Rev 1; 8/6 EVALUATION KIT AVAILABLE Electronically Programmable General Description The is a nonvolatile (NV) electronically programmable voltage reference. The reference voltage is programmed in-circuit during factory calibration/ programming. Programming the reference voltage,, is as simple as applying the desired voltage on and toggling the adjust pin () to lock the voltage level indefinitely, even if the device is power cycled. The replaces current cumbersome factory adjustment arrangements with a low-cost solution that can be adjusted using automated techniques. In addition, the 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. Power-Supply Calibration Threshold Setting Offset Nulling Bias Adjusting Power Amps Pressure Bridges Factory-Calibrated Equipment Applications Features Precise Electronically Adjustable Voltage Reference Enables Automated Factory Trimming of Devices Needing Voltage Adjustment Can be Adjusted to Within ±mv Wide Adjustable Output Voltage Range Within 3mV of the Supply Rails Low Temperature Coefficient ±1mA of Output-Current Drive NV Memory Stores the Voltage Indefinitely Output Short-Circuit Protection Low Cost Low Power Consumption 4.V to 5.5V Single-Supply Operation Small 5-Lead SOT23 Package -4 C to +125 C Temperature Operation K Evaluation Kit is Available PART Ordering Information TEMP RANGE PIN- PACKAGE SOT MARK R+T&R -4 C to +125 C 5 SOT23 435+ +Denotes lead-free package. Typical Operating Circuit Pin Configuration EXISTING SOLUTION SOLUTION TOP VIEW 1 5 SHUNT REFERENCE REFERENCE HAND-SELECTED.1% RESISTOR OR MECHANICAL POT GND REFERENCE GND 2 3 4 ACCESS FOR AUTOMATED ALIGNMENT SOT23 Maxim Integrated Products 1 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.
ABSOLUTE MAXIMUM RATINGS Voltage on Relative to GND...-.5V to +6.V Voltage on,, and Relative to GND...-.5V to ( +.5V), not to exceed +6.V Operating Temperature Range...-4 C to +125 C EEPROM Programming Adjust Temperature... C to +7 C to GND Short-Circuit Duration...Continuous Storage Temperature Range...-55 C to +125 C Soldering Temperature...See IPC/JEDEC J-STD-2 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 (T A = -4 C to +125 C) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage (Note 1) 4. 5.5 V Voltage Range.3 -.3 V Logic V IL -.3.3 x V Current I -1 +1 ma Load L 1 pf ELECTRICAL CHARACTERISTICS ( = +4.V to +5.5V, T A = -4 C to +125 C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS -4 C to +85 C;,, and = open circuit Supply Current I IN +85 C to +125 C;,, and = open circuit 1.4 2. Resistance R PD 95 kω Pullup Resistance R PU 18 kω Voltage Range R (Note 1).3 V C C -.3 V Tracking Accuracy TA (Note 2) ±2 mv Quantization Q (Note 3) ± mv Temperature Coefficient TC -4 C to +85 C, =.7V ±56 µv/ C -4 C to +25 C, = 5.V, 5.3V 7 34 6 +25 C to +85 C, = 5.V, 5.3V -24-7 +1 +85 C to +125 C, = 5.V, 5.3V -43-23 -3-4 C to +85 C -1.6 +1.8 Line Regulation LN +85 C to +125 C -1.6 +1.8 2.1 ma ppm/ C mv/v -4 C to +85 C, -1mA I +1mA 2. Load Regulation LD + 85 C to + 125 C, - 1.m A V OU T I + 1.m A 2.5 mv/ma Long-Term Stability LTS 1 hours at +25 C ppm Noise e n1.1hz f 1Hz 16 µv P-P e n2 1Hz f 1kHz 23 µv RMS 2
ELECTRICAL CHARACTERISTICS (continued) ( = +4.V to +5.5V, T A = -4 C to +125 C, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS PSRR PSRR f = 2kHz 28 db Self-Adjust Settling Time t ST (Note 4) 7 1 ms/v EEPROM Programming Time t W (Note 5) 9 12 ms Turn-On Time t ON and = open circuit (Note 6) 1 µs Toggle Low Time t 1 ns Factory-Trimmed Value FT +25 C, = 5.8V (Note 7) 12 mv NONVOLATILE MEMORY CHARACTERISTICS ( = +4.V to 5.5V, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Programming Cycles +7 C (Note 8) 5, Cycles Note 1: All voltages referenced to ground. Note 2: Tracking accuracy is defined as - after the has completed self-adjustment. Note 3: Quantization refers to the size of the voltage steps used to track the input signal. Note 4: Settling time is the maximum amount of time requires to self-adjust. The settling time is determined by the following formula: x t ST. Note 5: EEPROM programming time is the hold time required after the has completed self-adjustment before or can be removed or before can be toggled low once again. Note 6: Turn-on time is defined as the time required for to reach its specified accuracy after the required supply voltage is applied. Note 7: not loaded. Note 8: Guaranteed by design. ( = 5.V, T A = +25 C, unless otherwise noted.) Typical Operating Characteristics SUPPLY CURRENT (ma) 1.6 1.4 1.3 1.2 ACTIVE SUPPLY CURRENT vs. TEMPERATURE ( =.3V) = 5.5V = 5.V = 4.V toc1 SUPPLY CURRENT (ma) 1.8 1.7 1.6 1.4 1.3 ACTIVE SUPPLY CURRENT vs. TEMPERATURE ( = 3.5V) = 5.5V = 4.V = 5.V toc2 SUPPLY CURRENT (ma) 1.6 1.4 1.3 1.2 ACTIVE SUPPLY CURRENT vs. SUPPLY ( =.3V) T A = +25 C toc3 1.1 I L = ma = 1. -4-1 2 5 8 11 TEMPERATURE ( C) 1.2 I L = ma = 1.1-4 -1 2 5 8 11 TEMPERATURE ( C) T 1.1 A = -4 C I L = ma 1. 4. 4.3 4.6 4.9 5.2 5.5 SUPPLY (V) 3
( = 5.V, T A = +25 C, unless otherwise noted.) OUTPUT CHANGE (mv) 2. 1..5 -.5-1. - -1. LOAD REGULATION ( =.3V) T A = +25 C T A = -4 C = 4.V -.5.5 1. LOAD CURRENT (ma) toc4 OUTPUT CHANGE (mv) Typical Operating Characteristics (continued) 1..5 -.5-1. - -2. -2.5-1. LOAD REGULATION ( = 5.2V) T A = +25 C T A = -4 C = 5.5V -.5.5-1. LOAD CURRENT (ma) toc5 OUTPUT CHANGE (µv) -1-2 -3-4 -5 LINE REGULATION ( =.3V) T A = -4 C -6 4. 4.3 4.6 4.9 5.2 5.5 SUPPLY (V) toc6 OUTPUT CHANGE (µv) 2-2 -4-6 -8 LINE REGULATION ( = 3.5V) T A = -4 C -1 4. 4.5 5. 5.5 SUPPLY (V) toc7 PSRR (db) 8 7 6 5 4 3 2 1 POWER-SUPPLY REJECTION RATIO vs. FREQUENCY ( = 5.V) = 4.5V, -AC = 3mV RMS =.3V, -AC = 3mV RMS 1 1 1 1 FREQUENCY (khz) toc8 VOUT (µv) 3 2 1-1 -2-3 = 5.5V OUTPUT NOISE (.1Hz TO 1Hz) = 5V.5 1. 2. 2.5 3. 3.5 4. TIME (s) toc9 µvout NOISE / (VHz) 4.5 4. 3.5 3. 2.5 2. 1. OUTPUT NOISE (1Hz TO 1kHz) toc1 (V) 5. 4.5 4. 3.5 3. 2.5 2. 1. TURN-ON TRANSIENT toc11 +1mA I OUT -1mA AC-COUPLED 3mV/div LOAD TRANSIENT ( = 3.V, = 5.V) toc12.5 = 5.5V = 5V 1 1 1 FREQUENCY (Hz).5 1µs/div C OUT =1pF 4
( = 5.V, T A = +25 C, unless otherwise noted.) LINE TRANSIENT ( = 3.V) toc13 Typical Operating Characteristics (continued) SHUTDOWN TRANSIENT ( = 4.V) toc14 5.5V 4.V AC-COUPLED 3mV/div 1.1V/div C OUT = 1pF 2V/div UST TRANSIENT ( =.3V TO 4.V, = 5.V) toc15 1.1 1.8 1.6 1.4 NORMALIZED vs. TEMPERATURE ( =.7V) toc16 VOUT (V/V) 1.2 1..998 1V/div.996.994.992 = 5.V.99-4 -1 2 5 8 11 TEMPERATURE ( C) 1.1 1. NORMALIZED vs. TEMPERATURE ( = 5.V) toc17.999 VOUT (V/V).998.997.996 = 5.5V.995-4 -1 2 5 8 11 TEMPERATURE ( C) 5
GND PIN NAME FUNCTION 1 Adjust Control Input 2 GND Ground 3 Sample Voltage Input 4 Voltage Output 5 Power-Supply Voltage R PU R PD ADC AND CONTROL EEPROM Pin Description Block Diagram 12-BIT DAC V REF Detailed Description The provides a precise, NV output voltage,, making it an ideal solution for factory calibration of embedded systems. The output voltage can be adjusted over almost the entire operating supply range of the device, and it can be precisely set to within ±mv. A graphical description of the is provided in the block diagram. During factory calibration, a simple adjustment procedure must be followed. This entire procedure includes setting, toggling, waiting as 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. This voltage needs to be completely stable before the adjustment procedure begins, and it must remain stable throughout the entire adjustment procedure. The starts its self-adjust procedure when the pin is pulled low and held low for at least t, after which it can be released at any time. Once has been released, it should not be toggled again for the remainder of the adjustment procedure. After the falling edge on and the wait time, t, the selfadjust period begins. The length of the self-adjust period can be determined using the formula V x t ST, where V is OLD - NEW. x t ST x t ST t W t W t t t FIRST PROGRAMMING CYCLE ADDITIONAL PROGRAMMING CYCLES (IF REQUIRED) Figure 1. Timing Diagram 6
AUTOMATED TEST EQUIPMENT STEP 1: SET REFERENCE STEP 2: TOGGLE STEP 3: DETERMINE IF THE REFERENCE NEEDS USTMENT DIGITALLY CONTROLLED SOURCE DIGITAL PIN DRIVER DIGITALLY CONTROLLED MEASUREMENT BED-OF-NAILS TEST ACCESS GND DEVICE-UNDER-TEST (DUT) EEPROM SAMPLE-AND- INFINITE- HOLD PARAMETER MEASURED DURING CALIBRATION 4.V TO 5.5V CIRCUITRY REQUIRING USTMENT Figure 2. Application Circuit During the self-adjust period, the internally adjusts the on-board DAC until matches. After has stabilized to within the tracking accuracy, TA, of, it will be automatically stored in EEPROM. The storage period lasts for the duration of the EEPROM write time, t W. After the first adjustment procedure has completed, can be measured, and if necessary can be readjusted and the entire adjustment procedure can be repeated to fine-tune within the Q range. Following each self-adjust procedure, is saved indefinitely, even if the is power cycled. Automated Programming Procedure Figure 2 details an example of how the 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 pin, (2) control the input, and (3) sense the needed feedback parameter. During manufacture, an automated test procedure adjusts, by changing, until the feedback parameter is optimized. After the bed-of-nails operation is complete, both the and inputs are left open circuit. 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 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 replaces this cumbersome arrangement with a solution that is capable of being adjusted by automated techniques. An additional benefit of the is the ability to provide a much lower voltage (down to 3mV) than is possible with shunt voltage references. Another benefit of the 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
Layout Considerations To prevent an inadvertent programming cycle from occurring during power-up, minimize capacitive loading on the pin. A large capacitance on this pin could potentially hold in a low state long enough that a programming cycle is initiated. TRANSISTOR COUNT: 616 SUBSTRATE CONNECTED TO GROUND Chip Topology 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.1µf or.1µf. Use a high-quality, ceramic, surface-mount capacitor, and mount it as close as possible to the 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. Pages changed at Rev1: 1 Title changes all pages Revision History 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, 12 San Gabriel Drive, Sunnyvale, CA 9486 48-737-76 26 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. is a registered trademark of Dallas Semiconductor Corporation. Heaney