Datasheet

I =
CHOP
V
REFX
5 · R
ISENSE
¾
DRV8828
www.ti.com SLVSA11E –OCTOBER 2009–REVISED AUGUST 2013
The full-scale (100%) chopping current is calculated in Equation 1.
(1)
Example:
If a 0.5-Ω sense resistor is used and the VREFx pin is 3.3 V, the full-scale (100%) chopping current will be
3.3 V / (5 x 0.5 Ω) = 1.32 A.
Five input pins (I0 - I4) are used to scale the current in the bridge as a percentage of the full-scale current set by
the VREF input pin and sense resistance. The logic inputs I0, I1, I2, I3 and I4 have internal pulldown resistors of
100 kΩ. The function of the pins is shown in Table 3.
Table 3. H-Bridge Pin Functions
RELATIVE CURRENT
I[4..0]
(% FULL-SCALE CHOPPING CURRENT)
0x00h 0%
0x01h 5%
0x02h 10%
0x03h 15%
0x04h 20%
0x05h 24%
0x06h 29%
0x07h 34%
0x08h 38%
0x09h 43%
0x0Ah 47%
0x0Bh 51%
0x0Ch 56%
0x0Dh 60%
0x0Eh 63%
0x0Fh 67%
0x10h 71%
0x11h 74%
0x12h 77%
0x13h 80%
0x14h 83%
0x15h 86%
0x16h 88%
0x17h 90%
0x18h 92%
0x19h 94%
0x1Ah 96%
0x1Bh 97%
0x1Ch 98%
0x1Dh 99%
0x1Eh 100%
0x1Fh 100%
Decay Mode
During PWM current chopping, the H-bridge is enabled to drive current through the motor winding until the PWM
current chopping threshold is reached. This is shown in Figure 2 as case 1. The current flow direction shown
indicates the state when the PHASE pin is high.
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