 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| HV320 Initial Release Accurate, Re-Settable Electronic Circuit Breaker (Negative Supply Rail) Features ! ! ! ! ! ! ! ! ! General Description The Supertex HV320 re-settable electronic circuit breaker is designed to provide fast, consistent and accurate current limiting and load isolation during fault conditions. It may be used in a variety of applications in such markets as telecom, power, automotive, industrial, medical and security as well as in systems where active control is implemented in the negative supply lead. The current trip threshold is programmed by a sense resistor and operates from voltages ranging from 10V to 90V differentially. The HV320 can easily replace popular positive temperature coefficient (PTC) products such as RaychemTM PolySwitchesTM or re-settable polyfuses. HV320 overcomes numerous performance shortcomings of existing PTC's, including trip point inaccuracy, increased device resistance after initial reset, slow response time, susceptibility to temperature variations and very high trip current to operating current. During initial application of power, the gate of the external pass device is clamped low to suppress contact bounce glitches. Thereafter, the UV/OV supervisors and power-on reset work together to suppress gate turn on until the input power bounce ends. Once ON, HV320 continues to monitor the input voltage and the load current level. If a load fault occurs, the electronic circuit breaker will trip and the pass element will be turned off. To restart, the UV or OV pins must be toggled (for example by resetting the input voltage). Differential 10V to 90V operation (+VIN / -VEE) UV and OV Lock Out Power-On-Reset (POR) for debouncing Sense resistor programs circuit breaker Noise filter prevents false trip Programmable circuit breaker trip time Latched Operation Low Power, <0.4mA Small SO-8 package Applications ! ! ! ! ! ! ! ! ! ! ! -48V Central Office Switching -24V Cellular and Fixed Wireless Systems -24V PBX Systems Telecom Line Cards -48V Powered Ethernet for VoIP Distributed Power Systems Power Supply Input/Output Fault Isolator Electronic Circuit Breaker Servers and SANS - replaceable modules Automotive and Industrial Circuit Breakers BUS Networks (CAN BUS, etc.) Typical Application Circuit GND R1 487k Vin UV R2 6.81k HV320 OV Vee Load Sense R5 1k C2 10nF Gate R3 9.76 k C1 -48V R4 5 mOhm IRFB4710 Supertex Inc. does not recommend the use of its products in life support applications and will not knowingly sell its products for use in such applications unless it receives an adequate "products liability indemnification insurance agreement." Supertex does not assume responsibility for use of devices described and limits its liability to the replacement of devices determined to be defective due to workmanship. No responsibility is assumed for possible omissions or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the Supertex website: http://www.supertex.com. For complete liability information on all Supertex products, refer to the most current data book or to the Legal/Disclaimer page on the Supertex website. HV320 Ordering Information Package Option DEVICE 8 Pin SO HV320 HV320LG Absolute Maximum Ratings* Vee referenced to Vin pin VUV and VOV referenced to Vee Voltage Operating Ambient Temperature Operating Junction Temperature Storage Temperature Range +0.3V to -100V -0.3V to +12V -40C to +85C -40C to +125C -65C to +150C *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 devide at the absolute rating level may affect device reliability. All voltages are referenced to device ground. Electrical Characteristics (-10 * V AC Characteristics Symbol Parameter EE * -90V, -40C * T * +85C unless otherwise noted) Min Typ Max Units Conditions Supply (Referenced to Vin Pin) Vee Iee Supply Voltage Supply Current pin) 1.26 1.16 100 1.0 1.26 1.16 100 1.0 V V mV nA V V mV nA VOV = VEE + 0.5V @ 25 C Vuv = VEE + 1.9V @ 25 C Low to High Transition High to Low Transition Low to High Transition High to Low Transition -90 400 -10 450 V A VEE = -48V OV and UV Control (Referenced to V VUVH VUVL VUVHY IUV VOVH VOVL VOVHY IOV UV High Threshold UV Low Threshold UV Hysteresis UV Input Current OV High Threshold OV Low Threshold OV Hysteresis OV Input Current EE Circuit Breaker (V VSENSE-CB tCBTRIP ISENSE-CB UV = VEE + 1.9V, VOV = VEE + 0.5V, External MOSFET is IRFFR120N) 80 2.0 100 120 5.0 1.0 mV s nA Referenced to VEE pin @ 25 C May be extended by external RC circuit VSENSE-CB = 100mV @ 25 C Circuit Breaker Threshold Voltage Circuit Breaker Delay Time IRFB4710 and IRFFR120 are registered trademarks of International Rectifier. Raychem and PolySwitch are registered trademarks of Tyco International. 2 HV320 Gate Drive Output (Referenced to V VGATE IGATEUP IGATEDOWN VGATELOW Gate Drive Pull-Up Current EE pin, External MOSFET is IRFB4710*) 8.5 500 40 400 10 12 V A mA mV VUV = Vee +1.9V, VOV = Vee +0.5V VUV = Vee +1.9V, VOV = Vee +0.5V VUV = Vee, VOV = Vee +0.5V VUV = Vee, VOV = Vee +0.5V, Igate = 5mA Maximum Gate Drive Voltage Gate Drive Pull-Down Current Minimum Gate Drive Voltage Dynamic Characteristics (See timing below, External MOSFET is IRFB4710) tGATEHLOV tGATEHLUV OV High to GATE Low UV Low to GATE Low 500 500 ns ns Pulsed VOV from VEE+0.5V to VEE +1.9V Pulsed VUV from VEE+1.9V to VEE +0.5V VUV Vgate Vuvl tGATEHLUV VOV Vgate Vovh tGATEHLOV Pinout for LG Top View NC OV UV Vee 1 2 3 4 8 7 6 5 Vin NC Gate Sense Pin Description OV -- This Over Voltage (OV) sense pin, when raised above its high threshold limit, will immediately cause the GATE pin to be pulled low. The GATE pin will remain low until the voltage on this pin falls below the low threshold limit, initiating a new start-up cycle. UV - This Under Voltage (UV) sense pin, when below its low threshold limit, will immediately cause the GATE pin to be pulled low. The GATE pin will remain low until the voltage on this pin rises above the high threshold limit, initiating a new start-up cycle. VEE - This pin is the negative terminal of the power supply input to the circuit. VIN -- This pin is the positive terminal of the power supply input to the circuit. GATE -- This is the Gate Driver Output for the external N-Channel MOSFET. SENSE -- The current sense resistor connected from this pin to the VEE Pin programs the circuit breaker trip threshold. - 3 HV320 Functional Block Diagram UV Regulator & POR + Vin Vbg Logic UVLO buffer - OV Gate + 100mV Vee + - Sense Functional Description HV320 as a fuse and circuit breaker replacement: Telecom, data networks, automotive, industrial controls and some computer applications require the ability to isolate the power source from a load fault without having to physically replace a fuse or manually reset a mechanical circuit breaker. Traditionally a fast acting fuse or Positive Temperature Coefficient (PTC) device such as Raychem's PolySwitch or a manual / thermal circuit breaker have been used to limit the fault current. The problems with PTCs are numerous. First, they are extremely temperature dependent. For example the required trip current can vary as high as 150% of nominal value at lower temperatures such as -40C and as low as 50% of nominal value at higher temperatures such as +85C. Second, the ratio of trip current to steady state current can range from 7 to 70. This implies for an application where steady state current is 4A, traces must be over designed to withstand the trip current of 100A, a ratio of 25:1. Third, PTC's once tripped, require 20 seconds to minutes to reset and even when they are reset, the resistance value can permanently change as much as 240%. This implies PTC's are not suitable for repeated short circuit applications. Lastly the surface mount PTCs typically have large end cap terminations that absorb heat during the reflow process and can result in insufficient solder and cold solder joints. It is not uncommon for PCB surface contaminations to be present, thus resulting in poor solderability, hence loss of yield. Typically, fuses are rated in Amp^2-seconds. For a SMT 1206 size fast-acting 2A, 63V fuse rated at 0.23 A - square 4 second, it could take more than 200A for 5s before the fusing element melts. HV320 is an ideal alternative to thermal and manual circuit breakers in DC input applications. It has wide variety of uses in the automotive industry, such as PCB trace / device protection and DC motors and solenoid actuator current limit protection. These devices are typically used in windows and seat adjustment operations as well as automatic trunk opening mechanisms. Since these devices are operated manually, they can remain energized by the operator even after the mechanical lever has reached its end of travel. In this case, back EMF that normally opposes the supply voltage will drop to zero and a large current surge can begin to flow. HV320 can accurately be programmed to trip the current. In industrial applications, HV320 can offer broad solutions in DC solenoid-operated valves, DC motors and other electromagnetic loads. Fault current magnitude can be scaled to different current ratings by proper selection of the sense resistor and the external N-Channel MOSFET. For higher current applications, IGBT devices may be considered. The HV320 is intended to provide this circuit breaker function on supply rails in the range of -10 to -90 Volts. Description of Operation During initial application of power, a unique proprietary circuit holds off the external MOSFET, preventing an input glitch while an internal regulator establishes an internal operating voltage of approximately 10V. Until the proper internal voltage is achieved, all circuits are held reset and the gate to source voltage of the external MOSFET is clamped low. Once the internal under voltage lock out HV320 (UVLO) has been satisfied, the circuit checks the input supply under voltage (UV) and over voltage (OV) sense circuits to ensure that the input voltage is within programmed limits. These limits are determined by the selected values of resistors R1, R2 and R3 that form a voltage divider. Once the input voltage is within the programmed limits, the controller will force the GATE terminal to nominal 10V and the circuit breaker supervisor is enabled. When the voltage on the SENSE pin rises to 100mV, indicating an over current condition, the circuit breaker will trip in less than 5s. This time may be extended by the addition of external components (refer to Application Circuit 3 on page 9). The gate voltage is latched off when an over current condition is detected and is reset by removal and reapplication of input power. At any time during the start up cycle or thereafter, crossing the UV and OV limits (including hysteresis) will cause an immediate reset of all internal circuitry. When the input supply voltage returns to a value within the programmed UV and OV limits, a new start up sequence will be initiated. Safety recommendation: For safety critical applications where UL, CSA or other safety agency approvals are required, a fuse must be placed in series with HV320. Although HV320 will protect a fuse from opening in many instances, from the safety agency point of view, ICs cannot displace a fuse. Test Set Up Circuit GND Vin R1 487k 100uF 100V R2 6.81k OV Vee R3 9.76 k C1 Sense R5 1k C2 10nF IRFR120 Gate Output Short Circuit Switch UV HV320 Load -48V R4 50 mOhm Waveforms Vgs 5V/div Steady state operation followed by a lead short FET Current 2V/div FET Current 1V/div Figure 1 Figure 2 5 HV320 Design Information Setting Under Voltage and Over Voltage Shut Down The UV and OV pins are connected to comparators with typical 1.26V thresholds and 100mV of hysteresis. They are used to detect under voltage and over voltage conditions at the input to the circuit. Whenever the OV pin rises above its high threshold (1.26V) or the UV pin falls below its low threshold (1.16V), the GATE voltage is immediately pulled low. Calculations can be based on either the desired input voltage operating limits or the input voltage shutdown limits. In the following equations the shutdown limits are assumed. The under voltage and over voltage shut down thresholds can be programmed by means of the three resistor divider formed by R1, R2 and R3. Since the input currents on the UV and OV pins are negligible the resistor values may be calculated as follows: UVOFF = VUVL = 1.16 = *VEEUV(off)*x (R2+R3)/(R1+R2+R3) OVOFF = VOVL = 1.26 = *VEEOV(off)*x R3/(R1+R2+R3) Where *VEEUV(off)*and *VEEOV(off)* relative to VEE are Under and Over Voltage Shut Down Threshold points. If we select a divider current of 100A at a nominal operating input voltage of 50 Volts, then R1+R2+R3 = 50V/100uA = 500k Ohm From the second equation, for an OV shut down threshold of 65V, the value of R3 may be calculated. OVOFF = 1.26 = (65xR3)/500k R3 = (1.26x 500k)/65 = 9.69k The closest 1% value is 9.76k Ohm. From the first equation, for a UV shut down threshold of 35V, the value of R2 can be calculated. UVOFF = 1.16 = 35 x (R2+R3) / 500k R2 = ((1.16 x 500k)/35) - 9.76k = 6.81k The closest 1% value is 6.81k Ohm. Then R1 = 500k - R2 - R3 = 483k Ohm. The closest 1% value is 487K Ohm. From the calculated resistor values the OV and UV start up threshold voltages can be calculated as follows: UVON = VUVH = 1.26 = *VEEUV(on) *x (R2+R3)/(R1+R2+R3) OVON = VOVL = 1.16 = *VEEOV(on) *x R3/(R1+R2+R3) Where *VEEUV(on) * and *VEEOV(on) * are Under and Over Voltage Start Up Threshold points relative to Vee. 6 Pass Transistor ON OFF Req = C1 = 487 x (6.81 + 9.76) 487 + 6.81 + 9.76 10 x 10-3 16000 x 1.60 = 16K VC1 ( t ) = VIN x Where VC1= 1.26 VIN = 1.60V tPOR = desired POR time to overcome the bounce Req = R1 (R2 + R3) From the above C1 can be calculated: C1 = tPOR Req x 1.60 Then *VEEUV(on) * = 1.26 x (R1+R2+R3)/(R2+R3) *VEEUV(on) *= 1.26 x (487k+6.81k+9.76k)/(6.81k+9.76k ) = 38.29V and *VEEOV(on) *= 1.16 x (R1+R2+R3)/R3 *VEEOV(on) *= 1.16 x (487k +6.81k +9.76k)/9.76k = 59.85V Therefore, the circuit will start when the input supply voltage is in the range of 38.29V to 59.85V. To overcome longer bounce time during insertion, POR time must be extended. An additional cap C1 (Page 1) must be added from the UV pin to VEE. The value of this cap can be calculated accordingly: ( (1-e Req x C1 -tPOR ) ) For example for tPOR = 10ms and Values show on Page 1, the C1 calculates to be: C1 .39F a .47F can be used. Under Voltage/Over Voltage Operation GND UVOFF UVON Vin OVON OVOFF HV320 Pd * (Rjc + Rcs + Rsa) + TA Tj_derated Start Up Overload Protection If there is an output overload or short circuit during start up, the circuit breaker will trip when the voltage at the sense pin reaches 100mV. The gate is clamped low indefinitely until input power is cycled, the UV pin is pulsed low (<1.16V), or the OV pin is pulsed high (>1.26V). See Figure 2 on Page 5. Circuit Breaker The circuit breaker will trip in less than 5s when the voltage on the SENSE pin reaches a nominal 100mV. A resistor in series with the SENSE pin and a capacitor connected between the SENSE and VEE pins may be added to delay the rate of voltage rise on the SENSE pin, thus permitting a current overshoot and delaying Circuit Breaker activation. See Figure 1 on Page 5. Selection of External R_sense As a design example, consider a 500W load of a -48V rectifier: at a minimum regulation voltage of -42V, the input current is 11.9A, assuming that the trip point is set for 16A, the value of the sense resistor. R_sense = 80mV / ITRIP = 0.08/16 = 0.005 Ohm Where 80mV is the minimum circuit breaker trip level, the maximum circuit breaker threshold is 120mV. This will make the current trip level at 24A. The power dissipation of the sense resistor is: PRSENSE = (VSENSE-CB max) / R-sense = (0.12) / 0.005 = 2.88W Two 0.01 Ohm, 2W, 2512 size SMT resistor may be used in parallel. See Kelvin Connection to Sense Resistor. Selection of External Pass Devices The N-Channel may be selected based on maximum input operating voltage, RDS, maximum operating load current and peak short circuit current. Continuing with the example, the lowest Rds(on) International Rectifier N-Channel MOSFET at 100V Vdss is 14 m-Ohm. The IRFB4710* (TO-220) may be used for this application. FET Power Dissipation = (ICBmax^2) x Rds(on) x K = 24^2 x 0.014 x 1.4 = 11.3W The K=1.4 factor is increased Rdson with respect to temperature rise. Assuming Rjc = 0.74C/W and Rcs = 0.5C/W and the maximum operating temperature being 55C, then the needed heat sink thermal resistance can be calculated per: To Negative Terminal of Power Source To Source of MOSFET 2 2 11.3 * (0.74 + 0.5 +Rsa) + 55C 150C Rsa 7C Kelvin Connection to Sense Resistor Physical layout of the printed circuit board is critical for correct current sensing. Ideally trace routing between the current sense resistor and the VEE and SENSE pins should be direct and as short as possible with zero current in the sense traces. The use of Kelvin Connection from SENSE pin and VEE pin to the respective ends of the current sense resistor is recommended. To Vee Pin To Sense Pin Sense Resistors 7 HV320 Filtering Voltage Spikes on the Input Supply In some systems over voltage spikes of very short duration may exist and can prematurely trip the circuit breaker. For these systems a small capacitor may be added from the OV pin to the VEE pin to filter the voltage spikes. GND R1 487k UV R2 6.81k OV Vee C1 Sense R5 1k C2 10nF IRFB4710 Gate Vin HV320 LOAD R3 9.76 k -48V R4 5 mOhm Application Circuit 1 Increasing Under Voltage Hysteresis If the internally fixed under voltage hysteresis is insufficient for a particular system application, then it may be increased by using separate resistor dividers for OV and UV and providing a resistor feedback path from the gate pin to the UV pin. GND R1 475k UV R2 16.2k R3 511k OV R Vee Sense Gate Vin HV320 LOAD R4 10k R6 1k C1 10nF IRFB4710 -48V R5 5 mOhm Application Circuit 2 8 HV320 Extending Circuit Breaker Delay Connecting a resistor in series with the SENSE pin and a capacitor between the SENSE and VEE pins as shown in the following diagram may be used to extend the Circuit Breaker delay time beyond the 5s internally set delay time. GND R1 487k UV R2 6.81k OV Vee Sense R5 C R4 5 mOhm R 1k C2 10nF IRFB4710 Gate Vin HV320 LOAD R3 9.76 k -48V Application Circuit 3 Supertex inc. (c)2003 Supertex Inc. All rights reserved. Unauthorized use ofr reproduction prohibited. 1225 Bordeaux Drive, Sunnyvale, CA 94089 TEL: (408) 222-8888 * FAX: (408) 222-4895 www.supertex.com 9 |
Price & Availability of HV320
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |