9
RETURN
POWER SUPPLY
+15V
– 15V
+5V
22 F
0.1 F
2.2 F
22 F
0.1 F
PW-82351
J1-16
J2-15
J2-8
J2-14
J2-16
J2-10
LOGIC OR EXTERNAL
CIRCUITRY
+
FIGURE 6. ROUTING FOR POWER SUPPLY / INTERCONNECT GROUND POINTS
POWER ON SEQUENCE
When power is applied, the motor drive starts a power on
sequence prior to accepting any control signals on the logic
inputs UA, LA, UB, LB, UC, LC or the internal commutation logic.
The cycle lasts for 1 ms and is activated by the low state of the
UV FLAG. When a low state is detected the following occurs:
1. Internal gate drive signals are set to a low state.
2. All user supplied signals to the logic inputs are ignored.
During the power sequencing procedure the internal logic shall:
1. Cycle each gate drive one at a time from a logic low to a
logic high and will keep repeating this sequence.
2. All user supplied signals to the logic inputs are ignored.
3. Set the SC FLAG to a high state and ignore any desatu
ration condition.
After 1 ms the logic will:
1. Set all gate drive inputs to a logic low.
2. Enable the logic inputs and set the gate drive accordingly.
3. Resume normal operation.
PHASE AOUT,BOUT,COUT
The motor is connected between the three output terminals
Phase Aout, Phase Bout, and Phase Cout. These outputs
switch between Vcc and RTN. FIGURE 8 shows the output
current capability.
SHORT CIRCUIT OPERATION
The PW-82351 outputs are completely short-circuit-protected
from either a hard or soft short to the VCC or RTN lines. Each
output transistor is individually short-circuit-protected by circuit-
ry that detects the desaturation voltage for that transistor when
a short is occurring. Once a short circuit condition is detected,
all the output transistors are shutdown and the drive is disabled
for 16 ms to allow the transistor time to cool down. After the 16
ms period the drive is enabled and power is re-applied to the
output pins to see if the short has cleared. If the short is still
present, the shutdown process is repeated. The PW-82351 will
continue operating in this mode (detect a short, disable for 16
ms, enable) until the short is cleared or the drive is permanent-
ly disabled by the system through the DISABLE / ENABLE con-
trol input.
SHORT-CIRCUIT FLAG (SC FLAG)
The SC FLAG output will drop to a logic low when a short has
been detected. The SC FLAG output will be latched low until
the internal short circuit detection circuitry has timed out for 16
ms. The SC FLAG will then be reset high. If the short is still
present the flag will be set low again and the cycle will be
repeated. By counting the number of times the SC FLAG
drops low, the user can determine how many restart cycles are
appropriate before permanently disabling the drive.