20
votes
Accepted
Is there any benefit to using a voltage booster (such as Batteriser) on "dead" batteries?
"Is there any benefit to using a voltage booster on batteries that are below a device's cutoff/operating voltage?"
Of course there are benefits in that situation: a battery that would otherwise be ...
- 48.4k
18
votes
Accepted
What is purpose of an Undervoltage Sensing Circuit?
I guess you are trying to understand why you need an IC to do what a simple transistor could do "in the old days", which is pulling a reset pin low (or high), right? If that's the case, a couple of ...
- 506
8
votes
Is there any benefit to using a voltage booster (such as Batteriser) on "dead" batteries?
Our goal is to keep the load on the batteries running as long as possible. In general, these loads are either fixed resistance (like a basic flashlight) or fixed power (like almost anything electronic ...
- 17.4k
7
votes
Accepted
Under-voltage lockout and a 555 (astable 50% duty cycle) lets LED flash – now save more power
At 50% duty cycle about an average 8mA is going into the LED and another 4.5mA is going into Ra.
The TLC555 itself draws maybe another 0.6mA.
That's 13mA * 60h = 780mAh. not so far from your 1200mAh ...
- 379k
6
votes
What is purpose of an Undervoltage Sensing Circuit?
From the product page at On Semi website.
."The MC33064/MC34064 is an undervoltage sensing circuit specifically designed for use as a reset controller in microprocessor-based systems."
- 22.5k
6
votes
Accepted
Undervoltage lockout
This is the simplest circuit I can think of using BJTs that will provide under-voltage lockout.
simulate this circuit – Schematic created using CircuitLab
How it works:
If Vin is higher than ...
- 20.1k
5
votes
What is purpose of an Undervoltage Sensing Circuit?
There is a bunch of voltage-sensitive activity inside a MCU, and not all activity has problems at the same (out of spec) VDD.
A precise UVD ensures all the activities get the desired VDD, even tho ...
- 33.7k
5
votes
Accepted
Powering 4 12V 0.45Amp fans off USB?
The piece of knowledge missing is the relationship between voltage, current and power, \$ P = VI \$.
From this we can work out:
One fan will require \$ P = VI = 12 \times 0.45 = 5.4 \; W \$.
Four ...
- 169k
5
votes
Accepted
What is the maximum DOD for a Li-Ion Battery?
The lowest safe voltage for a lithium cell is around 3.0V irrespective of the capacity. Below this the cell will be damaged, but for longer life don’t discharge below 3.2V
- 6,826
4
votes
Is there any benefit to using a voltage booster (such as Batteriser) on "dead" batteries?
If one has a device which will draw 20mA continuously at any voltage above the minimum required for operation, and will work equally well at any such voltage, a buck-boost switcher that scan scale a ...
- 46.1k
4
votes
How bad is it to undervoltage a 12-volt lead-acid battery?
Answering to the question "Is there data available to quantify a loss in lead-acid battery quality from low-voltage events?" here are two good sources:
"Battery life is directly related to how deep ...
- 163
4
votes
What is purpose of an Undervoltage Sensing Circuit?
In a normal usage, the user will press the power button to turn a device off. When the MCU sense the button press, it will initiate shut down sequence and the firmware should set the pointer to the ...
- 1,720
3
votes
What is purpose of an Undervoltage Sensing Circuit?
Undervoltage situations can be bad for microcontrollers and memories. Many microcontrollers have a basic undervoltage protection system built in for this reason. The most common failure mode is ...
- 1,789
3
votes
Lead-Acid battery discharged to 5V - how much damage?
When a battery sits for a length of time in a discharged state that's when the plates will suffer the most damage, the lower the voltage the worse it gets of course. if the discharge is very brief and ...
- 31
3
votes
How to supply either 5V or 0V without the gradual PSU voltage bleed?
simulate this circuit – Schematic created using CircuitLab
Figure 1. AC monitoring and shut-off.
Monitor the AC instead. RLY1 will drop out when the AC is switched off. It's contact will open ...
- 169k
3
votes
Can the UVLO threshold be below the minimum supply voltage?
You are looking at two different bits of information. Both of which can be true.
Minimum supply voltage is 8.7V. This is the lowest the input voltage can be where the performance of the IC is ...
- 3,891
2
votes
How bad is it to undervoltage a 12-volt lead-acid battery?
I have experience with well over ten thousand batteries. Under Voltage batteries destroy the battery by causing sulfation in Lead Acid Batteries, or Dendrites in Lithium. Both are very destructive. ...
2
votes
Circuit to protect against undervoltage?
You can connect a push/pull voltage detector (PMIC supervisor) such as the Microchip MCP112 or TC54 to a logic-level MOSFET, e.g. as described in the TC54 datasheet:
(page 6)
There are some popular ...
- 426
2
votes
Can undervoltage kill a circuit?
Another possibility is that your player has an EEPROM that is updated at certain times (eg. to remember the last song that was played) and if voltage drops too low while writing the memory gets ...
- 55.6k
2
votes
Accepted
Can undervoltage kill a circuit?
Yes. Some circuits are non-linear, or particularly, anti-linear: when voltage goes down, current goes up. Notably, boost converters which pump up supply voltage to get their working voltage (e.g. ...
2
votes
Accepted
Controlling BLDC with IR 2130 - stuck at fault, unable to reset
the /FAULT output is an open-drain output. You need an external pull-up resistor to your VCCIO logic supply voltage (3.3V or 5V).
The open-drain output has a low-on resistance in the 55-75 Ohm range. ...
- 131
2
votes
Voltage Cutoff Circuit for battery based application
You will need an additional "switch" in series with the load circuit to disconnect the load. Q1 Cannot disconnect the load because of the manner in which it is connected in its present role.
A P ...
- 148k
2
votes
Accepted
Why does this LTC1440 Comparator switch so slowly?
You've only plotted four points on the curve (which are joined by straight lines). Try decreasing the increment in the DC sweep to 0.01 or something like that.
- 379k
2
votes
Should I add an undervoltage protection for lithium battery-powered projects?
It depends on whether you have a cell or a pack. A cell (usually referred to as a battery) is only the element itself. A pack contains a cell(s) but will have additional protection, usually ...
2
votes
How do ASIC designers approach designing for extremely low supply voltages like 0.3V?
I think you may have confused energy and power. One major component of power consumption in CMOS digital circuits is the power required to switch signal capacitance, and this power is proportional to \...
- 31.2k
2
votes
Accepted
Implementing UVLO on battery charging and boost controller ICs
Is there a way to utilize LBO to build a UVLO ? with a transistor
perhaps ?
I don't think so.
Reason: To be able to use LBI/LBO requires that the enable remains active all the time and, if enable is ...
- 436k
2
votes
Node voltage calculation
It would depend on the microcontroller output, how much current it can source and sink, if it's high, low or high impedance, how close to the supply rails it can go.
If the controller was able to go ...
- 17.8k
2
votes
Can the UVLO threshold be below the minimum supply voltage?
The UVLO threshold specification says that the device might not start at any voltage below 8.9 V. So in practice, your supply must be above 8.9 V.
However, if your particular chip happens to start at ...
- 18.5k
2
votes
Trying to fix leakage issue in this under-voltage cut-off circuit
Get rid of the 741 op amp and use an op amp whose output can go to near zero volts. As a result, Q2 is never completely off, resulting in Q1 never being completely off.
Also, in simulation you can try ...
- 5,220
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