D1830/A
3 of 7
OPERATION — PUSHBUTTON RESET
The DS1830 provides a pushbutton switch for manual reset control. When any of the DS1830/A resets
are not active (low) a reset cycle can be initiated by a pushbutton reset. The pushbutton reset is generated
by pulling the PBRST pin low for at least 1ms. When the push- button is held low all resets are forced
active. The reset will remain active until the pushbutton input is released and then will start a sequenced
time-out based on the condition of the TD input. The Pushbutton input is pulled high through an internal
40kW pull-up resistor and debounced via internal circuitry. See Figure 2 for an application example and
Figure 3 for the timing diagram.
PUSHBUTTON RESET Figure 2
TIMING DIAGRAM — PUSHBUTTON RESET Figure 3
OPERATION — TIME DELAY SELECT
The DS1830 provides an input to select three time delay characteristics for the reset outputs. The TD
input has 3 states high (V
CC
), low (ground) and no connect (N.C.). Table 2 details the minimum timing
based on the state of the TD input. If the TD input is connected to ground; RST1 will have a minimum
time delay of 10 ms after V
CC
is in tolerance. If the TD input is floated; RST1 will have a minimum time
delay of 20 ms after V
CC
is in tolerance. If the TD input is connected to V
CC
, RST1 will have a minimum
time delay of 50 ms after V
CC
is in tolerance. An oscillator and clock chain generate the reset timing with
each time delay based on the same device oscillator. The time delay for RST2 will be 5 times as long as
RST1 and RST3 will be 10 times the duration of RST1 .
TD CONTROL MINIMUM RESET TIMING Table 2
TD
T
RST1
T
RST2
T
RST3
TD = GND 10ms 50ms 100ms
TD = N.C. 20ms 100ms 200ms
TD = V
CC
50ms 250ms 500ms
