MIC2874 Evaluation Board 1.2A High-Brightness Flash LED Driver with Single-Wire Serial Interface General Description Getting Started The MIC2874 is a high-current, high-efficiency flash LED driver that operates in both torch and flash modes. MIC2874 has a built-in internally compensated currentmode PWM 4MHz boost converter that allows the usage of very small inductors and output capacitors. It is used to step up the supply voltage to a high enough voltage at the OUT pin to drive the LED current when the supply voltage is lower than the required output voltage. When the supply voltage exceeds the required output voltage, the synchronous switch of the converter is fully turned on and the LED driver operates in linear mode. MIC2874 also features a configurable safety timer that automatically shuts down the LED current after the set duration has expired if the programmed LED current exceeds a certain current threshold. These features make the MIC2874 an ideal solution for high-resolution camera phone LED flash light driver applications. 1. Connect external supply to the PVIN terminals. The MIC2874 can be controlled through the single-wire serial interface and/or external control pins. A robust single-wire serial interface allows simple control by the host processor to support typical camera functions such as auto-focus, white balance, and image capture. Datasheets and support documentation are available on Micrel’s web site at: www.micrel.com. Requirements The MIC2874 evaluation board requires a bench input power source that is adjustable from 2.7V to 5.5V and is able to deliver greater than 4.5 amps at 2.7 volts. Precautions The evaluation board does not have reverse polarity protection. Applying a negative voltage across the PVIN terminal to PGND terminal may damage the device. The MIC2874 evaluation board is tailored for a Lithium-ion range input supply voltage. It should not exceed 5.5V on the input. Apply desired input voltage to the PVIN (J1) and PGND (J2) terminals of the evaluation board, paying careful attention to polarity and supply range. Since the default low-battery detection threshold voltage is 3.0V, the supply voltage should be set between 3.0V and 5.5V when testing the MIC2874 without using the single-wire interface. The low-battery detection threshold can be set to another value or disabled via single-wire interface. An ammeter may be connected between the power supply positive terminal and the evaluation board PVIN terminal. Ensure that the supply voltage is monitored across the PVIN and PGND terminals. The ammeter and /or power lead resistance can reduce the input voltage supply. 2. Enable/Disable the MIC2874. The MIC2874 evaluation board has an enable (DC) pin (J4 or JP2 lower pin). The MIC2874 is enabled in idle (standby) mode when the DC pin is asserted high. Setting a jumper at JP2 can connect the DC pin to PVIN. If this pin is driven low for more than 405µs, the IC will shut down. Alternatively, the IC can be enabled or disabled by software through single-wire interface. 3. Enable/Disable the flash mode. The FEN (J5 or JP3 lower pin) is the flash mode enable pin. A low-to-high transition at this pin initiates the flash mode and the safety timer. Setting a jumper at JP3 can connect FEN to PVIN. If FEN pin is left floating, it will be pulled down internally by built-in 1µA current source when the device is enabled. Alternatively, the flash mode can be enabled or disabled by software through single-wire interface. 4. Graphic user interface support. Graphical user interface software can be used with the MICUSB Dongle EV for configuring and testing of the MIC2874 with a standard computer. For more detail, refer to the MIC2874 Evaluation Software section. Ordering Information Part Number Description MIC2874YCS EV MIC2874 Evaluation Board MICUSB I2C Serial Programmer Board Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com August 27, 2014 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Evaluation Board Description threshold. Both the current threshold and the timer duration are programmable via the safety timer registers (addresses 3 and 5). Low-Battery Voltage Detection (LBVD) When the VIN voltage drops below the LBVD threshold (default = 3.0V) in flash or torch mode, the LED current driver is disabled. The LED driver can be resumed by raising the VIN above the LVBD threshold and toggling the corresponding flash or torch command. The LBVD threshold is adjustable thru the LBVD control register (address 4). Overvoltage Protection When the output voltage rises above an internal OVP threshold, MIC2874 is latched off automatically to avoid permanent damage to the IC. To clear the latched off condition, either power cycle the MIC2874 or assert the DC pin low. Short-Circuit Detection The MIC2874 performs a short-circuit test by driving the flash LED with a small (2mA typical) current for 200µs every time it begins to enable the LED driver. If (VOUT – VLED) < 1.7V at the end of the short-circuit test, the LED is considered to be shorted and MIC2874 will ignore the flash and/or torch mode command. Note that the short-circuit test is carried out every time prior to flash and torch mode, but the result is not latched. Figure 1. MIC2874 Evaluation Board Flash Mode The maximum and default current levels in the flash mode are 1.2A and 1A respectively. The flash mode current can be initiated by asserting the FEN pin high, or by setting the flash control register (address 1) through the single-wire interface for the desired flash duration, which is subjected to the safety timeout setting. The flash mode current is terminated when the FEN pin is brought low and the flash register is cleared, or when the configurable safety timer expires. Thermal Shutdown When the internal die temperature of MIC2874 reaches 155°C, the LED driver is disabled until the die temperature falls below 140°C and either FEN pin, FEN register, TEN register, or VIN is toggled. The flash mode current can be adjusted to a fraction of the maximum flash mode current level by selecting the desired value in the flash control register through the single-wire serial interface. Torch Mode By default, the maximum torch mode level is 300mA. The torch mode operation is activated by setting the torch control register (address 2) for the desired duration. The torch mode current is terminated when either the torch register is cleared or when the configurable safety timer expires. Like the flash mode current, the torch mode current can be set to a fraction of the maximum torch mode current level by selecting the desired torch current in the torch control register (address 2) through the single-wire serial interface. Configurable Safety Timer The safety timeout feature automatically shuts down the LED current after the safety timer duration is expired if the programmed LED current exceeds a certain current August 27, 2014 2 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Single-Wire Interface The single-wire interface allows the use of one multiplexed enable and data pin (DC) for control and communication in GPIO limited applications. The interface is implemented using a simple mechanism allowing any open drain or directly driven GPIO to control the MIC2874. Idle mode is entered automatically at the end of a communication frame by holding DC high for ≥TEND, enabling the device by bringing DC high when in shutdown mode, or when an error is detected by the single-wire interface logic. Shutdown mode can be entered at any time by pulling down DC for ≥TEND, discarding any current communication and resetting the internal registers. If a communication is received between the TLAT period and the shutdown period, the communication is discarded. This state is also used to create an internal error state to avoid erroneously latching data where the communication process cannot be serviced in time. Each register has a maximum value associated with it. If the number of bits clocked in exceeds the maximum value for the register, the data is assumed to be an error and the data is discarded. The MIC2874 uses the single-wire interface for simple command and control functions. The interface provides fast access to write only registers with protection features to avoid potentially erroneous data writes and improve robustness. When DC is in a low state and no data is detected for longer than 405µs, the MIC2874 will automatically go into a low-power shutdown state, simultaneously resetting internal registers to default states. Overview The single-wire interface relies on a combination of bit edges and the period between edges in order to communicate across a single wire. Each word is transmitted as a series of pulses, with each pulse incrementing an internal data counter. A stop sequence, which consists of an inactive period where the DC pin remains high, is used to latch the data word internally. An address and data framing format is used to improve protection against erroneous writes by enforcing address and data field lengths as well as the timing duration between them. IDLE < TEND - TLAT VH VL TLAT TEND VH The timing of the MIC2874 is designed to easily meet a wide operating range when communicating with a device using a low cost on chip oscillator. Using this method guarantees that the device can always detect the delay introduced by the communication master. VL TLAT TEND SHUTDOWN Idle States and Error Conditions In shutdown mode, the MIC2874 is in a reset condition with all functions off while consuming minimal power. Register settings are reset to default state when coming out of shutdown state. In idle mode, all register settings persist and all MIC2874 functions continue in their current state. Table 1 summarizes the difference between the two idle modes: IDLE VH VL TLAT TEND IDLE Figure 2. Abort, Shutdown, and Idle Timing Waveforms Table 1. Differences between Idle Modes Mode Shutdown Idle VDC Low High ISUPPLY (all functions off) 1μA 230μA Register State Default Persist Start-Up Time 1μs 100ns August 27, 2014 3 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Communication Details The serial interface requires delimiters to indicate the start of a frame, data as a series of pulses, and end of a frame indicated by a lack of activity for longer than TLAT. The start of a frame is the first high to low transition of DC when in idle mode. The first rising edge resets the internal data counter to 0. MIC2874 Registers The MIC2874 supports five writeable registers for controlling the torch and flash modes of operation as shown in Table 2. Note that register addressing starts at 1. Writing any value above the maximum value shown for each register will cause an invalid data error and the frame will be discarded. Table 2. Five Writeable Registers of MIC2874 END OF FRAME 1 COUNT Address Name Maximum Value 1 FEN/FCUR 31 Flash Enable/Current 2 TEN/TCUR 31 Torch Enable/Current 3 STDUR 7 Safety Timer Duration Figure 3. Data Word Pulse Timing 4 LB_TH 9 Low-Battery Voltage Detection Threshold A pulse is delimited by the signal first going below VL and then above VH within the latch timeout TLAT. During this transition, minimum on (TON) and off (TOFF) periods are observed to improve tolerance to glitches. Each rising edge increments the internal data register. Data is automatically latched into internal shadow address or data registers after an inactivity period of DC remains high for longer than TLAT. 5 ST_TH 5 Safety Timer Threshold VH VL TOFF TON TLAT AUTOMATIC LATCH AFTER TLAT EXPIRES TON+TOFF<TLAT START Description To send register write commands, the address and data are entered in a series as two data words using the above pattern, with the second word starting after the first latch period has expired. After the second word is entered, the IDLE command should be issued by leaving the DC pin high for ≥ TEND to indicate the stop sequence of the address/data words frame. After receiving the stop sequence, the internal registers decode and update cycle is started, and the shadow register values are transferred to the decoder. Figure 4 shows an example of entering a write of data 5 to address 3. ADDRESS/DATA FRAME LATCH START START TLAT 0 1 2 3 LATCH END REGISTER WRITE TLAT < TEND 0 1 2 3 4 5 > TEND Figure 4. Communication Timing Example of Entering Write for Data 5 to Address 3 Only a correctly formatted address/data combination will be treated as a valid frame and processed by the MIC2874. Any other input, such as a single data word followed by TEND, or three successive data words will be discarded by the target hardware as an erroneous entry. Additionally, any register write to either an invalid register or with invalid register data will also be discarded. August 27, 2014 4 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Table 3. Flash Current Register Mapping into Internal FEN and FCUR Registers, and Relationship between Flash Current and the FCUR Register Setting Flash Current Register (FEN/FCUR: default 0) The flash current register enables and sets the flash mode current level. Valid values are 0 to 31; values 0 through 15 will set the flash current without enabling the flash (such that it can be triggered externally), values 16 through 31 will set the flash current and enable the flash. The flash current register mapping into the internal FEN and FCUR registers are shown in Table 3. Table 3 also describes the relationship between the flash current and the FCUR register setting. August 27, 2014 FEN/FCUR[4:0] Value 5 IFLASH (A) Dec. Binary FEN[4] FCUR[3:0] 0 00000 0 0000 1.200 1 00001 0 0001 1.150 2 00010 0 0010 1.100 3 00011 0 0011 1.050 4 00100 0 0100 1.000 5 00101 0 0101 0.950 6 00110 0 0110 0.900 7 00111 0 0111 0.850 8 01000 0 1000 0.800 9 01001 0 1001 0.750 10 01010 0 1010 0.700 11 01011 0 1011 0.650 12 01100 0 1100 0.600 13 01101 0 1101 0.550 14 01110 0 1110 0.400 15 01111 0 1111 0.250 16 10000 1 0000 1.200 17 10001 1 0001 1.150 18 10010 1 0010 1.100 19 10011 1 0011 1.050 20 10100 1 0100 1.000 21 10101 1 0101 0.950 22 10110 1 0110 0.900 23 10111 1 0111 0.850 24 11000 1 1000 0.800 25 11001 1 1001 0.750 26 11010 1 1010 0.700 27 11011 1 1011 0.650 28 11100 1 1100 0.600 29 11101 1 1101 0.550 30 11110 1 1110 0.400 31 11111 1 1111 0.250 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Table 4. Torch Current Register Mapping into Internal TEN and TCUR Registers, and Relationship between Torch Current and the TCUR Register Setting Torch Current Register (TEN/TCUR: default 0) The torch current register enables and sets the torch mode current level. Valid values are 0 through 31; values 0 − 15 will set the torch current without enabling the torch (such that it can be triggered by setting the internal TEN register value to 1), values 16 − 31 will set the torch current and enable the torch. A value of 0 at the internal TEN register will disable the torch. The torch current register maps into the internal TEN and TCUR registers as shown in Table 4. Table 4 also describes the relationship between the torch current and the TCUR register setting. August 27, 2014 TEN/TCUR[4:0] Value 6 ITORCH (mA) Dec. Binary TEN[4] TCUR[3:0] 0 00000 0 0000 300.0 1 00001 0 0001 287.5 2 00010 0 0010 275.0 3 00011 0 0011 262.5 4 00100 0 0100 250.0 5 00101 0 0101 237.5 6 00110 0 0110 225.0 7 00111 0 0111 212.5 8 01000 0 1000 200.0 9 01001 0 1001 187.5 10 01010 0 1010 175.0 11 01011 0 1011 162.5 12 01100 0 1100 150.0 13 01101 0 1101 137.5 14 01110 0 1110 100.0 15 01111 0 1111 62.5 16 10000 1 0000 300.0 17 10001 1 0001 287.5 18 10010 1 0010 275.0 19 10011 1 0011 262.5 20 10100 1 0100 250.0 21 10101 1 0101 237.5 22 10110 1 0110 225.0 23 10111 1 0111 212.5 24 11000 1 1000 200.0 25 11001 1 1001 187.5 26 11010 1 1010 175.0 27 11011 1 1011 162.5 28 11100 1 1100 150.0 29 11101 1 1101 137.5 30 11110 1 1110 100.0 31 11111 1 1111 62.5 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Safety Timer Duration Register (STDUR: default 7) The safety timer duration register sets the duration of the flash and torch mode when the LED current exceeds the programmed threshold current. Valid values are 0 for the minimum timer duration to 7 for the maximum duration. Safety Timer Threshold Current Register (ST_TH: default 4) Safety timer threshold current determines the amount of LED current flowing through the external LED before the internal LED safety timer is activated. Setting ST_TH to 0 disables the safety timer function, and setting the register to values 1 to 5 set the safety time threshold current 100mA to 300mA in 50mA steps. Table 5. Safety Timer Duration Register Setting and Safety Timer Duration Value Dec. Binary STDUR[2:0] (binary) Timeout (ms) 0 000 000 156.25 1 001 001 312.5 Dec. Binary 2 010 010 468.75 0 3 011 011 625 4 100 100 781.25 5 101 101 937.5 6 110 110 1093.75 7 111 111 1250 Table 7. Safety Timer Threshold Current Register Setting and Safety Timer Threshold Current Value ST_TH[2:0] Safety Timer Threshold Current (mA) 000 000 Disabled 1 001 001 100 2 010 010 150 3 011 011 200 4 100 100 250 5 101 101 300 Low-Battery Threshold Register (LB_TH: default 1) The LB_TH register sets the supply threshold voltage below which the internal low battery flag is asserted and the LED current driver is disabled. Table 6 shows the threshold values that correspond to the register settings. Setting 0 is reserved for disabling the function, and settings between 1 and 9 inclusively enable and set the LB_TH value between 3.0V and 3.8V with 100mV resolution. Table 6. Low-Battery Threshold Register Setting and Supply Threshold Voltage Value LB_TH[3:0] VBAT Threshold (V) 0000 0000 Disabled 1 0001 0001 3.0 2 0010 0010 3.1 3 0011 0011 3.2 4 0100 0100 3.3 5 0101 0101 3.4 6 0110 0110 3.5 7 0111 0111 3.6 8 1000 1000 3.7 9 1001 1001 3.8 Dec. Binary 0 August 27, 2014 7 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board MIC2874 Evaluation Software The MIC2874 evaluation software provides a graphic user interface (GUI) to program the MIC2874 evaluation board. A complete application note on the installation and operation of the evaluation software and the USB adapter user manual can be downloaded from Micrel’s web site at www.micrel.com. The evaluation software can write to registers inside the MIC2874 IC device via the single-wire interface for enabling or disabling the device, torch mode, flash mode, changing the WLEDs’ brightness in torch mode and flash mode, changing the safety timer duration and LED current threshold, and enabling and/or disabling breath and strobe special effects. Evaluation Kit Overview The MIC2874 can be operated as a standalone board or as a modular system where the evaluation board is connected to a PC via single-wire-to-USB interface board (MICUSB dongle EV). Connecting the USB-to-Single-Wire Adapter When interfacing the MIC2874 evaluation board with the MICUSB dongle, carefully match the GND pin of the evaluation board with the GND pin of the dongle as shown in Figure 5. The MICUSB dongle should be faced down. On the MIC2874 evaluation board, the GND pin is the first pin of the connector receptacle (JP1) when counting from the left side. The MICUSB dongle has GND labeled on both sides of the adapter board. Getting Started 1. Download the MIC2874 evaluation software and run setup.exe file. This step may take some time and require an internet connection to update the computer to .NET Framework 3.5. 2. Install the MICUSB Dongle EV driver from FTDI. Double-click on the file CDM20828_setup.exe. The latest driver can be downloaded from the FTDI website: www.ftdichip.com. 3. After installing the driver, locate the virtual COM port created by the FTDI driver in the Device Manager Menu, under Ports (COM & LPT). The corresponding port will have FTDI listed as the manufacturer. 4. Connect the MIC2874 evaluation board to the PC via the MICUSB Dongle EV. Remove the jumpers on JP2 and JP3 on the evaluation board. Power the MIC2874 evaluation board PVIN input. 5. Set the mini slide switch SW1 on the MICUSB Dongle EV. The SW1 should be toggled to the NOM position as shown in Figure 6. 6. Open the MIC2874 evaluation software in Programs under the Start Menu. Figure 5. MIC2874 Evaluation Board Interfaces with the MICUSB Dongle EV (adapter top side faces down) Figure 6. Top Side of the Adapter with the Mini Slide Switch Toggled to NOM Position August 27, 2014 8 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Evaluation Software The MIC2874 evaluation software graphic user interface (GUI) is shown in Figure 7 through Figure 11. When the evaluation software starts, it defaults to offline mode as shown on the right of the top menu bar in Figure 7. The offline mode is only for running the software without the communication or connection of the MIC2874 evaluation board. On the right side of the GUI panel is the MIC2874 control panel. In this panel, the user can perform the following MIC2874 operations: 1. Check or uncheck the “Enabled” option to enable or disable the MIC2874 device. 2. Adjust the flash brightness with the Flash Brightness Control slide bar from 1.2A to 0.25A in 16 steps. The maximum is on the left and the minimum is on the right. To control the MIC2874 evaluation board with the software GUI, the user begins by clicking the “Test” button in the Target Config tab. If the connections between the PC, dongle, and MIC2874 EVB are fine as instructed in “Connecting the USB-to-Single-Wire Adapter” sub-section and in steps 4 and 5 in the “Getting Started” sub-section, the “Target OK” will show up in the status bar at the bottom of the GUI as shown in Figure 8. 3. Fire flash or reset flash by clicking the “Toggle Flash” button. 4. Adjust the torch brightness with the Torch Brightness Control slide bar from 300mA to 62.5mA in 16 steps. The maximum is on the left and the minimum is on the right. If there is not a good connection, the “Target Not Detected” notification will show up in the status bar. The user will need to check with the cable connections before proceeding to the next step. When the “Target OK” status is shown, the user can click on the “Offline Mode” in the menu bar to change it to “Direct Editing Mode”. When the “Direct Editing Mode” appears at the top menu bar and the “Direct Editing Mode Active” is indicated as shown in Figure 9, the software GUI allows the user to control the operation of the MIC2874 evaluation board. 5. Set or reset torch by clicking on the “Toggle Torch” button. 6. Change the LED Safety Timer duration setting from 156ms to 1250ms with 8 options; Change the LED Safety Timer LED current threshold from 100mA to 300mA in 50mA step. The LED Safety Timer can also be disabled by setting the LED current threshold to the “Disable” option. Please refer to Table 5 and Table 7 for details. Introduction to the GUI Panel The left side of the GUI panel shows different tabs for the user to select for specific operations. The tab functions are: 7. Set the Low-Battery Threshold voltage from 3.0V to 3.8V in 0.1V step. The Low-Battery Threshold function can be disabled by choosing the “Disabled” option. 8. Click the “Breath” button, “Strobe” button, and set delay time options for special effects demonstration. 1. “Target Config” tab – the destination address is shown in this tab. User can also click the “Test” button in this tab to check and establish communication between the evaluation board and PC. Setting of Single-Wire Interface Data Rate The data rate of the single-wire interface can be set in the “SWI” menu, located in the top menu bar. (See Figure 11.) The user can set the data rate to 100kHz, 1MHz, 3MHz, or 6MHz from the pull-down menu. 2. “Registers” tab – as show in Figure 10, user can check with the MIC2874 registers information and perform on-the-fly write operation to the IC registers. If the user knows the exact valid data value to the registers, the data value can be entered to the data edit box corresponding to the target register and then click the “Write” button. When the mouse curser is hovering over the register Address, Data, or Read Only edit/check boxes, a dynamic tooltips box will show up to indicate the corresponding register name and the functional name of the individual register bits. 3. “Help” tab – some hints about the steps for establishing host communications show up inside this tab. August 27, 2014 9 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Figure 7. MIC2874 Evaluation Software GUI Initial Start-up Window in Offline Mode Figure 8. MIC2874 Evaluation Software GUI Indicating Target OK at Status Bar Figure 9. MIC2874 Evaluation Software GUI in Direct Editing Mode August 27, 2014 10 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Figure 10. MIC2874 Evaluation Software GUI with Registers Tab Selected Figure 11. Setting Data Rate from Pulldown Menu August 27, 2014 11 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Evaluation Board Schematic August 27, 2014 12 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Bill of Materials Item C1, C2 Part Number C1608X5R1A475K080AC SPFCW04301BL Manufacturer TDK (1) (2) Samsung Philips SML-LXL99UWC-TR/5 Lumex(4) L1 PIFE20161B-R47MS-39 U1 MIC2874YCS 2 High-Power Flash LED, 4.1mm × 3.9mm × 2.1mm, 220lux @ ILED = 1A 1 LUXEON Flash 6 Module, 4mm × 4mm × 2.2mm, 180lux @ ILED = 1A (3) LXCL-MN06-3002 2ER103CW06000002 Qty. Capacitor 4.7 µF, 10V, 10%, X5R, 0603 D1 D2 Description LED SQ 5W COOL WHT 6000K SMD, 190lm (5) Edison-Opto Cyntec(6) Micrel, Inc.(7) DNI LED, 3W, COOL WHT 6000K SMD, 210lm Inductor, 0.47µH, 3.9A, 2.0mm × 1.6mm × 1.2mm 1 1.2A High-Brightness Flash LED Driver with Single-Wire Serial Interface 1 Notes: 1. TDK: www.tdk.com. 2. Samsung: www.samsung.com. 3. Philips: www.philipslumileds.com. 4. Lumex: www.lumex.com. 5. Edison-Opto: www.edison-opto.com. 6. Cyntec: www.cyntec.com. 7. Micrel, Inc.: www.micrel.com. August 27, 2014 13 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board PCB Layout Recommendations Top Layer Bottom Layer August 27, 2014 14 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com Micrel makes no representations or warranties with respect to the accuracy or completeness of the information furnished in this data sheet. This information is not intended as a warranty and Micrel does not assume responsibility for its use. Micrel reserves the right to change circuitry, specifications and descriptions at any time without notice. No license, whether express, implied, arising by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Micrel’s terms and conditions of sale for such products, Micrel assumes no liability whatsoever, and Micrel disclaims any express or implied warranty relating to the sale and/or use of Micrel products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2014 Micrel, Incorporated. August 27, 2014 15 Revision 1.0 Micrel, Inc. MIC2874 Evaluation Board Revision History Date Change Description/Edits by: August 27, 2014 Rev. 16 Revision 1.0