MAX6709 Maxim, MAX6709 Datasheet - Page 10

• Manufacturer Part Number: MAX6709
• Description: Low-Voltage / High-Accuracy / Quad Voltage Monitors in MAX Package
• Manufacturer: Maxim

Or, solved in terms of R1:
The unused inputs (except the adjustable) are internally
connected to ground through the lower resistors of the
threshold-setting resistor pairs. The adjustable input,
however, must be connected to ground if unused.
The MAX6714 RESET output asserts low when V
drops below its specified threshold or MR asserts low
and remains low for the reset timeout period (140ms
min) after V
(Figure 8). The output is open drain with a weak (10µA)
internal pullup to V
nal pullup resistor is required to interface with other
logic devices. An external pullup resistor to any voltage
from 0 to 5.5V overdrives the internal pullup if interfac-
ing to different logic supply voltages (Figure 9). Internal
circuitry prevents reverse current flow from the external
pullup voltage to V
Many µP-based products require manual reset capabili-
ty, allowing the operator, a test technician, or external
logic circuitry to initiate a reset. A logic low on MR
asserts RESET low. RESET remains asserted while MR is
low, and during the reset timeout period (140ms min)
after MR returns high. The MR input has an internal 20kΩ
pullup resistor to V
Drive MR with TTL or CMOS-logic levels, or with open-
drain/collector outputs. Connect a normally open momen-
tary switch from MR to GND to create a manual reset
function; external debounce circuitry is not required. If
MR is driven from long cables or if the device is used in a
Low-Voltage, High-Accuracy, Quad Voltage
Monitors in µMAX Package
Figure 7. Setting the Auxiliary Monitor
10
______________________________________________________________________________________
CC
R1 = R2 ((V
exceeds its threshold and MR deasserts
V
INTH
CC
CC
CC
R1
R2
.
, so it can be left open if unused.
. For many applications, no exter-
INTH
V
REF
= 0.62V
R1 = R2
/ 0.62V) - 1)
Manual Reset Input
(
V
0.62V
Unused Inputs
INTH
Reset Output
- 1
)
CC
noisy environment, connecting a 0.1µF capacitor from
MR to GND provides additional noise immunity.
The MAX6714 can be configured to assert a reset from a
second voltage by connecting the power-fail output to
manual reset. As the V
goes low and asserts the reset output for the reset time-
out period after the manual reset input is deasserted.
(See Typical Operating Circuit.)
The MAX6709/MAX6714 operate from a single 2.0V to
5.5V supply. In noisy applications, bypass V
0.1µF capacitor as close to V
Figure 9. Interfacing to Different Logic Supply Voltage
Figure 8. RESET Output Timing Diagram
RESET
V
V
Power-Supply Bypassing and Grounding
TH_
CC
Reseting the µP from a 2nd Voltage
V
MAX6714
V
CC
CC
GND
= 3.3V
t
RD
RESET
10%
PFI_
falls below its threshold, PFO
CC
100kΩ
as possible.
RESET
t
RP
GND
(MAX6714)
V
5V
CC
V
TH_
CC
with a
90%