MAX6887 データシートの表示（PDF） - Maxim Integrated

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MAX6887

Hex/Quad, Power-Supply Supervisory Circuits

Maxim Integrated 

Hex/Quad, Power-Supply Supervisory Circuits

detector input (IN1–IN6) to monitor a user-defined sup-

ply voltage:

0.6V

=

VMON

×

⎛

⎝⎜

R2 ⎞

R1+ R2⎠⎟

where VMON is the desired voltage to be monitored.

Use the following procedure to design the proper volt-

age-divider and calculate thresholds:

1) Pick a value for R2. Use the equation above with

the desired supply voltage to be monitored and

solve for R1. Use high-value resistors R1 and R2 to

minimize current consumption due to low leakage

currents.

2) To find the actual undervoltage and overvoltage

thresholds, use the following equations:

VACTUALUV

=

VMON

×

⎛

⎝⎜

VREFUV

0.6V

⎞

⎠⎟

VACTUALOV

=

VMON

×

⎛

⎝⎜

VREFOV

0.6V

⎞

⎠⎟

VREFUV and VREFOV are the undervoltage and overvolt-

age thresholds listed in Tables 1 and 2 that allow

adjustable thresholds. Their values are based on toler-

ances of ±7.5% and ±12.5% from a 0.6V reference.

See the Selector Guide to find which thresholds in

Tables 1 and 2 are adjustable.

Manual Reset (MR)

Many µP-based products require manual reset capability

to allow an operator or external logic circuitry to initiate a

reset. The manual reset input (MR) can be connected

directly to a switch without an external pullup resistor or

debouncing network. MR is internally pulled up to BP.

Leave unconnected if not used. MR is internally pulled

up to BP through a 10µA current source. MR is designed

to reject fast, falling transients (typically 100ns pulses)

and MR must be held low for a minimum of 1µs to assert

RESET. Connect a 0.1µF capacitor from MR to ground to

provide additional noise immunity. After MR transitions

from low to high, RESET remains asserted for the dura-

tion of its time delay.

Margin Output Disable (MARGIN)

MARGIN allows system-level testing while power sup-

plies exceed the normal operating ranges. Drive

MARGIN low to hold RESET, OV, and WDO in their

Table 1. MAX6887 Threshold Options

PART

MAX6887AETE

MAX6887BETE

MAX6887CETE

MAX6887DETE

MAX6887EETE

MAX6887FETE

MAX6887GETE

MAX6887HETE

MAX6887QETE

MAX6887IETE

MAX6887JETE

MAX6887KETE

MAX6887LETE

MAX6887METE

MAX6887NETE

MAX6887OETE

MAX6887PETE

MAX6887RETE

IN1

4.620

4.620

4.620

3.060

3.060

3.060

3.060

3.060

0.557

4.380

4.380

4.380

2.880

2.880

2.880

2.880

2.880

0.527

UV THRESHOLDS (V)

IN2

IN3

IN4

IN5

3.060 2.310 1.670 0.557

3.060 2.310 0.557 0.557

3.060 1.670 0.557 0.557

2.310 1.670 1.390 0.557

2.310 1.670 0.557 0.557

2.310 1.390 0.557 0.557

2.310 0.557 0.557 0.557

1.670 0.557 0.557 0.557

0.557 0.557 0.557 0.557

2.880 2.190 1.580 0.527

2.880 2.190 0.527 0.557

2.880 1.580 0.527 0.557

2.190 1.580 1.310 0.557

2.190 1.580 0.527 0.557

2.190 1.310 0.527 0.557

2.190 0.527 0.527 0.557

1.580 0.527 0.527 0.557

0.527 0.527 0.527 0.527

IN6

0.557

0.557

0.557

0.557

0.557

0.557

0.557

0.557

0.557

0.527

0.557

0.557

0.557

0.557

0.557

0.557

0.557

0.527

IN1

5.360

5.360

5.360

3.540

3.540

3.540

3.540

3.540

0.643

5.620

5.620

5.620

3.700

3.700

3.700

3.700

3.700

0.673

OV THRESHOLDS (V)

IN2

IN3

IN4

IN5

3.540 2.680 1.930 0.643

3.540 2.680 0.643 0.643

3.540 1.930 0.643 0.643

2.680 1.930 1.610 0.643

2.680 1.930 0.643 0.643

2.680 1.610 0.643 0.643

2.680 0.643 0.643 0.643

1.930 0.643 0.643 0.643

0.643 0.643 0.643 0.643

3.700 2.810 2.020 0.673

3.700 2.810 0.673 0.673

3.700 2.020 0.673 0.673

2.810 2.020 1.680 0.673

2.810 2.020 0.673 0.673

2.810 1.680 0.673 0.673

2.810 0.673 0.673 0.673

2.020 0.673 0.673 0.673

0.673 0.673 0.673 0.673

IN6

0.643

0.643

0.643

0.643

0.643

0.643

0.643

0.643

0.643

0.673

0.673

0.673

0.673

0.673

0.673

0.673

0.673

0.673

8 _______________________________________________________________________________________

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