Supertex inc. HV7802 High Side Current Monitor 8V to 450V Configurable Output Features ►► Supply voltage 8V to 450V ►► Configurable as a current or voltage output device ►► Maximum sense amplifier offset of 15mV ►► Max VSENSE of 500mV ►► Fast rise and fall time, from 700ns to 2.0µs ►► Maximum quiescent current of 50µA Applications General Description The HV7802 high side current monitor IC contains a transconductance amplifier which translates a high side current measurement voltage into an output current with resistor programmable transconductance gain. An optional second resistor transforms this output current into an output voltage with an overall voltage gain set by the ratio of the two resistors. The measurement voltage typically originates at a current sense resistor, which is located in a “high side” circuit, for example a circuit not directly associated with ground. ►► SMPS current monitor ►► Battery current monitor ►► Motor control This monitor IC features a very wide input voltage range, configurable gain, small size, low component count, low power consumption, ease of use, and low cost. Offline, battery, and portable applications can be served equally well due to the wide input voltage range and the low quiescent current. Typical Application Circuit ISENSE VSENSE 8V to 450V Input RSENSE RA RA IN I OUT = V SENSE /R A V OUT = R B • I OUT G V = R B /R A RP (optional) LOAD HV7802 GND R OUT VOUT IOUT RB Doc.# DSFP-HV7802 A062813 V Supertex inc. www.supertex.com HV7802 Pin Configuration Ordering Information Part Number Package Option Packing HV7802MG-G 8-Lead MSOP 2500/Reel GND NC OUT NC 8 7 6 5 2 3 4 -G denotes a lead (Pb)-free / RoHS compliant package Absolute Maximum Ratings 1 Parameter IN Value VIN, VLOAD 8-Lead MSOP -0.5V to +460V VOUT -0.5V to +10V VSENSE -0.5V to +5.0V (top view) Product Marking Top Marking ±10mA ILOAD Operating ambient temperature -40°C to +85°C Operating junction temperature -40°C to +125°C Storage temperature -65°C to +150°C RA LOAD NC 7802 LLLL Bottom Marking YYWW Absolute maximum ratings are those values beyond which damage to the device may occur. Functional operation under these conditions is not implied. Continuous operation of the device at the absolute rating level may affect device reliability. All voltages are referenced to device ground. L = Lot Number YY = Year Sealed WW = Week Sealed = “Green” Packaging Package may or may not include the following marks: Si or 8-Lead MSOP Notes: 1. Referenced to GND 2. VSENSE = VIN - VLOAD Typical Thermal Resistance Package θja 8-Lead MSOP 216OC/W Note: Thermal testboard per JEDEC JESD51-7 Electrical Characteristics (T = 25°C unless otherwise specified, V A Sym SENSE = VIN - VLOAD, VIN = 8V to 450V) Parameter Min Typ Max Units Conditions VIN Supply voltage 8.0 - 450 V * --- IQ Quiescent supply current - - 50 µA - VIN = 8V to 450V, VSENSE = 0mV - - 200 µA - --- 0 - 15 79 - 121 177 - 223 470 - 530 - 0.7 - - - 2.0 - 0.7 2.0 Supply Input and Output IOUT VOUT Ouput current Output voltage, RA = RB = 5.000kΩ VSENSE = 0mV mV - VSENSE = 100mV VSENSE = 200mV VSENSE = 500mV Dynamic Characteristics * tRISE Output rise time, 10% to 90% tFALL Output fall time, 90% to 10% µs - µs - VSENSE step 5.0mV to 500mV VSENSE step 0mV to 500mV VSENSE step 500mV to 0mV Values apply over the full temperature range. Doc.# DSFP-HV7802 A062813 2 Supertex inc. www.supertex.com HV7802 Block Diagram Principle of Operation VSENSE R SENSE RA IN The operational amplifier forces the voltage across RA to track VSENSE, therefore, VRA = VSENSE. Transconductance gain is equal to (1/RA). ISENSE RA RP (Optional, see text) IRA flows from the OUT pin to low side circuitry. Current to voltage conversion can be accomplished by a resistor, RB, as shown in the block diagram, with a transimpedance gain equal to RB. LOAD Typically we would like to exploit the full current capability of the transimpedance amplifier. A RA of 5kΩ will provide this current, assuming a full scale sense voltage of 500mV and a full scale sense current of 100µA. Bias Circuits In a voltage output application, the output resistor RB is determined by the desired overall voltage gain of (RB / RA). For example, a RB of 10kΩ results in a voltage gain of two. HV7802 GND OUT VOUT OUT Pin Loading Effects Note that the output is not buffered having an output impedance equal to RB. Loading of the output causes voltage gain to drop and rise and fall time to increase. RB Application Information For example, assume a gain of one, using RA = RB = 5kΩ. In this case the load resistance should exceed 5MΩ in order to limit the gain drop to 1 part in 1000. General The HV7802 high side current monitor IC features accurate current sensing, small size, low component count, low power consumption, exceptional input voltage range, ease of use and low cost. Assuming an output resistance of 5kΩ, a capacitive load of 20pF results in a load pole with a time constant of 100ns, not enough to materially affect the output rise and fall time (about 700ns). Typical use is measurement of line and load current for purpose of overcurrent protection, metering and current regulation. Sense Resistor Considerations Limit the sense resistor voltage to 500mV during normal operating conditions. Limit the power dissipation in the sense resistor to suit the application; a high sense voltage benefits accuracy, but may result in high power dissipation as well. High side current sensing, as opposed to ground referenced or low side current sensing, is desirable or required when: ►► The current to be measured does not flow in a circuit associated with ground. Consider the use of Kelvin connections for applications where considerable voltage drops may occur in the PCB traces. A layout pattern, which minimizes voltage drops across the sense lines is shown below. ►► The measurement at ground level can lead to ambiguity due to changes in the grounding arrangement during field use. + VSENSE - ►► The introduction of a sense resistor in the system ground is undesirable due to issues with safety, EMI, or signal degradation caused by common impedance coupling. IN Doc.# DSFP-HV7802 A062813 3 LOAD RSENSE Supertex inc. www.supertex.com HV7802 Choose a low inductance type sense resistor if preservation of bandwidth is important. Kelvin connections help by minimizing the inductive voltage drops as well. The inductive voltage drop may be substantial when operating at high frequency. A trace or component inductance of just 10nH contributes an impedance of 6.2mΩ at 100kHz, which constitutes a 6% error when using a 100mΩ sense resistor. Limit the Zener current to 10mA under worst case conditions. A 100kΩ resistor limits the maximum Zener diode current to 4.5mA when VSENSE is 450V, whether positive or negative. Note that the protection resistor may affect bandwidth. The resistor forms a RC network with the trace and pin capacitance at the LOAD pin. For example, capacitance of 5.0pF results in a time constant of 500ns. Transient Protection The protection resistor may cause an offset voltage due to bias current at the LOAD input. A 100kΩ protection resistor could cause an offset of 100µV, or 0.2% of full scale, under worst case bias current. Note that bias current is nominally zero since LOAD is a high impedance CMOS input, resulting in zero bias current induced offset voltage. Add a protection resistor (RP) in series with the LOAD pin if VSENSE can exceed 5.0V in positive sense or 600mV in negative sense, whether in steady state or in transient conditions. A large VSENSE may occur during system startup or shutdown when charging and discharging large capacitors. VSENSE may be large due to fault conditions, such as short circuit or a broken or missing sense resistor. An internal 5.0V Zener diode with a current rating of 10mA protects the sense amplifier inputs. The block diagram shows the orientation of this diode. The Zener diode provides clamping at 5.0V for a positive VSENSE and at 600mV for a negative VSENSE. Pin Description Pin # Pin Name 1 IN Sense amplifier input and supply. 2 RA Provides gain setting of the transconductance amplifier. Connect gain setting resistor (RA) between Pin 1 and Pin 2. 3 LOAD Sense amplifier input. High impedance input with Zener diode protection. Add an external protection resistor in series with LOAD if VSENSE exceeds the range of -600mV to +5.0V. 4 NC No Connect. This pin must be left floating for proper operation 5 NC No Connect. This pin must be left floating for proper operation. 6 OUT 7 NC 8 GND Doc.# DSFP-HV7802 A062813 Description Output of the transconductance amplifier. Output current to output voltage conversion can be accomplished through addition of an external resistor (RB) at this pin. Overall voltage gain is determined by the ratio of RB to RA. No Connect. This pin must be left floating for proper operation. Supply return. 4 Supertex inc. www.supertex.com HV7802 8-Lead MSOP Package Outline (MG) 3.00x3.00mm body, 1.10mm height (max), 0.65mm pitch D θ1 8 Note 1 (Index Area D/2 x E1/2) E1 E L2 L θ L1 1 Gauge Plane Seating Plane View B Top View View B A A A2 Seating Plane A1 e b Side View View A-A A Note: 1. A Pin 1 identifier must be located in the index area indicated. The Pin 1 identifier can be: a molded mark/identifier; an embedded metal marker; or a printed indicator. Symbol Dimension (mm) A A1 A2 b D E E1 MIN 0.75* 0.00 0.75 0.22 2.80* 4.65* 2.80* NOM - - 0.85 - 3.00 4.90 3.00 MAX 1.10 0.15 0.95 0.38 3.20* 5.15* 3.20* e 0.65 BSC L 0.40 0.60 0.80 L1 0.95 REF L2 0.25 BSC θ θ1 0O 5O - - 8O 15O JEDEC Registration MO-187, Variation AA, Issue E, Dec. 2004. * This dimension is not specified in the JEDEC drawing. Drawings are not to scale. Supertex Doc. #: DSPD-8MSOPMG, Version H041309. (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information go to http://www.supertex.com/packaging.html.) Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives an adequate “product liability indemnification insurance agreement.” Supertex inc. does not assume responsibility for use of devices described, and limits its liability to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications refer to the Supertex inc. (website: http//www.supertex.com) Supertex inc. ©2013 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Doc.# DSFP-HV7802 A062813 5 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com