ZHCSPQ7A december 2022 – april 2023 MCT8315A
PRODUCTION DATA
- 1
- 1 特性
- 2 應用
- 3 說明
- 4 Revision History
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Output Stage
- 7.3.2 Device Interface
- 7.3.3 Step-Down Mixed-Mode Buck Regulator
- 7.3.4 AVDD Linear Voltage Regulator
- 7.3.5 Charge Pump
- 7.3.6 Slew Rate Control
- 7.3.7 Cross Conduction (Dead Time)
- 7.3.8 Speed Control
- 7.3.9 Starting the Motor Under Different Initial Conditions
- 7.3.10 Motor Start Sequence (MSS)
- 7.3.11 Closed Loop Operation
- 7.3.12 Speed Loop
- 7.3.13 Input Power Regulation
- 7.3.14 Anti-Voltage Surge (AVS)
- 7.3.15 Output PWM Switching Frequency
- 7.3.16 Fast Start-up (< 50 ms)
- 7.3.17 Fast Deceleration
- 7.3.18 Active Demagnetization
- 7.3.19 Motor Stop Options
- 7.3.20 FG Configuration
- 7.3.21
Protections
- 7.3.21.1 VM Supply Undervoltage Lockout
- 7.3.21.2 AVDD Undervoltage Lockout (AVDD_UV)
- 7.3.21.3 BUCK Undervoltage Lockout (BUCK_UV)
- 7.3.21.4 VCP Charge Pump Undervoltage Lockout (CPUV)
- 7.3.21.5 Overvoltage Protection (OVP)
- 7.3.21.6 Overcurrent Protection (OCP)
- 7.3.21.7 Buck Overcurrent Protection
- 7.3.21.8
Cycle-by-Cycle (CBC) Current Limit (CBC_ILIMIT)
- 7.3.21.8.1 CBC_ILIMIT Automatic Recovery next PWM Cycle (CBC_ILIMIT_MODE = 000xb)
- 7.3.21.8.2 CBC_ILIMIT Automatic Recovery Threshold Based (CBC_ILIMIT_MODE = 001xb)
- 7.3.21.8.3 CBC_ILIMIT Automatic Recovery after 'n' PWM Cycles (CBC_ILIMIT_MODE = 010xb)
- 7.3.21.8.4 CBC_ILIMIT Report Only (CBC_ILIMIT_MODE = 0110b)
- 7.3.21.8.5 CBC_ILIMIT Disabled (CBC_ILIMIT_MODE = 0111b or 1xxxb)
- 7.3.21.9 Lock Detection Current Limit (LOCK_ILIMIT)
- 7.3.21.10 Thermal Warning (OTW)
- 7.3.21.11 Thermal Shutdown (TSD)
- 7.3.21.12 Motor Lock (MTR_LCK)
- 7.3.21.13 Motor Lock Detection
- 7.3.21.14 SW VM Undervoltage Protection
- 7.3.21.15 SW VM Overvoltage Protection
- 7.3.21.16 IPD Faults
- 7.4 Device Functional Modes
- 7.5 External Interface
- 7.6 EEPROM access and I2C interface
- 7.7 EEPROM (Non-Volatile) Register Map
- 7.8 RAM (Volatile) Register Map
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Mechanical, Packaging, and Orderable Information
7.3.16 Fast Start-up (< 50 ms)
MCT8315A has the capability to accelerate a motor from 0 to 100% speed within 50ms. This will only work on low inertia motors which are capable of this level of acceleration. In order to achieve fast start-up, the commutation instant detection needs to be configured to hybrid mode by setting INTEG_ZC_METHOD to 1b. In the hybrid mode, the commutation instant is determined by using back-EMF integration at low-medium speeds and by using built-in comparators (BEMF zero crossing) at higher speeds. MCT8315A automatically transitions between back-EMF integration and comparator based commutation depending on the motor speed as shown in Figure 7-36. The duty cycles for commutation method transition at lower speeds are directly configured by INTEG_DUTY_THR_LOW and INTEG_DUTY_THR_HIGH and at higher speeds are indirectly configured by INTEG_CYC_THR_LOW and INTEG_CYC_THR_HIGH. These duty cycles should be configured to provide a sufficient hysteresis band to avoid repeated commutation method transitions near threshold duty cycles. The BEMF threshold values used to determine the commutation instant in the back-EMF integration method are configured by BEMF_THRESHOLD1 and BEMF_THRESHOLD2.
Figure 7-36 Commutation Method Transition