AMIS30532C5321G Datasheet, PDF (4/29 Pages) ON Semiconductor – Micro-Stepping Motor Driver

AMIS−30532
EQUIVALENT SCHEMATICS
Following figure gives the equivalent schematics of the user relevant inputs and outputs. The diagrams are simplified
representations of the circuits used.
4K
IN
OUT
TYPE 1: CLR input
4K
IN
TYPE 4: DO and ERRB open drain outputs
Rout
SLA
TYPE 2 : CLK , DI, CSB , NXT , DIR inputs
VDD
VBB
VDD
VBB
TYPE 5: SLA analog output
TYPE 3: VDD and VBB p^. ower supply inputs
Figure 3. In− and Output Equivalent Diagram
PACKAGE THERMAL CHARACTERISTICS
The AMIS−30532 is available in a NQFP32 package. For
cooling optimizations, the NQFP has an exposed thermal
pad which has to be soldered to the PCB ground plane. The
ground plane needs thermal vias to conduct the heat to the
bottom layer. Figure 3 gives an example for good power
distribution solutions.
For precise thermal cooling calculations the major
thermal resistances of the device are given. The thermal
media to which the power of the devices has to be given are:
• Static environmental air (via the case)
• PCB board copper area (via the exposed pad)
The thermal resistances are presented in Table 5: DC
Parameters.
The major thermal resistances of the device are the Rth
from the junction to the ambient (Rthja) and the overall Rth
from the junction to exposed pad (Rthjp). In Table 5 below
one can find the values for the Rthja and Rthjp, simulated
according to JESD−51:
The Rthja for 2S2P is simulated conform JEDEC
JESD−51 as follows:
• A 4−layer printed circuit board with inner power planes
and outer (top and bottom) signal layers is used
• Board thickness is 1.46 mm (FR4 PCB material)
• The 2 signal layers: 70 mm thick copper with an area of
5500 mm² copper and 20% conductivity
• The 2 power internal planes: 36 mm thick copper with
an area of 5500 mm² copper and 90% conductivity
The Rthja for 1S0P is simulated conform to JEDEC
JESD−51 as follows:
• A 1−layer printed circuit board with only 1 layer
• Board thickness is 1.46 mm (FR4 PCB material)
• The layer has a thickness of 70 mm copper with an area
of 5500 mm² copper and 20% conductivity
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