3940
FULL-BRIDGE POWER
MOSFET CONTROLLER
Functional Description (cont’d)
Control Logic
PHASE ENABLE MODE
0
0
0
0
0
1
1
1
1
1
1
0
0
0
0
1
0
0
0
0
X
0
1
0
1
X
0
1
0
1
SR
X
1
1
0
0
X
1
1
0
0
GLA
1
0
1
0
1
0
1
1
0
0
GLB
0
1
1
0
0
1
0
1
0
1
GHA
0
1
0
0
0
1
0
0
0
0
GHB
1
0
0
0
0
0
1
0
0
0
SA
Lo
Hi
Lo
Z
Lo
Hi
Lo
Lo
Z
Z
SB
Hi
Lo
Lo
Z
Z
Lo
Hi
Lo
Z
Lo
Mode of Operation
Reverse
Fast decay, SR enabled
Slow decay, braking mode
Fast decay, coast
Slow decay, SR disabled
Forward
Fast decay, SR enabled
Slow decay, braking mode
Fast decay, coast
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
No Fault
Short-to-Battery"#
Short-to-Ground"$
Open Bridge (V
DRAIN
)"%
V
REG13
Undervoltage
V
BB
Overvoltage
V
BB
Undervoltage
Thermal Shutdown
Sleep
RESET
1
1
1
1
1
1
1
1
0
FAULT
0
1
1
1
1
1
1
1
1
CP Reg.
ON
ON
ON
ON
ON
ON
OFF
OFF
OFF
VREG13
ON
ON
ON
ON
ON&
ON
OFF
OFF
OFF
VREG5
ON
ON
ON
ON
ON
ON
ON&
ON&
OFF
GHx
–
0
0
0
0'
0
0'
0'
Z
GLx
–
0
0
0
0'
0
0'
0'
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 V
REG13
< 4 V, the outputs will start to open (become high impedance). See “Sleep Mode”.
10
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
ALLEGRO [ ALLEGRO MICROSYSTEMS ]
