Rainbow Electronics MAX16066 - Manual (Page 50)

12-Channel/8-Channel, Flash-Configurable System
Managers with Nonvolatile Fault Registers
MAX16065/MAX16066
50 _____________________________________________________________________________________
SAVE: This is an extension to the standard IEEE 1149.1
instruction set that triggers a fault log. The current ADC
conversion results along with fault information are saved
to flash depending on the configuration of the Critical
Fault Log Control register (r6Dh).
SETFLSHADD: This is an extension to the standard IEEE
1149.1 instruction set that allows access to the flash
page. Flash registers include ADC conversion results,
DACOUT enables, and GPIO_ input/output data. Use
this page to access registers 200h to 2FFh
RSTFLSHADD: This is an extension to the standard
IEEE 1149.1 instruction set. Use RSTFLSHADD to return
to the default page and disable access to the flash page.
SETUSRFLSH: This is an extension to the standard IEEE
1149.1 instruction set that allows access to the user flash
page. When on the configuration flash page, send the
SETUSRFLSH command, all addresses are recognized
as flash addresses only. Use this page to access regis-
ters 300h to 3FFh.
RSTUSRFLSH: This is an extension to the standard IEEE
1149.1 instruction set. Use RSTUSRFLSH to return to
the configuration flash page and disable access to the
user flash.
Restrictions When Writing to Flash
Flash must be written to 8 bytes at a time. The initial
address must be aligned to 8-byte boundaries—the 3
LSBs of the initial address must be ‘000’. Write the 8
bytes using eight successive Write Data commands.
Applications Information
Unprogrammed Device Behavior
When the flash has not been programmed using the
JTAG or SMBus interface, the default configuration of
the EN_OUT_ outputs is open-drain active-low. This
means that the EN_OUT_ outputs are high impedance.
When it is necessary to hold an EN_OUT_ high or low to
prevent premature startup of a power supply before the
flash is programmed, connect a resistor from EN_OUT_
to ground or the supply voltage. Avoid connecting a
resistor to ground when the output is to be configured as
open-drain with a separate pullup resistor.
Device Behavior at Power-Up
When V CC is ramped from 0, the RESET output is high
impedance until V CC reaches 1.4V, at which point RESET
goes low. All other outputs are high impedance until V CC
reaches 2.7V, when the flash contents are copied into
register memory. This takes 150Fs (max), after which the
outputs assume their programmed states.
Programming the
MAX16065/MAX16066 in Circuit
The MAX16065/MAX16066 can be programmed in the
application circuit by taking into account the following
points during circuit design:
U
The MAX16065/MAX16066 needs to be powered from
an intermediate voltage bus or auxiliary voltage sup-
ply so programming can occur even when the board’s
power supplies are off. This could also be achieved by
using ORing diodes so that power can be provided
through the programming connector.
U
The SMBus or JTAG bus lines should not connect
through a bus multiplexer powered from a voltage rail
controlled by the MAX16065/MAX16066. If the device
needs to be controlled by an on-board FP, consider
connecting the FP to one bus (such as SMBus) and
use the other bus for in-circuit programming.
U
An unprogrammed MAX16065/MAX16066’s EN_OUT_s
go high impedance. Ensure that this does not cause
undesired circuit behavior. If necessary, connect pull-
down resistors to prevent power supplies from turning on.
Maintaining Power
During a Fault Condition
Power to the MAX16065/MAX16066 must be maintained
for a specific period of time to ensure a successful flash
fault log operation during a fault that removes power to
the circuit. Table 33 shows the amount of time required
depends on the settings in the fault control register
(r6Dh[1:0]).
Maintain power for shutdown during fault conditions in
applications where the always-on power supply cannot
be relied upon by placing a diode and a large capacitor
between the voltage source, V
IN , and V CC (Figure 17).
The capacitor value depends on V IN and the time delay
Table 32. 32-Bit User-Code Data
MSB LSB
Don’t Care SMBus slave id User ID (r8A[7:0])
00000000000000000 See Table 27