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| AN137 LITHIUM I O N B A T T E R Y C H A R G E R USING C8051F300 Relevant Devices This application note applies to the following devices: C8051F300 K e y P o in ts * On-chip high-speed, 8-bit ADC provides superior accuracy in monitoring charge voltage (critical to prevent overcharging in Li-Ion applications), maximizing charge effectiveness and battery life. On-chip PWM provides means to implement buck converter with a very small external inductor. On-chip Temp sensor provides an accurate and stable drive voltage for determining battery temperature. An external RTD (resistive temperature device) can also be used via the flexible analog input AMUX. A single C8051F30x platform provides full product range for multi-chemistry chargers, expediting time to market and reducing inventory. Introduction Driven by the need for untethered mobility and ease of use, many systems rely on rechargable bat- * teries as their primary power source. The battery charging circuitry for these systems is typically implemented using a fixed-function IC to control * the charging current/voltage profile. The C8051F30x family provides a flexible alternative to fixed-function battery chargers. This application note discusses how to use the C8051F30x * family in Li-Ion battery charger applications. The Li-Ion charging algorithms can be easily adapted to other battery chemistries, but an understanding of other battery chemistries is required to ensure proper charging for those chemistries. Figure 1. Lithium Ion Battery Charge Block Diagram. V Pos (+) LDO Buck Converter PWM Out 8051F30x LED Cygnal Integrated Products AIN Resistor Divider Li-Ion Cells 8k FLASH, PWM, Temp Sensor, Precision Time Base V Neg (-) Sense Resistor Rev. 1.2 12/03 Copyright (c) 2003 by Silicon Laboratories AN137-DS12 AN137 Charging Basics Batteries are exhaustively characterized to determine safe yet time-efficient charging profiles. The optimum charging method for a battery is dependent on the battery's chemistry (Li-Ion, NiMH, NiCd, SLA, etc.). However, most charging strategies implement a 3-phase scheme: 1. Low-current conditioning phase 2. Constant-current phase 3. Constant-voltage phase/charge termination batteries use a rate of change in voltage or temperature to determine when to terminate. Note that while charging a battery, most of the electrical energy is stored in a chemical process, but not all as no system is 100 percent efficient. Some of the electrical energy is converter to thermal energy, heating up the battery. This is fine until the battery reaches full charge at which time all the electrical energy is converted to thermal energy. In this case, if charging isn't terminated, the battery can be damaged or destroyed. Fast chargers (chargers that charge batteries fully in less than a couple hours) compound this issue, as these chargers use a high charge current to minimize charge time. As one can see, monitoring a battery's temperature is critical (especially for Li-Ion as they explode if overcharged). Therefore, the temperature is monitored during all phases. Charge is terminated immediately if the temperature rises out of range. All batteries are charged by transferring electrical energy into them (refer to the references at the end of this note for a battery primer). The maximum charge current for a battery is dependent on the battery's rated capacity (C). For example, a battery with a cell capacity of 1000mAh is referred to as being charged at 1C (1 times the battery capacity) if Li-Ion Battery Charger the charge current is 1000mA. A battery can be Hardware charged at 1/50C (20 mA) or lower if desired. However, this is a common trickle-charge rate and Currently, Li-Ion batteries are the battery chemistry is not practical in fast charge schemes where short of choice for most applications due to their high energy/space and energy/weight characteristics charge-time is desired. when compared to other chemistries. Most modern Most modern chargers utilize both trickle-charge Li-Ion chargers use the tapered charge termination, and rated charge (also referred to as bulk charge) minimum current (see Figure 2), method to ensure while charging a battery. The trickle-charge current the battery is fully charged as does the example is usually used in the initial phases of charging to code provided at the end of this note. minimize early self heating which can lead to premature charge termination. The bulk charge is usu- Buck Converter ally used in the middle phase where the most of the The most economical way to create a tapered terbattery's energy is restored. mination charger is to use a buck converter. A buck During the final phase of battery charge, which converter is a switching regulator that uses an generally takes the majority of the charge time, inductor and/or a transformer (if isolation is either the current or voltage or a combination of desired), as an energy storage element to transfer both are monitored to determine when charging is energy from the input to the output in discrete complete. Again, the termination scheme depends packets (for our example we use an inductor; the on the battery's chemistry. For instance, most Lith- capacitor in Figure 3 is used for ripple reduction). ium Ion battery chargers hold the battery voltage Feedback circuitry regulates the energy transfer via constant, and monitor for minimum current. NiCd the transistor, also referred to as the pass switch, to maintain a constant voltage or constant current 2 Rev. 1.2 AN137 Figure 2. Lithium Ion Charge Profile. Charge Voltage Charge Current Conditioning Current regulation Phase Voltage regulation Time within the load limits of the circuit. See Figure 3 voltage decreases and vice versa. Therefore, confor details. trolling the duty cycles allows one to regulate the voltage or the current to within desired limits. Tapered Charger Using the F30x Selecting the Buck Converter Inductor Figure 3 illustrates an example buck converter using the `F30x. The pass switch is controlled via To size the inductor in the buck converter, one first the on-chip 8-bit PWM (Pulse Width Modulator) assumes a 50 percent duty cycle, as this is where output of the PCA. When the switch is on, current the converter operates most efficiently. will flow like in Figure 3A. The capacitor is charged from the input through the inductor. The Duty cycle is given by Equation 1, where T is the inductor is also charged. When the switch is period of the PWM (in our example T = 10.5S). opened (Figure 3B), the inductor will try to maintain its current flow by inducing a voltage as the DutyCycle = ton -------T current through an inductor can't change instantaneously. The current then flows through the diode Equation 1. Duty Cycle. and the inductor charges the capacitor. Then the cycle repeats itself. On a larger scale, if the duty cycle is decreased (shorter "on" time), the average Figure 3. Buck Converter. (A) Inductor Pass Switch On Pass Switch Off (B) Inductor Power Source Shottky Diode Capacitor Battery Power Source Shottky Diode Capacitor Battery Rev. 1.2 3 AN137 With this established, select a PWM switching fre- To ensure accurate voltage and current measurements, the algorithms use a two-point system caliquency. As Equation 2 bration scheme. In this scheme, the user is expected to apply two known voltages and two known curL = ( Vi - Vsat - Vo )ton --------------------------------------------------2Iomax rents, preferable, one point near ground and the other point near full-scale. The algorithm then Equation 2. Inductor Size. takes these two points, calculates a slope and an offset for both the current and voltage channels, and stores the results in FLASH. All future convershows, the larger the PWM switching frequency, sions are scaled relative to these slope and offset the smaller (and more cost effective) the inductor. calculations. Note that if an external amplifier is Our example code configures the `F30x's 8-bit used for the current channel, it will need to be calihardware PWM to use the internal master clock of brated with a similar two-point calibration scheme 24.5MHz divided by 256 to generate a 95.7kHz to ensure maximum accuracy. switch rate. Now we can calculate the inductor's size. Assuming Vi, the charging voltage, is 15V, Vsat, the saturation voltage, is 0.5V, the desired output voltage, Vo, is 4.2V, and I0MAX, the maximum output current, is 1500 mA, the inductor should be at least 18H. Temperature To monitor the temperature, the algorithms use the on-chip temperature sensor. The sensor is left uncalibrated, but still provides a sufficiently accurate temperature measurement. For more accurate temperature measurement, one or two-point temperature calibration is required. Note that the capacitor in this circuit is simply a ripple reducer. The larger it is the better as ripple is An external temperature sensor can be used if inversely proportional to the size of the cap. For desired. The AMUX can to be reconfigured to more details on buck converters, refer to the refer- accommodate this additional input voltage. ences listed at the end of this note. Current Li-Ion Battery Charger Soft wa re The software example that follows demonstrates a Li-Ion battery charger using the C8051F300. The F300 is designed for high-level languages like "C" and includes an 8-bit 8051 based micro-controller, an 8-bit 500 ksps ADC, 8k FLASH, an 8-bit and 16-bit PWM, and a 2% accurate oscillator all onchip. The algorithms discussed are written entirely in "C" making them easily portable. Refer to the Voltage F300's datasheet for a full description of the The battery's voltages are divided down and monidevice. tored via external resistors. Note that this example Calibration uses the supply voltage as the ADC voltage reference. Any monitored voltage above the reference voltage must be divided down for accurate moni- The charge-current to the battery cells is monitored by taking a differential voltage reading across a small but accurate sense resistor. The current is amplified through the on-chip PGA, digitized by the on-chip 8-bit ADC, and scaled accordingly via the slope and offset calibration coefficients. An external gain stage may be necessary if more resolution is desired for the current measurement. 4 Rev. 1.2 AN137 toring. If a more accurate reference is required, an battery's current condition and starts charging from external voltage reference can be used. Adjustment that point. to the divide resistors must be made accordingly. Charging - Phase1 Conclusion In phase 1, (for description purposes, we assume the battery is initially discharged), the `F30x regulates the battery's current to ILOWCURRENT (typically 1/50 C) until the battery's voltage reaches VMINVOLTBULK. Note that the battery's charge current is current limited to ILOWCURRENT to ensure safe initial charge and to minimize battery self- References heating. If at any time the temperature increases out Maxim Integrated Product, "DC-DC Converter of limit, charging is halted. Tutorial". Martinez, Carlos and Drori, Yossi and Ciancio, Once the battery reaches VMINVOLTBULK the Joe, "AN126 Smart Battery Primer", Xicor, October 1999. charger enters phase 2, where the battery's algorithm controls the PWM pass switch to ensure the output voltage provides a constant charge-current IBULK to the battery (rate or bulk current is usually 1C and is definable in the header file as is ILOWCURRENT and VMINVOLTBULK). Charging - Phase 2 The C8051F300's high level of analog integration, small form-factor, integrated FLASH memory, and low power consumption makes it ideal for flexible next generation battery charging applications. This application note discussed how to use the C8051F30x family in Lithium Ion battery charger applications. Example code is provided as well. Charging - Phase 3 After the battery reaches VTop (typically 4.2 V in single cell charger), the charger algorithm enters phase 3, where the PWM feeds back and regulates the battery's voltage. In phase 3, the battery continues to charge until the battery's charge current reaches IMINIBULKl, after which, the battery is charged for an additional 30 minutes and then charge terminates. Phase 3 typically takes the majority of the charging time. Note that in most practical applications, such as a portable PC, the batteries may be in any of the three phases when charging is activated. This doesn't really affect the charger as it simply monitor's the Rev. 1.2 5 AN137 Appendix Figure 4. 1 Cell Battery Charger Schematic. 6 Rev. 1.2 AN137 Figure 5. 1 Cell Buck Converter Schematic. Rev. 1.2 7 AN137 Figure 6. main() Flow Chart. main() Config_F300() CalibrateADCfor Measurement() Enable Interrupts Infinite Loop Yes/No Clear Termination Flags Clear Charge Status Flags SW0 Pressed? ? Yes Yes Error Detected ? No No No Error Detected ? Status = BULK ? Yes Turn on LED0 Turn off LED0, Error BULK_charge() Infinite Loop No Status = LOWCURRENT ? Yes LOWCURRENT_charge() Yes/No 8 Rev. 1.2 AN137 Figure 7. CalibrateADCforMeasurement() Flow Chart. CalibrateADCforMearurement() SW0 Pushed ? Yes No No Setup ADC0's AMUX, Throughput, Gain, for near zero-scale voltage cal point Acquire 16-bit Measurement Setup ADC0's AMUX, Throughput, Gain, for near full-scale voltage cal point Acquire16-bit Measurement Calculate Voltage Slope Coefficient Calculate Voltage Offset Coefficient Erase Memory Page 0x1A00 Store Voltage Offset and Slope Coefficients in FLASH Memory SW0 Pushed ? Yes Setup ADC0's AMUX, Throughput, Gain, for near zero-scale Current cal point Acquire 16-bit Measurement Setup ADC0's AMUX, Throughput, Gain, for near full-scale Current cal point Acquire16-bit Measurement Calculate Current Slope Coefficient Calculate Current Offset Coefficient Store Current Offset and Slope Coefficients in FLASH Memory END Rev. 1.2 9 AN137 Figure 8. Monitor_Battery() Flow Chart. Monitor_Battery() Measurement Type ? Current Charge Voltage Temperature Battery Voltage AMUX = Current AMUX = Volt Stop PWM Stop PWM AMUX = Temperature AMUX = Volt AV = 0 I=0 No I10? Voltage w/ or w/out PWM Current Temperature Yes Start ADC0 Calculate Voltage w/ Calibration Coefficients Calculate Current w/ Calibration Coefficients Calculate Temperature w/ Calibration Coefficients No ADC0 Done? Yes AV = AV + ADC0 Turn PWM on Return Desired Parameter AV = AV/10 END 10 Rev. 1.2 AN137 Figure 9. Bulk_Charge() Flow Chart (Part 1). Bulk_Charge() Start PWM w/ Zero Output Status = const_C No T Within Limits ? Yes No V Yes Set Appropriate Flags Calculate bulk_finish_time Green LED On No Status = BULK & No Error? Yes No Status = const_c ? Yes Regulate Battery Current Read Charge Voltage Yes Change Status from const_C to const_V Charge Voltage Within Limits ? No B C A D Rev. 1.2 11 AN137 Figure 10. BULKCurrent() Flow Chart (Part 2). B C A D No Status = const_V ? Yes Regulate Voltage() Yes Time Overflow ? No Temp. Overflow ? No Stop PWM & Flag Error Yes Stop PWM & Flag Error No 60 Sec. Over ? Yes const_V, NOT Delay & Current Below Threshold ? Yes No Calculate bulk_finish_time Status = Delay Delay Time Over ? Yes Stop PWM Status = const_C Status = LOWCURRENT Green LED Off No END 12 Rev. 1.2 AN137 Figure 11. LowCurrent_Charge() Flow Chart. LOWCURRENT_charge() No ResetTimeBase() V Prepare Flags to enter Bulk Mode No No ERROR & LOWCURRENT =1 ? Yes Yes Change Status from const_C to const_V Charge Voltage Within Limits ? No No Temp within Limits ? Yes Regulate Current No V Status = const_V Yes Regulate Voltage Status = Delay Green LED Blinking Yes Green LED Off Stop PWM and flag error END Lowcurrent Finish Time reached? No Rev. 1.2 13 AN137 Figure 12. Turn_PWM_Off() Flow Chart. Turn_PWM_Off() No CEX0 Counter <0x0F? Yes Increment CEX0 Counter CEX0 Counter <0x0F? No Yes Disable PWM Mode END 14 Rev. 1.2 AN137 Figure 13. Measure() Flow Chart. measure() Set accumulator and counter i variables to zero Clear End of Conversion Flag Start New Conversion Conversion Complete ? Yes accumulator = accumulator + ADC0 Increment i No i=0 ? Yes Return 16-bit Measurement No END Rev. 1.2 15 AN137 Figure 14. Regulate_Voltage() Flow Chart. Regulate_Voltage() Measure Battery's voltage Voltage < VOLT_BULK & PCA not max ? Yes Make Duty Cycle Larger No No Voltage > VOLT_BULK & PCA not 0 Yes Make Duty Cycle Smaller Voltage < VOLT_BULK + Tolerence & > VOLT_BULK ? No Yes END 16 Rev. 1.2 AN137 Figure 15. Regulate_Current() Flow Chart. Regulate_Current() Measure Current Current < passed current & PCA not max ? Yes Make Duty Cycle Larger No No Current > passed current & PCA not 0 Yes Make Duty Cycle Smaller Current = passed value ? No Yes Monitor Voltage w/ PWM off Voltage < VOLT_LOWCURRENT Tolerence ? Yes CHARGE_STATUS = const_V No END Rev. 1.2 17 AN137 Figure 16. PCA_OVERFLOW_ISR() Flow Chart. PCA_OVERFLOW_ISR() Reset PCA Counter and PCA Interrupts Decrement time.count 0 = time.count No Yes Reset time.count to overflow value Increment time.sec No 60 = time.sec ? Yes Reset time.sec Increment time.min No LOW CURRENT charge & no errors ? Yes No 60 = time.min ? Yes Increment time.hour No odd second ? Yes No Turn on LED Reset time.min 24 = time.hour Yes Reset time.hour Turn Off LED END 18 Rev. 1.2 AN137 //----------------------------------------------------------------------------// // Copyright 2002 Cygnal Integrated Products, Inc. // // Filename: LIION_BC_MAIN.h // Target Device: 8051F300 // Created: 11 SEP 2002 // Created By: DKC // Tool chain: KEIL Eval C51 // // This header file is used to define all preprocessor directives, prototypes, // and global variable for LIION_BC_MAIN.c. // // The user should modify this header file before proceeding as key // battery parameter limits are set here. // //----------------------------------------------------------------------------// Function Prototypes //----------------------------------------------------------------------------void Config_F300(void); void Reset_Time_Base(void); void CalibrateADCforMeasurement(void); void Regulate_Current(int); void Regulate_Voltage(void); void Turn_PWM_Off(void); int Monitor_Battery(unsigned char); void Bulk_Charge(void); void Lowcurrent_Charge(void); unsigned int Measure(void); void Delay_Loop(void); //----------------------------------------------------------------------------// UNIONs, STRUCTUREs, and ENUMs //----------------------------------------------------------------------------typedef union LONG { // byte-addressable LONG long l; unsigned char b[4]; } LONG; typedef union INT { int i; unsigned char b[2]; } INT; typedef struct { unsigned long int t_count; int sec; int min; int hour; }time_struct; // byte-addressable INT // global seconds // global minutes // global hour //----------------------------------------------------------------------------// Global Variable Definitions Rev. 1.2 19 AN137 //----------------------------------------------------------------------------time_struct TIME; // Global Struct to Track Time char bdata TERMINATION; // Global Variable to Track Termination char bdata CHARGE_STATUS; // Global Variable to Track Charging INT code CHECK_BYTE _at_ 0x1A00; // 0x0A0A Default value, for later use LONG code VOLT_SLOPE _at_ 0x1A60; // Volt Slope Register LONG code VOLT_OFFSET _at_ 0x1A64; // Volt Offset Register LONG code I_NOAMP_SLOPE _at_ 0x1A70; // Current Slope Register,ext. amp off LONG code I_NOAMP_OFFSET _at_ 0x1A74; // Current Offset Register,ext. amp.off LONG temp_LONG_1,temp_LONG_2; // Temporary Storage Variables INT temp_INT_1,temp_INT_2; // Temporary Storage Variables //----------------------------------------------------------------------------// Bit maskable CHARGE STATUS Register Definition //----------------------------------------------------------------------------sbit BULK = CHARGE_STATUS^0; // bit 0 : BULK charge status bit sbit LOWCURRENT = CHARGE_STATUS^1; // bit 1 : LOWCURRENT charge status bit sbit ERROR = CHARGE_STATUS^2; // bit 2 : ERROR before/during charging sbit CONST_V = CHARGE_STATUS^3; // bit 3 : charged w/ constant VOLTAGE sbit CONST_C = CHARGE_STATUS^4; // bit 4 : charged w/ constant CURRENT sbit DELAY = CHARGE_STATUS^5; // bit 5 : BULK charge DELAY for LiIon // after CURRENT threshold detection sbit READY = CHARGE_STATUS^6; // bit 6 : Lowcurrent charge is // terminated; battery is charged sbit FREE1 = CHARGE_STATUS^7; // bit 7 : Not Currently used //----------------------------------------------------------------------------// Bit Maskable TERMINATION Register Definition //----------------------------------------------------------------------------sbit TEMP_MIN = TERMINATION^0; // bit 0 : minimum TEMPERATURE overflow sbit TEMP_MAX = TERMINATION^1; // bit 1 : maximum TEMPERATURE overflow sbit I_MIN = TERMINATION^2; // bit 2 : minimum CURRENT overflow sbit I_MAX = TERMINATION^3; // bit 3 : maximum CURRENT overflow sbit TIME_MAX = TERMINATION^4; // bit 4 : maximum time overflow sbit VOLT_MAX = TERMINATION^5; // bit 5 : maximum VOLTAGE overflow sbit VOLT_MIN = TERMINATION^6; // bit 6 : minimum VOLTAGE overflow sbit FREE2 = TERMINATION^7; // bit 7 : Not Currently used //----------------------------------------------------------------------------// Bit maskable PORT Definitions //----------------------------------------------------------------------------sbit SDA = P0 ^ 0; // bit 0 : SDA In/Output, Pin P0. sbit SCL = P0 ^ 1; // bit 1 : SCL Output, Pin P1. sbit CEX0 = P0 ^ 2; // bit 2 : PWM Output, Pin P2. sbit LED0 = P0 ^ 3; // bit 3 : LED0, Pin P0.3 sbit SW0 = P0 ^ 7; // bit 7 : Switch0, Pin P0.7 // // // // AMUX Selections; Analog Inputs bit 4 : Temp. Ch.; Analog In bit 5 : Current Ch.; Analog In bit 6 : Voltage Ch.; Analog In #define TBAT #define IBAT #define VBAT 0xF8; 0x65; 0xF6; //----------------------------------------------------------------------------// 8051F300 PARAMETERS //----------------------------------------------------------------------------#define SYSCLK 24500000 // System clock frequency 20 Rev. 1.2 AN137 #define #define #define #define #define #define TEMP_SENSOR_GAIN TEMP_GAIN CURRENT_GAIN VREF SCRATCH_PAGE PWM_CLOCK 3300 2 4 3200 0x1C00 SYSCLK/255 // // // // // // Temp Sensor Gain in (uV / degC) PGA gain setting PGA gain setting ADC Voltage Reference (mV) FLASH page used for temp storage PWM frequency is 96 kHz //----------------------------------------------------------------------------// Calibration/Calculation PARAMETERS //----------------------------------------------------------------------------#define V1_CAL 67 // 1st cal point for 2 point cal. #define V2_CAL 2800 // 2nd cal point for 2 point cal. #define I1_CAL 67 // 1st cal point for 2 point cal. #define I2_CAL 133 // 2nd cal point for 2 point cal. #define RSENSE 1 // RSENSE is assumed to be 1/2 ohm #define RESB 20 // 10k Ohms, Voltage Divide Resistor #define RESAB 30 // 20k Ohms, Voltage Divide Resistor #define TEMP_SLOPE ((long) TEMP_GAIN * TEMP_SENSOR_GAIN * 65536 / 100 / VREF) // An estimate of the Temperature //----------------------------------------------------------------------------// Battery/Pack Parameters //----------------------------------------------------------------------------#define CELLS 1 // Number of cells in the battery pack #define CAPACITY 150 // mAh, Battery Capacity (LiIon) #define LiIon_CELL_VOLT 4200 // mV, Nominal Charge Voltage #define I_BULK (unsigned int)(CAPACITY) #define I_LOWCURRENT (unsigned int)(CAPACITY/4) #define VOLT_BULK (unsigned int)(LiIon_CELL_VOLT) #define VOLT_LOWCURRENT #define VOLT_TOLERANCE #define CURRENT_TOLERENCE (unsigned int)(LiIon_CELL_VOLT) (unsigned int)(LiIon_CELL_VOLT/100)// 1 Percent Acc (unsigned int)(CAPACITY/10) // 10 Percent Acc //----------------------------------------------------------------------------// Battery Characteristics: Charge TERMINATION Limits //----------------------------------------------------------------------------#define MIN_TEMP_ABS 26300 // Abs. min. TEMPERATURE = -10 C, 263K #define MAX_TEMP_ABS 32300 // Abs. max. TEMPERATURE = 50C, 323K: Rev. 1.2 21 AN137 #define #define #define #define #define #define MIN_VOLT_BULK MAX_VOLT_ABS MIN_I_BULK MAX_TIME_LOWCURRENT MAX_TIME_BULK BULK_TIME_DELAY 3000 // Minimum BULK Voltage (unsigned int)(CELLS * LiIon_CELL_VOLT) (unsigned int)(CAPACITY/4) 30 // Max Lowcurrent Charge Time = 90min 90 // Maximum BULK Charge Time = 90 min // at 1C CURRENT 30 // DELAY = 30min after "MIN_I_BULK" // END OF FILE 22 Rev. 1.2 AN137 //----------------------------------------------------------------------------// // Copyright 2002 Cygnal Integrated Products, Inc. // // Filename: LIION_BC_MAIN.c // Target Device: 8051F300 // Created: 11 SEP 2002 // Created By: DKC // Tool chain: KEIL Eval C51 // // This is a stand alone battery charger for a Lithium ION battery. // It utilizes a buck converter, controlled by the on-chip 8-bit PWM, // to provide constant current followed by constant voltage battery charge. // //----------------------------------------------------------------------------// Includes //----------------------------------------------------------------------------#include // // // // // Enable VDD Monitor Skip P0.4,5,6; they're analog In Enable SMBus on P0.0, P0.1, and CEX0 as PWM at P0.2 Enable crossbar and weak pull-ups P0MDOUT P0MDIN OSCICN ADC0CN = 0x0C; = 0x8F; = 0x07; = 0xC0; // Set P0.2 & P0.3 output to push-pull // Configure P0.4,5,6 as Analog Inputs // Set SYSCLK to 24.5MHz, internal osc. // Turn on the ADC Module; // enable low power mode for settling // Configure ADC's to use VDD for // Voltage Reference, // Enable On-chip Temperature Sensor //----------------------------------------------------------------------------// PCA Configuration //----------------------------------------------------------------------------PCA0MD = 0x00; // Disable WDT PCA0MD = 0x08; // Set PWM Time base = SYSCLK PCA0L PCA0H PCA0CN //Module PCA0CPM0 PCA0CPL0 PCA0CPH0 = 0x00; = 0x00; = 0x40; 0 = 0x00; = 0xF0; = 0xF0; // Initialize PCA Counter to Zero REF0CN = 0x0C; // Enable PCA Counter // Clear PCA Counter Overflow flag // Configure CCM0 to 8-bit PWM mode // Initialize PCA PWM to small duty cycle // 0xF0 Ensures a Soft Initial Charge Rev. 1.2 23 AN137 //Module 1 PCA0CPM1 = 0x49; PCA0CPL1 = 0xFF; // // // // // // Configure Module 1 as software timer Initialize to 255 so that Interrupt is generated when PCA ends 8-bit PWM Cycle PCA0CPH is the high byte of the Output Compare Module PCA0CPH1 = 0x00; EIE1 } = 0x08; // Enable PCA Overflow Interrupt //----------------------------------------------------------------------------// Reset_Time_Base - Resets all Time Counting Values //----------------------------------------------------------------------------void Reset_Time_Base() { TIME.sec = 0x00; TIME.min = 0x00; TIME.hour = 0x00; TIME.t_count = PWM_CLOCK; } //----------------------------------------------------------------------------// Delay - This is a Delay to permit time for Switches to Debounce //----------------------------------------------------------------------------void Delay_Loop (void) { long i=0; for (i=0;i<100000;i++); } //----------------------------------------------------------------------------// Initialize CalibrateADCforVoltageMeasurement //----------------------------------------------------------------------------// This function calibrates the voltage channel and stores the calibration // coefficients in the parameters volt_slope and volt_offset. // void CalibrateADCforMeasurement() // This calibration routine uses a 2 point cal. { unsigned char xdata *pwrite; // FLASH write pointer EA = 0; // Disable All Interrupts // Wait until 1st calibration voltage is ready for cal while (SW0 == 1); // Wait until SW0 pushed Delay_Loop(); // Wait for Switch Bounce // Once ready, Get the first calibration voltage AMX0SL = VBAT; // Select appropriate input for AMUX ADC0CF = (SYSCLK/5000000) << 3; // ADC conversion clock = 5.0MHz ADC0CF &=0xF8; // Clear any Previous Gain Settings ADC0CF |= 0x01; // PGA gain = 1 temp_INT_1.i = Measure(); // Wait until 2nd calibration voltage is ready for cal while (SW0 == 1); // Wait until SW0 pushed Delay_Loop(); // Wait for Switch Bounce 24 Rev. 1.2 AN137 // Once ready, Get the 2nd calibration voltage AMX0SL = VBAT; // Change Mux for second point temp_INT_2.i = Measure(); // Calculate the SLOPE // V1 and V2 are in tenth of a degree temp_LONG_1.l = (unsigned)(temp_INT_2.i-temp_INT_1.i); temp_LONG_1.l *= (unsigned)100; // Account for Math Truncation Error temp_LONG_1.l /= (unsigned)(V2_CAL - V1_CAL); // Calculate the OFFSET temp_LONG_2.l = (unsigned)temp_INT_1.i; temp_LONG_2.l -= (signed)(temp_LONG_1.l * V1_CAL/100); temp_LONG_1.l = 2050; temp_LONG_2.l = 0; // If no cal. use these // as default values // Erased memory at page 0x1A00 pwrite = (char xdata *)&(CHECK_BYTE.b[0]); PSCTL = 0x03; // MOVX writes target FLASH memory; // FLASH erase operations enabled // FLASH key sequence #1 // FLASH key sequence #2 // initiate PAGE erase FLKEY = 0xA5; FLKEY = 0xF1; *pwrite = 0x00; // Write the Volt SLOPE and OFFSET to Flash PSCTL = 1; // MOVX writes to Flash pwrite = (char xdata *)&(VOLT_SLOPE.b[0]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_1.b[0]; pwrite = (char xdata *)&(VOLT_SLOPE.b[1]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_1.b[1]; pwrite = (char xdata *)&(VOLT_SLOPE.b[2]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_1.b[2]; pwrite = (char xdata *)&(VOLT_SLOPE.b[3]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_1.b[3]; flash write flash write flash write flash write pwrite = (char xdata *)&(VOLT_OFFSET.b[0]); FLKEY = 0xA5; FLKEY = 0xF1; // enable flash write *pwrite = temp_LONG_2.b[0]; pwrite = (char xdata *)&(VOLT_OFFSET.b[1]); FLKEY = 0xA5; FLKEY = 0xF1; // enable flash write *pwrite = temp_LONG_2.b[1]; pwrite = (char xdata *)&(VOLT_OFFSET.b[2]); FLKEY = 0xA5; FLKEY = 0xF1; // enable flash write *pwrite = temp_LONG_2.b[2]; Rev. 1.2 25 AN137 pwrite = (char xdata *)&(VOLT_OFFSET.b[3]); FLKEY = 0xA5; FLKEY = 0xF1; // enable flash write *pwrite = temp_LONG_2.b[3]; PSCTL = 0; // MOVX writes target XRAM //----------------------------------------------------------------------------// Initialize CalibrateADCforCurrentMeasurement_NOAMP //----------------------------------------------------------------------------// This function calibrates the current channel with no external amp // and stores the calibration coefficients in the // parameters i_noamp_slope and i_noamp__offset. // // This calibration routine uses a 2 point cal. // Wait until calibration voltage is ready for cal while (SW0 == 1); // Wait until SW0 pushed Delay_Loop(); // Wait for Switch Bounce // Once ready, Get the first calibration voltage AMX0SL = IBAT; // Select appropriate input for AMUX ADC0CF = (SYSCLK/5000000) << 3; // ADC conversion clock = 5.0MHz ADC0CF &=0xF8; // Clear any Previous Gain Settings ADC0CF |= 0x03; // Set PGA gain = 4 temp_INT_1.i = Measure(); // Acquire 16-bit Conversion temp_INT_1.i *= 2; // Account for Differential Mode // Wait until 2nd calibration voltage is ready for cal while (SW0 == 1); // Wait until SW0 pushed Delay_Loop(); // Wait for Switch Bounce // Once ready, Get the 2nd calibration voltage temp_INT_2.i = Measure(); // Acquire 16-bit Conversion temp_INT_2.i *=2; // Account for Differential Mode // Calculate the temp_LONG_1.l = temp_LONG_1.l *= temp_LONG_1.l /= temp_LONG_1.l /= SLOPE (unsigned)(temp_INT_2.i - temp_INT_1.i); (unsigned)100; // Account for Math Truncation Error (unsigned)(I2_CAL - I1_CAL); (unsigned)CURRENT_GAIN;// Account for Gain // Calculate the OFFSET temp_LONG_2.l = (signed)(temp_INT_1.i/CURRENT_GAIN); temp_LONG_2.l -= (signed)(temp_LONG_1.l * V1_CAL/100); temp_LONG_1.l = 2050; temp_LONG_2.l = 0; // If no cal. use these // as default values // Memory at 0x1A00 is already erased // Write the Volt SLOPE and OFFSET to Flash PSCTL = 1; // MOVX writes to Flash pwrite = (char xdata *)&(I_NOAMP_SLOPE.b[0]); FLKEY = 0xA5; FLKEY = 0xF1; // enable flash write *pwrite = temp_LONG_1.b[0]; pwrite = (char xdata *)&(I_NOAMP_SLOPE.b[1]); FLKEY = 0xA5; FLKEY = 0xF1; // enable flash write *pwrite = temp_LONG_1.b[1]; pwrite = (char xdata *)&(I_NOAMP_SLOPE.b[2]); 26 Rev. 1.2 AN137 FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_1.b[2]; pwrite = (char xdata *)&(I_NOAMP_SLOPE.b[3]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_1.b[3]; pwrite = (char xdata *)&(I_NOAMP_OFFSET.b[0]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_2.b[0]; pwrite = (char xdata *)&(I_NOAMP_OFFSET.b[1]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_2.b[1]; pwrite = (char xdata *)&(I_NOAMP_OFFSET.b[2]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_2.b[2]; pwrite = (char xdata *)&(I_NOAMP_OFFSET.b[3]); FLKEY = 0xA5; FLKEY = 0xF1; // enable *pwrite = temp_LONG_2.b[3]; PSCTL = 0; } //----------------------------------------------------------------------------// Measure //----------------------------------------------------------------------------// // This routine averages 65536 ADC samples and returns a 16-bit unsigned // result. // unsigned int Measure (void) { unsigned i; // sample counter unsigned long accumulator=0L; // here's where we integrate the // ADC samples // read the ADC value and add to running total i = 0; do { AD0INT = 0; // clear end-of-conversion indicator AD0BUSY = 1; // initiate conversion while(!AD0INT); // wait for conversion to complete accumulator += ADC0; // read adc value and accumulate i++; // update counter } while (i != 0x0000); // the accumulator now contains 16 added bits of which 8 are usable return (unsigned int) (accumulator >> 8); } //----------------------------------------------------------------------------// Regulate_Current //----------------------------------------------------------------------------// This routine monitors the battery's current and adjusts // the PWM (i.e. duty cycle) to keep the current at a known value flash write flash write flash write flash write flash write flash write // MOVX writes target XRAM Rev. 1.2 27 AN137 // void Regulate_Current(int passed_current) { unsigned int temp = 0; do{ temp = Monitor_Battery(CURRENT); if (temp < passed_current) PCA0CPH0--; if (temp > passed_current) PCA0CPH0++; }while ((temp < (passed_current - CURRENT_TOLERENCE)) || (temp > (passed_current + CURRENT_TOLERENCE))); // I_BULK or I_LOWCURRENT is set now temp = Monitor_Battery(VOLTAGE_PWM_OFF); // If VOLTAGE within range, // change from constant CURRENT charge // mode to constant VOLTAGE charge mode if ((temp >= (VOLT_LOWCURRENT - VOLT_TOLERANCE)) && (temp <= (VOLT_LOWCURRENT + VOLT_TOLERANCE))) { CONST_C = 0; CONST_V = 1; } } //----------------------------------------------------------------------------// Regulate_Voltage //----------------------------------------------------------------------------// This routine monitors the battery's voltage and adjusts // the PWM (i.e. duty cycle) to keep the voltage at a known value // void Regulate_Voltage(void) { unsigned int temp = 0; // set VOLT_BULK (with "soft start") do{ temp = Monitor_Battery(VOLTAGE); if (temp < VOLT_BULK) PCA0CPH0--; if (temp > VOLT_BULK) PCA0CPH0++; }while ((temp < (VOLT_BULK - VOLT_TOLERANCE)) || (temp > (VOLT_BULK + VOLT_TOLERANCE))); // VOLTAGE is set now } //----------------------------------------------------------------------------// Turn_PWM_Off //----------------------------------------------------------------------------// This routine peforms a soft charge turn off by taking the PWM's // duty cycle slowly to zero. // void Turn_PWM_Off(void) { // Measure Current 28 Rev. 1.2 AN137 do{ if (PCA0CPH0 < 0xF0) PCA0CPH0++; }while (PCA0CPH0 < 0xF0); // Duty Cycle is now small and safe to turn off. PCA0CPM0 = 0x00; } //----------------------------------------------------------------------------// Monitor_Battery //----------------------------------------------------------------------------// This routine acts as a switch when gathering different conversion types. // It adjusts the throughput, adjust the AMUX and returns the current in mA, // voltage in mV, and temperature in C, 2% accurate. // int Monitor_Battery(unsigned char value) { char i; unsigned long av =0; long signed result; ADC0CF = (SYSCLK/5000000) << 3; ADC0CF &= 0xF8; switch (value) { case TEMPERATURE: Turn_PWM_Off(); AMX0SL = TBAT; ADC0CF |= 0x02; break; case VOLTAGE: AMX0SL = VBAT; ADC0CF |= 0x01; break; case VOLTAGE_PWM_OFF: Turn_PWM_Off(); AMX0SL = VBAT; ADC0CF |= 0x01; break; case CURRENT: AMX0SL = IBAT; ADC0CF |= 0x03; break; } //Compute average of next 10 A/D conversions for(av=0,i=10;i;--i){ AD0INT = 0; // clear end-of-conversion indicator AD0BUSY = 1; // initiate conversion while(!AD0INT); // wait for conversion to complete av = av+ADC0; } // ADC conversion clock = 5.0MHz // Clear any Previous Gain Settings // Disable PWM // Turn PWM Off // Select appropriate input for AMUX // Set PGA gain = 2 // Select appropriate input for AMUX // Set PGA gain = 1 // Turn PWM Off // Select appropriate input for AMUX // Set PGA gain = 1 // Select appropriate input for AMUX // Set PGA gain = 4 Rev. 1.2 29 AN137 av = av/10; av = av<<8; // Compute the average // Convert to 16-bit conversion // ...to account for 16-bit cal. // coefficients // Turn on PWM PCA0CPM0 = 0x42; switch (value) { case TEMPERATURE: result = (long) av * 1000/TEMP_SLOPE; break; case VOLTAGE: case VOLTAGE_PWM_OFF: result = (av - VOLT_OFFSET.l); result /= VOLT_SLOPE.l; result *= 100; result *= RESAB; result /= RESB; break; case CURRENT: result = av*2; result -= I_NOAMP_OFFSET.l; result /= I_NOAMP_SLOPE.l; result *= 100; result /= RSENSE; result *= RESAB; result /= RESB; result /= CURRENT_GAIN; break; } return (int) result; } //----------------------------------------------------------------------------// Bulk_Charge Function //----------------------------------------------------------------------------void Bulk_Charge(void) { unsigned int temp = 0; unsigned int bulk_finish_hour = 0; unsigned int bulk_finish_min = 0; unsigned int delay_hour = 0; unsigned int delay_min = 0; unsigned int last_min = 0; Reset_Time_Base(); // Reset Time Base to zero // // // // Account Convert Account Account for System Errors to Voltage in Millivolts for Math Truncation Error for Divide Resistors // // // // // // Account Account Convert Account Account Account for Differential Mode for System Errors to Milliamps for Math Truncation Error for Sense Resistor for Divide Resistors // Calculate BULK charge finish time bulk_finish_min = (TIME.min + MAX_TIME_BULK); bulk_finish_hour = TIME.hour; while (bulk_finish_min > 60) { bulk_finish_min = bulk_finish_min - 60; bulk_finish_hour++; } 30 Rev. 1.2 AN137 CONST_C = 1; DELAY = 0; // Start in constant current charge mode // Reset timer DELAY temp = Monitor_Battery(TEMPERATURE); // Monitor Temperature // Is temperature within range? if ((temp > MIN_TEMP_ABS) && (temp < MAX_TEMP_ABS)) { temp = Monitor_Battery(VOLTAGE); // Monitor Voltage // Is Voltage within range? if ((temp <= (MAX_VOLT_ABS + VOLT_TOLERANCE)) && temp > MIN_VOLT_BULK) { PCA0CPM0 = 0x42; // Configure CCM0 to 8-bit PWM mode // Enter main loop in Bulk_Charge() while ((BULK == 1) && (ERROR == 0)) { if (CONST_C == 1) Regulate_Current(I_BULK); // Charge with Constant Current else if (CONST_V == 1) Regulate_Voltage(); // Charge with Constant Voltage // Now, Check for error and charge termination conditions // If above max charge time, flag error // Test for BULK Charge Time Out // Monitor Time if ((TIME.hour == bulk_finish_hour) && (TIME.min == bulk_finish_min) && (DELAY == 0)) { Turn_PWM_Off(); // Turn Off PWM TIME_MAX = 1; // Set Time max error flag ERROR = 1; // Set general error flag } // Monitor Temperature temp = Monitor_Battery(TEMPERATURE); if ((temp < MIN_TEMP_ABS) && (temp > MAX_TEMP_ABS)) { Turn_PWM_Off(); if (temp < MIN_TEMP_ABS) TEMP_MIN = 1; else TEMP_MAX = 1; ERROR } // Minute elapsed? // Check for minimum current // if reached, enter last DELAY charge if (TIME.min != last_min) { last_min = TIME.min; if ((CONST_V == 1) && (DELAY == 0) && (Monitor_Battery(CURRENT) <= MIN_I_BULK)) = 1; // Turn Off PWM // Set Temperature below minimum flag // Set Temperature exceeds maximum flag // Set general error flag Rev. 1.2 31 AN137 { // Calculate TOP OFF Battery Time finish time delay_min = (TIME.min + BULK_TIME_DELAY); delay_hour = TIME.hour; while (delay_min > 60) { delay_min = delay_min - 60; delay_hour++; } DELAY = 1; // Set Delay Flag } // Monitor Delay time, time up? if ((TIME.hour == delay_hour)&&(TIME.min == delay_min) && (DELAY == 1)) { Turn_PWM_Off(); // Turn Off PWM CONST_V = 0; // Exit CONST_V CONST_C = 1; // Prepare to enter CONST_C BULK = 0; // Prepare to exit BULK mode LOWCURRENT = 1; // Prepare to enter LOWCURRENT Mode } } } } else if(ERROR == 0) { if (temp > (MAX_VOLT_ABS + VOLT_TOLERANCE)) { VOLT_MAX = 1; // Set Max Voltage error flag ERROR = 1; // Set general error flag } else if(temp < MIN_VOLT_BULK) { VOLT_MIN = 1; // Set Minimum bulk voltage error flag LOWCURRENT = 1; // Switch to LOWCURRENT mode BULK = 0; // Exit Bulk Charge mode } // battery's voltage very low } } else if(ERROR == 0) { if (temp < MIN_TEMP_ABS) TEMP_MIN = 1; else TEMP_MAX = 1; ERROR = 1; } } //----------------------------------------------------------------------------// Lowcurrent_Charge //----------------------------------------------------------------------------void Lowcurrent_Charge(void) { unsigned int temp = 0; unsigned int lowcurrent_finish_min = 0; // Absolute temperature out of range? // End Main While loop // Set Temperature below minimum flag // Set Temperature exceeds maximum flag // Set general error flag 32 Rev. 1.2 AN137 unsigned int lowcurrent_finish_hour = 0; Reset_Time_Base(); // Reset Time base to zero // Calculate LOWCURRENT finish time lowcurrent_finish_min = (TIME.min + MAX_TIME_LOWCURRENT); lowcurrent_finish_hour = TIME.hour; while (lowcurrent_finish_min > 60) { lowcurrent_finish_min = lowcurrent_finish_min - 60; lowcurrent_finish_hour++; } // Enter Main Lowcurrent Loop. // Only exits are upon error and full charge while ((LOWCURRENT == 1) && (ERROR == 0)) { temp = Monitor_Battery(TEMPERATURE);// Get Temperature Reading // Is TEMPERATURE within limits if ((temp > MIN_TEMP_ABS) && (temp < MAX_TEMP_ABS)) { // Is Battery's Charge Voltage below max charge voltage temp = Monitor_Battery(VOLTAGE); // Get Voltage Reading if (temp <= (VOLT_LOWCURRENT + VOLT_TOLERANCE)) { if (CONST_C == 1) // CONST_C ?, charge w/ constant current Regulate_Current(I_LOWCURRENT); if (CONST_V == 1) Regulate_Voltage(); // CONST_V?, charge w/ constant voltage if ((temp >= MIN_VOLT_BULK) && (DELAY == 0))// Bulk Threshold voltage met? { LOWCURRENT = 0; // Exit LOWCURRENT mode BULK = 1; // Switch to Bulk Charge mode } // Check elapsed time if ((TIME.hour == lowcurrent_finish_hour) && ( TIME.min == lowcurrent_finish_min)) { TIME_MAX = 1; // Set Time MAX error flag ERROR = 1; // Set general error flag } } else if(ERROR == 0) { VOLT_MAX = 1; ERROR = 1; } } else if(ERROR == 0) { if (temp < MIN_TEMP_ABS) TEMP_MIN = 1; else TEMP_MAX = 1; ERROR = 1; } } // Voltage to high? // Set Max voltage error flag // Set general error flag // Absolute temperature out of range? // Set Temperature below minimum flag // Set Temperature exceeds maximum flag // Set general error flag Rev. 1.2 33 AN137 } //----------------------------------------------------------------------------// Main Function //----------------------------------------------------------------------------void main(void) { EA = 0; // Disable All Interrupts Reset_Time_Base(); Config_F300(); // Config F300 CalibrateADCforMeasurement(); // Calibrate F300 EA = 1; while(1) { LED0 = 0; TERMINATION = 0x00; CHARGE_STATUS = 0x00; BULK = 1; CONST_C = 1; while (SW0 == 1); Delay_Loop(); while (ERROR == 0) { if (BULK == 1) { LED0 = 1; Bulk_Charge(); } if (LOWCURRENT == 1) Lowcurrent_Charge(); } if (ERROR == 1) { Turn_PWM_Off();; LED0 = 0; EA = 0; while (1); } } } //----------------------------------------------------------------------------// PCA_ISR //----------------------------------------------------------------------------// This routine counts the elapsed time in seconds, minutes, hours. // It also toggles LED0 every second when in Lowcurrent Charge Mode. // This routine interrupts every time the PCA counter overflows, every 256 // SYSCLK cycles. After SYSCLK/256 interrupts, one second has elapsed. // void PCA_OVERFLOW_ISR (void) interrupt 9 { // Enable All Active Interrupts // Turn LED0 off // Reset Termination Flags // Reset Charge Status Flags // Start in LOWCURRENT Charge mode // Wait until SW0 pushed // Wait for Switch Bounce // Turn LED0,indicates Bulk Mode // Enter Bulk Charge Mode // Enter Lowcurrent_Charge function // Toggle LED0 at 1 Hz rate via ISR // // // // // Turn PWM Off Turn OFF LED0 to indicate "ERROR". Disable All Interrupts Enter a eternal loop No recovery except "reset-button" 34 Rev. 1.2 AN137 PCA0CN = 0x40; PCA0H = 0x00; // Reset all PCA Interrupt Flags // Reset High Byte of PCA Counter // of 8-bit PWM we are using Module1 if (0x0000 == --TIME.t_count) { TIME.t_count = PWM_CLOCK; if ( 60 == ++TIME.sec ) { TIME.sec = 0x00; if ( 60 == ++TIME.min ) { TIME.min = 0x00; if ( 24 == ++TIME.hour ) TIME.hour = 0x00; } } // Reset 1 Second Clock // Account for elapsed seconds // Reset second counter every minute // Account for elapsed minutes // Reset minute counter every hour // Account for elapsed hours // Reset hour counter every day if ((LOWCURRENT == 1) && (ERROR == 0)) { // Blink LED0 at 1 Hz if in Lowcurrent if (TIME.sec % 2) LED0 = 0; // Turn on LED every odd second else LED0 = 1; // Turn on LED every even second } } } // END OF FILE Rev. 1.2 35 AN137 Contact Information Silicon Laboratories Inc. 4635 Boston Lane Austin, TX 78735 Tel: 1+(512) 416-8500 Fax: 1+(512) 416-9669 Toll Free: 1+(877) 444-3032 Email: productinfo@silabs.com Internet: www.silabs.com The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice. Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features or parameters. Silicon Laboratories reserves the right to make changes without further notice. Silicon Laboratories makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Silicon Laboratories assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. Silicon Laboratories products are not designed, intended, or authorized for use in applications intended to support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where personal injury or death may occur. Should Buyer purchase or use Silicon Laboratories products for any such unintended or unauthorized application, Buyer shall indemnify and hold Silicon Laboratories harmless against all claims and damages. Silicon Laboratories and Silicon Labs are trademarks of Silicon Laboratories Inc. Other products or brandnames mentioned herein are trademarks or registered trademarks of their respective holders. 36 Rev. 1.2 |
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