High-Side Measurement CURRENT SHUNT MONITOR

INA39 INA69 www.ti.com High-Side Measurement CURRENT SHUNT MONITOR FEATURES COMPLETE UNIPOLAR HIGH-SIDE CURRENT MEASUREMENT CIRCUIT WIDE SUPPLY AND COMMON-MODE RANGE INA39:.7V to 40V INA69:.7V to 60V INDEPENDENT SUPPLY AND INPUT COMMON-MODE VOLTAGES SINGLE RESISTOR GAIN SET LOW QUIESCENT CURRENT (60µA typ) SOT3- PACKAGE APPLICATIONS CURRENT SHUNT MEASUREMENT: Automotive, Telephone, Computers PORTABLE & BATTERY-BACKUP SYSTEMS BATTERY CHARGERS POWER MANAGEMENT CELL PHONES PRECISION CURRENT SOURCE DESCRIPTION The INA39 and INA69 are high-side, unipolar, current shunt monitors. Wide input common-mode voltage range, high-speed, low quiescent current, and tiny SOT3 packaging enable use in a variety of applications. Input common-mode and power-supply voltages are independent and can range from.7v to 40V for the INA39 and.7v to 60V for the INA69. Quiescent current is only 60µA, which permits connecting the power supply to either side of the current measurement shunt with minimal error. The device converts a differential input voltage to a current output. This current is converted back to a voltage with an external load resistor that sets any gain from to over 00. Although designed for current shunt measurement, the circuit invites creative applications in measurement and level shifting. Both the INA39 and INA69 are available in SOT3- and are specified for the 40 C to +8 C industrial temperature range. R S I S V IN+ Up To 60V V IN+ kω V IN kω Load GND OUT V O = I S R S /kω Copyright 000, Texas Instruments Incorporated Printed in U.S.A. December, 000

SPECIFICATIONS At T A = 40 C to +8 C, V S = V, V IN+ = V, R OUT = kω, unless otherwise noted. INA39NA INA69NA PARAMETER CONDITION MIN TYP MAX MIN TYP MAX UNITS INPUT Full-Scale Sense Voltage V SENSE = V + IN V IN 00 00 mv Common-Mode Input Range.7 40 60 V Common-Mode Rejection V IN+ =.7V to 40V, V SENSE = 0mV 00 db V IN+ =.7V to 60V, V SENSE = 0mV 00 0 db Offset Voltage () RTI ±0. ± mv vs Temperature T MIN to T MAX µv/ C vs Power Supply, V =.7V to 40V, V SENSE = 0mV 0. 0 µv/v V =.7V to 60V, V SENSE = 0mV 0. 0 µv/v Input Bias Current V + IN, V IN 0 ua OUTPUT Transconductance V SENSE = 0mV 0mV 990 000 00 µa/v vs Temperature V SENSE = 00mV 0 na/ C Nonlinearity Error V SENSE = 0mV to 0mV ±0.0 ±0. % Total Output Error V SENSE = 00mV ±0. ± % Output Impedance GΩ pf Voltage Output Swing to Power Supply, () 0.9 (). V Swing to Common Mode, V CM V CM 0.6 V CM.0 V FREQUENCY RESPONSE Bandwidth R OUT = 0kΩ 440 khz R OUT = 0kΩ 0 khz Settling Time (0.%) V Step, R OUT = 0kΩ. µs V Step, R OUT = 0kΩ.0 µs NOISE Output-Current Noise Density 0 pa/ Hz Total Output-Current Noise BW = 00kHz 7 na RMS POWER SUPPLY Operating Range,.7 40 60 V Quiescent Current V SENSE = 0, I O = 0 60 µa TEMPERATURE RANGE Specification, T MIN to T MAX 40 8 C Operating C Storage 6 0 C Thermal Resistance θ JA 00 C/W NOTE: () Defined as the amount of input voltage, V SENSE, to drive the output to zero. INA39, INA69

PIN CONFIGURATION TOP VIEW OUT GND V IN 3 4 V IN ABSOLUTE MAXIMUM RATINGS () SOT3 ELECTROSTATIC DISCHARGE SENSITIVITY This integrated circuit can be damaged by ESD. Burr-Brown recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. Supply Voltage, INA39... 0.3V to 60V INA69... 0.3V to 7V Analog Inputs, V IN +, V IN INA39 Common Mode... 0.3V to 60V Differential (V IN + ) (V IN )... 40V to V INA69 Common Mode... 0.3V to 7V Differential (V IN + ) (V IN )... 40V to V Analog Output, Out... 0.3V to 40V Operating Temperature... C to + C Storage Temperature... C to + C Junction Temperature... +0 C Lead Temperature (soldering, 0s)... +300 C NOTE: () Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified is not implied. PACKAGE/ORDERING INFORMATION PACKAGE SPECIFIED DRAWING TEMPERATURE PACKAGE ORDERING TRANSPORT PRODUCT PACKAGE NUMBER RANGE MARKING NUMBER () MEDIA INA39NA SOT3- Surface Mount 33 40 C to +8 C B39 INA39NA/0 Tape and Reel " " " " " INA39NA/3K Tape and Reel INA69NA SOT3- Surface Mount 33 40 C to +8 C A69 INA69NA/0 Tape and Reel " " " " " INA69NA/3K Tape and Reel NOTE: () Models with a slash (/) are available only in Tape and Reel in the quantities indicated (e.g., /3K indicates 3000 devices per reel). Ordering 3000 pieces of INA39NA/3K will get a single 3000-piece Tape and Reel. INA39, INA69 3

TYPICAL PERFORMANCE CURVES At T A = + C, = V, V IN + = V, = kω, unless otherwise noted. Gain (db) 40 30 0 0 0 0 = 0kΩ = kω GAIN vs FREQUENCY = 00kΩ Common-Mode Rejection (db) 0 00 80 60 40 0 COMMON-MODE REJECTION vs FREQUENCY G = 00 G = 0 G = 0 00 k 0k 00k M 0M Frequency (Hz) 0 0. 0 00 k 0k Frequency (Hz) 00k Power-Supply Rejection (db) 40 0 00 80 60 40 POWER-SUPPLY REJECTION vs FREQUENCY G = 00 G = 0 G = Total Output Error (%) 0 0 C + C TOTAL OUTPUT ERROR vs V IN +0 C V IN = (V + IN V IN ) 0 0 00 k 0k 00k Frequency (Hz) 0 0 7 00 V IN (mv) 0 00 Total Output Error (%) 0 TOTAL OUTPUT ERROR vs POWER-SUPPLY VOLTAGE Output error is essentially independent of both supply voltage and input common-mode voltage. G = 0 0 0 30 40 0 Power-Supply Voltage (V) G = G = 0 60 70 Quiescent Current (µa) 00 80 60 40 QUIESCENT CURRENT vs POWER-SUPPLY VOLTAGE 0 Use INA69 with () > 40V 0 0 0 0 30 40 0 60 70 Power-Supply Voltage (V) +0 + + 4 INA39, INA69

TYPICAL PERFORMANCE CURVES (Cont.) At T A = + C, = V, V IN + = V, = kω, unless otherwise noted. STEP RESPONSE STEP RESPONSE.V G = 00 0.V V G = 0 0V V G = 00 0V V G = 0 0V 0µs/div 0µs/div INA39, INA69

OPERATION Figure shows the basic circuit diagram for both the INA39 and INA69. Load current, I S, is drawn from supply, V S, through shunt resistor, R s. The voltage drop in the shunt resistor, V S, is forced across R g by the internal op-amp, causing current to flow into the collector of Q. External resistor,, converts the output current to a voltage, V OUT, at the Out pin. The transfer function for the INA39 is: I O = g m (V IN + V IN ) () where g m = 000µA/V () In the circuit of Figure, the input voltage, (V IN + V IN ), is equal to I S R S and the output voltage, V OUT, is equal to I O. The transconductance, g m, of the INA39 is 000µA/V. The complete transfer function for the current measurement amplifier in this application is: V OUT = (I S ) (R S ) (000µA/V) ( ) (3) The maximum differential input voltage for accurate measurements is 0.V, which produces a 00µA output current. A differential input voltage of up to V will not cause damage. Differential measurements (pins 3 and 4) must be unipolar with a more-positive voltage applied to pin 3. If a more-negative voltage is applied to pin 3, the output current, I O, will be zero, but it will not cause damage. BASIC CONNECTION Figure shows the basic connection of the INA39. The input pins, V + IN and V IN, should be connected as closely as possible to the shunt resistor to minimize any resistance in series with the shunt resistance. The output resistor,, is shown connected between pin and ground. Best accuracy is achieved with the output voltage measured directly across. This is especially important in high-current systems where load current could flow in the ground connections, affecting the measurement accuracy. No power supply bypass capacitors are required for stability of the INA39. However, applications with noisy or high impedance power supplies may require de-coupling capacitors to reject power supply noise. Connect bypass capacitors close to the device pins. POWER SUPPLIES The input circuitry of the INA39 can accurately measure beyond its power supply voltage,. For example, the power supply can be V while the load power supply is voltage is up to +36V (or +60V with INA69). However, the output voltage range of the OUT terminal (pin ) is limited by the lesser of the two voltages (see Output Voltage Range ). SELECTING R S AND The value chosen for the shunt resistor, R S, depends on the application and is a compromise between small-signal accuracy and maximum permissible voltage loss in the measurement line. High values of R S provide better accuracy at lower V P Load Power Supply +.7 to 40V () Shunt R S I S power can be common or indepedent of load supply..7 () 40V () V + IN V IN R G kω R G kω Load Q VOLTAGE GAIN EXACT (Ω) NEAREST % (Ω) k k k k k 4.99k 0 0k 0k 0 0k 0k 0 0k 49k 00 00k 00k INA39 OUT I 0 + NOTE: () Maximum V P and voltage is 60V with INA69. V O FIGURE. Basic Circuit Connections. 6 INA39, INA69

currents by minimizing the effects of offset, while low values of R S minimize voltage loss in the supply line. For most applications, best performance is attained with an R S value that provides a full-scale shunt voltage of 0mV to 00mV. Maximum input voltage for accurate measurements is 00mV. is chosen to provide the desired full-scale output voltage. The output impedance of the INA39 Out terminal is very high which permits using values of up to 00kΩ with excellent accuracy. The input impedance of any additional circuitry at the output should be much higher than the value of to avoid degrading accuracy. Some Analog-to-Digital (A/D) converters have input impedances that will significantly affect measurement gain. The input impedance of the A/D converter can be included as part of the effective if its input can be modeled as a resistor to ground. Alternatively, an op-amp can be used to buffer the A/D converter input, as shown in Figure. See Figure for recommended values of. output swing. The maximum output voltage compliance is limited by the lower of the two equations below: V out max = () 0.7V (V + IN V IN ) (4) or V out max = V IN 0.V () (whichever is lower) BANDWIDTH Measurement bandwidth is affected by the value of the load resistor,. High gain produced by high values of will yield a narrower measurement bandwidth (see Typical Performance Curves). For widest possible bandwidth, keep the capacitive load on the output to a minimum. If bandwidth limiting (filtering) is desired, a capacitor can be added to the output, as shown in Figure 3. This will not cause instability. I S f 3dB INA39 OPA340 Z IN INA39 f 3dB = π C L V O Buffer of amp drives A/D converter without affecting gain. C L FIGURE. Buffering Output to Drive A/D Converter. OUTPUT VOLTAGE RANGE The output of the INA39 is a current, which is converted to a voltage by the load resistor,. The output current remains accurate within the compliance voltage range of the output circuitry. The shunt voltage and the input common-mode and power supply voltages limit the maximum possible FIGURE 3. Output Filter. APPLICATIONS The INA39 is designed for current shunt measurement circuits as shown in Figure, but its basic function is useful in a wide range of circuitry. A creative engineer will find many unforeseen uses in measurement and level shifting circuits. A few ideas are shown in Figures 4 through 7. V R INA39 R INA39 REF00 00µA V 0 V 0 R Gain Set by R R Output Offset = (V R )R R +R a). Using resistor divider. Gain Set by Output Offset = (00µA)( ) (independent of ) b). Using current source. FIGURE 4. Offsetting the Output Voltage. INA39, INA69 7

±A Charger Ω 3 4 4 3 +V kω kω kω kω +V + 48V Load INA69 INA69 IN448 IN448 Comparator SIGN 0KΩ 0KΩ 00KΩ 0 to V V O FIGURE. Bipolar Current Measurement. R S 4 3 3 4 +V +V +V REF OUT BUF IN BUF OUT Digital I/O REF BUF INA39 INA39 MUX PGIA -Bit A/D kω A/D converter programmed for differential input. Depending on polarity of current, one INA39 provides an output voltage, the other's output is zero. kω Clock Divider Oscillator ADS7870 Serial I/O FIGURE 6. Bipolar Current Measurement Using Differential Input of A/D Converter. 8 INA39, INA69

Other INA69s INA69 +V Digital I/O on ADS7870 provides power to select the desired INA69. Diodes prevent output current of " on" INA69 from flowing into "off" INA69. REF OUT BUF IN BUF OUT INA69 Digital I/O REF BUF MUX PGIA -Bit A/D IN448 Clock Divider Oscillator ADS7870 Serial I/O FIGURE 7. Multiplexed Measurement Using Logic Signal for Power. INA39, INA69 9

IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its products to the specifications applicable at the time of sale in accordance with TI s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. Customers are responsible for their applications using TI components. In order to minimize risks associated with the customer s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such products or services might be or are used. TI s publication of information regarding any third party s products or services does not constitute TI s approval, license, warranty or endorsement thereof. Reproduction of information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations and notices. Representation or reproduction of this information with alteration voids all warranties provided for an associated TI product or service, is an unfair and deceptive business practice, and TI is not responsible nor liable for any such use. Resale of TI s products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service, is an unfair and deceptive business practice, and TI is not responsible nor liable for any such use. Also see: Standard Terms and Conditions of Sale for Semiconductor Products. www.ti.com/sc/docs/stdterms.htm Mailing Address: Texas Instruments Post Office Box 6303 Dallas, Texas 76 Copyright 00, Texas Instruments Incorporated