3940
FULL-BRIDGE POWER
MOSFET CONTROLLER
Functional Description (cont’d)
Control Logic
PHASE ENABLE MODE SR
GLA GLB GHA GHB SA SB Mode of Operation
0
0
0
0
0
1
0
0
0
0
X
0
1
0
1
X
1
1
0
0
1
0
1
0
1
0
1
1
0
0
0
1
0
0
0
1
0
0
0
0
Lo
Hi
Lo
Z
Hi
Lo
Lo
Z
Reverse
Fast decay, SR enabled
Slow decay, braking mode
Fast decay, coast
Lo
Z
Slow decay, SR disabled
1
1
1
1
1
1
0
0
0
0
X
0
1
0
1
X
1
1
0
0
0
1
1
0
0
1
0
1
0
1
1
0
0
0
0
0
1
0
0
0
Hi
Lo
Lo
Z
Lo
Hi
Lo
Z
Forward
Fast decay, SR enabled
Slow decay, braking mode
Fast decay, coast
Z
Lo
Slow decay, SR disabled
NOTES: All faults will coast the motor, i.e., GHA = GHB = GLA = GLB = 0 to switch off all bridge MOSFETs.
X = Indicates a “don’t care”.
Z = Indicates a high-impedance state.
Fault Responses
Fault Mode
RESET FAULT CP Reg.
VREG13
VREG5
GHx
GLx
No Fault
1
1
1
1
1
1
1
1
0
1
1
1
1
1
1
1
ON
ON
ON
ON
ON
ON
OFF
OFF
ON
ON
ON
ON
ON&
ON
ON
ON
ON
ON
ON
ON
ON&
ON&
–
0
0
0
0'
0
–
0
0
0
0'
0
Short-to-Battery"#
Short-to-Ground"$
Open Bridge (VDRAIN)"%
VREG13 Undervoltage
VBB Overvoltage
VBB Undervoltage
Thermal Shutdown
OFF
OFF
0'
0'
0'
0'
Sleep
0
1
OFF
OFF
OFF
Z
Z
NOTES: " = These faults are latched but will clear during RESET = 0 pulse. GHx = GLx = 0 during RESET = 0, except see '.
Other faults will not clear except when their cause is removed.
# = Short-to-battery can only be detected when the corresponding GLx = 1.
$ = Short-to-ground can only be detected when the corresponding GHx = 1.
% = Bridge fault appears as a short-to-ground fault on all motor phases.
& = Not instructed off but may be low voltage because of the fault indicated.
' = During undervoltage conditions, the low sides of GHx and GLx are instructed to be “on” so that the outputs are
low = 0; however, with VREG13 < 4 V, the outputs will start to open (become high impedance). See “Sleep Mode”.
115 Northeast Cutoff, Box 15036
10
Worcester, Massachusetts 01615-0036 (508) 853-5000
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
