AS1904, AS1905, AS1906
Data Sheet - D e t a i l e d D e s c r i p t i o n
8 Detailed Description
Interfacing to Microprocessors with Bi-Directional Reset Pins
The device has an open drain RESETN output, which enables easy interfacing to microprocessors (µP) with bi-direc-
tional reset pins, such as the Motorola 68HC11. The RESETN pin of the microcontroller (µC) can be connected directly
to the µP supervisor's RESETN output with a single pull-up resistor (see Figure 1 on page 1).
Negative-Going VDD Transients
The device is optimized to ignore short-duration, negative-going V
DD
transients (glitches) in order to avoid incorrect
resets.
In the graph Maximum Transient Duration vs. Reset Threshold Overdrive (page 6) , the conditions are shown, for
which the reset pulses are not generated. In the graph the maximum pulse width that a negative V
DD
transient may
have when a reset signal is generated. As the amplitude of the transient increases, the maximum allowable pulse width
decreases.
Options
Table 4. Coding of Factory-trimmed Reset Active Time-Out Period
Device
AS190x_xx
AS190x_xx
AS190x_xx
AS190x_xx
Table 5. Output Variants
Device
AS1904xxx
AS1905xxx
AS1906xxx
Output Functionality
Active Low (RESETN)
Active High (RESET)
Open Drain (RESETN)
Suffix
A
B
C
D
t
TP
in Milliseconds
Min
3
12
60
300
Typ
5
20
100
500
Max
8
32
160
800
Table 6. Coding of Factory-Trimmed Reset Threshold Voltages
Reset Threshold Voltage, V
TH
in V
Device
AS190xx__
AS190xx__
AS190xx__
AS190xx__
AS190xx__
AS190xx__
AS190xx__
AS190xx__
AS190xx__
AS190xx__
Suffix
Min
22
23
24
25
26
27
28
29
30
31
2.167
2.285
2.364
2.463
2.591
2.660
2.758
2.886
2.955
3.034
T
A
= +25°C
Typ
2.2
2.32
2.4
2.5
2.63
2.7
2.8
2.93
3.0
3.08
Max
2.233
2.355
2.436
2.538
2.669
2.741
2.842
2.974
3.045
3.126
T
A
= -40 to +85°C
Min
2.145
2.262
2.340
2.438
2.564
2.633
2.730
2.857
2.925
3.003
Max
2.255
2.378
2.460
2.563
2.696
2.768
2.870
3.003
3.075
3.157
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Revision 1.41
6-9
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