Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF HTML

MC3425 Datasheet(PDF) 6 Page - ON Semiconductor

Part No. MC3425
Description  POWER SUPPLY SUPERVISORY/ OVER AND UNDERVOLTAGE PROTECTION CIRCUIT
Download  12 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  ONSEMI [ON Semiconductor]
Homepage  http://www.onsemi.com
Logo 

MC3425 Datasheet(HTML) 6 Page - ON Semiconductor

Zoom Inzoom in Zoom Outzoom out
 6 / 12 page
background image
MC3425
6
MOTOROLA ANALOG IC DEVICE DATA
CIRCUIT DESCRIPTION
The MC3425 is a power supply supervisory circuit
containing all the necessary functions required to monitor
over and undervoltage fault conditions. The block diagram
is shown below in Figure 15. The Overvoltage (O.V.) and
Undervoltage (U.V.) Input Comparators are both
referenced to an internal 2.5 V regulator. The U.V. Input
Comparator has a feedback activated 12.5
µA current sink
(IH) which is used for programming the input hysteresis
voltage (VH). The source resistance feeding this input (RH)
determines the amount of hysteresis voltage by VH = IHRH
= 12.5
× 10–6 RH.
Separate Delay pins (O.V. DLY, U.V. DLY.) are provided for
each channel to independently delay the Drive and Indicator
outputs, thus providing greater input noise immunity. The two
Delay pins are essentially the outputs of the respective input
comparators, and provide a constant current source,
IDLY(source), of typically 200 µA when the noninverting input
voltage is greater than the inverting input level. A capacitor
connected from these Delay pins to ground, will establish a
predictable delay time (tDLY) for the Drive and Indicator
outputs. The Delay pins are internally connected to the
noninverting inputs of the O.V. and U.V. Output Comparators,
which are referenced to the internal 2.5 V regulator.
Therefore, delay time (tDLY) is based on the constant current
source, IDLY(source), charging the external delay capacitor
(CDLY) to 2.5 V.
tDLY =
Vref CDLY
IDLY(source)
=
2.5 CDLY
200
µA
= 12500 CDLY
Figure 5 provides CDLY values for a wide range of time
delays. The Delay pins are pulled low when the respective
input comparator’s noninverting input is less than the
inverting input. The sink current, IDLY(sink), capability of the
Delay pins is
≥ 1.8 mA and is much greater than the typical
200
µA source current, thus enabling a relatively fast delay
capacitor discharge time.
The Overvoltage Drive Output is a current–limited
emitter–follower capable of sourcing 300 mA at a turn–on
slew rate at 2.0 A/
µs, ideal for driving “Crowbar” SCR’s. The
Undervoltage Indicator Output is an open–collector, NPN
transistor, capable of sinking 30 mA to provide sufficient drive
for LED’s, small relays or shut–down circuitry. These current
capabilities apply to both channels operating simultaneously,
providing device power dissipation limits are not exceeded.
The MC3425 has an internal 2.5 V bandgap reference
regulator with an accuracy of
± 4.0% for the basic device.
Note: All voltages and currents are nominal.
Input Section
Output Section
VCC
O.V.
DRV
U.V.
IND
O.V.
Sense
U.V.
Sense
U.V.
DLY
O.V.
DLY
Gnd
200
µA
3
4
IH
52
7
+
2.5V
Reference
Regulator
+
Output
Comparator
U.V.
8
1
6
+
+
+
+
+
+
+
Output
Comparator
O.V.
Input
Comparator
O.V.
Input
Comparator
U.V.
200
µA
12.5
µA
Figure 15. Representative Block Diagram


Html Pages

1  2  3  4  5  6  7  8  9  10  11  12 


Datasheet Download




Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn