Detailed description – Rainbow Electronics MAX16071 User Manual

Page 11

12-Channel/8-Channel, Flash-Configurable System

Managers with Nonvolatile Fault Registers

MAX16070/MAX16071

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Detailed Description

The MAX16070 monitors up to twelve system power sup-
plies and the MAX16071 can monitor up to eight system
power supplies. After boot-up, if EN is high and the soft-
ware enable bit is set to ‘1,’ monitoring begins based on
the configuration stored in flash. An internal multiplexer
cycles through each MON_ input. At each multiplexer
stop, the 10-bit ADC converts the monitored analog volt-
age to a digital result and stores the result in a register.
Each time a conversion cycle (50Fs, max) completes,
internal logic circuitry compares the conversion results
to the overvoltage and undervoltage thresholds stored in
memory. When a result violates a programmed threshold,
the conversion can be configured to generate a fault.
GPIO_ can be programmed to assert on combinations
of faults. Additionally, faults can be configured to shut off
the system and trigger the nonvolatile fault logger, which
writes all fault information automatically to the flash and
write-protects the data to prevent accidental erasure.
The MAX16070/MAX16071 contain both SMBus and
JTAG serial interfaces for accessing registers and flash.
Use only one interface at any given time. For more infor-
mation on how to access the internal memory through
these interfaces, see the SMBus-Compatible Interface
and JTAG Serial Interface sections. The memory map
is divided into three pages with access controlled by
special SMBus and JTAG commands.
The factory-default values at POR (power-on reset) for all
RAM registers are ‘0’s. POR occurs when V

reaches

the undervoltage-lockout threshold (UVLO) of 2.8V (max).
At POR, the device begins a boot-up sequence. During
the boot-up sequence, all monitored inputs are masked

from initiating faults and flash contents are copied to
the respective register locations. During boot-up, the
MAX16070/MAX16071 are not accessible through the
serial interface. The boot-up sequence takes up to
150Fs, after which the device is ready for normal opera-
tion. RESET is asserted low up to the boot-up phase and
remains asserted for its programmed timeout period once
sequencing is completed and all monitored channels
are within their respective thresholds. Up to the boot-up
phase, the GPIO_s are high impedance.

Power

Apply 2.8V to 14V to V

to power the MAX16070/

MAX16071. Bypass V

to ground with a 10FF capaci-

tor. Two internal voltage regulators, ABP and DBP,
supply power to the analog and digital circuitry within
the device. For operation at 3.6V or lower, disable the
regulators by connecting ABP and DBP to V

ABP is a 3.0V (typ) voltage regulator that powers the inter-
nal analog circuitry. Bypass ABP to GND with a 1FF ceram-
ic capacitor installed as close to the device as possible.
DBP is an internal 3.0V (typ) voltage regulator. DBP pow-
ers flash and digital circuitry. All push-pull outputs refer to
DBP. Bypass the DBP output to GND with a 1FF ceramic
capacitor installed as close as possible to the device.
Do not power external circuitry from ABP or DBP.

Enable

To enable monitoring, the voltage at EN must be above
1.4V and the software enable bit in r73h[0] must be set
to ‘1.’ To power down and disable monitoring, either pull
EN below 1.35V or set the Software Enable bit to ‘0.’
See Table 1 for the software enable bit configurations.
Connect EN to ABP if not used.

Table

1. Software Enable Configurations

ADDRESS

FLASH

ADDRESS

BIT RANGE

DESCRIPTION

73h

273h

[0]

Software enable

[1]

Reserved

[2]

1 = Margin mode enabled

[3]

Early warning threshold select
0 = Early warning is undervoltage
1 = Early warning is overvoltage

[4]

Independent watchdog mode enable
1 = Watchdog timer is independent of sequencer
0 = Watchdog timer boots after sequence completes