Detailed Description
The MAX5086 high-voltage linear regulator includes an
integrated microprocessor reset circuit with an
adjustable reset timeout period (see the
Adjustable
Reset Timeout Period (CT)
section). The device guaran-
tees a 250mA load current and is available with a pre-
set output voltage of 3.3V (MAX5086A) or 5V
(MAX5086B). Both devices can be configured to pro-
vide an adjustable output voltage from 2.5V to 11V. The
internal reset circuit monitors the regulator output volt-
age and asserts RESET low when the regulator output
falls below the reset threshold voltage. Other features
include an enable (regulator control input), 21µA (max)
shutdown current, short-circuit protection (see the
Output Short-Circuit Current Limit
section), and thermal
shutdown (see the
Thermal Protection
section).
Regulator
The MAX5086 accepts an input voltage range from
6.5V to 45V and offers a fixed output voltage of 3.3V or
5V. For an adjustable output voltage operation, use an
external resistive divider network connected between
OUT, SET, and GND (see Figure 2).
Enable Input (EN)
EN is a logic-level enable input that turns ON/OFF the
device. Drive EN high to turn on the device and drive
EN low to place the device in shutdown. The MAX5086
draws 13µA (typ) of supply current when in shutdown.
EN withstands voltages up to +45V, allowing EN to be
connected to IN for an always-on operation.
Remote Sensing (OUTSENSE)
For fixed output voltage versions, OUTSENSE must be
used for load voltage sensing. Leave OUTSENSE open
circuit when using adjustable output voltage version.
Reset Output (
RESET
)
A supervisor circuit is fully integrated in the MAX5086
and uses the same reference voltage as the regulator.
RESET goes low if V
OUT
drops below the preset output
voltage threshold, and remains low at least for the time-
out period after V
OUT
rises above the reset voltage
threshold.
Adjustable Reset Timeout Period (CT)
The MAX5086 features a user-adjustable reset timeout.
Connect a capacitor from CT to GND to set the reset
timeout period (see Figure 2) and use the following
equation to calculate the timeout period:
t
RP
= C
CT
x 0.6175 x 10
6
where C
CT
is the value of the external capacitor con-
nected from CT to GND and t
RP
is in seconds.
Thermal Protection
When the junction temperature exceeds T
J
= 175°C an
internal thermal sensor signals the shutdown logic,
which turns off the pass transistor, allowing the IC to
cool. The thermal sensor turns the pass transistor on
again after the IC’s junction temperature cools by 25°C,
resulting in a cycled output during continuous thermal-
overload conditions. Thermal protection protects the
MAX5086 in the event of fault conditions. During contin-
uous operation, do not exceed the absolute maximum
junction temperature rating of T
J
= +150°C.
Output Short-Circuit Current Limit
The MAX5086 features a current limit. The output can
be shorted to GND for an indefinite period of time (for
V
IN
< 16V) without damage to the device.
MAX5086
45V, 250mA, Low-Quiescent-Current
Linear Regulator with Adjustable Reset Delay
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