempsensors Wireless (PLL/VCO) www.national.com/wireless THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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