US 6,556,478 B2 · Method and apparatus for a voltage responsive RESET for EEPROM

Abstract

An under voltage lockout {overscore (RESET)} circuit is connected to the {overscore (RESET)} terminal of a EEPROM. The EEPROM is used in a system which may include a computer or processor and which may be used in space. The under voltage lockout {overscore (RESET)} circuit maybe an under voltage lockout circuit used on a LinFinity SG1526/B or a Unitrode UC1526 regulating pulse width modulator which maintain the {overscore (RESET)} voltage low at all values of power supply voltage source voltage less than a predetermined level. In one embodiment the under voltage lockout {overscore (RESET)} circuit output voltage does not have a “floating voltage” which rises to a level higher than its value when a comparator initially senses that a power supply voltage source voltage is less than the predetermined amount. This is a flat {overscore (RESET)} characteristic under voltage lockout. The {overscore (RESET)} circuit in combination with the EEPROM and computer has particular utility in space applications when a “floating voltage” may be undesirable and may cause failure in a satellite.

Claims14

Dependent claims

A system comprising:

an EEPROM having a {overscore (RESET)} terminal;
a voltage reference generator;
a voltage divider coupled to a power supply voltage source voltage;
a comparator having a first input coupled to the voltage reference generator and a second input coupled to the voltage divider, and an output;
a switch coupled to the comparator, and
said switch coupled to the {overscore (RESET)} terminal of the EEPROM.

3 more elements

A system comprising in combination:

a EEPROM having a {overscore (RESET)} terminal;
a processor having read, write, and address lines connected to said EEPROM;
an under voltage lockout {overscore (RESET)} circuit connected to the EEPROM {overscore (RESET)} terminal and having the following hysteresis characteristics:
(1) when a power supply voltage source voltage is greater than a first predetermined amount, the power supply voltage source voltage is equal to a {overscore (RESET)} voltage;
(2) when the power supply voltage source voltage drops to the first predetermined amount after having been greater than the first predetermined amount, the power supply voltage source voltage remains equal to the {overscore (RESET)} voltage until a second lower predetermined value of the power supply voltage source voltage is reached;
(3) when the power supply voltage source voltage reaches the second lower predetermined value of the power supply voltage source voltage, the under voltage lock out {overscore (RESET)} voltage drops to an amount which is less than a voltage where the EEPROM becomes unerasable and unprogrammable;
(4) when the power supply voltage source voltage is at the second predetermined value and then rises to the first predetermined amount, the under voltage lockout {overscore (RESET)} voltage then rises to equal the power supply voltage source voltage;
and
wherein when the power supply voltage source voltage is less than the first predetermined power supply voltage source voltage, the under voltage lockout {overscore (RESET)} voltage at all times remains at an amount equal to the LOW value of {overscore (RESET)} voltage at the second value of the power supply voltage source voltage.

6 more elements

Dependencies are inferred from the claim text.

Method and apparatus for a voltage responsive RESET for EEPROM

Life of this patent

Method and apparatus for a voltage responsive RESET for EEPROM

Life of this patent

Abstract

Claims14