Monitor Input (IN)
Connect the center point of a resistive-divider to IN to
monitor external voltages (see R1 and R2 of Figure 4). IN
has a rising threshold of VTH = 0.5V and a falling threshold
of 0.495V (5mV hysteresis). When VIN rises above VTH
and EN is high, OUT goes high after the adjustable tDELAY
period. When VIN falls below 0.495V, OUT goes low after
a 18μs delay. IN has a maximum input current of 60nA, so
large value resistors are permitted without adding significant
error to the resistive-divider.
Adjustable Delay (CDELAY)
When VIN rises above VTH with EN high, the internal
250nA current source begins charging an external capacitor
connected from CDELAY to GND. When the voltage
at CDELAY reaches 1V, the output asserts (OUT goes
high). When the output asserts, CCDELAY is immediately
discharged. Adjust the delay (tDELAY) from when VIN
rises above VTH (with EN high) to OUT going high
according to the equation:
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DELAY CDELAY
t C (4 10 ) (30µs)= × × Ω+
where tDELAY is in seconds and CCDELAY is in Farads.
Enable Input (EN)
The MAX16052/MAX16053 offer an active-high enable
input (EN). With VIN above VTH, drive EN high to force
OUT high after the capacitor-adjustable delay time. The
EN-to-OUT delay time (tPROP) can be calculated from
when EN goes above the EN threshold using the equation:
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PROP CDELAY
t C (4 10 ) (14µs)= × × Ω+
where tPROP is in seconds and CCDELAY is in Farads.
Drive EN low to force OUT low within 300ns for the
MAX16052 and within 400ns for the MAX16053.
Output (OUT)
The MAX16052 offers an active-high, open-drain output
while the MAX16053 offers an active-high push-pull
output. The push-pull output is referenced to VCC. The
open-drain output requires a pullup resistor and can be
pulled up to 28V.
Applications Information
Input Threshold
The MAX16052/MAX16053 monitor the voltage on IN with
an external resistive-divider (Figure 4). R1 and R2 can
have very high values to minimize current consumption
due to low IN leakage currents (60nA max). Set R2 to
some conveniently high value (200kΩ for ±1% additional
variation in threshold, for example) and calculate R1
based on the desired monitored voltage using the following
formula:
MONITOR
TH
V
R1 R2 1
V−
= ×
where VMONITOR is the desired monitored voltage and
VTH is the reset input threshold (0.5V).
Pullup Resistor Values (MAX16052 Only)
The exact value of the pullup resistor for the open-drain
output is not critical, but some consideration should be
made to ensure the proper logic levels when the device
is sinking current. For example, if VCC = 2.25V and the
pullup voltage is 28V, 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.
Note that the ability to sink current is dependent on the
VCC supply voltage.
Ensuring a Valid OUT Down to VCC = 0V
(Push-Pull OUT)
In applications in which OUT must be valid down to VCC = 0V,
add a pulldown resistor between OUT and GND for the
push-pull output (MAX16053). The resistor sinks any
stray leakage currents, holding OUT low (Figure 3). The
value of the pulldown resistor is not critical; 100kΩ is large
enough not to load OUT and small enough to pull OUT to
ground. The external pulldown cannot be used with the
open-drain OUT output.
Figure 3. Ensuring OUT Valid to VCC = 0V
GND
OUT
VCC
VCC
100kΩ
MAX16053
MAX16052/MAX16053 High-Voltage, Adjustable
Sequencing/Supervisory Circuits
www.maximintegrated.com Maxim Integrated
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