MAX6875 Просмотр технического описания (PDF) - Maxim Integrated

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MAX6875

EEPROM-Programmable, Hex/Quad, Power-Supply Sequencers/Supervisors

Maxim Integrated 

EEPROM-Programmable, Hex/Quad,

Power-Supply Sequencers/Supervisors

Powering the MAX6874/MAX6875

The MAX6874/MAX6875 derive power from the positive

voltage-detector inputs: IN1 or IN3–IN5. A virtual diode-

ORing scheme selects the positive input that supplies

power to the device (see the Functional Diagram). IN1

must be at least +4V or one of IN3–IN5 (MAX6874)/

IN3–IN4 (MAX6875) must be at least +2.7V to ensure

device operation. An internal LDO regulates IN1 down

to +5.4V.

The highest input voltage on IN3–IN5 (MAX6874)/

IN3–IN4 (MAX6875) supplies power to the device, unless

VIN1 ≥ +6.5V, in which case IN1 supplies power to the

device. For +4V < VIN1 < +6.5V and one of VIN3 through

VIN5 > +2.7V, the input power source cannot be deter-

mined due to the dropout voltage of the LDO. Internal

hysteresis ensures that the supply input that initially pow-

ered the device continues to power the device when

multiple input voltages are within 50mV of each other.

ABP powers the analog circuitry; bypass ABP to GND

with a 1µF ceramic capacitor installed as close to the

device as possible. The internal supply voltage, mea-

sured at ABP, equals the maximum of IN3–IN5

(MAX6874)/IN3–IN4 (MAX6875) if VIN1 = 0, or equals

+5.4V when VIN1 > +6.5V. Do not use ABP to provide

power to external circuitry.

The MAX6874/MAX6875 also generate a digital supply

voltage (DBP) for the internal logic circuitry and the

EEPROM; bypass DBP to GND with a 1µF ceramic

capacitor installed as close to the device as possible.

The nominal DBP output voltage is +2.55V. Do not use

DBP to provide power to external circuitry.

Inputs

The MAX6874/MAX6875 contain multiple logic and volt-

age-detector inputs. Table 1 summarizes these various

inputs.

Set the threshold voltages for each voltage-detector

input with registers 00h–05h. Each threshold voltage is

an undervoltage threshold. Set the threshold range for

each voltage detector with register 0Dh.

Table 1. Programmable Features

FEATURE

High-Voltage Input

(IN1)

DESCRIPTION

• Undervoltage threshold

• +2.5V to +13.2V threshold in 50mV increments

• +1.25V to +7.625V threshold in 25mV increments

Voltage Input (IN2)

• Undervoltage threshold

• +2.5V to +5.5V threshold in 50mV increments

• +1.25V to +3.05V threshold in 25mV increments

Voltage Input

IN3–IN6 (MAX6874),

IN3–IN4 (MAX6875)

• Undervoltage threshold

• +1V to +5.5V threshold in 20mV increments

• +0.5V to +3.05V threshold in 10mV increments

Programmable Outputs

PO1–PO8 (MAX6874),

PO1–PO5 (MAX6875)

•

•

•

•

Active high or active low

Open-drain output

Dependent on MR, MARGIN, IN_, GPI1–GPI4 , WD, and/or PO_

Programmable timeout periods of 25µs, 1.5625ms, 6.25ms, 25ms, 50ms, 200ms, 400ms, or 1.6s

General-Purpose

Logic Inputs,

• Active-high or active-low logic levels

GPI1–GPI4 (MAX6874), • Configure GPI_ as inputs to watchdog timers or programmable output stages

GPI1–GPI3 (MAX6875)

Watchdog Timer

• Clear dependent on any combination of one GPI_ input and one programmable output, a GPI_ input

only, or a programmable output only

• Initial watchdog timeout period of 6.25ms, 25ms, 100ms, 400ms, 1.6s, 6.4s, 25.6s, or 102.4s

• Normal watchdog timeout period of 6.25ms, 25ms, 100ms, 400ms, 1.6s, 6.4s, 25.6s, or 102.4s

• Watchdog enable/disable

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