A3981KLPTR-T Allegro Microsystems Inc, A3981KLPTR-T Datasheet - Page 11

• Manufacturer Part Number: A3981KLPTR-T
• Description: AUTOMOTIVE PROGRAMMABLE STEPPER DRVR
• Manufacturer: Allegro Microsystems Inc

Specifications of A3981KLPTR-T

• Applications: Stepper Motor Driver, 2 Phase
• Number Of Outputs: 1
• Voltage - Load: 7 V ~ 28 V
• Voltage - Supply: 3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

A3981
Alternative to the Fault Output flag, the DIAG output can be pro-
grammed via the serial interface to output: the stall detect signal,
which goes low when a stall is detected; the phase A PWM-on
signal, which is high during the phase A PWM on-time; or an
analog signal indicating the silicon temperature.
If required, specific fault information can be determined by read-
ing the diagnostic registers (see Serial Interface section).
The first bit (bit 15) in both diagnostic registers contains a com-
mon Fault Register flag which will be high if any of the fault bits
in either register has been set. This allows a fault condition to be
detected using the serial interface, by simply taking STRn low.
As soon as STRn goes low the fist bit in the diagnostic registers
can be read to determine if a fault has been detected at any time
since the last diagnostic registers reset. In all cases the fault bits
in the diagnostic registers are latched and only cleared after a
diagnostic registers reset.
Note that the Fault Register flag in the diagnostic registers, does
not provide the same function as the Fault Output flag on the
DIAG pin. The Fault Output flag on the DIAG pin provides an
indication that either a fault is present or the outputs have been
disabled due to a short circuit fault. The Fault Register flag sim-
ply provides an indication that a fault has occurred since the last
diagnostic registers reset and has been latched.
Table 1. Fault Table
Temperature Warning
VREG Undervoltage
VDD Undervoltage
VBB Overvoltage
Overtemperature
Diagnostic
Bridge Short
Bridge Open
Stall Detect
Set Fault Register flag
Set Fault Register flag
Disable outputs, set
Disable outputs, set
Disable outputs, set
Disable outputs, set
Fault Register flag
Fault Register flag
Fault Register flag
Fault Register flag
Power-down,
Set ST flag
full reset
Action
Latched
Automotive, Programmable Stepper Driver
Yes
No
No
No
No
No
No
No
At the system level the supply voltages and chip temperature are
monitored.
Supply Voltage Monitors
The logic supply, the motor supply, and the regulator output are
monitored: the motor supply for overvoltage, and the regulator
output and logic supply for undervoltage.
• If the motor supply voltage, V
• If the motor supply voltage, V
• If the output of the internal regulator, V
• If the logic supply voltage, V
Note that both the VREG undervoltage monitor and the V
undervoltage monitor indicate a fault by using the same fault
bit, UV, in both Fault registers. The state of the UV fault bit is
determined by the logical OR of the fault output from these two
undervoltage monitors.
Temperature Monitors
Three specific temperature thresholds are provided: a hot
warning, a cold warning, and an overtemperature shutdown. In
addition, the analog internal signal used to determine the chip
temperature can be selected in Configuration Register 1 as the
output on the DIAG pin through the serial interface. The analog
scale is T
VBB overvoltage threshold, the A3981 will disable the outputs
and indicate the fault. When the motor supply voltage goes be-
low the VBB overvoltage threshold, the outputs will be re-en-
abled and the fault flag removed. The fault bits in the diagnostic
registers remain set until cleared by a diagnostic registers reset.
VBB undervoltage threshold, the A3981 will indicate the fault
and reduce the VREG undervoltage threshold to the low level.
When the motor supply voltage goes above the VBB under-
voltage threshold, the VREG undervoltage threshold will be
increased to the high level and the fault flag removed. The fault
bits in the diagnostic registers remain set until cleared by a
diagnostic registers reset.
VREG undervoltage threshold, the A3981 will disable the
outputs and indicate the fault. When the regulator output rises
above the VREG undervoltage threshold, the outputs will be
re-enabled and the fault flag removed. The fault bits in the diag-
nostic registers remain set until cleared by a diagnostic registers
reset.
voltage threshold, the A3981 will be completely disabled except
to monitor the V
rises above the VDD undervoltage threshold, a power-on reset
will take place and all registers will be reset to the default state.
J
≈ (V
DIAG
DD
– V
voltage level. When the logic supply voltage
TO
) / A
115 Northeast Cutoff
1.508.853.5000; www.allegromicro.com
Allegro MicroSystems, Inc.
Worcester, Massachusetts 01615-0036 U.S.A.
DD
T
BBA
BBA
.
, goes below the VDD under-
and V
and V
REG
BBB
BBB
, goes below the
, goes above the
, goes below the
BB
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