A5975DTR STMicroelectronics, A5975DTR Datasheet
A5975DTR
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A5975DTR Summary of contents
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Features ■ Qualified following the AEC-Q100 requirements (see PPAP for more details) ■ output current ■ Operating input voltage from ■ 3 (±2%) reference voltage ■ Output voltage adjustable from ...
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Contents Contents 1 Pin settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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A5975D 8.1 Component selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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List of tables List of tables Table 1. Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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A5975D List of figures Figure 1. Application schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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Pin settings 1 Pin settings 1.1 Pin connection Figure 2. Pin connection (top view) 1.2 Pin description Table 1. Pin description N Pin 1 OUT 2 SYNCH 3 INH 4 COMP GND 8 V 6/50 ...
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A5975D 2 Electrical data 2.1 Maximum ratings Table 2. Absolute maximum ratings Symbol V Input voltage 8 OUT pin DC voltage V 1 OUT pin peak voltage at Δt = 0.1 μs I Maximum output current ...
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Electrical characteristics 3 Electrical characteristics T = -40 °C to 125 ° Table 4. Electrical characteristics Symbol Operating input V CC voltage range MOSFET on- R DS(on) resistance Maximum limiting I L current f Switching frequency SW Duty ...
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A5975D Table 4. Electrical characteristics (continued) Symbol High input voltage Low input voltage Slave synch current Master output amplitude Output pulse width Reference section Reference voltage Line regulation Load regulation Short-circuit current 1. Guaranteed by design. Parameter Test condition V ...
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Datasheet parameters over the temperature range 4 Datasheet parameters over the temperature range 100% of the population in the production flow is tested at three different ambient temperatures (-40 °C, +25 °C, and +125 °C) to guarantee the datasheet parameters ...
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A5975D 5 Functional description The main internal blocks are shown in the device block diagram in ● A voltage regulator supplying the internal circuitry. From this regulator, a 3.3 V reference voltage is externally available ● A voltage monitor circuit ...
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Functional description 5.1 Power supply and voltage reference The internal regulator circuit (shown in voltage pre-regulator, the bandgap voltage reference and the bias block that provides current to all the blocks. The starter supplies the start-up currents to the entire ...
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A5975D which provides the synchronization signal to the others. Therefore the SYNCH is an I/O pin to deliver or recognize a frequency signal. The synchronization circuitry is powered by the internal reference (V V pin and the signal ground of ...
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Functional description Figure 6. Synchronization example 5.4 Current protection The A5975D features two types of current limit protection; pulse-by-pulse and frequency foldback. The schematic of the current limitation circuitry for the pulse-by-pulse protection is shown in Figure 7. The output ...
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A5975D Figure 7. Current limitation circuitry 5.5 Error amplifier The voltage error amplifier is the core of the loop regulation transconductance operational amplifier whose non inverting input is connected to the internal voltage reference (1.235 V), while ...
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Functional description However, there is a limit introduced by the recovery time of the recirculation diode. In fact, when the current of the power element is equal to the inductor current, the diode turns off and the drain of the ...
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A5975D 5.7 Inhibit function The inhibit feature is used to put the device in standby mode. With the INH pin higher than 2.2 V, the device is disabled and the power consumption is reduced to less than 100 µA. With ...
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Additional features and protection 6 Additional features and protection 6.1 Feedback disconnection If the feedback is disconnected, the duty cycle increases towards the maximum allowed value, bringing the output voltage close to the input supply. This condition could destroy the ...
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A5975D 7 Closing the loop Figure 9. Block diagram of the loop 7.1 Error amplifier and compensation network The output LC filter of a step-down converter contributes with 180-degree phase shift in the control loop. For this reason a compensation ...
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Closing the loop Figure 10. Error amplifier equivalent circuit and compensation network The poles of this transfer function are (if C Equation 3 Equation 4 whereas the zero is defined as: Equation the low frequency which sets ...
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A5975D 7.2 LC filter The transfer function of the LC filter is given by: Equation where R is defined as the ratio between V LOAD If R >>ESR, the previous expression of A ...
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Closing the loop 7.3 PWM comparator The PWM gain is given by the following formula: Equation 12 where V is the maximum value of a sawtooth waveform and V OSCMAX minimum value. A voltage feed-forward is implemented to ensure a ...
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A5975D Figure 11. Module plot Figure 12. Phase plot The cut-off frequency and the phase margin are: Equation 38kHz Phase margin = 45° C Doc ID 018760 Rev 1 Closing the loop 23/50 ...
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Application information 8 Application information 8.1 Component selection ● Input capacitor The input capacitor must be able to support the maximum input operating voltage and the maximum RMS input current. As step-down converters draw current from the input in pulses, ...
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A5975D ● Tantalum capacitors: Very good, small tantalum capacitors with very low ESR are becoming more available. However, they can occasionally burn if subjected to very high current during charge. Therefore better to avoid this type of capacitor ...
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Application information Equation 21 and it can be seen that if the inductor value decreases, the peak current (which must be lower than the current limit of the device) increases. So, when the peak current is fixed, a higher inductor ...
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A5975D Figure 13. Layout example 8.3 Thermal considerations 8.3.1 Thermal resistance the equivalent static thermal resistance junction-to-ambient of the device; it can be THJ-A calculated as the parallel of many paths of heat conduction from the junction ...
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Application information ● Switching losses due to turning on and off. These are derived using the following equation: Equation where T and T RISE switching losses when driving an inductive load (see switching time. Figure 14. Switching ...
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A5975D The overall losses are: Equation The junction temperature of device is: Equation 27 Equation 28 8.3.2 Thermal impedance Z The thermal impedance of the system, considered as the device in the HSO8 package soldered on the ...
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Application information Figure 15. Power losses estimation (V The red trace represents the maximum power which can be taken away, as calculated above, while the other traces are the total internal losses for different output voltages. The embedded conduction losses ...
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A5975D In applications where the current to the output is pulsed, the thermal impedance should be considered instead of the thermal resistance. The thermal impedance of the system could be much lower than the thermal resistance, which is a static ...
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Application information 8.4 RMS current of the embedded power MOSFET As the A5975D embeds the high side switch, the internal power dissipation is sometimes the bottleneck for the output current capability (refer to operating temperature). Nevertheless, as mentioned in the ...
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A5975D This can be understood considering the inductor current ripple during the ON and OFF phases: ● ON phase Equation 29 ● OFF phase Equation 30 where V is the voltage drop across the diode, DCR D In short-circuit conditions, ...
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Application information Figure 19. Short-circuit current V Figure 20. Short-circuit current V 34/ Doc ID 018760 Rev 1 A5975D ...
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A5975D Figure 21. Short-circuit current V 8.6 Application circuit Figure 22 shows the demonstration board application circuit, where the input supply voltage can range from and the output voltage is adjustable from 1.235 ...
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... POSCAP 6TVB330ML 330 µH, 25 mΩ 5.6 kΩ, 1%, 0.1 W 0603 3.3 kΩ, 1%, 0.1 W 0603 10 kΩ, 1%, 0.1 W 0603 STPS5L60S MSS1246T-123 12 µH, I Doc ID 018760 Rev 1 Description Manufacturer Taiyo Yuden Sanyo STMicroelectronics 3A Coilcraft RMS 20°C A5975D ...
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A5975D Figure 25. PCB layout (front side) 8.7 Positive buck-boost regulator The device can be used to implement a step-up/down converter with a positive output voltage. The output voltage is given by: Equation 33 where the ideal duty cycle D ...
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Application information The switch peak current must be lower than the minimum current limit of the overcurrent protection (see Table 4 DC current of the device consequence, the maximum output current is: Equation 37 where I represents the ...
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A5975D Equation 40 Equation 41 An important point to take into account is that the ground pin of the device is connected to the negative output voltage. Therefore, the device is subjected to a voltage equal to V which must ...
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Application information Figure 29. 350 mA LED boost current source The device is powered from the output voltage so the maximum voltage drop across the LEDs and resistor sense The output voltage is given by: Equation 42 ...
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A5975D The switch peak current must be lower than the minimum current limit of the overcurrent protection (see Table 4 DC current of the device consequence, the maximum output current is: Equation 46 where I represents the rated ...
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Application information Equation 47 MLCCs (multiple layer ceramic capacitor) with values in the range of 10 µF-22 µF and rated voltages in the range of 10 V-25 V are available today at relatively low cost from many manufacturers. These capacitors ...
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A5975D 8.12 External soft-start network At startup, the device can quickly increase the current up to the current limit in order to charge the output capacitor. If soft ramp-up of the output voltage is required, an external soft-start network can ...
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Typical characteristics 9 Typical characteristics Figure 33. Line regulator Figure 35. Output voltage vs. junction temperature Figure 37. Quiescent current vs. junction temperature 44/50 Figure 34. Shutdown current vs. junction temperature Figure 36. Switching frequency vs. junction temperature Figure 38. ...
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A5975D Figure 39. Junction temperature vs. output current (V Figure 41. Efficiency vs. output current (V IN Figure 40. Efficiency vs. output current Doc ID 018760 Rev 1 Typical characteristics ( 45/50 ...
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Package mechanical data 10 Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ® ECOPACK packages, depending on their level of environmental compliance. ECOPACK specifications, grade definitions, and product status are available ...
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A5975D Figure 42. Package dimensions Doc ID 018760 Rev 1 Package mechanical data 47/50 ...
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... Ordering information 11 Ordering information Table 11. Ordering information Order codes A5975D A5975DTR 48/50 Package HSOP8 Doc ID 018760 Rev 1 A5975D Packaging Tube Tape and reel ...
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A5975D 12 Revision history Table 12. Document revision history Date 19-Apr-2011 Revision 1 Initial release Doc ID 018760 Rev 1 Revision history Changes 49/50 ...
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