Datasheet MAX40056F, MAX40056T, MAX40056U (Maxim) - 19
| Hersteller | Maxim |
| Beschreibung | Bidirectional Current Sense Amplifier with PWM-Rejection |
| Seiten / Seite | 21 / 19 — Typical Application Circuits (continued). MAX40056. MAX44290. Current … |
| Dateiformat / Größe | PDF / 1.4 Mb |
| Dokumentensprache | Englisch |
Typical Application Circuits (continued). MAX40056. MAX44290. Current Sensing in a 3-Phase Servo Motor
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link to page 19 MAX40056F/MAX40056T/ Bidirectional Current Sense MAX40056U Amplifier with PWM-Rejection
Typical Application Circuits (continued)
VPOWER = 9V TO 48V RSENSE_POWER Φ1 Φ2 Φ3 VDD R
MAX40056
OUT(Φ1) VDD RSENSEΦ1 REF R VDD OUT(Φ3) R OUT(Φ2)
MAX44290
RSENSEΦ2 REF
MAX40056
200kΩ 100kΩ Φ1 Φ2 Φ3 R = 5kΩ RSENSE_PGND OUT(Φ3)(V) = VREF(V) – (OUT(Φ1) +OUT(Φ2))(V) Figure 6. Current Sensing in a 3-Phase Servo Motor
Current Sensing in a 3-Phase Servo Motor
The outputs of two current sense amplifiers can be summed, as shown in Figure 6, to generate a voltage representing the third winding's current. By Kirchhoff’s Law, the third winding current equals the sum of the other two windings, so a simple op-amp summing circuit with three equal-valued resistors is sufficient to produce a voltage proportional to third winding current. Select a large enough resistor value to avoid excessively loading the op-Amp or the CSA outputs. All three amplifiers share the system reference voltage, allowing ratio-metric measurements. If the three amplifiers drive ADC inputs, they will typically share the ADC’s supply voltage. This circuit provides instantaneous winding currents of all three phases without any further computation or knowledge of the PWM pulse phases or duty cycles. Note that the supply bypass capacitors, transient suppressors and catch diodes were omitted for clarity. www.maximintegrated.com Maxim Integrated | 19 Document Outline General Description Applications Benefits and Features Typical Operating Characteristic and Simplified Block Diagram Absolute Maximum Ratings Package Information 8 µMAX 8 WLP Electrical Characteristics Typical Operating Characteristics Pin Configuration Pin Description Detailed Description Overview PWM Rejection Input Stage Low Input Offset Voltage and Low Gain Error CSA Output Voltage Reference Window Comparator and Hysteresis Applications Information Input Sense Voltage Range Choice of Reference Voltage Important Considerations Kelvin Connections Stray Inductance Typical Application Circuits Current Sensing in a 3-Phase Servo Motor Ordering Information Revision History
Typical Application Circuits (continued)
VPOWER = 9V TO 48V RSENSE_POWER Φ1 Φ2 Φ3 VDD R
MAX40056
OUT(Φ1) VDD RSENSEΦ1 REF R VDD OUT(Φ3) R OUT(Φ2)
MAX44290
RSENSEΦ2 REF
MAX40056
200kΩ 100kΩ Φ1 Φ2 Φ3 R = 5kΩ RSENSE_PGND OUT(Φ3)(V) = VREF(V) – (OUT(Φ1) +OUT(Φ2))(V) Figure 6. Current Sensing in a 3-Phase Servo Motor
Current Sensing in a 3-Phase Servo Motor
The outputs of two current sense amplifiers can be summed, as shown in Figure 6, to generate a voltage representing the third winding's current. By Kirchhoff’s Law, the third winding current equals the sum of the other two windings, so a simple op-amp summing circuit with three equal-valued resistors is sufficient to produce a voltage proportional to third winding current. Select a large enough resistor value to avoid excessively loading the op-Amp or the CSA outputs. All three amplifiers share the system reference voltage, allowing ratio-metric measurements. If the three amplifiers drive ADC inputs, they will typically share the ADC’s supply voltage. This circuit provides instantaneous winding currents of all three phases without any further computation or knowledge of the PWM pulse phases or duty cycles. Note that the supply bypass capacitors, transient suppressors and catch diodes were omitted for clarity. www.maximintegrated.com Maxim Integrated | 19 Document Outline General Description Applications Benefits and Features Typical Operating Characteristic and Simplified Block Diagram Absolute Maximum Ratings Package Information 8 µMAX 8 WLP Electrical Characteristics Typical Operating Characteristics Pin Configuration Pin Description Detailed Description Overview PWM Rejection Input Stage Low Input Offset Voltage and Low Gain Error CSA Output Voltage Reference Window Comparator and Hysteresis Applications Information Input Sense Voltage Range Choice of Reference Voltage Important Considerations Kelvin Connections Stray Inductance Typical Application Circuits Current Sensing in a 3-Phase Servo Motor Ordering Information Revision History