LINEAR dn427f Data Sheet
Summary
The LTC2953 is a robust, low-power pushbutton controller designed for system designers tackling complex power management challenges in electronic devices. It provides a comprehensive solution for manually toggling power, even when encountering signal chatter or critical supply voltage drops. This manual details its failsafe monitoring features, including Ultra-Low Voltage (UVLO) and Power Fail comparators, ensuring orderly power on/off sequences by integrating adjustable timing and lockout logic, protecting the system from faulty components and battery depletion.
Page 1 Text Content
Pushbutton On/Off Controller with Failsafe Voltage Monitoring Design Note 427 Victor Fleury
Introduction enables a DC/DC converter or turns on a power switch. These circuits communicate with system logic to make
Have you had the exasperating experience of a laptop or
sure that power turns on and turns off in an orderly
PDA defi antly not responding to your commands? You
manner. Additionally, failsafe features should disable
frantically press key after key, but to no avail. As hope
system power if there is a problem with either the input or
turns to anger (but just before you throw the company’s
output power supply. The pushbutton monitor must also
laptop through the window) you slam your fi nger against
be rugged: absorb high levels of electrostatic discharge,
the on/off power button. Ten seconds later, your laptop
tolerate voltage transients below ground and operate at
fi nally surrenders and the screen goes black in a high
high voltage levels.
pitched whimper.
The LTC2953 pushbutton on/off controller with voltage
The unresponsive pushbutton was likely the result of an
monitoring addresses all of these issues by providing a
unresponsive μP or system logic—as evidenced by the
complete solution for interfacing to the on/off pushbutton
crash. By pressing and holding the on/off pushbutton,
of electronic devices. This tiny IC integrates the timing
the LTC2953 provides the user with the ability to force
circuitry needed to clean up the pushbutton chatter and
system power off, even under fault conditions. This long
provides a simple communication protocol for orderly
pushbutton command works independently of system
system power turn on and turn off. The LTC2953 includes
logic and automatically shuts off power after the adjustable
a deglitched lockout comparator that prevents the system
timer expires. The length of time the pushbutton must
from drawing power from a dead battery or low supply.
be held low in order to force a power down is adjustable
The device also provides a single adjustable supply reset
with an external capacitor on the PDT pin.
monitor with 200ms delay.
Pushbutton Challenges
The LTC2953’s wide input voltage range (2.7V to 27V)
The ON/OFF pushbutton of electronic devices presents
is designed to operate from single-cell to multicell bat-
the system designer with a unique set of challenges. The
tery stacks, thus eliminating the need for a high voltage
circuits that monitor the pushbutton translate the chat-
tering pushbutton signal into a clean voltage step that , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
VIN VOUT
8.4V 2150k DC/DC 3.3V
UVLO ENVIN SHDN
PB, UVLO AND KILL
23.2k 499k 100k IGNORED
LTC2953-1 PFI VM
100k 32ms 512ms
RST RST
(LTC2953-1)
PFO GPIO
SYSTEM
INT INT
LOGIC
PB KILL KILL
GND PDT KILL SYSTEM SETS
DO NOT CARE
ON/OFF KILL HIGH
DN427 F01
t PDT = 6.4 SECONDS
DN427 F02
Figure 1. Typical Application Figure 2. Orderly Power On
Page Summary Contents For LINEAR dn427f Data Sheet
Manual Details
| Brand | Linear |
|---|---|
| Pages | 2 |
| File Size | 87.85 KB |
| Published | May 31, 2026 |
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