19-2743; Rev 1; 5/03 High-Accuracy, 76V, High-Side Current Monitors in SOT23 Features ♦ Wide Reference Current Dynamic Range Guaranteed 250nA to 2.5mA with 5% Monitor Accuracy Extended 10nA to 10mA with 10% Monitor Accuracy ♦ Current (MAX4007) or Voltage (MAX4008) Monitor Outputs ♦ Reference Current-Limit Protection (20mA, typ) ♦ Voltage Clamp Protects Subsequent Output Circuitry ♦ +2.7V to +76V Wide Voltage Range Operation ♦ 6-Pin SOT23 Packages The MAX4007/MAX4008 are available in tiny, spacesaving 6-pin SOT23 packages, and operate over the extended temperature range of -40°C to +85°C. Applications Ordering Information PART TEMP RANGE PIN-PACKAGE TOP MARK Photodiode Current-Monitoring Systems MAX4007EUT-T -40°C to +85°C 6 SOT23-6 ABNM Portable Instrumentation MAX4008EUT-T -40°C to +85°C 6 SOT23-6 ABNO Medical Instrumentation Laboratory Instrumentation Consumer Electronics Current-to-Voltage Conversion Level Translation Pin Configuration Selector Guide PART PINPACKAGE INTERNAL TYPICAL RESISTOR ACCURACY (%) MAX4007EUT-T 6 SOT23-6 None 5 MAX4008EUT-T 6 SOT23-6 10kΩ 1 TOP VIEW CLAMP 1 GND 2 MAX4007 MAX4008 OUT 3 Typical Operating Circuit appears at end of data sheet. 6 BIAS 5 N.C. 4 REF 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 MAX4007/MAX4008 General Description The MAX4007/MAX4008 precision, high-side, high-voltage current monitors are specifically designed for monitoring photodiode current in fiber applications. They offer a connection point for the reference current and a monitor output that produces a signal proportional to the reference current. The monitor output of the MAX4007 is a current proportional to the reference current. The monitor output of the MAX4008 is a voltage proportional to the reference current. The current monitors have six decades of dynamic range and monitor reference currents of 250nA to 2.5mA with better than 5% accuracy. The photodiode current can be monitored from 10nA to 10mA with reduced accuracy. The MAX4007/MAX4008 accept a supply voltage of +2.7V to +76V, suitable for APD or PIN photodiode applications. Internal current limiting (20mA, typ) protects the devices against short circuit to ground. A clamp diode protects the monitor output from overvoltage. Additionally, these devices feature thermal shutdown if the die temperature reaches +150°C. MAX4007/MAX4008 High-Accuracy, 76V, High-Side Current Monitors in SOT23 ABSOLUTE MAXIMUM RATINGS CLAMP to GND ......................................................-0.3V to +80V BIAS, REF to GND ..................................................-0.3V to +80V OUT to GND .........................................-0.3V to (VCLAMP + 0.6V) Short Circuit, REF to GND ..........................................Continuous Current into Any Pin..........................................................±30mA Continuous Power Dissipation (TA = +70°C) 6-Pin SOT23 (derate 8.7mW/°C above +70°C)............696mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10s) .................................+300°C 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. ELECTRICAL CHARACTERISTICS (VBIAS = 40V, GND = 0V, REF = open, VOUT = 0V (MAX4007), CLAMP = open, -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL Bias Voltage Range VBIAS Bias Quiescent Current IBIAS Reference Voltage VREF Thermal Shutdown Engage Temperature CONDITIONS Inferred from power-supply rejection test TYP 2.7 MAX UNITS 76 V IREF = 250nA 90 200 µA IREF = 2.5mA 3.6 4 mA IREF = 2.5mA VBIAS - 1.1 VBIAS - 0.8 V TSHDN REF shorted to GND, junction temperature rising 150 °C Trip-Point Temperature Hysteresis THYS REF shorted to GND, junction temperature falling 5 °C Input Current Limit ILIM VREF = VBIAS - 5V 20 mA f = 0.1Hz to 10Hz MAX4007 Output Current Noise iNOUT f = 0.1Hz to 10kHz IREF = 250nA 0.3 IREF = 2.5mA 63 IREF = 250nA 9.2 IREF = 2.5mA 1240 pARMS IREF = 250nA 0.041 IREF = 2.5mA 0.63 IREF = 250nA 1.3 IREF = 2.5mA 12.5 IREF = 250nA 50 GΩ IREF = 2.5mA 5 MΩ MAX4008 10 kΩ Output Leakage REF = open 1 pA Output Voltage Range VOUT VBIAS = 2.7V to 76V, IREF = 0 to 1mA, MAX4007: ∆IOUT/IOUT = ±1%, MAX4008: ∆VOUT/IOUT = ±1% 0 to VBIAS - 0.85 V Output Clamp Voltage VOUT VCLAMP 0.6 V f = 0.1Hz to 10Hz MAX4008 Output Voltage Noise eNOUT f = 0.1Hz to 10kHz Output Resistance 2 MIN ROUT MAX4007 0 to VBIAS - 1.5 _______________________________________________________________________________________ µVRMS High-Accuracy, 76V, High-Side Current Monitors in SOT23 (VBIAS = 40V, GND = 0V, REF = open, VOUT = 0V (MAX4007), CLAMP = open, -40°C to +85°C. Typical values are at TA = +25°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL Output Clamp Leakage MAX4007 Current Gain CONDITIONS MIN VCLAMP = 0 to 76V IOUT/IREF VOUT/IREF 0.09 0.0999 0.11 IREF = 2.5mA 0.094 0.095 0.106 0.9 0.992 1.1 IREF = 2.5mA 0.95 0.998 1.05 Power-Up Settling Time IREF = 250nA MAX4007: VBIAS = 2.7V to 76V IREF = 1mA (∆VOUT/VOUT) /∆VBIAS MAX4008: IREF = 1mA VBIAS = 2.7V to 76V tS IOUT settles within 0.1%, CIN = 10nF between REF and GND mA/mA 0.0997 IREF = 250nA (∆IOUT/IOUT) /∆VBIAS UNITS pA IREF = 250nA IREF = 10mA, VBIAS = 12V Power-Supply Rejection Ratio (PSRR) MAX 1 IREF = 10mA, VBIAS = 12V MAX4008 Transimpedance Gain TYP V/mA 1.00 50 1000 50 1000 50 1000 ppm/V IREF = 250nA 7.5 ms IREF = 2.5mA 90 µs Note 1: All devices are 100% tested at room temperature (TA = +25°C). All temperature limits are guaranteed by design. _______________________________________________________________________________________ 3 MAX4007/MAX4008 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) BIAS CURRENT vs. REFERENCE CURRENT VBIAS = 40V 1 0.1 10 10.00 IREF = 2.5mA BIAS CURRENT (mA) BIAS CURRENT (mA) BIAS CURRENT (mA) IREF = 2.5mA 100.00 MAX4007/08 toc02 MAX4007/08 toc01 10 BIAS CURRENT vs. TEMPERATURE 1.00 MAX4007/08 toc03 BIAS CURRENT vs. SUPPLY VOLTAGE 1 0.1 IREF = 250nA 0.10 IREF = 250nA VBIAS = 40V 0.01 0.01 0.01 10n 26 20 100n 1µ 10µ GAIN ERROR vs. REFERENCE CURRENT 1m 3 9 MAX4007/08 toc04 VBIAS = 40V 8 1 0 -1 IREF = 10nA IREF = 250nA IREF = 2.5µA 4 3 2 -3 1 -4 0 -5 VBIAS = 40V 5 IREF = 250µA IREF = 2.5mA IREF = 10mA 10µ 100µ 1m 10m -0.2 -0.4 -0.6 IREF = 250nA -0.8 IREF = 25µA IREF = 2.5mA IREF = 5mA -1.4 -15 10 35 60 85 2.0 20.5 CH1 57.5 76.0 STARTUP DELAY (VBIAS = 40V, IREF = 2.5mA) MAX4007/8 toc08 A 39.0 VBIAS (V) STARTUP DELAY (VBIAS = 40V, IREF = 250nA) MAX4007/8 toc07 85 0 TEMPERATURE (°C) TRANSIENT RESPONSE (VBIAS = 40V) 60 0.2 -1.2 -40 IREF (A) 35 -1.0 -1 1µ 10 GAIN ERROR vs. BIAS VOLTAGE 6 -2 100n -15 TEMPERATURE (°C) 7 GAIN ERROR (%) 2 10n -40 10m GAIN ERROR vs. TEMPERATURE 5 4 100µ IREF (A) MAX4007/08 toc06 14 SUPPLY VOLTAGE (V) GAIN ERROR (%) 8 MAX4007/08 toc05 2 GAIN ERROR (%) MAX4007/MAX4008 High-Accuracy, 76V, High-Side Current Monitors in SOT23 MAX4007/8 toc09 VBIAS BIAS D.U.T. REF OUT R1 CH2 RREF CH1 13pF RTEST CH1 40V CH1 BIAS D.U.T. REF OUT B 0V 0V CH2 CH2 VBIAS BIAS D.U.T. REF OUT CH1 6.3kΩ CH2 BGND 10kΩ R1 CH2 RREF 12.1kΩ 13pF 0V RTEST 0V AGND 400ns/div A: CH2, 5V/div, IREF = 0 TO 2.5mA B: CH1, 1V/div, IOUT = 0 TO 0.25mA 4 RREF = 158mΩ R1 = 118mΩ RTEST = 1.67mΩ CH1: 10V/div CH2: 20mV/div 20ms/div RREF = 15.8kΩ R1 = 0Ω RTEST = 140kΩ CH1: 10V/div CH2: 10V/div 20ms/div _______________________________________________________________________________________ High-Accuracy, 76V, High-Side Current Monitors in SOT23 STARTUP DELAY (VBIAS = 5V, IREF = 250nA) STARTUP DELAY (VBIAS = 5V, IREF = 2.5mA) MAX4007/8 toc10 SHORT-CIRCUIT RESPONSE (VBIAS = 40V) MAX4007/8 toc12 MAX4007/8 toc11 TA = +85°C CH1 CH1 A 0V 0V VBIAS CH1 BIAS D.U.T. REF OUT CH1 B C D VBIAS BIAS D.U.T. REF OUT CH1 R1 CH2 CH2 R1 CH2 RREF 13pF 0A CH2 RREF RTEST 13pF 0V RTEST 0V 40ms/div 4ms/div RREF = 16.8mΩ R1 = 118mΩ RTEST = 1.67mΩ CH1: 2V/div CH2: 10V/div 20ms/div RREF = 1.68kΩ R1 = 0Ω RTEST = 14.0kΩ CH1: 2V/div CH2: 1V/div CH1: IBIAS, 10.0mA/div A: REF SHORTS TO GND B: CURRENT LIMIT ACTIVE C: THERMAL SHUTDOWN D: POST COOL-DOWN RETRY VOLTAGE DROP vs. REFERENCE CURRENT SHORT-CIRCUIT RESPONSE (VBIAS = 76V) MAX4007/8 toc13 MAX4007/08 toc14 1.40 VBIAS = 2.7V TA = +85°C 1.20 B CH1 C D VBIAS - VREF (V) 1.00 A 0.80 0.60 0.40 0A 0.20 40ms/div CH1: IBIAS, 10.0mA/div A: REF SHORTS TO GND B: CURRENT LIMIT ACTIVE C: THERMAL SHUTDOWN D: POST COOL-DOWN RETRY A B C A: TA = -40°C B: TA = +25°C C: TA = +85°C D: TA = +100°C D 0 100n 1µ 10µ 100µ 1m 10m REFERENCE CURRENT (A) _______________________________________________________________________________________ 5 MAX4007/MAX4008 Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) High-Accuracy, 76V, High-Side Current Monitors in SOT23 MAX4007/MAX4008 Pin Description PIN NAME FUNCTION MAX4007 MAX4008 1 1 CLAMP 2 2 GND Ground 3 — OUT Current-Monitor Output. OUT sources a current of 1/10th IREF. 4 4 REF Reference Current Output. REF provides the source current to the cathode of the photodiode. 5 5 N.C. No Connection. Not internally connected. 6 6 BIAS Bias Voltage Input. Bias voltage for photodiode. — 3 OUT Current-Monitor Output. OUT presents a voltage proportional to IREF at 1V/mA. An internal 10kΩ resistor connects OUT to GND (see Functional Diagram). Clamp Voltage Input. External potential used for voltage clamping of VOUT. Functional Diagrams BIAS BIAS MAX4007 MAX4008 CURRENT MONITOR CURRENT MONITOR 1x 10x 10x 1x CLAMP OUT OUT CURRENT CLAMP REF CURRENT CLAMP REF GND Detailed Description The MAX4007/MAX4008 are versatile current monitors intended for monitoring DC photodiode current in fiber applications (see Functional Diagram). The MAX4007 output is a current that is exactly one-tenth the reference current. The MAX4008 outputs a voltage that is proportional to the reference current with a transimpedance gain of 1V/mA achieved by a factory-trimmed, internal 10kΩ resistor. 6 CLAMP 10kΩ GND Both current devices have six decades of dynamic range and monitor reference current ranging from 250nA to 2.5mA, the nominal operating range, with better than 5% accuracy across the entire reference current, bias voltage, and temperature ranges. The corresponding monitor outputs produce 25nA to 0.25mA (MAX4007) and 0.25mV to 2.5V (MAX4008). When the reference currents are extended to the broader range of 10nA to 10mA, an accuracy of less than 10% is maintained. Internal current limiting (20mA, _______________________________________________________________________________________ High-Accuracy, 76V, High-Side Current Monitors in SOT23 Applications Information Clamping the Monitor Output Voltage CLAMP provides a means for diode clamping the voltage at OUT; thus, VOUT is limited to VCLAMP + 0.6V. CLAMP can be connected to either an external supply, to BIAS, or may be left floating if voltage clamping is not required. Using APD or PIN Photodiodes in Fiber Applications When using the MAX4007/MAX4008 to monitor APD or PIN photodiode currents in fiber applications, several issues must be addressed. In applications where the photodiode must be fully depleted, keep track of voltages budgeted for each component with respect to the available supply voltage(s). The current monitors require as much as 1.1V between BIAS and REF, which must be considered part of the overall voltage budget. Additional voltage margin can be created if a negative supply is used in place of a ground connection, as long as the overall voltage drop experienced by the MAX4007/MAX4008 is less than or equal to 76V. For this type of application, the MAX4007 is suggested so the output can be referenced to “true” ground and not the negative supply. The MAX4007’s output current can be referenced as desired with either a resistor to ground or a transimpedance amplifier. Take care to ensure that output voltage excursions do not interfere with the required margin between BIAS and OUT. In many fiber applications, OUT is connected directly to an ADC that operates from a supply voltage that is less than the voltage at BIAS. Connecting the MAX4007/MAX4008s’ clamping diode output, CLAMP, to the ADC power supply helps avoid damage to the ADC. Without this protection, voltages can develop at OUT that might destroy the ADC. This protection is less critical when OUT is connected directly to subsequent transimpedance amplifiers (linear or logarithmic) that have low-impedance, near-ground-referenced inputs. If a transimpedance amp is used on the low side of the photodiode, its voltage drop must also be considered. Leakage from the clamping diode is most often insignificant over nominal operating conditions, but grows with temperature. To maintain low levels of wideband noise, lowpass filtering the output signal is suggested in applications where only DC measurements are required. Determining the required filtering components is straightforward, as the MAX4007 exhibits a very high output impedance (>5MΩ), while the MAX4008 exhibits an output resistance of 10kΩ. In some applications where pilot tones are used to identify specific fiber channels, higher bandwidths are desired at OUT to detect these tones. Consider the minimum and maximum currents to be detected, then consult the frequency response and noise typical operating curves. If the minimum current is too small, insufficient bandwidth could result, while too high a current could result in excessive noise across the desired bandwidth. Refer to the MAX4009 family data sheet for devices intended for fiber applications using pilot tones. Bypassing and External Components In applications where power-supply noise can interfere with DC diode measurements, additional filtering is suggested. Such noise is commonly seen when switching power supplies are used to generate the photodiode bias voltage. As shown in the Typical Operating Circuit, a pi filter (two 0.22µF capacitors and one 2.2µH inductor) greatly suppresses power-supply switching noise. If such a filter is already present in the bias generating circuit, only a simple bypass capacitor at the BIAS pin is suggested. The output lowpass filter, a 10kΩ resistor and a 10nF capacitor, further reduce permeating powersupply noise, as well as other wideband noise that might otherwise restrict measurements at low-signal levels. Again, reducing the bandwidth of the OUT signal can affect performance of pilot-tone systems. To restrict high-frequency photodiode signals from affecting the current monitors and BIAS power supply, an RF choke and 10nF capacitor can be added. The capacitance presented to REF should not exceed 10nF; larger values increase startup time and could cause the thermal shutdown circuit to activate during startup. _______________________________________________________________________________________ 7 MAX4007/MAX4008 typ) protects the device against short-circuit-to-ground conditions, and a thermal shutdown feature reduces both the reference current and the monitor current to zero if the die temperature reaches +150°C. The MAX4007/MAX4008 accept a supply voltage of +2.7V to +76V, suitable for APD photodiode applications. A clamping diode, shown in the Functional Diagram, is provided to protect subsequent output circuitry from an overvoltage condition. High-Accuracy, 76V, High-Side Current Monitors in SOT23 MAX4007/MAX4008 Typical Operating Circuit +2.7V TO +76V 2.2µH 0.22µF 0.22µF BIAS +5V CURRENT MONITOR 10x 1x CURRENT CLAMP REF CLAMP +5V OUT ADC 10kΩ MAX4007 10nF GND APD PIN PHOTODIODE TIA TO LIMITING AMPLIFIER HIGH-SPEED DATA PATH Chip Information TRANSISTOR COUNT: 195 PROCESS: BiCMOS 8 _______________________________________________________________________________________ High-Accuracy, 76V, High-Side Current Monitors in SOT23 6LSOT.EPS PACKAGE OUTLINE, SOT-23, 6L 21-0058 F 1 1 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 9 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. MAX4007/MAX4008 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to www.maxim-ic.com/packages.)