HIP5600IS2

® HIP5600 WN ITHDRA PART W BSOLETE SS O PROCE ESIGNS NEW D NO September 1998 File Number 3270.7 Thermally Protected High Voltage Linear Regulator The HIP5600 is an adjustable 3-terminal positive linear voltage regulator capable of operating up to either 400VDC or 280VRMS. The output voltage is adjustable from 1.2VDC to within 50V of the peak input voltage with two external resistors. This high voltage linear regulator is capable of sourcing 1mA to 30mA with proper heat sinking. The HIP5600 can also provide 40mA peak (typical) for short periods of time. Protection is provided by the on chip thermal shutdown and output current limiting circuitry. The HIP5600 has a unique advantage over other high voltage linear regulators due to its ability to withstand input to output voltages as high as 400V(peak), a condition that could exist under output short circuit conditions. Common linear regulator configurations can be implemented as well as AC/DC conversion and start-up circuits for switch mode power supplies. The HIP5600 requires a minimum output capacitor of 10µF for stability of the output and may require a 0.02µF input decoupling capacitor depending on the source impedance. It also requires a minimum load current of 1mA to maintain output voltage regulation. All protection circuitry remains fully functional even if the adjustment terminal is disconnected. However, if this happens the output voltage will approach the input voltage. Features • Operates from 50VDC to 400VDC • Operates from 50VRMS to 280VRMS Line • UL Recognized • Variable DC Output Voltage 1.2VDC to VIN - 50V • Internal Thermal Shutdown Protection • Internal Over Current Protection • Up to 40mA Peak Output Current • Surge Rated to ±650V; Meets IEEE/ANSI C62.41.1980 with Additional MOV CAUTION: This product does not provide isolation from AC line. Applications • Switch Mode Power Supply Start-Up • Electronically Commutated Motor Housekeeping Supply • Power Supply for Simple Industrial/Commercial/Consumer Equipment Controls • Off-Line (Buck) Switch Mode Power Supply Ordering Information PART NUMBER HIP5600IS HIP5600IS2 TEMP. RANGE -40oC to +100oC -40oC to +100oC PACKAGE 3 Lead Plastic SIP 3 Lead Gullwing Plastic SIP Pinouts HIP5600 (TO-220) TOP VIEW TAB ELECTRICALLY CONNECTED TO VOUT VOUT HIP5600 (MO-169) TOP VIEW HIP5600 VOUT ADJ VOUT ADJ 63 VIN CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright © Intersil Americas Inc. 2002. All Rights Reserved VIN HIP5600 Functional Block Diagram RECTIFIER FOR AC OPERATION VIN HIP5600 PASS TRANSISTOR SHORT-CIRCUIT PROTECTION VOUT BIAS NETWORK C2 + + RF1 FEEDBACK OR CONTROL AMPLIFIER + - VOLTAGE REFERENCE ADJ Schematic Diagram VIN D1 D2 Q1 Q2 D3 R3 R1 D4 R2 D7 D8 Q4 R4 Q5 R5 D5 C1 R7 Q3 R6 R8 Q7 R10 R9 ADJ Q8 Q6 Q10 D6 Q9 R11 Q14 R14 Q13 R15 VOUT FIGURE 1. 64 - C1 THERMAL SHUTDOWN + RF2 Q11 R12 Q12 R13 D9 HIP5600 Absolute Maximum Ratings Input to Output Voltage, Continuous . . . . . . . . . . . . +480V to -550V Input to Output Voltage, Peak (Non Repetitive, 2ms) . . . . . . . ±650V Junction Temperature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +150oC ADJ to Output, Voltage to ADJ . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±5V Storage Temperature Range . . . . . . . . . . . . . . . . . -65oC to +150oC Lead Temperature (Soldering 10s). . . . . . . . . . . . . . . . . . . . +265oC Thermal Information (Typical) Thermal Resistance Plastic SIP Package . . . . . . . . . . . . . . θJA 60oC/W θJC 4oC/W CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. Operating Conditions Operating Voltage Range . . . . . . . . . . . . . . 80VRMS to 280V RMS or 50V DC to 400VDC Operating Temperature Range . . . . . . . . . . . . . . . .-40oC to +100oC Electrical Specifications Conditions VIN = 400VDC, IL = 1mA, CL = 10µF, VADJ = 3.79V, VOUT = 5V (Unless Otherwise Specified) Temperature = Case Temperature. PARAMETER INPUT Input Voltage Max Peak Input Voltage Input Frequency (Note 1) Bias Current (IBIAS Note 2) REFERENCE IADJ IADJTC (Note 1) IADJ LOAD REG (Note 1) VREF (Note 3) VREF TC (Note 1) Line Regulation VREF LINE REG Load Regulation VREF LOAD REG PROTECTION CIRCUITS Output Short Circuit Current Limit Thermal Shutdown TTS (IC surface, not case temperature. Note 1) Thermal Shutdown Hysteresis (Note 1) NOTES: 1. Characterized not tested 2. Bias current ≡ input current with output pin floating. 3. VREF = VOUT - VADJ V IN = 50V VIN = 400V VIN = 400V +25oC 35 127 134 45 142 mA oC CONDITION TEMP MIN TYP MAX UNITS DC Non-Repetitive (2ms) Full Full Full Full 50 DC 0.4 0.5 400 ±650 1000 0.6 V V Hz mA +25oC IL = 1mA IL = 1mA to 10mA Full +25oC +25oC IL = 1mA 50VDC to 400VDC Full +25oC Full IOUT = 1mA to 10mA +25oC Full 50 1.07 - 65 +0.15 -215 1.18 -460 9 9 3 3 80 1.30 14.5 29 5 6 µA µA/oC nA/mA V µV/oC µV/V µV/V mV/mA mV/mA - - 34 - oC 65 HIP5600 Application Information Introduction In many electronic systems the components operate at 3V to 15V but the system obtains power from a high voltage source (AC or DC). When the current requirements are small, less than 10mA, a linear regulator may be the best supply provided that it is easy to design in, reliable, low cost and compact. The HIP5600 is similar to other 3 terminal regulators but operates from much higher voltages. It protects its load from surges +250V above its 400V operating input voltage and has short circuit current limiting and thermal shutdown self protection features. Output Voltage The HIP5600 provides a temperature independent 1.18V reference, VREF , between the output and the adjustment terminal (V REF = VOUT - VADJ). This constant reference voltage is impressed across RF1 (see Figure 2) and results in a constant current (I1) that flows through RF2 to ground. The voltage across RF2 is the product of its resistance and the sum of I1 and IADJ. The output voltage is given in Equations 1(A, B). V OUT = (V REF RF1 + RF2 ( RF2 ) ) ------------------------------ + I ADJ RF1 HIP5600 AC/DC VOUT ADJ VIN VOUT(NOMINAL) 3.3V 4.9V 12.0V 14.8V VREF IADJ I1 RF1 RF2 AC/DC RF1 3.6k 2.7k 1.8k 1.1k RF2 5.6k 7.5k 15k 12k VOUT FIGURE 2. (EQ. 1A) Example: Given: VIN = 200VDC , VOUT = 15V, IOUT = 2mA to 12mA, θSA = 10oC/W, RF1 = 1.1kΩ 5% low, RF2 = 12kΩ 5% high, ∆IOUT equals 10mA and ∆Temp equals +60 oC (ambient temperature +25oC to +85oC). The worst case ∆VOUT for the given conditions is -1.13V. The shift in VOUT is attributed to the following: -1.55V manufacturing tolerances, +1.33V external resistors, -0.62V load regulation and -0.29V temperature effects. Regulator With Zener RF1 + RF2 = ( 1.18 ) × ------------------------------ + 65 µ A ( RF2 ) V OUT RF1 (EQ. 1B) HIP5600 VOUT = 1.18 + VZ VOUT 3.7V VOUT ADJ VIN AC/DC VZ 2.5V 3.9V 9.1V 11V 15V Error Budget ∆RF2 RF 1 + RF2 ∆V OUT = ∆V T REF ------------------------- + ∆I T ADJ RF2 + I A DJ RF 2 -----------RF1     5.1V 10.3V RF2 R F2 R F1 Where; ∆V RE F ≡ ∆V REF + V REF T LOA DREG ( ∆I OUT ) + V REF TC ( ∆Temp ) +V TC ( θ ) ∆( IOUT ⋅ V IN ) + V REF SA REFLINEREG ∆I T ADJ ≡ ∆I ADJ + I A DJ +I ADJ TC ( θ LO ADRE G ( ∆I OUT ) + IADJ TC ( ∆Te mp ) SA ) ∆( I OUT ⋅ V IN ) Note: ∆RFx = % tolerance of resistor x -------------RFx Equations 2(A,B,C) are provided to determine the worst case output voltage in relation to; manufacturing tolerances (∆VREF and ∆IREF),% tolerance in external resistors (∆RF1/RF1, ∆RF2/RF2), load regulation (VREF LOAD REG , IADJ LOAD REG ), line regulation (VREF LINE REG) and the effects of temperature (VREFTC, IREFTC), which includes self heating (θSA). 66     R F2 + V RE F --------R F1   ∆R F2 ∆RF1 ------------- – ------------- (EQ. 2A) VREF IADJ I1 RF1 VZ 12.2V VOUT 16.2V RF1 = 10k AC/DC (EQ. 2B) FIGURE 3. (EQ. 2C) The output voltage can be set by using a zener diode (Figure 3) instead of the resistor divider shown in Figure 2. The zener diode improves the ripple rejection ratio and reduces the value of the worst case output voltage, as illustrated in the example to follow. The bias current of the zener diode is set by the value of RF1 and IADJ. The regulator / zener diode becomes an attractive solution if ripple rejection or the worst case tolerance of the output voltage is critical (i.e. one zener diode cost less than one 10µF capacitor (C3) and one 1/4W resistor RF2). Minimum power dissipation is possible by reducing I1 current, with little effect on the output voltage regulation. The output voltage is given in Equation 3. Equations 4(A,B, C) are provided to determine the worst case output voltage in relation to; manufacturing tolerances HIP5600 V OUT = V REF + V Z (EQ. 3) Error Budget ∆V OUT = ∆V T REF + ∆V T Z ∆VT +V REF HIP5600 HIP5600 AC/DC ADJ AC/DC (EQ. 4A) VOUT VOUT VIN ≡ ∆V REF + V RE F LOADREG ( ∆I OUT ) + V REF TC ( ∆Temp ) ADJ REF TC ( θ SA ) ∆( I OUT ⋅ V IN ) + V REFLINEREG (EQ. 4B) VREF RS I1 RF1 RF2 AC/DC VREF VOUT IADJ VIN I1 RS ∆V T Z ≡ V Z to l er an ce ( V Z ) + V Z TC ( ∆Te mp ) (EQ. 4C) RF1 RF2 AC/DC VOUT IADJ of HIP5600 and the zener diode (∆VREF and ∆Vz), load regulation of the HIP5600 (VREF LOAD REG), and the effects of temperature on the HIP5600 and the zener diode (VREFTC, VZTC). Example: Given: VIN = 200V, V OUT = 14.18V (VREF = 1.18V, VZ = 13V), ∆VZ = 5%, VZTC = +0.079% / °C (assumes 1N5243BPH), ∆IOUT equal 10mA and ∆Temp equal +60 oC. The worst case ∆VOUT is 0.4956V. The shift in VOUT is attributed to the following: -0.2 (HIP5600) and 0.69 (zener diode). The regulator/zener diode configuration gives a 3.5% (0.49/14.18) worst case output voltage error where, for the same conditions, the regulator/resistor configuration results in an 7.5% (1.129/15) worst case output voltage error. External Capacitors A minimum10µF output capacitor (C2) is required for stability of the output stage. Any increase of the load capacitance greater than 10µF will merely improve the loop stability and output impedance. A 0.02µF input decoupling capacitor (C1) between VIN and ground may be required if the power source impedance is not sufficiently low for the 1MHz - 10MHz band. Without this capacitor, the HIP5600 can oscillate at 2.5MHz when driven by a power source with a high impedance for the 1MHz 10MHz band. An optional bypass capacitor (C3) from VADJ to ground improves the ripple rejection by preventing the ripple at the Adjust pin from being amplified. Bypass capacitors larger than 10µF do not appreciably improve the ripple rejection of the part (see Figure 20 through Figure 25). Load Regulation For improved load regulation, resistor RF1 (connected between the adjustment terminal and VOUT) should be tied directly to the output of the regulator (Figure 4A) rather than near the load Figure 4B. This eliminates line drops (RS) from appearing effectively in series with RF1 and degrading regulation. For example, a 15V regulator with a 0.05Ω resistance between the regulator and the load will have a load regulation due to line resistance of 0.05Ω x ∆IL. If RF1 is connected near the load the effective load regulation will be 11.9 times worse (1+R2/R1, where R2 = 12k, R1 = 1.1k). (A) FIGURE 4. (B) Protection Diodes The HIP5600, unlike other voltage regulators, is internally protected by input diodes in the event the input becomes shorted to ground. Therefore, no external protection diode is required between the input pin and the output pin to protect against the output capacitor (C2) discharging through the input to ground. If the output is shorted in the absence of D1 (Figure 5), the bypass capacitor voltage (C3) could exceed the absolute maximum voltage rating of ±5V between VOUT and VIN . Note; No protection diode (D1) is needed for output voltages less than 6V or if C3 is not used. VIN HIP5600 C1 0.02µF D1 PROTECTS AGAINST C3 DISCHARGING WHEN THE OUTPUT IS SHORTED. + VOUT RF1 C3 10µF D1 C2 10 µF VOUT ADJ FIGURE 5. REGULATOR WITH PROTECTION DIODE Selecting the Right Heat Sink Linear power supplies can dissipate a lot of power. This power or heat must be safely dissipated to permit continuous operation. This section will discuss thermal resistance and show how to calculate heat sink requirements. Electronic heat sinks are generally rated by their thermal resistance. Thermal resistance is defined as the temperature rise per unit of heat transfer or power dissipated, and is expressed in units of degrees centigrade per watt. For a particular application determine the thermal resistance (θSA) which the heat sink must have in order to maintain a junction temperature below the thermal shut down limit (TTS). 67 VIN RF2 HIP5600 A thermal network that describes the heat flow from the integrated circuit to the ambient air is shown in Figure 6. The basic relation for thermal resistance from the IC surface, historically called “junction”, to ambient (θJA) is given in Equation 5. The thermal resistance of the heat sink (θSA) to maintain a desired junction temperature is calculated using Equation 6. PD TJ = J UNCTION Example, Given: VIN = 400VDC θJC = 4.8oC/W TA = + 50oC VREF = 1.18V ≡I VOUT = 15V TTS = + 127οC RF1 = 1.1k ILOAD = 15mA IADJ = 80µA P = 6.2W = (VIN - VOUT)(IIN ) I θJC TC = CASE TS = HEAT SINK IN ADJ + ------------------ + I - V REF RF1 LOAD θCS θSA HEAT SINK Find: Proper heat sink to keep the junction temperature of the HIP5600 from exceeding TTS (+127oC). Solution: Use Equation 6, (EQ. 7) (EQ. 8) TA = AMBIENT AIR –T T TS A θ SA = --------------------------- – θ JC P FIGURE 6.       θ JA = --------------------P Where: TJ – T A °C -------W °C 127 ° C – 50 ° C θ SA = ------------------------------------------ – 4.8 ° C = 7.62 -------6.2 W (EQ. 5) T =T J TS θ JA = θJC + θ CS + θ SA ∴ θ SA + θ Where: CS ≈θ and T TS – T A SA = --------------------------- – θ JC P The selection of a heat sink with θSA less than +7.62oC/W would ensure that the junction temperature would not exceed the thermal shut down temperature (TTS) of +127×oC. A Thermalloy P/N7023 at 6.2W power dissipation would meet this requirement with a θSA of +5.7×oC/W. Operation Without A Heatsink The package has a θJA of +60oC/W. This allows 0.7W power dissipation at +85oC in still air. Mounting the HIP5600 to a printed circuit board (see Figure 39 through Figure 41) decreases the thermal impedance sufficiently to allow about 1.6W of power dissipation at +85oC in still air. Thermal Transient Operation For applications such as start-up, the HIP5600 in the TO-220 package can operate at several watts -without a heat sinkfor a period of time before going into thermal shutdown. (EQ. 6) θJA = (Junction to Ambient Thermal Resistance) The sum of the thermal resistances of the heat flow path. θJA = θJC + θCS + θSA TJ = (Junction Temperature) The desired maximum junction temperature of the part. TJ = TTS TTS = (Thermal Shutdown Temperature) The maximum junction temperature that is set by the thermal protection circuitry of the HIP5600 (min = +127oC, typ = +134oC and max = +142oC). θJC = (Junction to Case Thermal Resistance) Describes the thermal resistance from the IC surface to its case. θJC = 4.8oC/W θCS = (Case to Mounting Surface Thermal Resistance) The resistance of the mounting interface between the transistor case and the heat sink. For example, mica washer. θSA = (Mounting Surface to Ambient Thermal Resistance) The resistance of the heat sink to the ambient air. Varies with air flow. TA = Ambient Temperature P = The power dissipated by the HIP5600 in watts. P = (VIN - VOUT)(IOUT) Worst case θSA is calculated using the minimum TTS of +127oC in Equation 6. PD = I IN (VIN - VOUT) TJ = JUNCTION 0.6 θJC DIE/PACKAGE INTERFACE 0.4 θJC TS = HEAT SINK OR CASE θSA TA = AMBIENT AIR CS + 0.5CP 0.5C P CD FIGURE 7. THERMAL CAPACITANCE MODEL OF HIP5600 Figure 7 shows the thermal capacitances of the TO-220 package, the integrated circuit and the heat sink, if used. When power is initially applied, the mass of the package absorbs heat which limits the rate of temperature rise of the 68 HIP5600 junction. With no heat sink CS equals zero and θSA equals the difference between θJA and θJC. The following equations predict the transient junction temperature and the time to thermal shutdown for ambient temperatures up to +85oC and power levels up to 8W. The output current limit temperature coefficient (Figure 39) precludes continuous operation above 8W.    TJ ( t ) = TA + T1 + T2 + T3 –t ------- (EQ. 11A) –t ---TJ ( t ) = TA + P θJC + P θSA 1 – e τ Where: (EQ. 9) Where: τ ≡ θSA ( C P + C S ) τ 1 ≡ θ SA ( C P + C S ) –t ------- For the TO-220, CP is 0.9Ws to 1.1Ws per degree compared to about 2.6mWs per degree for the integrated circuit and C S is 0.9Ws per degree per gram for aluminum heat sinks. Figure 8 shows the time to thermal shutdown versus power dissipation for a part in +22oC still air and at various elevated ambient temperatures with a θSA of +27oC/W from forced air flow. For the shorter shutdown times, the θSA value is not important but the thermal capacitances are. A more accurate equation for the transient silicon surface temperature can be derived from the model shown in Figure 7. Due to the distributed nature of the package thermal capacitance, the second time constant is 1.7 times larger than expected. 10 2 Where: τ 3 ≡ 0.6 θ C JC D Thermal Shutdown Hysteresis Figure 9 shows the HIP5600 thermal hysteresis curve with VIN = 100VDC , VOUT = 5V and IOUT = 10mA. Hysteresis is added to the thermal shutdown circuit to prevent oscillations as the junction temperature approaches the thermal shutdown limit. The thermal shutdown is reset when the input voltage is removed, goes negative (i.e. AC operation) or when the part cools down. 10 HEATING TIME TO THERMAL SHUTDOWN (s) 10 1 +22×oC IOUT (mA) +70×oC 8.0 6.0 10 0 +85×oC 4.0 COOLING 2.0 +100×oC 10-1 +115× oC +120 o×C 10-2 0.0 2.0 4.0 6.0 8.0 10 0.0 98.0 105.0 113.0 120 127 CASE TEMPERATURE (oC) 135 142 FIGURE 9. THERMAL HYSTERESIS CURVE AC to DC Operation Since the HIP5600 has internal high voltage diodes in series with its input, it can be connected directly to an AC power line. This is an improvement over typical low current supplies constructed from a high voltage diode and voltage dropping resistor to bias a low voltage zener. The HIP5600 provides better line and load regulation, better efficiency and heat POWER DISSIPATION (W) FIGURE 8. TIME TO THERMAL SHUTDOWN vs POWER DISSIPATION 69     T ≡ 0.6P θ 1 – eτ 3 3 JC     –t ------- SHUTDOWN REGION          P ( θ JC + θ SA ) + T – T A TS t = – τ ln -----------------------------------------------------------------P θSA    (EQ. 10) Where: ( 0.5C + C ) 0.5C P P S τ 2 ≡ 0.7 θJC ----------------------------------------------------------CP + C S     T 2 ≡ 0.4P θ JC 1 – e τ 2         T ≡ Pθ 1 –e τ 1 1 SA     (EQ. 11B)    (EQ. 11C) (EQ. 11D) HIP5600 transfer. The latter because the TO-220 package permits easy heat sinking. The efficiency of either supply is approximately the DC output voltage divided by the RMS input voltage. The resistor value, in the typical low current supply, is chosen such that for maximum load at minimum line voltage there is some current flowing into the zener. This resistor value results in excess power dissipation for lighter loads or higher line voltages. Using the circuit in Figure 3 with a 1000µF output capacitor the HIP5600 only takes as much current from the power line as the load requires. For light loads, the HIP5600 is even more efficient due to it’s interaction with the output capacitor. Immediately after the AC line goes positive, the HIP5600 tries to replace all the charge drained by the load during the negative half cycle at a rate limited by the short circuit current limit (see “A1” and “B1” Figure 10). Since most of this charge is replaced before the input voltage reaches its RMS value, the power dissipation for this charge is lower than it would be if the charge were transferred at a uniform rate during the cycle. When the product of the input voltage and current is averaged over a cycle, the average power is less than if the input current were constant. Figure 11 shows the HIP5600 efficiency as a function of load current for 80VRMS and 132VRMS inputs for a 15.6V output. Referring again to Figure 10, Curve “A1” shows the input current for a 10mA output load and curve “B1” with a 3mA output load. The input current spike just before the negative going zero crossing occurs while the input voltage is less than the minimum operating voltage but is so short it has no detrimental effect. The input current also includes the charging current for the 0.02µF input decoupling capacitor C1. The maximum load current cannot be greater than 1/2 of the short circuit current because the HIP5600 only conducts over 1/2 of the line cycle. The short circuit current limit (Figure 38) depends on the case temperature, which is a function of the power dissipation. Figure 38 for a case temperature of +100oC (i.e. no heat sink) indicates for AC operation the maximum available output current is 10mA (1/2 x 20mA). Operation from full wave rectified input will increase the maximum output current to 20mA for the same +100oC case temperature. As a reminder, since the HIP5600 is off during the negative half cycle, the output capacitor must be large enough to supply the maximum load current during this time with some acceptable level of droop. Figure 10 also shows the output ripple voltage, for both a 10mA and 3mA output loads “A2” and “B2”, respectively. Do’s And Don’ts DC Operation 1. Do not exceed the absolute maximum ratings. 2. The HIP5600 requires a minimum output current of 1mA. Minimum output current includes current through RF1. Warning: If there is less than 1mA load current, the output voltage will rise. If the possibility of no load exists, RF1 should be sized to sink 1mA under these conditions. V REF 1.07V RF1 MIN = ------------------ = --------------- = 1k Ω 1mA 1mA 120VRMS, 60Hz I IN B1 A1 20mA/DIV. B2 VOUT A2 100mV/DIV. 2ms/DIV. FIGURE 10. AC OPERATION 25 23 21 EFFICIENCY (%) 19 18 16 14 12 10 VIN = 132VRMS VIN = 80VRMS 3. Do not “HOT” switch the input voltage without protecting the input voltage from exceeding ±650V. Note: inductance from supplies and wires along with the 0.02µF decoupling capacitor can form an under damped tank circuit that could result in voltages which exceed the maximum ±650V input voltage rating. Switch arcing can further aggravate the effects of the source inductance creating an over voltage condition. Recommendation: Adequate protection means (such as MOV, avalanche diode, surgector, etc.) may be needed to clamp transients to within the ±650V input limit of the HIP5600. 4. Do not operate the part with the input voltage below the minimum 50VDC recommended. Low voltage operation: For input voltages between 0V DC and +5VDC nothing happens (IOUT = 0), for input voltages between +5V DC and +35V DC there is not enough voltage for the pass transistor to operate properly and therefore a high frequency (2MHz) oscillation occurs. For input voltages +35VDC to +50VDC proper operation can occur with some parts. VOUT = 1 5.6VDC 0.0 5.0 10.0 LOAD CURRENT (mA) 15.0 FIGURE 11. EFFICIENCY AS A FUNCTION OF LOAD CURRENT 70 HIP5600 5. Warning: the output voltage will approach the input voltage if the adjust pin is disconnected, resulting in permanent damage to the low voltage output capacitor. AC Operation 1. Do not exceed the absolute maximum ratings. 2. The HIP5600 requires a minimum output current of 0.5mA. Minimum output current includes current through RF1. Warning: If there is less than 0.5mA output current, the output voltage will rise. If the possibility of no load exists, RF1 should be sized to sink 0.5mA under these conditions. V REF 1.07V RF1 MIN = ------------------ = ----------------- = 2k Ω 0.5mA 0.5m A minimized by connecting the test equipment ground as close to the circuit ground as possible. CAUTION: Dangerous voltages may appear on exposed metal surfaces of AC powered test equipment. Application Circuits + 50VDC TO 400VDC BUS HIP5600 C1 0.02µF VOUT ADJ VIN ± + VOUT 3. If using a laboratory AC source (such as VARIACs or step-up transformers, etc.) be aware that they contain large inductances that can generate damaging high voltage transients when they are switched on or off. Recommendations (1) Preset VARIAC output voltage before applying power to part. (2) Adequate protection means (such as MOV, avalanche diode, surgector, etc.) may be needed to clamp transients to within the ±650V input limit of the HIP5600. 4. Do not operate the part with the input voltage below the minimum 50VRMS recommended. Low voltage operation similar to DC operation (reference step 4 under DC operation). 5. Warning: the output voltage will approach the input voltage if the adjust pin is disconnected, resulting in permanent damage to the low voltage output capacitor. RF1 C3 10µF C2 10 µF RF2 FIGURE 12. DC/DC CONVERTER The HIP5600 can be configured in most common DC linear regulator applications circuits with an input voltage between 50VDC to 400VDC (above the output voltage) see Figure 12. A 10µF capacitor (C2) provides stabilization of the output stage. Heat sinking may be required depending upon the power dissipation. Normally, choose RF1