MAX6895–MAX6899
Ultra-Small, Adjustable Sequencing/
Supervisory Circuits
used with a p-channel MOSFET in an overvoltage pro-
tection circuit. Figure 9 shows the MAX6895 in a low-
voltage sequencing application using an n-channel
MOSFET. Figure 10 shows the MAX6895 used in a mul-
tiple-output sequencing application.
Pullup Resistor Values
(MAX6897/MAX6898)
The exact value of the pullup resistors for the open-drain
outputs is not critical, but some consideration should be
made to ensure the proper logic levels when the device
is sinking current. For example, if V
CC
= 2.25V and the
pullup voltage is 28V, you would try to keep the sink current
less than 0.5mA as shown in the
Electrical Characteristics
table. As a result, the pullup resistor should be greater
than 56kΩ. For a 12V pullup, the resistor should be larger
than 24kΩ. It should be noted that the ability to sink cur-
rent is dependent on the V
CC
supply voltage.
Using an n-Channel Device for Sequencing
Typical Application Circuits
In higher power applications, using an n-channel device
reduces the loss across the MOSFETs as it offers a
lower drain-to-source on-resistance. However, an n-
channel MOSFET requires a sufficient VGS voltage to
fully enhance it for a low RDS_ON. The application in
Figure 9 shows the MAX6895 in a switch sequencing
application using an n-channel MOSFET.
Similarly, if a higher voltage is present in the system, the
open-drain version can be used in the same manner.
Figures 8, 9, 10 show typical applications for the
MAX6895–MAX6899. Figure 8 shows the MAX6895
3.3V ALWAYS ON
5V BUS 1.2V INPUT
1.2V OUTPUT
0 TO 28V
ENABLE
R1
OUT
V
CC
R
PULLUP
P
MONITORED
3.3V
R1
OUT
ENABLE
V
CC
N
MAX6897
IN
CDELAY
GND
IN
MAX6895
R2
R2
GND
CDELAY
C
CDELAY
Figure 8. Overvoltage Protection
Figure 9. Low-Voltage Sequencing Using an n-Channel
MOSFET
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