a4940 Allegro MicroSystems, Inc., a4940 Datasheet
a4940
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a4940 Summary of contents
Page 1
... DC motors. A unique charge pump regulator provides full ( > gate drive for battery voltages down and allows the A4940 to operate with a reduced gate drive, down to 5 bootstrap capacitor is used to provide the above battery supply voltage required for N-channel MOSFETs. A unique ...
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... A4940 Selection Guide Part Number A4940KLPTR-T 4000 pieces per reel Absolute Maximum Ratings* Characteristic Load Supply Voltage Logic Supply Voltage Logic Inputs Logic Outputs Pin VREG Pins CP1, CP2 Pin RDEAD Pins SA, SB Pins GHA, GHB Pins GLA, GLB Pins CA, CB ...
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... A4940 VBB VDD Diagnostics & FAULT Protection AHI ALO Control Logic BHI BLO RESET RDEAD Automotive Full Bridge MOSFET Driver Functional Block Diagram C P CP2 CP1 Charge VREG Pump Regulator Bootstrap Monitor CA GHA High Side SA Low GLA Side GND Bootstrap Monitor ...
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... A4940 ELECTRICAL CHARACTERISTICS Characteristics Supply and Reference V Functional Operating Range Range DD V Quiescent Current BB V Quiescent Current DD VREG Output Voltage Bootstrap Diode Forward Voltage Bootstrap Diode Resistance Bootstrap Diode Current Limit Gate Output Drive Turn-On Time Turn-Off Time Pull-up On Resistance ...
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... A4940 ELECTRICAL CHARACTERISTICS Characteristics Logic Inputs and Outputs FAULT Output (Open drain) 3 FAULT Output Leakage Current 3 RDEAD Current Input Low Voltage Input High Voltage Input Hysteresis Input Current (Except RESET) 3 Input Pull-down Resistor (RESET) RESET Pulse Time Protection VREG Undervoltage Lockout ...
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... V logic outputs. Cross-conduction (shoot- through) in the external bridge is avoided by an adjustable dead time. A low power sleep mode allows the A4940, the power bridge, and the load to remain connected to a vehicle battery supply without the need for an additional supply switch. ...
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... RES age fault that disables the outputs. defaults to DEAD Note that the A4940 can be configured to start without any exter- nal logic input so, pull up the RESET pin external resistor. The resistor value should be between 20 and 33 kΩ. Diagnostics Several diagnostic features are integrated into the A4940 to provide indication of fault conditions ...
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... Before a high-side drive can be turned on, the voltage across the associated bootstrap capacitor must be higher than the turn-on voltage limit. If this is not the case, then the A4940 will start a bootstrap charge cycle by activating the complementary low-side drive. Under normal circumstances, this will charge the bootstrap capacitor above the turn-on voltage in a few microsec- onds and the high-side drive will then be enabled ...
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... MOSFETs are switched at the same time; for example, when using synchronous rectification or after a bootstrap capacitor charging cycle. In the A4940, the dead time for both phases is set by a single dead-time resistor between the RDEAD and DEAD AGND pins ...
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... V voltage drops below this threshold, when the corresponding high-side is active, the A4940 will turn on the necessary low-side MOSFET, and continue charging until the bootstrap capacitor exceeds the undervoltage threshold plus the hysteresis, V ...
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... Figure 2. Supply routing suggestions Automotive Full Bridge MOSFET Driver are recommendations regarding some of these considerations: • The A4940 ground, GND, and the high-current return of the ex- ternal MOSFETs should return separately to the negative side of the motor supply filtering capacitor. This minimizes the effect of switching noise on the device logic and analog reference. • ...
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... A4940 Cx 20V 19V 18V GHx 18V 18V Sx VREG 18V GLx GND (A) Gate drive outputs ESD AHI 3 kΩ ALO BHI BLO 8.5V (E) Logic inputs: no pull-down resistor Automotive Full Bridge MOSFET Driver Input and Output Structures CP1 CP2 VREG 18V (B) Supply protection structures ESD 1 kΩ ...
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... A4940 Terminal List Number AGND AHI ALO BHI BLO CA CB CP1 CP2 FAULT GHA GHB GLA GLB GND PAD RDEAD RESET SA SB VBB VDD VREG Automotive Full Bridge MOSFET Driver Pin-out Diagram FAULT 24 RESET 1 23 RDEAD GND 2 22 AGND GLB 3 VDD ...
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... A4940 Package LP 24-Pin TSSOP with Exposed Thermal Pad 7.80±0. 4.32 NOM 24X 0.10 C 0.30 0.65 BSC 0.19 Copyright ©2009, Allegro MicroSystems, Inc. The products described here are manufactured under one or more U.S. patents or U.S. patents pending. Allegro MicroSystems, Inc. reserves the right to make, from time to time, such de par tures from the detail spec tions as may be required to per- mit improvements in the per for mance, reliability, or manufacturability of its products ...