PTQA430025N2AD

Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 www.ti.com SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 100-W 48-V INPUT ISOLATED DC/DC CONVERTER Check for Samples: PTQA430025, PTQA430033, PTQA420050 FEATURES 1 • • • • • • • • • • • • • • DESCRIPTION 100-W Output Input Voltage Range: 36 V to 75 V 92% Efficiency 1500 Vdc Isolation Fast Transient Response On/Off Control Overcurrent Protection Differential Remote Sense Adjustable Output Voltage Output Overvoltage Protection Over-Temperature Shutdown Undervoltage Lockout Standard 1/4-Brick Footprint UL Safety Agency Approval The PTQA series of power modules are single-output isolated DC/DC converters, housed in an industry standard quarter-brick package. These modules are rated up to 100W with a maximum load current of up to 30 A. The PTQA series operates from a standard 48-V telecom central office (CO) supply and occupies only 3.3 in2 of PCB area. The modules offer OEMs a compact and flexible high-output power source in an industry standard footprint. They are suitable for distributed power applications in both telecom and computing environments, and may be used for powering high-end microprocessors, DSPs, general purpose logic and analog. Features include a remote On/Off control with optional logic polarity, an undervoltage lockout (UVLO), a differential remote sense, and an industry standard output voltage adjustment using an external resistor. Protection features include output overcurrent protection (OCP), overvoltage protection (OVP), and thermal shutdown (OTP). The modules are fully integrated for stand-alone operation, and require no additional components. STANDARD APPLICATION SENSE (+) +VO 7 +VI Sense(+) 1 +V I CI (Optional) 3 −VI +VO PTQA430xxxN Adjust −VI Remote On/Off 2 −VO Sense(−) 8 6 CO (Optional) 4 L O A D −VO 5 SENSE (–) 1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2006–2009, Texas Instruments Incorporated Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 www.ti.com This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. ORDERING INFORMATION For the most current package and ordering information, see the Package Option Addendum at the end of this datasheet, or see the TI website at www.ti.com. Table 1. PART NUMBERING SCHEME Input Voltage PTQA Output Current 4 4 = 48 V Output Voltage 30 Enable 033 Electrical Options N 30 = 30A 025 = 2.5 V N = Negative 20 = 20A 033 = 3.3 V P = Positive 2 Pin Style A D 2 = VO Adjust D = Through-hole, Pb-free S = SMD, SnPb solder ball 050 = 5.0 V Z = SMD, SnAgCu solder ball ABSOLUTE MAXIMUM RATING UNIT TA VI, MAX Operating Temperature Range Maximum Input Voltage –40°C to 85°C (1) Over VI Range Continuous voltage 80 V Peak voltage for 100 ms duration 100 V PTQA420050x2 PO, Maximum Output Power PTQA430033x2 100 W MAX PTQA430025x2 TS Storage Temperature Mechanical Shock Mechanical Vibrarion Per Mil-STD-883, Method 2002.3 1 ms, 1/2 Sine, mounted Per Mil-STD-883, Method 2007.2 20-2000 Hz, PCB mounted AD Suffix 250 G AS or AZ Suffix 175 G AD Suffix 15 G AS or AZ Suffix 2.5 G Weight Flammability (1) 2 75 W –40°C to 125°C 30 grams Meets UL 94V-O See SOA curves or consult factory for appropriate derating. Submit Documentation Feedback Copyright © 2006–2009, Texas Instruments Incorporated Product Folder Links: PTQA430025 PTQA430033 PTQA420050 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 www.ti.com SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 ELECTRICAL CHARACTERISTICS PTQA430025 (Unless otherwise stated, TA =25°C, VI = 48 V, VO = 2.5 V, CO = 0 μF, and IO = IOmax) PARAMETER PTQA430025 TEST CONDITIONS MIN IO Output Current Over VI range 0 VI Input Voltage Range Over IO Range 36 VO tol Set Point Voltage Tolerance Regtemp Temperature Variation –40°C >TA > 85°C Regline Line Regulation Over VI range Regload Load Regulation Over IO range ΔVotot Total Output Voltage Variation Includes set-point, line, load, –40°C >TA > 85°C ΔVADJ Output Adjust Range PO ≤ 75 W η Efficiency IO = 50% IOmax VR VO Ripple (pk-pk) 20 MHz bandwidth ttr Transient Response ΔVtr TYP MAX 30 48 75 UNIT A V ±1 (1) %VO ±1.15 %VO ±5 mV ±5 ±1.5 –20 mV ±3 %VO 10 %VO 100 mVpp 91% 50 0.1 A/μs slew rate, 50% to 75% IOmax 150 μs mV VO over/undershoot 25 ITRIP Overcurrent Threshold Shutdown, followed by auto-recovery 41 A OVP Output Overvoltage Protection Output shutdown and latch off 120 %VO OTP Over Temperature Protection Temperature Measurement at thermal sensor. Hysteresis = 10°C nominal. 105 °C fs Switching Frequency Over VI range 300 kHz UVLO Undervoltage Lockout VOFF VI decreasing, IO = 6 A 32.5 VHYS Hysteresis 1.5 V On/Off Input: Negative Enable VIH Input High Voltage VIL Input Low Voltage IIL Input Low Current Referenced to –VI 2.4 Open (2) –0.2 0.8 –0.3 V mA On/Off Input: Positive Enable VIH Input High Voltage VIL Input Low Voltage IIL Input Low Current IISB Standby Input Current Output disabled (pin 2 status set to Off) CI External Input Capacitance Between +VI and –VI CO External Output Capacitance Between +VO and –VO Isolation Voltage Input-to-output and input-to-case Isolation Capacitance Input-to-output Isolation Resistance Input-to-output (1) (2) Referenced to –VI 4.5 Open (2) –0.2 0.8 V –0.5 mA 37 mA μF 100 0 30000 1500 μF Vdc 1200 10 pF MΩ If Sense(–) is not used, pin 5 must be connected to pin 4 for optimum output voltage accuracy. The Remote On/Off input has an internal pull-up and may be controlled with an open collector (drain) interface. An open circuit correlates to a logic high. Consult the application notes for interface considerations. Copyright © 2006–2009, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: PTQA430025 PTQA430033 PTQA420050 3 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 www.ti.com ELECTRICAL CHARACTERISTICS PTQA430033 (Unless otherwise stated, TA =25°C, VI = 48 V, VO = 3.3 V, CO = 0 μF, and IO = IOmax) PARAMETER PTQA430033 TEST CONDITIONS MIN IO Output Current Over VI range 0 VI Input Voltage Range Over IO Range 36 VO tol Set Point Voltage Tolerance Regtemp Temperature Variation –40°C >TA > 85°C Regline Line Regulation Over VI range Regload Load Regulation Over IO range ΔVotot Total Output Voltage Variation Includes set-point, line, load, –40°C >TA > 85°C ΔVADJ Output Adjust Range PO ≤ 100 W η Efficiency IO = 50% IOmax VR VO Ripple (pk-pk) 20 MHz bandwidth ttr Transient Response ΔVtr TYP MAX 30 48 75 UNIT A V ±1 (1) %VO ±1.15 %VO ±5 mV ±5 ±1.5 –20 mV ±3 %VO 10 %VO 100 mVpp 92% 50 0.1 A/μs slew rate, 50% to 75% IOmax 150 μs mV VO over/undershoot 33 ITRIP Overcurrent Threshold Shutdown, followed by auto-recovery 41 A OVP Output Overvoltage Protection Output shutdown and latch off 120 %VO OTP Over Temperature Protection Temperature Measurement at thermal sensor. Hysteresis = 10°C nominal. 105 °C fs Switching Frequency Over VI range 300 kHz UVLO Undervoltage Lockout VOFF VI decreasing, IO = 6 A 32.5 VHYS Hysteresis 1.5 V On/Off Input: Negative Enable VIH Input High Voltage VIL Input Low Voltage IIL Input Low Current Referenced to –VI 2.4 Open (2) –0.2 0.8 –0.3 V mA On/Off Input: Positive Enable VIH Input High Voltage VIL Input Low Voltage IIL Input Low Current IIsb Standby Input Current Output disabled (pin 2 status set to Off) CI External Input Capacitance Between +VI and –VI CO External Output Capacitance Between +VO and –VO Isolation Voltage Input-to-output and input-to-case Isolation Capacitance Input-to-output Isolation Resistance Input-to-output (1) (2) 4 Referenced to –VI 4.5 Open (2) –0.2 0.8 V –0.5 mA 42 mA μF 100 0 30000 1500 μF Vdc 1200 10 pF MΩ If Sense(–) is not used, pin 5 must be connected to pin 4 for optimum output voltage accuracy. The Remote On/Off input has an internal pull-up and may be controlled with an open collector (drain) interface. An open circuit correlates to a logic high. Consult the application notes for interface considerations. Submit Documentation Feedback Copyright © 2006–2009, Texas Instruments Incorporated Product Folder Links: PTQA430025 PTQA430033 PTQA420050 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 www.ti.com SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 ELECTRICAL CHARACTERISTICS PTQA420050 (Unless otherwise stated, TA =25°C, VI = 48 V, VO = 5.0 V, CO = 0 μF, and IO = IOmax) PARAMETER PTQA420050 TEST CONDITIONS MIN IO Output Current Over VI range 0 VI Input Voltage Range Over IO Range 36 VO tol Set Point Voltage Tolerance Regtemp Temperature Variation –40°C >TA > 85°C Regline Line Regulation Over VI range Regload Load Regulation Over IO range ΔVotot Total Output Voltage Variation Includes set-point, line, load, –40°C >TA > 85°C ΔVADJ Output Adjust Range PO ≤ 100 W η Efficiency IO = 50% IOmax VR VO Ripple (pk-pk) 20 MHz bandwidth ttr Transient Response ΔVtr TYP MAX 20 48 75 UNIT A V ±1 (1) %VO ±1.15 %VO ±5 mV ±5 ±1.5 –20 mV ±3 %VO 10 %VO 100 mVpp 92.5% 50 0.1 A/μs slew rate, 50% to 75% IOmax 100 μs mV VO over/undershoot 50 ITRIP Overcurrent Threshold Shutdown, followed by auto-recovery 29 A OVP Output Overvoltage Protection Output shutdown and latch off 120 %VO OTP Over Temperature Protection Temperature Measurement at thermal sensor. Hysteresis = 10°C nominal. 105 °C fs Switching Frequency Over VI range 300 kHz UVLO Undervoltage Lockout VOFF VI decreasing, IO = 6 A 32.5 VHYS Hysteresis 1.5 V On/Off Input: Negative Enable VIH Input High Voltage VIL Input Low Voltage IIL Input Low Current Referenced to –VI 2.4 Open (2) –0.2 0.8 –0.3 V mA On/Off Input: Positive Enable VIH Input High Voltage VIL Input Low Voltage IIL Input Low Current IIsb Standby Input Current Output disabled (pin 2 status set to Off) CI External Input Capacitance Between +VI and –VI CO External Output Capacitance Between +VO and –VO Isolation Voltage Input-to-output and input-to-case Isolation Capacitance Input-to-output Isolation Resistance Input-to-output (1) (2) Referenced to –VI 4.5 Open (2) –0.2 0.8 V –0.5 mA 58 mA μF 100 0 30000 1500 μF Vdc 1200 10 pF MΩ If Sense(–) is not used, pin 5 must be connected to pin 4 for optimum output voltage accuracy. The Remote On/Off input has an internal pull-up and may be controlled with an open collector (drain) interface. An open circuit correlates to a logic high. Consult the application notes for interface considerations. Copyright © 2006–2009, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: PTQA430025 PTQA430033 PTQA420050 5 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 www.ti.com PIN DESCRIPTIONS +VI: The positive input for the module with respect to –VI. When powering the module from a –48-V telecom central office supply, this input is connected to the primary system ground. –VI: The negative input supply for the module, and the 0 VDC reference for the Remote On/Off input. When powering the module from a +48-V supply, this input is connected to the 48-V return. Remote On/Off: This input controls the On/Off status of the output voltage. It is either driven low (–VI potential), or left open-circuit. For units identified with the NEN option, applying a logic low to this pin will enable the output. And for units identified with the PEN option, the output will be disabled. VO Adjust: Allows the output voltage to be trimmed by up or down between +10% and –20% of its nominal value. The adjustment method uses a single external resistor. Connecting the resistor between VO Adjust and –VO adjusts the output voltage lower, and placing it between VO Adjust and +VO adjusts the output higher. The calculations for the resistance value follows industry standard formulas. For further information consult the application note on output voltage adustment. +VO: The positive power output with respect to –VO, which is DC isolated from the input supply pins. If a negative output voltage is desired, +VO should be connected to the secondary circuit common and the output taken from –VO. –VO: The negative power output with respect to +VO, which is DC isolated from the input supply pins. This output is normally connected to the secondary circuit common when a positive output voltage is desired. Sense(+): Provides the converter with an output sense capability to regulate the set-point voltage directly at the load. When used with Sense(-), the regulation circuitry will compensate for voltage drop between the converter and the load. The pin may be left open circuit, but connecting it to +VO improves load regulation. Sense(–): Provides the converter with an output sense capability when used in conjunction with Sense(+) input. For optimum output voltage accuracy this pin should always be connected to –VO. PTQA430xxxN (Top View) +VO 1 +VI Sense(+) 2 On/Off 3 −VI Adjust Sense(−) −VO 6 Submit Documentation Feedback 8 7 6 5 4 Copyright © 2006–2009, Texas Instruments Incorporated Product Folder Links: PTQA430025 PTQA430033 PTQA420050 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 www.ti.com SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 TYPICAL CHARACTERISTICS PTQA430025, VO = 2.5 V (1) (2) EFFICIENCY vs LOAD CURRENT OUTPUT RIPPLE vs LOAD CURRENT 95 VI = 75 V 75 VI = 60 V 70 VI = 48 V 60 55 50 VI= 75 V 10 40 PD − Power Dissipation − W VO − Output Voltage Ripple − mVPP 80 65 VI= 60 V 45 85 Efficiency − % 12 50 VI = 36 V 90 η− POWER DISSIPATION vs LOAD CURRENT 35 30 25 20 VI= 48 V 15 VI= 36 V 8 VI = 75 V VI = 60 V 6 VI = 48 V 4 VI = 36 V 10 2 5 45 0 40 0 5 10 15 20 25 0 0 30 5 IO − Output Current − A Figure 1. 10 15 20 IO − Output Current − A 25 30 0 5 10 15 20 25 30 IO − Output Current − A Figure 2. Figure 3. AMBIENT TEMPERATURE vs LOAD CURRENT 90 TA - Ambient Temperature - °C 80 Natural Convection 70 LFM = 400 60 LFM = 200 50 LFM = 100 40 30 VI = 48 V 20 0 5 10 15 20 IO - Output Current - A 25 30 Figure 4. (1) (2) All data listed in Figure 1, Figure 2, and Figure 3 have been developed from actual products tested at 25°C. This data is considered typical data for the dc-dc converter. The temperature derating curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperature. Derating limits apply to modules soldered directly to a 100–mm × 100–mm, double-sided PCB with 2 oz. copper. For surface mount packages, multiple vias (plated through holes) are required to add thermal paths around the power pins. Please refer to the mechanical specification for more information. Applies to Figure 4. Copyright © 2006–2009, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: PTQA430025 PTQA430033 PTQA420050 7 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 www.ti.com TYPICAL CHARACTERISTICS PTQA430033, VO = 3.3 V (1) (2) EFFICIENCY vs LOAD CURRENT 40 VI = 36 V 90 VO − Output Voltage Ripple − mVPP 85 Efficiency − % 80 η− 14 VI= 60 V 35 75 VI = 48 V 70 VI = 60 V VI = 75 V 65 POWER DISSIPATION vs LOAD CURRENT 60 55 50 VI = 75 V VI= 75 V 12 30 PD – Power Dissipation – W 95 OUTPUT RIPPLE vs LOAD CURRENT 25 20 VI= 48 V 15 VI= 36 V 10 10 8 VI = 60 V 6 4 2 5 45 40 0 5 10 15 20 25 30 VI = 48 V 0 0 0 5 IO − Output Current − A 10 15 20 IO − Output Current − A Figure 5. 25 30 0 Figure 6. 5 VI = 36 V 10 15 20 IO – Output Current – A 25 30 Figure 7. AMBIENT TEMPERATURE vs LOAD CURRENT 90 TA − Ambient Temperature − °C 80 70 400 LFM 60 50 200 LFM 40 100 LFM 30 Natural Convection VI = 48 V 20 0 5 10 15 20 25 30 IO − Output Current − A Figure 8. (1) (2) 8 All data listed in Figure 5, Figure 6, and Figure 7 have been developed from actual products tested at 25°C. This data is considered typical data for the dc-dc converter. The temperature derating curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperature. Derating limits apply to modules soldered directly to a 100–mm × 100–mm, double-sided PCB with 2 oz. copper. For surface mount packages, multiple vias (plated through holes) are required to add thermal paths around the power pins. Please refer to the mechanical specification for more information. Applies to Figure 8. Submit Documentation Feedback Copyright © 2006–2009, Texas Instruments Incorporated Product Folder Links: PTQA430025 PTQA430033 PTQA420050 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 www.ti.com SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 TYPICAL CHARACTERISTICS PTQA420050, VO = 5.0 V (1) (2) EFFICIENCY vs LOAD CURRENT OUTPUT RIPPLE vs LOAD CURRENT 40 10 VI = 36 V VI = 60 V VI = 75 V 35 85 VO − Output Voltage Ripple − mVPP 90 VI = 60 V VI = 48 V 80 VI = 75 V 75 70 VI 36 V 48 V 60 V 75 V 65 5 10 15 IO − Output Current − A 25 20 VI = 48 V 15 VI = 36 V 10 VI 36 V 48 V 60 V 75 V 5 60 0 30 36 V 48 V 60 V 75 V 8 7 VI = 60 V 6 5 4 VI = 36 V 3 2 VI = 48 V 1 VO = 5 V 0 20 VI = 75 V VI 9 PD − Power Dissipation − W 95 η − Efficiency − % POWER DISSIPATION vs LOAD CURRENT 0 5 Figure 9. 10 15 IO − Output Current − A 20 0 0 5 Figure 10. 10 15 IO − Output Current − A 20 Figure 11. AMBIENT TEMPERATURE vs LOAD CURRENT 90 400 LFM TA − Ambient Temperature − °C 80 70 100 LFM 60 200 LFM 50 40 30 Natural Convection VO = 5 V VI = 48 V 20 0 5 10 15 20 IO − Output Current − A Figure 12. (1) (2) All data listed in Figure 9, Figure 10, and Figure 11 have been developed from actual products tested at 25°C. This data is considered typical data for the dc-dc converter. The temperature derating curves represent operating conditions at which internal components are at or below manufacturer's maximum rated operating temperature. Derating limits apply to modules soldered directly to a 100–mm × 100–mm, double-sided PCB with 2 oz. copper. For surface mount packages, multiple vias (plated through holes) are required to add thermal paths around the power pins. Please refer to the mechanical specification for more information. Applies to Figure 12. Copyright © 2006–2009, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: PTQA430025 PTQA430033 PTQA420050 9 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 www.ti.com APPLICATION INFORMATION Operating Features and System Considerations for the PTQA Series of DC/DC Converters Overcurrent Protection To protect against load faults, these converters incorporate output overcurrent protection. Applying a load to the output that exceeds the converter's overcurrent threshold (see applicable specification) will cause the output voltage to momentarily fold back, and then shut down. Following shutdown the module will periodically attempt to automatically recover by initiating a soft-start power-up. This is often described as a hiccup mode of operation, whereby the module continues in the cycle of successive shutdown and power up until the load fault is removed. Once the fault is removed, the converter automatically recovers and returns to normal operation. Output Overvoltage Protection Each converter incorporates protection circuitry that continually senses for an output overvoltage (OV) condition. The OV threshold is set approximately 20% higher than the nominal output voltage. If the converter output voltage exceeds this 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 can only be done by momentarily removing the input power to the converter. For fail-safe operation and redundancy, the OV protection uses circuitry that is independent of the converter’s internal feedback loop. Overtemperature Protection Overtemperature protection is provided by an internal temperature sensor, which closely monitors the temperature of the converter’s printed circuit board (PCB). If the sensor exceeds a temperature of approximately 105°C, the converter will shut down. The converter will then automatically restart when the sensed temperature drops back to approximately 95°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. Undervoltage Lockout The Undervoltage lockout (UVLO) is designed to prevent the operation of the converter until the input voltage is at the minimum input voltage. This prevents 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 circuitry also overrides the operation of the Remote On/Off control. Primary-Secondary Isolation These converters incorporate electrical isolation between the input terminals (primary) and the output terminals (secondary). All converters are production tested to a withstand voltage of 1500 VDC. This specification complies with UL60950 and EN60950 requirements. This allows the converter to be configured for either a positive or negative input voltage source. The data sheet Pin Descriptions section provides guidance as to the correct reference that must be used for the external control signals. Input Current Limiting The converter is not internally fused. For safety and overall system protection, the maximum input current to the converter must be limited. Active or passive current limiting can be used. Passive current limiting can be a fast acting fuse. A 125-V fuse, rated no more than 10 A, is recommended. Active current limiting can be implemented with a current limited Hot-Swap controller. 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 typical characteristics). 10 Submit Documentation Feedback Copyright © 2006–2009, Texas Instruments Incorporated Product Folder Links: PTQA430025 PTQA430033 PTQA420050 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 www.ti.com SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 Differential Remote Sense The remote sense pins allows the converter to precisely regulate the DC output voltage at a remote location. This might be a power plane on an inner layer of the host PCB. Connecting Sense(+) directly to +VO , and Sense(–) to –VO will improve output voltage accuracy. In the event that the sense pins are left open-circuit, an internal 10-Ω resistor between each sense pin and its corresponding output prevents an excessive rise in the output voltage. For practical reasons, the amount of IR voltage compensation should be limited to 0.5 V maximum. The remote sense feature is designed to compensate for limited amounts of IR voltage drop. It is not intended to compensate for the forward drop of a non-linear or frequency dependent components that may be placed in series with the converter output. Examples of such components include OR-ing diodes, filter inductors, ferrite beads, and fuses. Enclosing these components with the remote sense connections effectively places them inside the regulation control loop, which can affect the stability of the regulator. Copyright © 2006–2009, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: PTQA430025 PTQA430033 PTQA420050 11 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 www.ti.com Using the Remote On/Off Function on the PTQA Series of DC/DC Converters For applications requiring output voltage On/Off control, the PTQA series of DC/DC converters incorporate a Remote On/Off control (pin 2). This feature can be used to switch the module off without removing the applied input source voltage. When placed in the Off state, the standby current drawn from the input source is typically reduced to 3 mA. Negative Output Enable (NEN) Models using the negative enable option, the Remote On/Off (pin 2) control must be driven to a logic low voltage for the converter to produce an output. This is accomplished by either permanently connecting pin 2 to –VI (pin 3), or driving it low with an external control signal. Table 2 shows the input requirements of pin 2 for those modules with the NEN option. Table 2. On/Off Control Requirements for Negative Enable PARAMETER MIN TYP MAX VIH Disable 2.4 V 20 V VIL Enable –0.2 V 0.8 V Vo/c Open-Circuit II Pin 2 at –VI 9V 15 V –0.75 mA Positive Output Enable (PEN) For those models with the positive enable (PEN) option, leaving pin 2 open circuit, (or driving it to an equivalent logic high voltage), will enable the converter output. This allows the module to produce an output voltage whenever a valid input source voltage is applied to +VI with respect to –VI. If a logic-low signal is then applied to pin 2 the converter output is disabled. Table 3 gives the input requirements of pin 2 for modules with the PEN option. Table 3. On/Off Control Requirements for Positive Enable PARAMETER MIN TYP MAX VIH Enable 4.5 V 20 V VIL Disable –0.2 V 0.8 V Vo/c Open-Circuit II Pin 2 at –VI 5V 7V –0.5 mA Notes: 1. The Remote On/Off control uses –VI (pin 3) as its ground reference. All voltages are with respect to –VI. 2. An open-collector device (preferably a discrete transistor) is recommended. A pull-up resistor is not required. If one is added the pull-up voltage should not exceed 20 V. Caution: Do not use a pull-resistor to +VI (pin 1). The remote On/Off control has a maximum input voltage of 20 V. Exceeding this voltage will overstress, and possibly damage, the converter. 3. The Remote On/Off pin may be controlled with devices that have a totem-pole output. This is provided the output high level voltage (VOH) meets the module's minimum VIH specified in Table 2. If a TTL gate is used, a pull-up resistor may be required to the logic supply voltage. 4. The converter incorporates an undervoltage lockout (UVLO). The UVLO keeps the converter off until the input voltage is close to the minimum specified operating voltage. This is regardless of the state of the Remote On/Off control. Consult the product specification for the UVLO input voltage thresholds. 12 Submit Documentation Feedback Copyright © 2006–2009, Texas Instruments Incorporated Product Folder Links: PTQA430025 PTQA430033 PTQA420050 Not Recommended for New Designs PTQA430025, PTQA430033, PTQA420050 www.ti.com SLTS261C – MAY 2006 – REVISED SEPTEMBER 2009 PTQA430xxxP Q1 BSS138 2 Remote On/Off 1 = Disable −VI 3 −VI Figure 13. Recommended Control or Remote On/Off Input Turn-On: With a valid input source voltage applied, the converter produces a regulated output voltage within 75 ms of the output being enabled. Figure 14 shows the output response of the PTQA430033P following the removal of the logic-low signal from the Remote On/Off (pin 2); see Figure 13. This corresponds to the drop in Q1 VGS in Figure 14. Although the rise-time of the output voltage is short (