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[FAQ] How to drop a DRV8452 into a DRV8434S socket? Advantages?

Part Number: DRV8452
Other Parts Discussed in Thread: DRV8434S

The DRV8452 (SPI version) and DRV8434S are pin-to-pin compatible with each other, with DRV8452 offering some newer features and performance improvements at a competitive price-point.  Very few changes are required to redesign a system to use the newer, higher-power DRV8452.  This FAQ goes through items to keep in mind when upgrading from DRV8434S to DRV8452.  

Advantages of DRV8452:

  • Larger Full-scale current, from 2.5A to 4A in the same package
  • Advanced features:  The DRV8452 has many new features including Auto-torque, Auto-microstepping, Silent Step, Standstill power saving, Customizable Microstepping

Differences to keep in mind:

  • VREF:  Due to having a larger full-scale current, the same voltage of VREF on DRV8452 will result in a larger amount of current vs the DRV8434S.  DRV8452 full-scale current (IFS) is 4A in PWP package, and DRV8434S IFS is 2.5A, so multiply the DRV8434S VREF voltage by 2.5/4 to achieve the same current regulation level. 
    • For example, if VREF = 0.80V in DRV8434S.  0.80V * 2.5 / 4 = 0.50V for same current regulation level in DRV8452. 
  • External components:  Several external components require different values between each device:
    • COMPONENT DRV8434S Recommended DRV8452 Recommended
      CVCP X7R, 0.22 uF, 16 V capacitor X7R, 1 uF, 16 V capacitor
      CSW X7R, 0.022 uF, VM-rated capacitor X7R, 0.1 uF, VM-rated capacitor
      CDVDD X7R, 0.47 uF to 1uF, 6.3 V capacitor X7R, 1 uF 6.3 V ceramic capacitor
  • Off-Time PWM Chopping:  The values of the time for Off-Time PWM chopping are slightly different between the two devices.  See table below
    • TOFF state DRV8434S DRV8452 UNIT
      TOFF = 00b 7 9 μs

      TOFF = 01b

      16 19 μs
      TOFF = 10b 24 27 μs
      TOFF = 11b 32 35 μs
  • Decay Mode:  Three decay modes are unavailable in DRV8452 as shown in the table below. 
    • DECAY bits [2:0] DRV8434S DRV8452
      000b Increasing SLOW, decreasing SLOW Slow decay
      001b Increasing SLOW, decreasing MIXED 30% Reserved
      010b Increasing SLOW, decreasing MIXED 60% Reserved
      011b Increasing SLOW, decreasing FAST Reserved
      100b Increasing MIXED 30%, decreasing MIXED 30% Mixed 30% decay
      101b Increasing MIXED 60%, decreasing MIXED 60% Mixed 60% decay
      110b Smart tune Dynamic Decay Smart tune Dynamic Decay
      111b Smart tune Ripple Control Smart tune Ripple Control
  • Register Map:  Many registers have been added and some register fields have been moved or renamed. See the table below for an illustration of the changes. 
    • Register fields moved:
      • TRQ_DAC: Moved from Register Address 0x03 to 0x0E and was expanded from 4-bits to 8-bits.
      • OL_MODE:  Moved from Register Address 0x03 to 0x0C and moved bitfield from 1 to 6.
      • EN_OL: Moved from Register Address 0x06 to 0x0C and moved bitfield from 3 to 7.
    • Register fields removed:
      • REV_ID
    • Register fiends renamed:
      • EN_SSC has changed to DIS_SSC. The functionality of this bit has also flipped.  In DRV8434S, setting this bit = 1 results in Spread-Spectrum Enabled, whereas in DRV8452 this bit = 1 results in Spread-Spectrum Disabled
    • Note that the Register Name has changed for most registers, due to register 0x03 being renamed from "CTRL1" in DRV8434S to "DIAG3" in DRV8452.  This resulted in all the CTRL# being decremented by 1 - CTRL2 renamed to CTRL1, CTRL3 renamed to CTRL2, etc.  From a programming perspective since the Register Address didn't change this won't require any extensive firmware fixes.