U6084B-FP ATMEL Corporation, U6084B-FP Datasheet - Page 4

• Manufacturer Part Number: U6084B-FP
• Description: PWM Power Control with Automatic Duty-cycle Reduction
• Manufacturer: ATMEL Corporation

Example for Oscillator
Frequency Calculation
Pins 7, 8, 10 and 15
Pin 9 – Status Short
Circuit Latch
4
U6084B
where
V
V
V
The above mentioned threshold voltages are calculated for the following values given in
the datasheet.
V
V
V
V
For a duty cycle of 100%, the oscillator frequency, f, is as follows:
Therefore:
For a duty cycle of less than 100%, the oscillator frequency, f, is as follows:
where C
A selection of different values of C
from 10 to 2000 Hz.
Not connected.
The status of the short-circuit latch can be monitored via pin 9 (open collector output).
Table 2. Pin 9 Function
V
V
V
f
f
f
f
Pin 9
L
H
1
1
T100
T<100
TL
Batt
T100
T<100
TL
T100
T<100
TL
=
=
=
=
,
= 0.7,
= 11.4 V
= Low switching threshold
----------------------------------------------------------- -
2
------------------------------------------------------------------ -
2
---------------------------------------------------------------------------------------------------------- -
2
------------------------------------------------------------------------------------------------------------------------------ -
2
=
2
= 12 V, I
= High switching threshold 100% duty cycle
= (12 V - 4 mA
and
=
= High switching threshold < 100% duty cycle
= 11.4 V
V
=
S
V
4
V
V
8 V 3.2 V
7.6 V 3.2 V
V
S
T100
T<100
= 470 pF
2
S
3
= 0.67 and
–
I
40 µA
3
are fixed values
S
osc
–
–
=
1
–
= 4 mA, R
0.28 = 3.2 V
2
V
=
V
TL
=
V
0.67 = 7.6 V
TL
Batt
Function
Short-circuit detected
Not short-circuit detected
V
V
Batt
I
Batt
osc
22 nF
–
C
150 )
C
40 µA
22 nF
I
–
2
S
–
3
2
I
3
where C
S
= 0.28.
+
I
S
= 150 ,
R
4
=
+
3
R
189 Hz
R
4
3
V
3
0.7
Batt
2
12 V
3
= 22 nF and I
2
1
2
and C
C
8 V
4
470 pF
4
provides a range of oscillator frequencies
=
osc
185 Hz
= 40 µA
4677B–AUTO–02/04