A5975ADTR STMicroelectronics, A5975ADTR Datasheet
A5975ADTR
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A5975ADTR Summary of contents
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Features ■ Qualified following the AEC-Q100 requirements (see PPAP for more details) ■ 2 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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A5975AD 8.1 Component selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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List of tables List of tables Table 1. Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...
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A5975AD 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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A5975AD 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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A5975AD 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, +125 °C) to guarantee the datasheet parameters inside ...
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A5975AD 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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A5975AD The synchronization feature of a set of the A5975AD is simply obtained by connecting together their SYNCH pins. The device with the highest switching frequency is the master which provides the synchronization signal to the others. Therefore the SYNCH ...
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Functional description Figure 6. Synchronization example 5.4 Current protection The A5975AD 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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A5975AD 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 5.6 PWM comparator and power stage This block compares the oscillator sawtooth and the error amplifier output signals to generate the PWM signal for the driving stage. The power stage is a highly critical block functions ...
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A5975AD Figure 8. Driving circuitry 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 ...
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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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A5975AD 7 Closing the loop Figure 9. Block diagram of the loop Doc ID 018761 Rev 1 Closing the loop 19/50 ...
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Closing 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 network between the COMP pin and GROUND is added. ...
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A5975AD Equation 4 whereas the zero is defined as: Equation the low frequency which sets the bandwidth, while the zero F P1 the frequency of the double pole of the LC filter (see below). F frequency. 7.2 ...
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Closing the loop Similarly for A LC Equation 11 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 ...
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A5975AD Figure 11. Module plot Figure 12. Phase plot The cut-off frequency and the phase margin are: Equation 44kHz Phase margin = 54° C Doc ID 018761 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, the ...
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A5975AD The drawback is the considerably high cost. 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 ...
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Application information Equation 21 and it can be observed 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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A5975AD 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 losses ...
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A5975AD The overall losses are: Equation The junction temperature of the device is: Equation 27 Equation 28 8.3.2 Thermal impedance Z The thermal impedance of the system, considered as the device in 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, whilst the other traces are the total internal losses for different output voltage. The embedded conduction losses ...
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A5975AD =40 °C and AMB As a consequence, the calculation of the internal power losses must be done for each specific operating condition given by the final application. In applications where the current to the output is ...
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Application information 8.4 RMS current of the embedded power MOSFET As the A5975AD 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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A5975AD 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 V is ...
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Application information Figure 19. Short-circuit current V Figure 20. Short-circuit current V 34/ Doc ID 018761 Rev 1 A5975AD ...
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A5975AD 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 µF, 25 mΩ 5.6 kΩ, 1%, 0.1 W 0603 3.3 kΩ, 1%, 0.1 W 0603 4.7 kΩ, 1%, 0.1 W 0603 STPS3L40U MSS1246T-103ML 10 µH, I Doc ID 018761 Rev 1 Description Manufacturer Taiyo Yuden Sanyo STMicroelectronics 20 °C 2.8 A Coilcraft RMS A5975AD ...
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A5975AD 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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A5975AD 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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A5975AD 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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A5975AD 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. Junction temperature vs. output current (V 44/50 Figure 34. Shutdown current vs. junction temperature Figure 36. Junction temperature vs. output current (V ...
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A5975AD Figure 39. Efficiency vs. output current ( Doc ID 018761 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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A5975AD Table 10. HSOP8 mechanical data Dim. Min ccc Figure 40. Package dimensions mm Typ. Max. 1.70 0.00 0.10 1.25 0.31 0.51 0.17 0.25 4.80 4.90 ...
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... Ordering information 11 Ordering information Table 11. Ordering information Order codes A5975AD A5975ADTR 48/50 Package HSOP8 Doc ID 018761 Rev 1 A5975AD Packaging Tube Tape and reel ...
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A5975AD 12 Revision history Table 12. Document revision history Date 19-Apr-2011 Revision 1 Initial release Doc ID 018761 Rev 1 Revision history Changes 49/50 ...
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