Rainbow Electronics ATA6824 - Manual (Page 10)

10
4931C–AUTO–09/06
ATA6824 [Preliminary]
5.5 Control Inputs DIR and PWM
5.5.1 Pin DIR
Logical input to control the direction of the external motor to be controlled by the IC. An internal
pull-down resistor is included.
5.5.2 Pin PWM
Logical input for PWM information delivered by external microcontroller. Duty cycle and fre-
quency at this pin are passed through to the H-bridge. An internal pull-down resistor is included.
The internal signal ON is high when
• At least one valid trigger has been accepted (SYNC = 1)
• V
BAT
is inside the specified range (UV = 0 and nOV = 1)
• The charge pump has reached its minimum voltage (CPOK = 1) and
• The device is not overheated (OT2 = 0)
In case of a short circuit, the appropriate transistor is switched off after a debounce time of about
10 µs. In order to avoid cross current through the bridge, a cross conduction timer is imple-
mented. Its time constant is programmable by means of an RC combination.
Table 5-1. Status of the IC Depending on Control Inputs and Detected Failures
Control Inputs Driver Stage for External Power MOS Comments
ON DIR PWM H1 L1 H2 L2
0 X X OFF OFF OFF OFF Standby mode
1 0 PWM ON OFF /PWM PWM Motor PWM forward
1 1 PWM /PWM PWM ON OFF Motor PWM reverse
Table 5-2. Status of the Diagnostic Outputs
Device Status Diagnostic Outputs Comments
CPOK OT1 OV UV SC DG1 DG2 DG3
0 X X X X – 1 – Charge pump failure
X 1 X X X – – 1 Overtemperature warning
X X 1 X X – 1 – Overvoltage
X X X 1 X – 1 – Undervoltage
X X X X 1 1 – – Short circuit
Note: X represents: don't care – no effect)
OT1: Overtemperature warning
OV: Overvoltage of VBAT
UV: Undervoltage of VBAT
SC: Short circuit
CPOK: Charge pump OK