MAX16053 Maxim Integrated Products, MAX16053 Datasheet - Page 9

• Manufacturer Part Number: MAX16053
• Description: High-Voltage Adjustable Sequencing/Supervisory Circuits
• Manufacturer: Maxim Integrated Products

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 V
old of 0.495V (5mV hysteresis). When V
V
t
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.
When V
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, C
immediately discharged. Adjust the delay (t
when V
high according to the equation:
where t
The MAX16052/MAX16053 offer an active-high enable
input (EN). With V
OUT high after the capacitor-adjustable delay time. The
EN-to-OUT delay time (t
when EN goes above the EN threshold using the equation:
where t
Drive EN low to force OUT low within 300ns for the
MAX16052 and within 400ns for the MAX16053.
The MAX16052 offers an active-high, open-drain output
while the MAX16053 offers an active-high push-pull out-
put. The push-pull output is referenced to V
open-drain output requires a pullup resistor and can be
pulled up to 28V.
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 con-
sumption due to low IN leakage currents (60nA max).
Set R2 to some conveniently high value (200kΩ for ±1%
DELAY
TH
and EN is high, OUT goes high after the adjustable
DELAY
IN
period. When V
PROP
IN
t
t
DELAY
PROP
rises above V
rises above V
is in seconds and C
is in seconds and C
=
Applications Information
=
C
C
IN
_______________________________________________________________________________________
CDELAY
CDELAY
Adjustable Delay (CDELAY)
above V
IN
TH
PROP
TH
TH
falls below 0.495V, OUT goes
×
(with EN high) to OUT going
×
(
= 0.5V and a falling thresh-
with EN high, the internal
4 10
(
TH
4 10
) can be calculated from
×
×
, drive EN high to force
Monitor Input (IN)
Enable Input (EN)
CDELAY
6
CDELAY
Input Threshold
6
Ω
Ω
Sequencing/Supervisory Circuits
) (
) (
Output (OUT)
+
+
14
IN
30
is in Farads.
is in Farads.
μ
DELAY
rises above
μ
s
CDELAY
s
)
)
CC
) from
. The
is
High-Voltage, Adjustable
additional variation in threshold, for example) and cal-
culate R1 based on the desired monitored voltage
using the following formula:
where V
V
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 V
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 depen-
dent on the V
In applications in which OUT must be valid down to
V
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 criti-
cal; 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 V
TH
CC
Pullup Resistor Values (MAX16052 Only)
is the reset input threshold (0.5V).
= 0V, add a pulldown resistor between OUT and
MONITOR
Down to V
CC
R
1
supply voltage.
MAX16053
is the desired monitored voltage and
=
GND
V
V
CC
CC
R
2
×
⎡
⎢
⎣
CC
V
OUT
MONITOR
Ensuring a Valid OUT
V
= 0V (Push-Pull OUT)
CC
TH
= 0V
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CC
−
1
⎤
⎥
⎦
= 2.25V and the
100kΩ
9