PT4481—48V 100-W 30-A Programmable Isolated DC/DC Converter SLTS024C (Revised 6/20/2002) Features • 36V to 75V Input Voltage Range • Programmable Output Voltage Range: 1.3V to 3.5V • -40° to +85°C Ambient • 1500 VDC Isolation • 89% Efficiency • On/Off Inhibit • Differential Remote Sense • N+1 Current Sharing • • • • • • Over-Current Protection Over-Temperature Protection Over-Voltage Protection Space-Saving Package Solderable Copper Case Safety Approvals: UL 60950 CSA 22.2 950 VDE EN60950 Pending Description Ordering Information Pin-Out Information The PT4481 Excalibur™ DC/DC converter module combines state-of-theart power conversion technology with un-paralleled flexibility. Incorporating high efficiency and ultra-fast transient response, these modules provide up to 30A of output current over the programmable voltage range of 1.3V to 3.5V. This represents a full 100W output at 3.3V. The modules include a number of inbuilt features to facilitate system integration. These include a foldback output current limit, over-temperature protection, and an inhibit on/off control. A differential remote sense is also provided to compensate for voltage drop between the converter and load. For applications requiring power supply redundancy, multiple PT4481 modules may connected for operation in an ‘N+1’ configuration. Each PT4481 connected will share the load current with other active PT4481 modules. PT4481o = 1.3 to 3.5 Volts Pin PT Series Suffix (PT1234 x ) Case/Pin Configuration Order Suffix Package Code * N A C Vertical Horizontal SMD (EKD) (EKA) (EKC) * Previously known as package styles 1200, 1210, and 1215. (Reference the applicable package code drawing for the dimensions and PC board layout) Function Pin Function 1 +Vin 14 –Vout 2 –Vin 15 –Vout 3 Inhibit 16 –Vout 4 Do not connect 17 –Vout 5 Do not connect 18 –Vout 6 Sync † 19 –Vout 7 (+)Remote Sense 20 (–)Remote Sense 8 +Vout 21 VID0 9 +Vout 22 VID1 10 +Vout 23 VID2 11 +Vout 24 VID3 12 +Vout 25 VID4 13 +Vout 26 Share † † Pins 6 & 26 are used for N+1 configuration (see related application note). For stand-alone operation, leave open circuit. • Shaded functions indicate those pins that are referenced to primary-side potential. Standard Application + V IN 1 + V in 2 – V in + C1 C2 Inhibit 3 + V OUT 7 + V sns + V out 8-13 PT4481 VID0 - VID4 • Co = Optional 330µF electrolytic capacitor -V out 1 4 - 1 9 -V sns 21 22 23 24 25 L O A D + Co 20 – V IN – V OUT • C1 = Optional 33µF, 100V electrolytic capacitor • C2 = Optional 1µF, 100V ceramic capacitor • Programming pins, VID0–VID4, are shown configured for Vo =3.3V • For normal operation, pin 3 (Inhibit) must be connected to –Vin. • For details on additional N+1 components consult the related application note. PROGRAMMING PINS For technical support and more information, see inside back cover or visit www.ti.com PT4481—48V 100-W 30-A Programmable Isolated DC/DC Converter Programming Information VID3 VID2 VID1 VID0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 PT4480 Series Comparison VID4=1 VID4=0 Vout Vout 2.0V 2.1V 2.2V 2.3V 2.4V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V 3.4V 3.5V 1.30V 1.35V 1.40V 1.45V 1.50V 1.55V 1.60V 1.65V 1.70V 1.75V 1.80V 1.85V 1.90V 1.95V 2.00V 2.05V Logic 0 = Connect to (–)Remote Sense, pin 20 Logic 1 = Open circuit (no pull-up resistors) VID3 & VID4 must not be changed while unit is operating Specifications Functionality Output Voltage Program Range Configuration for Current Sharing # PT4481 Regulator 1.3V– 3.5V N+1 with other PT4481s PT4482 Regulator 1.3V– 3.5V With PT4499 boosters PT4499 PT4482 Booster N/A Used only with PT4482 PT4483 Regulator 4.6V–5.7V N+1 with other PT4483s PT4484 Regulator 4.6V–5.7V With PT4498 boosters PT4498 PT4484 Booster N/A Used only with PT4484 PT4485 Regulator 6.5V– 17.5V N+1 with other PT4485s PT4486 Regulator 6.5V–17.5V With PT4497 boosters PT4497 PT4486 Booster N/A Used only with PT4486 # This specification covers only the PT4481 regulator. (Unless otherwise stated, Ta =25°C, Vin =48V, Vo =3.3V, Co =0µF, and Io =Iomax) Characteristic Symbol Conditions Min PT4481 Typ Max Units Output Current Input Voltage Range Set Point Voltage Tolerance Temperature Variation Line Regulation Load Regulation Total Output Voltage Variation Io Vin Vo tol Regtemp Regline Regload ∆Votot Over Vin range Over Io Range — 48 ±1 ±0.5 ±0.1 ±0.2 30 75 ±1.5 — ±1 ±1 A VDC %Vo %Vo %Vo %Vo — ±2 ±3 %Vo Efficiency η –40° ≤Tcase ≤ +100°C, Io =0 Over Vin range Over Io range Includes set-point, line, load, –40° ≤Tcase ≤ +100°C Io =15A 0 36 — — — — Vo Ripple (pk-pk) Vr 20MHz bandwidth Transient Response ttr ∆Vtr 89 87 81 60 45 N/A 1 75 ±5 — — — 75 55 — — — — Current Limit Ilim — 35 — A Current Share Tolerance Over-Voltage Protection Switching Frequency Under-Voltage Lockout Inhibit (Pin 3) Input High Voltage Input Low Voltage Input Low Current Ishr tol OVP ƒs UVLO 0.1A/µs load step, 50% to 75% Iomax Vo over/undershoot 1A/µs load step, 50% to 100% Iomax Vo over/undershoot Vin =36V, ∆Vo = –1% foldback continuous limit With other PT4481 modules in N+1 Shutdown and latch off Over Vin range — — — — — — — — — — — 270 — ±10 125 300 34.5 — — 350 — % %Vo kHz V 2.5 –0.5 — — — 0 1500 — 10 -40 — -40 — — –0.2 4 3 — — 1100 — — 120 — Open (1) +0.8 — 10 — 10,000 — — — +115 (2) — +125 V mA mA µF µF V pF MΩ °C °C °C 1.4 — — 106 Hrs — 500 — G’s — 20 (3) — G’s — 90 — grams Standby Input Current Internal Input Capacitance External Output Capacitance Isolation Voltage Capacitance Resistance Operating Temperature Range Over-Temperature Shutdown Storage Temperature Reliability VIH VIL IIL Iin standby Cin Cout Tc OTP Ts MTBF Mechanical Shock — Mechanical Vibration — Weight Flammability — — Vo =3.3V Vo =2.5V Vo =1.5V Vo >2V Vo ≤2V Referenced to –Vin (pin 2) pins 3 & 2 connected Between +Vo and –Vo Input–output/input–case Input to output Input to output Case temperature, over Vin range Case temperature, auto reset — Per Bellcore TR-332 50% stress, Ta =40°C, ground benign Per Mil-Std-883D, method 2002.3, 1mS, half-sine, mounted to a fixture Mil-Std-883D, Method 2007.2 Suffixes A, C 20-2000Hz, pcb mounted — Materials meet UL 94V-0 % mVpp µs %Vo µs %Vo Notes: (1) The Inhibit (pin 3) has an internal pull-up, which if left open circuit allows the converter to operate when input power is applied. The open-circuit is limited to 6.5V. Refer to the application notes for interface considerations. (2) See Safe Operating Area curves or contact the factory for the appropriate derating. (3) The case pins on through-hole pin configuration (suffix A) must be soldered. For more information see the applicable package outline drawing. For technical support and more information, see inside back cover or visit www.ti.com Typical Characteristics PT4481—48V 100-W 30-A Programmable Isolated DC/DC Converter Performance Characteristics, Vo =3.3V (See Note A) Safe Operating Area, Vin =48V Efficiency vs Output Current (See Note B) Stand Alone, No Heatsink 90 100 Efficiency - % VIN 80 48.0V 75.0V 36.0V 70 60 Ambient Temperature (°C) 80 90 Airflow 70 500LFM 400LFM 300LFM 200LFM 100LFM Nat conv 60 50 40 30 20 50 0 5 10 15 20 25 0 30 5 10 15 20 25 Iout (A) Iout (A) Ripple vs Output Current 100 80 Ripple - mV VIN 60 75.0V 48.0V 36.0V 40 20 0 0 5 10 15 20 25 30 Iout (A) Power Dissipation vs Output Current 20 16 Pd - Watts VIN 12 36.0V 75.0V 48.0V 8 4 0 0 5 10 15 20 25 30 Iout (A) Note A: Characteristic data has been developed from actual products tested at 25°C. This data is considered typical data for the Converter. Note B: SOA curves represent the conditions at which internal components are at or below the manufacturer’s maximum operating temperatures For technical support and more information, see inside back cover or visit www.ti.com 30 Application Notes PT4481 Configuring PT4481 DC/DC Converters for N+1 Operation & D2 in Figure 1-1), protect against reverse current flow under such conditions. Notes ‘N+1’ vs OR’ing 1. For ‘N+1’ redundancy, always use one more converter than is required to supply the load. The PT4481 DC/DC converter modules may be operated with other PT4481 modules in ‘N+1’ configurations. A simple OR’ing connection allows a number of converters to share the load current. An ‘N+1’ configuration adds redundancy by employing at least one more converter than is necessary to supply the load. This ensures that upon the loss of one converter, sufficient capacity remains to supply the load without interruption. As an example, a 45-A load configured for ‘N+1’ would require no less than three PT4481 converters. Two are needed to meet the load demand, plus one additional converter to ensure redundancy. Figure 1-1 shows the schematic for operating two PT4481 converters in an ‘N+1’ configuration for a 25-A load application. 2. The VID pins for all converter modules must be independently set to the same voltage program code. 3. All converters connected for ‘N+1’ operation must be located on the same printed circuit board. A similar footprint and trace layout for each converter will facilitate current sharing. 4 A number of high-current rectifier diodes are available with a low forward voltage drop. They are specifically designed for OR’ing applications in ‘N+1’ systems. Eg. The 82CNQ030, and MBRB2515. 5. As a result of excess capacity and the losses in the blocking diodes, system efficiency is reduced. Blocking Diodes A true ‘N+1’ redundant system must also protect the output bus against fault current back-feeding a converter. Without a blocking diode, a converter will sink current as a result of a fault at its output, or due to the loss of its input source. The blocking diodes 4, (D1 6. The interconnection of pin 6 (Sync), and pin 26 (Share) between all modules are required for load current sharing and operation at a common frequency. Figure 1-1; Connection Schematic for Operation in Parallel/N+1 Configuration PROGRAMMING PINS REMOTE SENSE (+) +VIN 25 F1 1 2 + CIN 24 23 22 VID4 – VID0 21 +V IN 7 +Sns 8–13 +V OUT D1, OR'ing Diode (Required) +VOUT PT4481 –V IN Inhibit 3 –V OUT 14–19 + COUT, 330µF (Required) Sync Share –Sns 20 6 26 25-A LOAD –VIN –VOUT Inhibit REMOTE SENSE (–) F2 + CIN 1 3 Inhibit 6 Sync D2, OR'ing Diode (Required) 26 20 Share –Sns +V OUT +V IN 8–13 PT4481 2 –V IN VID4 – VID0 25 24 23 22 –V OUT +Sns 21 7 14–19 COUT, 330µF (Required) + REMOTE SENSE (+) PROGRAMMING PINS For technical support and more information, see inside back cover or visit www.ti.com Application Notes PT4470, PT4480 Series Operating Features of the PT4470 and PT4480 Series of Isolated DC/DC Converters Under-Voltage Lockout An Under-Voltage Lock-Out (UVLO) inhibits the operation of the converter until the input voltage is above the UVLO threshold (see the applicable data sheet specification). Below this voltage, the module’s output is held off, irrespective of the state of the Inhibit control (pin 3). If the Inhibit control is connected to –Vin (pin 2), the module will automatically power up when the input voltage rises above the UVLO threshold. The UVLO allows the module to produce a clean transition during both power-up and power-down, even when the input voltage is rising or falling slowly. It also reduces the high start-up current during normal power-up of the converter, and minimizes the current drain from the input source during low-input voltage conditions. The UVLO threshold includes about 2V of hysteresis. Once operational, the converter will conform to its operating specifications when the minimum specified input voltage is reached. Over-Current Protection To protect against load faults, the PT4470/80 series of DC/DC converters incorporate an output current limit. Once the load current drawn from the module reaches the current limit threshold, any attempt by the load to draw additional current will result in a significant drop in the module’s regulated output voltage. The current limit circuitry incorporates a limited amount of foldback. This has the effect of slightly reducing the output current from the module when supplying an absolute short circuit. Upon removal of the load fault, the output voltage from the converter will automatically recover to its programmed regulation voltage. Output Over-Voltage Protection The PT4470/80 series of DC/DC converters incorporate circuitry that continually senses the output for an overvoltage (OV) condition. The OV threshold automatically tracks the VID output voltage program setting to a level 25% higher than that programmed at the control pins, VID0 through VID4. If the converter output voltage exceeds the OV threshold, the converter is immediately shut down and remains in a latched-off state. To resume normal operation the converter must be actively reset. This is accomplished by either cycling the status of the Inhibit control (pin 3) from “On” to “Off” and then back “On” again, or by momentarily removing the input power to the converter. For failsafe operation and redundancy, the OV protection uses circuitry that is independent of the converter’s internal feedback loop. For technical support and more information, see inside back cover or visit www.ti.com Over-Temperature Protection Over-temperature protection is provided by an internal temperature sensor, which closely monitors the temperature of the converter’s metal case. If the case temperature exceeds the specified limit (see applicable data sheet), the converter will shut down. The converter will then automatically restart when the sensed temperature drops by about 10°C. When operated outside its recommended thermal derating envelope (see data sheet SOA curves), the converter will typcially cycle on and off at intervals from a few seconds to one or two minutes. This is to ensure that the internal components are not permanently damaged from excessive thermal stress. Primary-Secondary Isolation Electrical isolation is provided between the input terminals (primary) and the output terminals (secondary). All converters are production tested to a primary-secondary withstand voltage of 1500VDC. This specification complies with UL60950 and EN60950 and the requirements for operational isolation. Operational isolation allows these converters to be configured for either a positive or negative input voltage source. The data sheet ‘Pin-Out Information’ uses shading to indicate which pins are associated with the primary. They include pins 1 through 5, inclusive. Fuse Recommendations If desired, an input fuse may be added to protect against the application of a reverse input voltage. Thermal Considerations Airflow may be necessary to ensure that the module can supply the desired load current in environments with elevated ambient temperatures. The required airflow rate may be determined from the Safe Operating Area (SOA) thermal derating chart (see converter specifications). The recommended direction for airflow is into the longest side of the module’s metal case. See Figure 1. Figure 1 Recommended direction for airflow is into (perpendicular to) the longest side. Application Notes PT4470, PT4480 Series Using the Inhibit Function on the PT4470 & PT4480 Series of Isolated DC/DC Converters The PT4470/44480 series of DC/DC converters incorporate an On/Off Inhibit function. This function may be used in applications that demand battery conservation, power-up/shutdown sequencing, and/or to coordinate power-up for active in-rush current control. The On/Off feature is provided by the Inhibit control, pin 3. The Inhibit pin of the PT4470/4480 series of converters is an active low enable. The pin must be either connected, or actively pulled low, to –Vin (pin 2) to enable the converter output (see standard application schematic). When pins 2 & 3 are connected, the converter provides a regulated output whenever a valid source voltage3 is applied between +Vin (pin 1), and –Vin (pin 2). If pin 3 is disconnected, or allowed to become high impedance, the regulator output will be disabled. 5 Table 2-1 provides details of the interface requirements for the Inhibit pin. Figure 2-1 shows how a discrete MOSFET (Q1) 4, may be referenced to –Vin and used to control the input. Table 2-1 Inhibit Control Requirements Parameter Min Max Enable (VIH) Disable (VIL) –0.5V 2.5V 0.8V (Open Circuit) Notes: 1. The Inhibit control uses –Vin (pin 2), on the primary side of the converter, as its ground reference. All voltages specified are with respect to –Vin. 6. Keep the on/off transition to less than 1ms. This prevents erratic operation of the ISR, whereby the output voltage may drift un-regulated between 0V and the rated output during power-up. Figure 2-1 +V IN 1 + 2 +V in – V in C1 1 =Enable 7 +V sns +V out 8 - 1 3 Inhibit 3 PT4472 VID0 - VID4 21 22 23 24 25 +2.5V -Vout 1 4 - 1 9 -Vsns 20 0V Q1 BSS138 PROGRAMMING PINS –V IN Turn-On Time: With input power applied, the converter typically produces a fully regulated output voltage within 25ms after applying a low-voltage signal to the Inhibit control pin. The actual turn-on time will vary with the input voltage, output load, and the total amount of capacitance connected to the output. Using the circuit of Figure 2-1, Figure 2-2 shows the typical output voltage and input current waveforms of a PT4472 after Q 1 is turned on. The turn on of Q1 correlates to the fall in Vinh. The output voltage was set to 2.5V. The waveform was measured with a 48-Vdc input voltage, and 15-A load current. Figure 2-2 2. The internal circuitry is simple pull-up resistor. The open-circuit voltage may be as high as 6.5Vdc. 3. These converters incorporate an “Under-Voltage Lockout” (UVLO) function. This function automatically disables the converter output until there is sufficient input voltage to produce a regulated output. Table 2 gives the applicable UVLO thresholds. Table 2-2 UVLO Thresholds 1 Series UVLO Threshold PT4470 PT4480 17.0V Typical 34.5V Typical Vout (1V/Div) Iin (2A/Div) Vin Range 18 – 36V 36 – 75V 4. The Inhibit input must be controlled with an opencollector (or open-drain) discrete transistor or MOSFET. Do not use a pull-up resistor. Vinh (5V/Div) HORIZ SCALE: 5ms/Div 5. When the converter output is disabled, the current drawn from the input supply is typically reduced to 4mA (10mA maximum). 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