MAX4207 19-3070 Rev 1 6/04 Precision Transimpedance Logarithmic Amplifier with Over 5 Decades of Dynamic Range General Description Features The MAX4207 logarithmic amplifier computes the log 2.7V to 5.5V Dual-Supply Operation ratio of an input current relative to a reference current 5 Decades of Dynamic Range (10nA to 1mA) (externally or internally generated) and provides a cor- responding voltage output with a default -0.25V/decade Monotonic Over a 1nA to 1mA Range scale factor. The device operates from dual 2.7V to -0.25V/Decade Internally Trimmed Output Scale 5.5V supplies and is capable of measuring five Factor decades of input current across a 10nA to 1mA range. The MAX4207s uncommitted op amp can be used for Adjustable Output Scale Factor a variety of functions, including filtering noise, adding Adjustable Output Offset Voltage offset, and adding additional gain. A 0.5V reference is also included to generate an optional precision current Internal 10nA to 10A Reference Current Source reference using an external resistor, which adjusts the Input Amplifiers Summing Nodes at Ground log intercept of the MAX4207. The output-offset voltage and the adjustable scale factor are also set using exter- Small 16-Pin Thin QFN Package (4mm x 4mm x nal resistors. 0.8mm) The MAX4207 is available in a space-saving 16-pin thin -40C to +85C Operating Temperature Range QFN package (4mm x 4mm x 0.8mm), and is specified Evaluation Kit Available (Order MAX4206EVKIT) for operation over the -40C to +85C extended temper- ature range. Applications Ordering Information Photodiode Current Monitoring PART TEMP RANGE PIN-PACKAGE Portable Instrumentation MAX4207ETE -40C to +85C 16 Thin QFN-EP* Medical Instrumentation *EP = Exposed paddle. Analog Signal Processing Typical Operating Circuit V CC Pin Configuration I IN 0.1F V CC V OUT LOGV2 TOP VIEW (LEADS ON BOTTOM) LOGIIN R2 C COMP REFIOUT SCALE R COMP REFIIN 16 15 14 13 C COMP R1 MAX4207 LOGV1 N.C. 1 12 CMVOUT R COMP REFVOUT 2 11 REFISET GND 3 MAX4207 10 V CC CMVIN REFVOUT V 4 9 N.C. EE CMVOUT R3 REFISET OSADJ 56 7 8 GND V EE R SET R4 0.1F V EE THIN QFN Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct at 1-888-629-4642, or visit Maxims website at www.maxim-ic.com. EVALUATION KIT AVAILABLE LOGV1 CMVIN LOGIIN OSADJ SCALE REFIIN REFIOUT LOGV2Precision Transimpedance Logarithmic Amplifier with Over 5 Decades of Dynamic Range ABSOLUTE MAXIMUM RATINGS (All voltages referenced to GND, unless otherwise noted.) Continuous Current (REFIIN, LOGIIN) ................................10mA V ...........................................................................-0.3V to +6V Continuous Power Dissipation (T = +70C) CC A V ............................................................................-6V to +0.3V 16-Pin Thin QFN (derate 16.9mW/C above +70C) ...1349mW EE Supply Voltage (V to V ) .............................................. +12V Operating Temperature Range ...........................-40C to +85C CC EE REFVOUT ....................................................(V - 0.3V) to +3.0V Junction Temperature .....................................................+150C EE OSADJ, SCALE, REFISET ...........................(V - 0.3V) to +5.5V Storage Temperature Range .............................-65C to +150C EE REFIIN, LOGIIN ........................................(V - 0.3V) to V Lead Temperature (soldering, 10s) .................................+300C EE CMVIN LOGV1, LOGV2, CMVOUT, REFIOUT ......................................(V - 0.3V) to (V + 0.3V) EE CC CMVIN............................................................(V - 0.3V) to +1V EE 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. DC ELECTRICAL CHARACTERISTICSDual-Supply Operation (V = +5V, V = -5V, GND = 0, I = 1A, I = 10A, LOGV2 = SCALE, LOGV1 = OSADJ, CMVIN = CMVOUT, R > 1M, LOG SET CC EE REF T = -40C to +85C. Typical values are at T = +25C, unless otherwise noted.) (Note 1) A A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS V (Note 2) 2.7 5.5 CC Supply Voltage V V (Note 2) -2.7 -5.5 EE T = +25C 5 6 A Supply Current I mA CC T = -40C to +85C 7.5 A Minimum 10 nA LOGIIN Current Range I LOG (Notes 3, 4) Maximum 1 mA Minimum 10 nA REFIIN Current Range I REF (Notes 3, 4) Maximum 1 mA Common-Mode Voltage V 0V CMVOUT Common-Mode Voltage Input V 0 0.5 V CMVIN Range I = 10nA, REF T = +25C 2 5 A I = 10nA to 1mA, LOG Log Conformity Error V mV LC K = -0.25V/decade T = -40C to +85C 10 A (Note 4) T = +25C -237.5 -250 -262.5 A mV/ Logarithmic Slope (Scale Factor) K decade T = -40C to +85C -231.25 - 268.75 A V/ Logarithmic Slope (Scale Factor) T = -40C to +85C 80 decade/ A Temperature Drift C T = +25C, V - V , A CMVIN REFIIN Input Offset Voltage V 0.6 5 mV IO V - V CMVIN LOGIIN Input Offset Voltage Temperature V V - V , V - V 6 V/C IOS CMVIN REFIIN CMVIN LOGIIN Drift T = +25C 1.218 1.238 1.258 A Voltage Reference Output V V REFVOUT T = -40C to +85C (Note 4) 1.195 1.275 A 2 MAX4207