MAX16033 View Datasheet(PDF) - Maxim Integrated

Part Name

Description

Manufacturer

MAX16033

Low-Power Battery Backup Circuits in Small µDFN Packages

Maxim Integrated 

Low-Power Battery Backup

Circuits in Small µDFN Packages

Monitoring a Negative Voltage

Connect the circuit as shown in Figure 9 to use the

power-fail comparator to monitor a negative supply rail.

PFO stays low when V- is good. When V- rises to cause

PFI to be above +1.235V, PFO goes high. Ensure VCC

comes up before the negative supply.

Negative-Going VCC Transients

The MAX16033–MAX16040 are relatively immune to

short-duration, negative-going VCC transients.

Resetting the µP when VCC experiences only small

glitches is not usually desired.

The Typical Operating Characteristics section contains

a Maximum Transient Duration vs. Reset Threshold

Overdrive graph. The graph shows the maximum pulse

width of a negative-going VCC transient that would not

trigger a reset pulse. As the amplitude of the transient

increases (i.e., goes further below the reset threshold

voltage), the maximum allowable pulse width decreas-

es. Typically, a VCC transient that goes 100mV below

the reset threshold and lasts for 25µs does not trigger a

reset pulse.

A 0.1µF bypass capacitor mounted close to VCC pro-

vides additional transient immunity.

3.0V OR 3.3V

VCC

R1

R2

V-

MAX16033–

MAX16040

PFI

PFO

GND

PFO

V-

VL VTRIP

0V

( ) VTRIP

=

⎡

R2⎢ VPFT +

⎣

VPFH

⎛1

⎝⎜ R1

+

1⎞

R2 ⎠⎟

−

VCC

R1

⎤

⎥

⎦

VL

=

R2⎡⎢(VPFT)

⎣

⎛1

⎝⎜ R1

+

1⎞

R2 ⎠⎟

−

VCC

R1

⎤

⎥

⎦

VPFT = 1.235V

VPFH = 12mV

Figure 9. Monitoring a Negative Voltage

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