Datasheet

MAX6887/MAX6888
Hex/Quad, Power-Supply Supervisory Circuits
8 _______________________________________________________________________________________
detector input (IN1–IN6) to monitor a user-defined sup-
ply voltage:
where V
MON
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:
V
REFUV
and V
REFOV
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
VV
V
V
VV
V
V
ACTUALUV MON
REFUV
ACTUALOV MON
REFOV
=×
⎛
⎝
⎜
⎞
⎠
⎟
=×
⎛
⎝
⎜
⎞
⎠
⎟
06
06
.
.
06
2
12
.V V
R
RR
MON
=×
+
⎛
⎝
⎜
⎞
⎠
⎟
Table 1. MAX6887 Threshold Options
UV THRESHOLDS (V) OV THRESHOLDS (V)
PART
IN1 IN2 IN3 IN4 IN5 IN6 IN1 IN2 IN3 IN4 IN5 IN6
MAX6887AETE 4.620 3.060 2.310 1.670 0.557 0.557 5.360 3.540 2.680 1.930 0.643 0.643
MAX6887BETE 4.620 3.060 2.310 0.557 0.557 0.557 5.360 3.540 2.680 0.643 0.643 0.643
MAX6887CETE 4.620 3.060 1.670 0.557 0.557 0.557 5.360 3.540 1.930 0.643 0.643 0.643
MAX6887DETE 3.060 2.310 1.670 1.390 0.557 0.557 3.540 2.680 1.930 1.610 0.643 0.643
MAX6887EETE 3.060 2.310 1.670 0.557 0.557 0.557 3.540 2.680 1.930 0.643 0.643 0.643
MAX6887FETE 3.060 2.310 1.390 0.557 0.557 0.557 3.540 2.680 1.610 0.643 0.643 0.643
MAX6887GETE 3.060 2.310 0.557 0.557 0.557 0.557 3.540 2.680 0.643 0.643 0.643 0.643
MAX6887HETE 3.060 1.670 0.557 0.557 0.557 0.557 3.540 1.930 0.643 0.643 0.643 0.643
MAX6887QETE 0.557 0.557 0.557 0.557 0.557 0.557 0.643 0.643 0.643 0.643 0.643 0.643
MAX6887IETE 4.380 2.880 2.190 1.580 0.527 0.527 5.620 3.700 2.810 2.020 0.673 0.673
MAX6887JETE 4.380 2.880 2.190 0.527 0.557 0.557 5.620 3.700 2.810 0.673 0.673 0.673
MAX6887KETE 4.380 2.880 1.580 0.527 0.557 0.557 5.620 3.700 2.020 0.673 0.673 0.673
MAX6887LETE 2.880 2.190 1.580 1.310 0.557 0.557 3.700 2.810 2.020 1.680 0.673 0.673
MAX6887METE 2.880 2.190 1.580 0.527 0.557 0.557 3.700 2.810 2.020 0.673 0.673 0.673
MAX6887NETE 2.880 2.190 1.310 0.527 0.557 0.557 3.700 2.810 1.680 0.673 0.673 0.673
MAX6887OETE 2.880 2.190 0.527 0.527 0.557 0.557 3.700 2.810 0.673 0.673 0.673 0.673
MAX6887PETE 2.880 1.580 0.527 0.527 0.557 0.557 3.700 2.020 0.673 0.673 0.673 0.673
MAX6887RETE 0.527 0.527 0.527 0.527 0.527 0.527 0.673 0.673 0.673 0.673 0.673 0.673