Rev 0; 1/06 KIT ATION EVALU LE B A IL A AV Sample-and-Infinite Hold Voltage Reference The DS4305 is a nonvolatile (NV) sample-and-infinitehold adjustable voltage reference. The reference voltage is programmed in-circuit during factory calibration/ programming. Programming the reference voltage, VOUT, is as simple as applying the desired voltage on VIN and toggling the adjust pin (ADJ) to lock the VOUT voltage level indefinitely, even if the device is power cycled. The DS4305 replaces current cumbersome factory adjustment arrangements with a low-cost solution that can be adjusted using automated techniques. In addition, the DS4305 has the ability to be readjusted after the unit has been fully assembled and tested. This results in a much more flexible manufacturing arrangement, lower inventory costs, and a quicker time-to-market. Features ♦ Precise Electronically Adjustable Voltage Reference ♦ Enables Automated Factory Trimming of Devices Needing Voltage Adjustment ♦ Can be Adjusted to Within ±1.5mV ♦ Wide Adjustable Output Voltage Range Within 300mV of the Supply Rails ♦ Low Temperature Coefficient ♦ ±1mA of Output-Current Drive ♦ NV Memory Stores the Voltage Indefinitely ♦ Output Short-Circuit Protection ♦ Low Cost Applications ♦ Low Power Consumption Power-Supply Calibration ♦ 4.0V to 5.5V Single-Supply Operation Threshold Setting ♦ Small 5-Lead SOT23 Package Offset Nulling ♦ -40°C to +125°C Temperature Operation Bias Adjusting ♦ DS4305K Evaluation Kit is Available Power Amps Pressure Bridges Ordering Information Factory-Calibrated Equipment PART TEMP RANGE DS4305R+T&R -40°C to +125°C PINPACKAGE SOT MARK 5 SOT23 4305+ +Denotes lead-free package. Pin Configuration Typical Operating Circuit EXISTING SOLUTION TOP VIEW DS4305 SOLUTION VCC REFERENCE VOLTAGE SHUNT VOLTAGE REFERENCE ADJ 1 GND 2 VIN 3 VCC DS4305 VOUT REFERENCE VOLTAGE 5 VCC 4 VOUT DS4305 GND HAND-SELECTED 0.1% RESISTOR OR MECHANICAL POT VIN ADJ ACCESS FOR AUTOMATED ALIGNMENT SOT23 ______________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 DS4305 General Description DS4305 Sample-and-Infinite Hold Voltage Reference ABSOLUTE MAXIMUM RATINGS Voltage on VCC Relative to GND ...........................-0.5V to +6.0V Voltage on VIN, ADJ, and VOUT Relative to GND ...-0.5V to (VCC + 0.5V), not to exceed +6.0V Operating Temperature Range .........................-40°C to +125°C EEPROM Programming Adjust Temperature..........0°C to +70°C VOUT to GND Short-Circuit Duration .........................Continuous Storage Temperature Range .............................-55°C to +125°C Soldering Temperature ...See IPC/JEDEC J-STD-020 Specification Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS (TA = -40°C to +125°C) PARAMETER SYMBOL CONDITIONS (Note 1) MIN TYP MAX UNITS Supply Voltage VCC 4.0 5.5 V VIN Voltage Range VIN 0.3 VCC - 0.3 V ADJ Logic 0 VIL -0.3 0.3 x VCC VOUT Current VOUTI -1 VOUT Load VOUTL V +1 mA 100 pF TYP MAX UNITS 1.4 2.0 ELECTRICAL CHARACTERISTICS (VCC = +4.0V to +5.5V, TA = -40°C to +125°C, unless otherwise noted.) PARAMETER Supply Current SYMBOL IIN CONDITIONS MIN -40°C to +85°C; VIN, ADJ, and VOUT = open circuit mA +85°C to +125°C; VIN, ADJ, and VOUT = open circuit 2.1 VIN Resistance RPD 95 ADJ Pullup Resistance RPU 18 VOUT Voltage Range VOUTR (Note 1) VOUT Tracking Accuracy VOUTTA VOUT Quantization VOUTQ VOUT TC VOUT Line Regulation VOUT LN VOUT Load Regulation VOUT LD Long-Term Stability VOUTLTS VOUT Noise 2 kΩ 0.3 VCC - 0.3 V (Note 2) ±20 mV (Note 3) ±1.5 -40°C to +85°C, VOUT = 0.7V VOUT Temperature Coefficient kΩ ±56 -40°C to +25°C, VOUT = 5.0V, VCC ≥ 5.3V 7 34 60 +25°C to +85°C, VOUT = 5.0V, VCC ≥ 5.3V -24 -7 +10 +85°C to +125°C, VOUT = 5.0V, VCC ≥ 5.3V -43 -23 -3 -40°C to +85°C -1.6 +1.8 +85°C to +125°C -1.6 +1.8 -40°C to +85°C, -1mA ≤ VOUT I ≤ +1mA 2.0 +85°C to +125°C, -1.0mA ≤ VOUT I ≤ +1.0mA 2.5 1000 hours at +25°C mV µV/°C ppm/°C mV/V mV/mA ppm en1 0.1Hz ≤ f ≤ 10Hz 160 µVP-P en2 10Hz ≤ f ≤ 1kHz 23 µVRMS _____________________________________________________________________ Sample-and-Infinite Hold Voltage Reference (VCC = +4.0V to +5.5V, TA = -40°C to +125°C, unless otherwise noted.) PARAMETER SYMBOL VOUT PSRR CONDITIONS VOUTPSRR MIN TYP MAX UNITS f = 200kHz 28 tST (Note 4) 7 10 ms/V EEPROM Programming Time tW (Note 5) 9 12 ms Turn-On Time tON VIN and ADJ = open circuit (Note 6) ADJ Toggle Low Time tADJ VOUT Self-Adjust Settling Time VOUT Factory-Trimmed Value dB 10 µs 100 ns +25°C, VCC = 5.8V (Note 7) VOUT FT 1200 mV NONVOLATILE MEMORY CHARACTERISTICS (VCC = +4.0V to 5.5V, unless otherwise noted.) PARAMETER SYMBOL Programming Cycles Note 1: Note 2: Note 3: Note 4: Note 5: Note 6: Note 7: Note 8: CONDITIONS MIN +70°C (Note 8) TYP MAX UNITS 50,000 Cycles All voltages referenced to ground. Tracking accuracy is defined as VOUT - VIN after the DS4305 has completed self-adjustment. Quantization refers to the size of the voltage steps used to track the input signal. Settling time is the maximum amount of time VOUT requires to self-adjust. The settling time is determined by the following formula: ∆VOUT x tST. EEPROM programming time is the hold time required after the DS4305 has completed self-adjustment before VIN or VCC can be removed or before ADJ can be toggled low once again. Turn-on time is defined as the time required for VOUT to reach its specified accuracy after the required supply voltage is applied. VOUT not loaded. Guaranteed by design. Typical Operating Characteristics (VCC = 5.0V, TA = +25°C, unless otherwise noted.) 1.4 VCC = 5.5V 1.3 VCC = 4.0V 1.2 1.1 IL = 0mA VCC = 5.5V 1.5 VCC = 5.0V 1.4 VCC = 4.0V 1.3 -10 ADJ = VCC 20 50 80 TEMPERATURE (°C) IL = 0mA 110 1.5 TA = +125°C TA = +85°C 1.4 1.3 TA = +25°C 1.2 TA = -40°C 1.1 ADJ = VCC IL = 0mA 1.0 1.1 -40 1.6 DS4305 toc02 1.6 1.2 1.0 ACTIVE SUPPLY CURRENT vs. SUPPLY VOLTAGE (VOUT = 0.3V) SUPPLY CURRENT (mA) VCC = 5.0V 1.7 SUPPLY CURRENT (mA) 1.5 SUPPLY CURRENT (mA) 1.8 DS4305 toc01 1.6 ACTIVE SUPPLY CURRENT vs. TEMPERATURE (VOUT = 3.5V) DS4305 toc03 ACTIVE SUPPLY CURRENT vs. TEMPERATURE (VOUT = 0.3V) -40 -10 20 50 80 TEMPERATURE (°C) 110 4.0 4.3 4.6 4.9 5.2 5.5 SUPPLY VOLTAGE (V) _____________________________________________________________________ 3 DS4305 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VCC = 5.0V, TA = +25°C, unless otherwise noted.) 0 TA = -40°C -0.5 TA = +25°C -1.0 0 -0.5 TA = -40°C -1.0 -1.5 TA = +125°C -2.0 VCC = 4.0V -0.5 0 0.5 DS4305 toc06 TA = +125°C -300 TA = -40°C -400 TA = +85°C -500 1.0 -1.0 -0.5 0 0.5 -1.0 4.0 4.3 4.6 4.9 5.2 LOAD CURRENT (mA) LOAD CURRENT (mA) SUPPLY VOLTAGE (V) LINE REGULATION (VOUT = 3.5V) POWER-SUPPLY REJECTION RATIO vs. FREQUENCY (VCC = 5.0V) DS4305 OUTPUT NOISE (0.1Hz TO 10Hz) TA = +85°C 0 80 VOUT = 0.3V, VCC-AC = 300mVRMS 70 5.5 300 DS4305 toc09 TA = -40°C DS4305 toc07 20 200 60 TA = +125°C -40 100 50 VOUT (µV) PSRR (dB) -20 VOUT = 4.5V, VCC-AC = 300mVRMS 40 30 -60 0 -100 20 -80 -200 10 -100 VCC = 5.5V 0 4.0 4.5 5.0 5.5 1 10 100 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 TIME (s) DS4305 OUTPUT NOISE (10Hz TO 1kHz) DS4305 TURN-ON TRANSIENT DS4305 LOAD TRANSIENT (VOUT = 3.0V, VCC = 5.0V) 4.0 VOLTAGE (V) 2.5 2.0 1.5 DS4305 toc11 DS4305 toc10 4.5 3.5 3.0 +1mA VCC IOUT 3.0 2.5 VOUT -1mA 2.0 VOUT AC-COUPLED 300mV/div 1.5 1.0 1.0 VCC = 5.5V 0.5 VOUT = 5V 0 COUT =100pF 0 100 1000 4.0 DS4305 toc12 5.0 3.5 10 1000 FREQUENCY (kHz) 4.0 0.5 VOUT = 5V -300 SUPPLY VOLTAGE (V) 4.5 1µs/div FREQUENCY (Hz) 4 -200 -600 -2.5 -1.0 -100 VCC = 5.5V -1.5 OUTPUT VOLTAGE CHANGE (µV) OUTPUT VOLTAGE CHANGE (µV) 0.5 TA = +25°C TA = +85°C DS4305 toc08 OUTPUT VOLTAGE CHANGE (mV) TA = +85°C 1.0 0.5 0 DS4305 toc05 TA = +125°C 1.5 LINE REGULATION (VOUT = 0.3V) 1.0 OUTPUT VOLTAGE CHANGE (mV) 2.0 LOAD REGULATION (VOUT = 5.2V) DS4305 toc04 LOAD REGULATION (VOUT = 0.3V) µVOUT NOISE / (VHz) DS4305 Sample-and-Infinite Hold Voltage Reference _____________________________________________________________________ Sample-and-Infinite Hold Voltage Reference (VCC = 5.0V, TA = +25°C, unless otherwise noted.) DS4305 LINE TRANSIENT (VOUT = 3.0V) DS4305 SHUTDOWN TRANSIENT (VOUT = 4.0V) DS4305 toc13 DS4305 toc14 5.5V VCC 4.0V 1.1V/div VOUT AC-COUPLED 300mV/div VCC VOUT COUT = 100pF DS4305 VOUT ADJUST TRANSIENT (VIN = 0.3V TO 4.0V, VCC = 5.0V) DS4305 NORMALIZED VOUT vs. TEMPERATURE (VOUT = 0.7V) DS4305 toc15 DS4305 toc16 1.010 1.008 2V/div 1.006 ADJ VOUT (V/V) 1.004 1.00 0.998 0.996 VOUT 0.994 0.992 VCC = 5.0V 0.990 -40 -10 20 50 80 110 TEMPERATURE (°C) DS4305 NORMALIZED VOUT vs. TEMPERATURE (VOUT = 5.0V) DS4305 toc17 1.001 1.000 0.999 VOUT (V/V) 1V/div 1.002 0.998 0.997 0.996 VCC = 5.5V 0.995 -40 -10 20 50 80 110 TEMPERATURE (°C) _____________________________________________________________________ 5 DS4305 Typical Operating Characteristics (continued) Sample-and-Infinite Hold Voltage Reference Detailed Description DS4305 Pin Description PIN NAME 1 ADJ 2 GND 3 VIN 4 VOUT Voltage Output 5 VCC Power-Supply Voltage The DS4305 provides a precise, NV output voltage, VOUT, making it an ideal solution for factory calibration of embedded systems. The DS4305 output voltage can be adjusted over almost the entire operating supply range of the device, and it can be precisely set to within ±1.5mV. A graphical description of the DS4305 is provided in the block diagram. During factory calibration, a simple adjustment procedure must be followed. This entire procedure includes setting VIN, toggling ADJ, waiting as VOUT self-adjusts, and waiting for the completion of the EEPROM storage cycle (see the timing diagram in Figure 1). At the start of calibration, a voltage must be placed on VIN. This voltage needs to be completely stable before the adjustment procedure begins, and it must remain stable throughout the entire adjustment procedure. The DS4305 starts its self-adjust procedure when the ADJ pin is pulled low and held low for at least tADJ, after which it can be released at any time. Once ADJ has been released, it should not be toggled again for the remainder of the adjustment procedure. After the falling edge on ADJ and the wait time, tADJ, the VOUT selfadjust period begins. The length of the VOUT self-adjust period can be determined using the formula ∆V x tST, where ∆V is | VOUT OLD - VOUT NEW |. FUNCTION Adjust Control Input Ground Sample Voltage Input Block Diagram VCC DS4305 RPU ADJ ADC AND CONTROL VOUT 12-BIT DAC VIN VCC RPD VCC VREF EEPROM GND ∆VOUT ∆VOUT VOUT ∆VOUT x tST ∆VOUT x tST VIN tW tW ADJ tADJ tADJ tADJ FIRST PROGRAMMING CYCLE ADDITIONAL PROGRAMMING CYCLES (IF REQUIRED) Figure 1. Timing Diagram 6 _____________________________________________________________________ Sample-and-Infinite Hold Voltage Reference DEVICE-UNDER-TEST (DUT) DS4305 STEP 1: SET REFERENCE VOLTAGE 4.0V TO 5.5V VCC EEPROM DIGITALLY CONTROLLED VOLTAGE SOURCE VIN ADJ STEP 2: TOGGLE ADJ DIGITAL PIN DRIVER VOLTAGE SAMPLE-ANDINFINITEHOLD VOUT GND STEP 3: DETERMINE IF THE REFERENCE VOLTAGE NEEDS ADJUSTMENT DS4305 AUTOMATED TEST EQUIPMENT BED-OF-NAILS TEST ACCESS DIGITALLY CONTROLLED MEASUREMENT PARAMETER MEASURED DURING CALIBRATION CIRCUITRY REQUIRING VOLTAGE ADJUSTMENT Figure 2. Application Circuit During the VOUT self-adjust period, the DS4305 internally adjusts the on-board DAC until VOUT matches VIN. After VOUT has stabilized to within the tracking accuracy, VOUTTA, of VIN, it will be automatically stored in EEPROM. The storage period lasts for the duration of the EEPROM write time, tW. After the first adjustment procedure has completed, V OUT can be measured, and if necessary VIN can be readjusted and the entire adjustment procedure can be repeated to fine-tune VOUT within the VOUTQ range. Following each self-adjust procedure, VOUT is saved indefinitely, even if the DS4305 is power cycled. Automated Programming Procedure Figure 2 details an example of how the DS4305 can be adjusted in an application. During factory alignment, a three/four-node bed-of-nails is used to: (1) provide the adjustment voltage through the VIN pin, (2) control the ADJ input, and (3) sense the needed feedback parameter. During manufacture, an automated test procedure adjusts VOUT, by changing VIN, until the feedback parameter is optimized. After the bed-of-nails operation is complete, both the VIN and ADJ inputs are left open circuit. VOUT can be readjusted at any time by following the same procedure. The closed-loop nature of the adjustment process removes all the system inaccuracies such as resistor tolerances, amplifier offsets, gain mismatches, and even the inaccuracies in the automated equipment that provides the reference voltage. Typical Operating Circuit The Typical Operating Circuit shows an example of how the DS4305 can replace most existing calibration solutions. Many power supplies use a shunt voltage reference to provide the internal reference voltage, and fine-tune adjustments are often made with hand-selected discrete resistors. The DS4305 replaces this cumbersome arrangement with a solution that is capable of being adjusted by automated techniques. An additional benefit of the DS4305 is the ability to provide a much lower voltage (down to 300mV) than is possible with shunt voltage references. Another benefit of the DS4305 is the ability to be adjusted after the unit has been fully assembled and tested, resulting in a much more flexible manufacturing arrangement, lower inventory costs, and a quicker time-to-market. _____________________________________________________________________ 7 DS4305 Sample-and-Infinite Hold Voltage Reference Chip Topology Layout Considerations To prevent an inadvertent programming cycle from occurring during power-up, minimize capacitive loading on the ADJ pin. A large capacitance on this pin could potentially hold ADJ in a low state long enough that a programming cycle is initiated. TRANSISTOR COUNT: 6016 SUBSTRATE CONNECTED TO GROUND Power-Supply Decoupling To achieve best results, it is highly recommended that a decoupling capacitor is used on the IC power-supply pin. Typical values of decoupling capacitors are 0.01µF or 0.1µF. Use a high-quality, ceramic, surface-mount capacitor, and mount it as close as possible to the VCC and GND pins of the IC to minimize lead inductance. Package Information For the latest package outline information, go to www.maxim-ic.com/DallasPackInfo. Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2006 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. is a registered trademark of Dallas Semiconductor Corporation. Heaney