MAX6884ETP MAXIM [Maxim Integrated Products], MAX6884ETP Datasheet - Page 13

• Manufacturer Part Number: MAX6884ETP
• Description: EEPROM-Programmable, Hex Power-Supply Supervisory Circuits
• Manufacturer: MAXIM [Maxim Integrated Products]

The MAX6884/MAX6885 derive power from the voltage-
detector inputs: IN1–IN4 or through an externally sup-
plied V
positive input that supplies power to the device (see the
Functional Diagram). The highest input voltage on
IN1–IN4 supplies power to the device. One of V
must be at least 2.7V to ensure proper operation.
Internal hysteresis ensures that the supply input that initially
powered the device continues to power the device when
multiple input voltages are within 50mV of each other.
V
nection for the MAX6884/MAX6885 internal supply.
Bypass V
installed as close to the device as possible. The internal
supply voltage, measured at V
of IN1–IN4. If V
least 200mV higher than any voltage applied to IN–IN4
and V
the device when all IN_ are factory set as “ADJ.” Do not
use the internally generated V
external circuitry. Externally supply power through V
To externally supply power through V
1) Apply a voltage to only one of V
2) Program the internal/external V
3) Power down the device.
Subsequent power-ups and software reboots require an
externally supplied V
operational.
The MAX6884/MAX6885 also generate a digital supply
voltage (DBP) for the internal logic circuitry and the
EEPROM. Bypass DBP to GND with a 1µF ceramic
capacitor installed as close to the device as possible.
The nominal DBP output voltage is 2.55V. Do not use
DBP to provide power to external circuitry.
Table
REGISTER
ADDRESS
CC
IN1–IN4 (2.7V to 5.8V).
96h, Bit[5] = 1 (see Table 2).
16h
powers the analog circuitry and is the bypass con-
CC
CC
2. Internal/External V
must be brought up first. V
. A virtual diode-ORing scheme selects the
CC
Powering the MAX6884/MAX6885
ADDRESS
MEMORY
EEPROM
to GND with a 1µF ceramic capacitor
CC
96h
is externally supplied, V
______________________________________________________________________________________
CC
RANGE
to ensure the device is fully
BIT
[5]
[2]
[4]
[6]
CC
CC
Power-Supply Supervisory Circuits
, equals the maximum
CC
1 = V
0 = IN1–IN4 or V
Powered
Not Used
Not Used
Not Used
to provide power to
CC
CC
CC
CC
Power EEPROM at
DESCRIPTION
CC
(2.7V to 5.5V) or
:
always powers
Powered
CC
must be at
EEPROM-Programmable, Hex
IN1
CC
–V
CC
IN4
.
An internal 10-bit ADC (MAX6884 only) converts volt-
ages at IN1–IN4, AUXIN, and V
that automatically sequences through all inputs every
200ms. Registers 18h to 27h store the ADC data (see
Table
the serial interface. The ADC has no effect on program-
mable outputs RESET, UV/OV, or WDO.
The MAX6884/MAX6885 offer the following inputs: volt-
age-detector inputs IN1–IN4, auxiliary input AUXIN
(MAX6884 only), manual reset input MR, margin input
MARGIN, and reference input REFIN (MAX6884 only).
The MAX6884/MAX6885 offer six voltage-detector inputs:
IN1–IN6. Each voltage-detector input offers a program-
mable primary undervoltage threshold and a secondary
undervoltage/overvoltage threshold. Program thresholds
from 0.5V to 3.05V in 10mV increments, 1.0V to 5.8V in
20mV increments, or from 0.1667V to 1.0167V in 3.3mV
increments. Use the following equations to program
thresholds in the appropriate registers:
for 1V to 5.8V range in 20mV increments (program bits
R0Fh[5:0]).
for 0.5V to 3.05V range in 10mV increments (program
bits R0Fh[5:0]).
for 0.1667V to 1.0167V in 3.3mV increments (see the
External Voltage-Divider section).
where V
decimal code for the desired threshold (see
set a threshold for the 1V to 5.8V range, X must equal 240
or less. Set the secondary threshold for an undervoltage
or overvoltage threshold by programming bits R0Eh[5:0].
To achieve thresholds in between the 10mV and 20mV
steps or to monitor voltages higher than 5.8V, program a
voltage-detector input for high impedance through bits
R10h[5:0] and add a resister voltage-divider (see the
External Voltage-Divider section).
3). Read the ADC data from the MAX6884 with
TH
is the desired threshold voltage and X is the
X
X
=
X
=
V
=
TH
V
V
TH
0 0033
TH
0 02
0 01
−
.
.
.
−
ADC (MAX6884 Only)
0 1667
−
.
V
0 5
V
CC
1
.
V
V
V
through a multiplexer
V
Table
IN1–IN6
Inputs
4). To
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