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120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Features and Benefits 1. Industry-leading noise performance with greatly improved bandwidth through proprietary amplifier and filter design techniques 2. Small footprint package suitable for space-constrained applications 3. 1 mΩ primary conductor resistance for low power loss 4. High isolation voltage, suitable for line-powered applications 5. User-adjustable Overcurrent Fault level 6. Overcurrent Fault signal typically responds to an overcurrent condition in < 2 μs 7. Integrated shield virtually eliminates capacitive coupling from current conductor to die due to high dV/dt voltage transients 8. Filter pin capacitor improves resolution in low bandwidth applications 9. 3 to 5.5 V, single supply operation 10. Factory trimmed sensitivity and quiescent output voltage 11. Chopper stabilization results in extremely stable quiescent output voltage 12. Ratiometric output from supply voltage Package: 16-pin SOIC Hall Effect IC Package (suffix SI) Typical Application Circuit
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection General Description The SEC™ SC225KSIT current sensor provides economical and precise means for current sensing applications in industrial, commercial, and communications systems. The device is offered in a small footprint surface mount package that allows easy implementation in customer applications. The SC225KSIT consists of a precision linear Hall sensor integrated circuit with a copper conduction path located near the surface of the silicon die. Applied current flows through the copper conduction path, and the analog output voltage from the Hall sensor linearly tracks the magnetic field generated by the applied current. The accuracy of the SC225KSIT is maximized with this patented packaging configuration because the Hall element is situated in extremely close proximity to the current to be measured. High level immunity to current conductor dV/dt and stray electric fields, offered by SEC proprietary integrated shield technology, results in low ripple on the output and low offset drift in high-side, high voltage applications. The voltage on the Overcurrent Input (V OC pin) allows customers to define an overcurrent fault threshold for the device. When the current flowing through the copper conduction path (between the IP+ and IP– pins) exceeds this threshold, the open drain Overcurrent Fault pin will transition to a logic low state. Factory programming of the linear Hall sensor inside of the SC225KSIT results in exceptional accuracy in both analog and digital output signals. The internal resistance of the copper path used for current sensing i s ty pically 1 mΩ, f or l ow power loss. Also, the current conduction path is electrically isolated from the low voltage sensor inputs and outputs. This allows the SC225 KSIT family of sensors to be used in applications requiring electrical isolation, without the use of opto -isolators or other costly isolation techniques. The SC225KSIT is provided in a small, surface mount SOIC16 package. The lead frame is plated with 100% mat te tin, which is compatible with standard lead (Pb) free printed circuit board assembly processes. Internally, the device is Pb -free, except for flip -chip high-temperature Pb-based solder balls, currently exempt from RoHS. The device is fully calibrated prior to shipment from the factory.
Applications
- Motor control and protection 2. Load management and overcurrent detection 3. Power conversion and battery monitoring / UPS systems General Package Inform Part Number IP(A) Sens (typ) at V= 5 V (mV/A) Latched Fault TA(°C) Packing SC225KSIT ±50 28 Yes –40 to 125 Tape and Reel, 1000 pieces per reel
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Absolute Maximum Ratings Characteristic Symbol Notes Rating Unit Supply Voltage VCC 8 V Filter Pin VFILTER 8 V Analog Output Pin VIOUT 32 V Overcurrent Input Pin VOC 8 V Overcurrent FAULT Pin VFAULT 8 V Fault Enable (FAULT_EN) Pin VFAULTEN 8 V Voltage Reference Output Pin VZCR 8 V DC Reverse Voltage: V CC, FILTER, V IOUT, VOC, FAUL, FAULT _EN, and VZCR Pins VRdcx –0.5 V Excess to Supply Voltage: FILTER, V IOUT, VOC , FAULT , FAULT_EN, and VZCR Pins VEX Voltage by which pin voltage can exceed the VCC pin voltage 0.3 V Output Current Source IIOUT(Source) 3 mA Output Current Sink IIOUT(Sink) 1 mA Operating Ambient Temperature TA Range K –40 to 125 °C Junction Temperature TJ(max) 165 °C Storage Temperature Tstg –65 to 170 °C Isolation Characteristics Characteristic Symbol Notes Rating Unit Dielectric Strength Test Voltage* VISO Agency type-tested for 60 seconds per UL standard 1577 3000 VAC Working Voltage for Basic Isolation VWFSI For basic (single) isolation per UL standard 1577; for higher continuous voltage ratings, please contact SEC
277 VAC
Characteristic Symbol Test Conditions Value Unit Package Thermal Resistance RθJA When mounted on SEC demo board with 1332 mm2 (654 mm2 on component side and 678 mm2 on opposite side) of 2 oz. copper connected to the primary lead frame and 17 ºC/W
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Functional Block Diagram Terminal List Table, Latching Version Number Name Description 1 through 4 IP+ Sensed current copper conduction path pins. Terminals for current being sensed; fused internally, loop to IP– pins; unidirectional or bidirectional current flow. 5 through 8 IP– Sensed current copper conduction path pins. Terminals for current being sensed; fused internally, loop to I pins; unidirectional or bidirectional current flow. 9 GND Device ground connection.
10 VZCR
Voltage Reference Output pin. Zero current (0 A) reference; output voltage on this pin scales with V CC . (Not a highly accurate reference.) 11 FILTER Filter pin. Terminal for an external capacitor connected from this pin to GND to set the device bandwidth.
12 VIOUT
Analog Output pin. Output voltage on this pin is proportional to current flowing through the loop between the I P+ pins and IP– pins.
13 FAULT
Overcurrent Fault pin. When current flowing between IP+ pins and IP– pins exceeds the overcurrent fault threshold, this pin transitions to a logic low state. 14 VCC Supply voltage. 15 VOC Overcurrent Input pin. Analog input voltage on this pin sets the overcurrent fault threshold. 16 FAULT_EN Enables overcurrent faulting when high. Resets FAULT when low.
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection COMMON OPERATING CHARACTERISTICS Valid at TA = –40°C to 125°C, VCC = 5 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units
ELECTRICAL CHARACTERISTICS
VCC 3 – 5.5 V Nominal Supply Voltage VCCN – 5 – V Supply Current ICC VIOUT open, FAULT pin high – 11 14.5 mA Output Capacitance Load CLOAD VIOUT pin to GND – – 10 nF Output Resistive Load RLOAD VIOUT pin to GND 10 – – kΩ Magnetic Coupling from Device Conductor to Hall Element MC HALL Current flowing from IP+ to IP– pins – 9.5 – G/A Internal Filter Resistance RF(INT) – 1.7 – kΩ Primary Conductor Resistance RPRIMARY TA = 25°C – 1 – mΩ ANALOG OUTPUT SIGNAL CHARACTERISTICS Full Range Linearity ELIN IP = ±IP0A –0.75 ±0.25 0.75 % Symmetry ESYM IP = ±IP0A 99.1 100 100.9 % Bidirectional Quiescent Output VOUT(QBI) IP = 0 A, TA = 25°C – VCC/2 – V TIMING PERFORMANCE CHARACTERISTICS VIOUT Signal Rise Time tr TA = 25°C, Swing IP from 0 A to IP0A, no capacitor on FILTER pin, 100 pF fromVIOUT to GND 3 – μs VIOUT Signal Propagation Time tPROP TA = 25°C, no capacitor on FILTER pin,100 pF from VIOUT to GND – 1 – μs VIOUT Signal Response Time tRESPONSE TA = 25°C, Swing IP from 0 A to IP0A, no capacitor on FILTER pin, 100 pF fromVIOUT to GND – 4 – μs VIOUT Large Signal Bandwidth f3dB –3 dB, Apply IP such that VIOUT = 1 Vpk-pk, no capacitor on FILTER pin, 100 pF from VIOUT to GND – 120 – kHz Power-On Time tPO Output reaches 90% of steady-state level, no capacitor on FILTER pin, TA = 25°C – 35 – μs OVERCURRENT CHARACTERISTICS Setting Voltage for Overcurrent Switchpoint VOC VCC×0.25 – VCC×0.4 V Signal Noise at Overcurrent Comparator Input INCOMP – ±1 – A Overcurrent Fault Switchpoint Error 6,7 EOC Switchpoint in VOC safe operating area; assumes INCOMP = 0 A – ±5 – % Overcurrent FAULT Pin Output Voltage VFAULT 1 mA sink current at FAULT pin – – 0.4 V
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Fault Enable (FAULT_EN Pin) Input Low Voltage Threshold VIL – – 0.1 × VCC V Fault Enable (FAULT_EN Pin) Input High Voltage Threshold VIH 0.8 × VCC – – V Fault Enable (FAULT_EN Pin) Input Resistance RFEI – 1 – MΩ OVERCURRENT CHARACTERISTICS Fault Enable (FAULT_EN Pin) Delay tFED Set FAULT_EN to low, VOC = 0.25 × VCC , COC = 0 F; then run a DC IP exceeding the corresponding overcurrent threshold; then reset FAULT_EN from low to high and measure the delay from the rising edge of FAULT_EN to the falling edge of ¯ FAULT – 15 – μs Fault Enable (FAULT_EN Pin) Delay(Non-Latching versions)9 tFED(NL) Set FAULT_EN to low, VOC = 0.25 × VCC , COC = 0 F; then run a DC IP exceeding the corresponding overcurrent threshold; then reset FAULT_EN from low to high and measure the delay from the rising edge of FAULT_EN to the falling edge of FAULT – 150 – ns Overcurrent Fault Response Time tOC FAULT_EN set to high for a minimum of 20 μs before the overcurrent event; switchpoint set at VOC = 0.25 × VCC ; delay from IP exceeding overcurrent fault threshold to V FAULT < 0.4 V, – 1.9 – μs Undercurrent Fault Response Time(Non-Latching versions) tUC FAULT_EN set to high for a minimum of 20 μs before the undercurrent event; switchpoint set at VOC = 0.25 × VCC ; delay from IP falling below the overcurrent faultthreshold to V FAULT > 0.8 × VCC , without external COC capacitor, RPU = 330 kΩ – 3 – μs Overcurrent Fault Reset Delay tOCR Time from VFAULTEN < VIL to V FAULT > 0.8 × VCC , RPU = 330 kΩ – 500 – ns Overcurrent Fault Reset Hold Time tOCH Time from VFAULTEN <VIL to rising edge of V FAULT – 250 – ns Overcurrent Input Pin Resistance ROC TA = 25°C, VOC pin to GND 2 – – MΩ VOLTAGE REFERENCE CHARACTERISTICS Voltage Reference Output VZCR TA = 25 °C (Not a highly accurate reference) 0.48×VCC 0.5×VCC 0.51×VCC V Voltage Reference Output Load Current IZCR Source current 3 – – mA Sink current 50 – – μA Voltage Reference Output Drift ∆VZCR – ±10 – mV
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection 1. Devices are programmed for maximum accuracy at VCC = 5 V. The device contains ratiometry circuits that accurately alter the 0 A Output Voltage and Sensitivity level of the device in proportion to the applied VCC level. However, as a result of minor nonlinearities in the ratiometry circuit, additional output error will result when VCC varies from the VCC level at which the device was programmed. Customers that plan to operate the device at a VCC level other than the VCC level at which the device was programmed should contact their local SEC sales representative regarding expected device accuracy levels 2. Under these bias conditions. 3. RF(INT) forms an RC circuit via the FILTER pin. 4. This parameter can drift by as much as 0.8% over the lifetime of this product. 5. This parameter can drift by as much as 1% over the lifetime of this product. 6. See page 8 on how to set overcurrent fault switch point. 7. Switchpoint can be lower at the expense of switch point accuracy. 8. This error specification does not include the effect of noise. See the INCOMP specification in order to factor in the additional influence of noise on the fault switch point. 9. Fault Enable Delay is designed to avoid false tripping of an Overcurrent (OC) fault at power-up. A 15 μs (typical) delay will always be needed, every time FAULT_EN is raised from low to high, before the device is ready for responding to any overcurrent event. 10. During power-up, this delay is 15 μs in order to avoid false tripping of an Overcurrent (OC) fault.
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection PERFORMANCE CHARACTERISTICS TA Range K, valid at TA = – 40°C to 125°C, VCC = 5 V, unless otherwise specified Characteristic Symbol Test Conditions Min. Typ. Max. Units Optimized Accuracy Range IPOA –12.5 – 12.5 A Linear Sensing Range IR –37.5 – 37.5 A Noise VNOISE(rm TA = 25°C, Sens = 56 mV/A, Cf = 0, CLOAD = 4.7 nF, RLOAD open – 1.50 – mV Sensitivity Sens IP = 12.5 A, TA = 25°C – 56 – mV/A IP = 12.5 A, TA = 25°C to 125°C – 56 – mV/A IP = 12.5 A, TA = –40°C to 25°C – 57 – mV/A Electrical Offset Voltage Variation Relative to Vout VOE IP = 0 A, TA = 25°C – ±4 – mV IP = 0 A, TA = 25°C to 125°C – ±14 – mV IP = 0 A, TA = –40°C to 25°C – ±23 – mV Total Output Error ETOT Over full scale of IPOA, IP applied for 5 ms, TA = 25°C Over full scale of IPOA, IP applied for 5 ms, TA = 1. Although the device is accurate over the entire linear range, the device is programmed for maximum accuracy over the range defined by IPOA .The reason for this is that in many applications, such as motor control, the start-up current of the motor is approximately three times higher than the running current. 2. Vpk-pk noise (6 sigma noise) is equal to 6 × VNOISE(rms). Lower noise levels than this can be achieved by using Cf for applications requiring narrower bandwidth. See Characteristic Performance page for graphs of noise versus Cf and bandwidth versus Cf. 3. This parameter can drift by as much as 2.4% over the lifetime of this product. 4. This parameter can drift by as much as 13 mV over the lifetime of this product. 5. This parameter can drift by as much as 2.5% over the lifetime of this product.
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Characteristic Performance Bandwidth value，CF Capacitor connected between FILTER pin and GND Noise versus External Capacitor Value CF Capacitor connected between FILTER pin and GND
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Characteristic Performance Data Accuracy Data Electrical Offset Voltage versus Ambient Temperature Sensitivity versus Ambient Temperature Nonlinearity versus Ambient Temperature Symmetry versus Ambient Temperature Total Output Error versus Ambient Temperature
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Setting Overcurrent Fault Switchpoint The VOC needed for setting the overcurrent fault switchpoint can be calculated as follows: VOC = Sens × | IOC | , where VOC is in mV, Sens in mV/A, and IOC (overcurrent fault switchpoint) in A. | Ioc | is the overcurrent fault switchpoint for a bidirectional (AC) current, which means a bi-directional sensor will have two symmetrical overcurrent fault switchpoints, +IOC and –IOC . See the following graph for IOC and VOC ranges: Example:For SC225KSIT, if required overcurrent fault switchpoint is 50 A, and VCC = 5 V, then the required VOC can be calculated as follows: VOC = Sens × IOC = 28 × 50 = 1400 (mV) Overcurrent Fault Operation The primary concern with high-speed fault detection is that noise may cause false tripping. Various applications have or need to be able to ignore certain faults that are due to switching noise or other parasitic phenomena, which are application dependant. The problem with simply trying to filter out this noise in the main signal path is that in high-speed applications, with asymmetric noise, the act of filtering introduces an error into the measurement. To get around this issue, and allow the user to prevent the fault signal from being latched by noise, a circuit was designed to slew the FAULTpin voltage based on the value of the capacitor from that pin to ground. Once the voltage on the pin falls below 2 V, as established by an internal reference, the fault output is latched and pulled to ground quickly with an internal N-channel MOSFET. Fault Walk-through The following walk-through references various sections and attributes in the figure below. This figure shows different fault set/reset scenarios and how they relate to the voltages on the FAULTpin, FAULT_EN pin, and the internal Overcurrent (OC) Fault node, which is invisible to the customer. 1. Because the device is enabled (FAULT_EN is high for a minimum period of time, the Fault Enable Delay, tFED , 15 μs typical) and there is an OC fault condition, the device FAULTpin starts discharging.
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection 2. When the FAULTpin voltage reaches approximately 2 V, the fault is latched, and an internal NMOS device pulls the FAULTpin voltage to approximately 0 V. The rate at which the FAULTpin slews downward (see [4] in the figure) is dependent on the external capacitor, COC, on the FAULTpin. 3. When the FAULT_EN pin is brought low, the FAULTpin starts resetting if no OC fault condition exists, and if FAULT_EN is low for a time period greater than tOCH. The internal NMOS pull-down turns off and an internal PMOS pullup turns on (see [7] if the OC fault condition still exists). 4. The slope, and thus the delay to latch the fault is controlled by the capacitor, COC, placed on the FAULTpin to ground. During this portion of the fault (when the FAULTpin is between VCC and 2 V), there is a 3 mA constant current sink, which discharges COC. The length of the fault delay, t is equal to: mA VVCt CCOC )2( −×= where VCC is the device power supply voltage in volts, t is in seconds and COC is in Farads. This formula is valid for RPU equal to or greater than 330 kΩ. For lower-value resistors, the current flowing through the RPU resistor during a fault event, IPU , will be larger. Therefore, the current discharging the capacitor would be 3 mA – IPU and equation 1 may not be valid. 5. The FAULTpin did not reach the 2 V latch point before the OC fault condition cleared. Because of this, the fixed 3 mA current sink turns off, and the internal PMOS pull-up turns on to recharge COC through the FAULTpin. 6. This curve shows VCC charging external capacitor COC through the internal PMOS pull-up. The slope is determined by COC. 7. When the FAULT_EN pin is brought low, if the fault condition still exists, the latched FAULT pin will be pulled low by the internal 3mA current source. When fault condition is removed then the Fault pin charges as shown in step 6. 8. At this point there is a fault condition, and the part is enabled before theFAULTpin can charge to VCC. This shortens the user-set delay, so the fault is latched earlier. The new delay time can be calculated by equation 1, after substituting the voltage seen on the FAULTpin for VCC. 2 2 2 Vcc Fault_En Input OC Fault Condition (Active High) 4 8
120 kHz Bandwidth, High Voltage Isolation Current Sensor with Integrated Overcurrent Detection Package 16-pin SOICW For Reference Only; not for tooling use (reference MS-013AA) Dimensions in millimeters Dimensions exclusive of mold flash, gate burrs, and dambar protrusions Exact case and lead configuration at supplier discretion within limits shown