±5V, ±12V (±15V) Dedicated

Microprocessor Voltage Monitors

6

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_______________Detailed Description

The MAX8215/MAX8216 contain 5 comparators (Figure

1). The comparator with its output labeled DOUT is dis-

tinguished from the others in that it can be set up to mon-

itor various voltages; each of the other 4 comparators

monitors a specific voltage. The DOUT comparator’s

noninverting input is available external to the device; its

inverting input is tied internally to the reference.

The MAX8215/MAX8216 comparators have open-drain

outputs. Thus, these devices require pull-up resistors

for proper operation. See the

Typical Operating Circuit.

Open-drain outputs are useful for driving LEDs and for

situations in which the comparator outputs must be

connected together (i.e., wire-ORed).

__________Applications Information

Hysteresis

When the voltage on a typical comparator’s input is

at or near the voltage on the other input, ambient

noise generally causes the comparator output to

oscillate. The most common way to eliminate this

problem is by using hysteresis. When the two com-

parator input voltages are equal, hysteresis causes

one comparator input voltage to move quickly past

the other, thus taking the input out of the region

where oscillation occurs.

Standard comparators

need external resistors for hysteresis; these resistors

are not necessary when using any of the MAX8215

and MAX8216 comparators because hysteresis is

built in.

NAME

FUNCTION

1

VREF

Output of the internal 1.24V reference

2

GND

Ground. Connect to PGND.

3

+5V

Input for monitoring +5V supply

PIN

4

-5V

Input for monitoring -5V supply

5

+12V

(+15V)

MAX8215 input for monitoring +12V

(MAX8216 input for monitoring +15V)

6

-12V

(-15V)

MAX8215 input for monitoring -12V

(MAX8216 input for monitoring -15V)

7

DIN

Noninverting input of the auxiliary

comparator. Its inverting input is tied

to the internal reference.

8

PGND

9

DOUT

Output of the auxiliary comparator

_____________________Pin Description

to this pin.

Outputs of the four dedicated com-

parators

14

10, 11,

12, 13

OUT4,

OUT3,

OUT2,

OUT1

Power-supply positive voltage input.

Bypass to PGND.

+5V

OUT1

-5V

OUT2

OUT3

+12V (+15V)

OUT4

-12V (-15V)

DOUT

DIN

1.24V REFERENCE

VREF

( ) ARE FOR

MAX8216 ONLY.

MAX8215

MAX8216

PGND

GND

Figure 1. Block Diagram