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UC1620 Scheda tecnica(PDF) 3 Page - Texas Instruments |
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UC1620 Scheda tecnica(HTML) 3 Page - Texas Instruments |
3 / 8 page ELECTRICAL CHARACTERISTICS: PARAMETER TEST CONDITIONS UC3620 UC1620 UNIT MIN TYP MAX MIN TYP MAX Output Section (cont.) Output Rise Time RL = 44 Ω 150 150 ns Output Fall Time RL = 44 Ω 150 150 ns Under Voltage Lockout Startup Threshold 8.0 8.0 V Threshold Hysteresis 0.5 0.5 V Thermal Shutdown Junction Temperature Note 2 150 180 150 180 °C Total Standby Current Supply Current 32 55 32 55 mA Unless otherwise stated, these specifications apply for TA = 0°C to 70°C for 3620; TA = 55°C to +125°C for UC1620; VCC = 20V, RT = 20V, RT = 10k, CT = -2.2nF. TA=TJ. UC1620 UC3620 Note 2: These parameters, although guaranteed over the recommended operating conditions, are not 100% tested in production. Note 3: The total voltage drop is defined as the sum of both top and bottom side driver. CIRCUIT DESCRIPTION The UC3620 is designed for implementation of a com- plete 3- ∅ brushless DC servo drive using a minimum number of external components. Below is a functional de- scription of each major circuit feature. DECODER Table 1 shows the decoding scheme used in the UC3620 to decode and drive each of three high current totem pole output stages. A forward/reverse signal, pin 13, is used to provide direction. At any point in time, one driver is sour- cing, one driver is sinking, and the remaining driver is off or tri-stated. Pulse width modulation is accomplished by turning the sink driver off during the monostable reset time, producing a fixed off-time chop mode. Controlled output rise and fall times help reduce electrical switching noise while maintaining relatively small switching losses. Hall lines require pull-up resistors. CURRENT SENSING Referring to Figure 1, emitter current is sensed across RS and fed back through a low pass filter to the current sense pin 7. This filter is required to eliminate false trig- gering of the monostable due to leading edge current spikes. Actual filter values, although somewhat depend- ent on external loads, will generally be in the 1k Ω and 1000pF range. TIMING An R-C time constant on pin 9 is used by the monostable to generate a fixed off time at the outputs according to the formula: TOFF = .916RTCT As the peak current in the emitters approaches the value at the minus (-) input of the on-board comparator, the monostable is triggered, causing the outputs to be turned STEP FWD/ REV Ha Hb Hc AOUT BOUT COUT 1 1 101 H L O 2 1 100 H O L 3 1 110 O H L 4 1 010 L H O 5 1 011 L O H 6 1 001 O L H 1 0 101 L H O 2 0 100 L O H 3 0 110 O L H 4 0 010 H L O 5 0 011 H O L 6 0 001 O H L H = HIGH OUTPUT L = LOW OUTPUT O = OPEN OUTPUT TABLE 1 Figure 1. Current Sense Filter 3 |
Codice articolo simile - UC1620 |
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Descrizione simile - UC1620 |
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