attiny25v ATMEL Corporation, attiny25v Datasheet - Page 108

• Manufacturer Part Number: attiny25v
• Description: Microcontroller With 2/4/8k Bytes In-system Programmable Flash
• Manufacturer: ATMEL Corporation

14. Dead Time Generator
108
ATtiny25/45/85
The Dead Time Generator is provided for the Timer/Counter1 PWM output pairs to allow driving
external power control switches safely. The Dead Time Generator is a separate block that can
be connected to Timer/Counter1 and it is used to insert dead times (non-overlapping times) for
the Timer/Counter1 complementary output pairs (OC1A-OC1A and OC1B-OC1B). The sharing
of tasks is as follows: the timer/counter generates the PWM output and the Dead Time Genera-
tor generates the non-overlapping PWM output pair from the timer/counter PWM signal. Two
Dead Time Generators are provided, one for each PWM output. The non-overlap time is adjust-
able and the PWM output and it’s complementary output are adjusted separately, and
independently for both PWM outputs.
Figure 14-1. Timer/Counter1 & Dead Time Generators
The dead time generation is based on the 4-bit down counters that count the dead time, as
shown in Figure 46. There is a dedicated prescaler in front of the Dead Time Generator that can
divide the Timer/Counter1 clock (PCK or CK) by 1, 2, 4 or 8. This provides for large range of
dead times that can be generated. The prescaler is controlled by two control bits DTPS11..10
from the I/O register at address 0x23. The block has also a rising and falling edge detector that
is used to start the dead time counting period. Depending on the edge, one of the transitions on
the rising edges, OC1x or OC1x is delayed until the counter has counted to zero. The compara-
tor is used to compare the counter with zero and stop the dead time insertion when zero has
been reached. The counter is loaded with a 4-bit DT1xH or DT1xL value from DT1x I/O register,
depending on the edge of the PWM generator output when the dead time insertion is started.
Figure 14-2. Dead Time Generator
PWM1x
T/C1 CLOCK
DEAD TIME
PRESCALER
DT1AH
DT1AL
PCKE
T15M
CK
PCK
DTPS11..10
CLOCK CONTROL
DEAD TIME GENERATOR
OC1A
PWM1A
OC1A
TIMER/COUNTER1
PWM GENERATOR
4-BIT COUNTER
COMPARATOR
I/O REGISTER
DT1x
DEAD TIME GENERATOR
OC1B
PWM1B
OC1B
DT1BH
DT1BL
2586K–AVR–01/08
OC1x
OC1x