MAX16046/MAX16048
12-Channel/8-Channel EEPROM-Programmable
System Managers with Nonvolatile Fault Registers
58 ______________________________________________________________________________________
LOAD ADDRESS: This is an extension to the standard
IEEE 1149.1 instruction set to support access to the
memory in the MAX16046/MAX16048. When the LOAD
ADDRESS instruction latches into the instruction regis-
ter, TDI connects to TDO through the 8-bit memory
address test data register during the shift-DR state.
READ DATA: This is an extension to the standard IEEE
1149.1 instruction set to support access to the memory
in the MAX16046/MAX16048. When the READ instruc-
tion latches into the instruction register, TDI connects to
TDO through the 8-bit memory read test data register
during the shift-DR state.
WRITE DATA: This is an extension to the standard
IEEE 1149.1 instruction set to support access to the
memory in the MAX16046/MAX16048. When the WRITE
instruction latches into the instruction register, TDI con-
nects to TDO through the 8-bit memory write test data
register during the shift-DR state.
REBOOT: This is an extension to the standard IEEE
1149.1 instruction set to initiate a software controlled
reset to the MAX16046/MAX16048. When the REBOOT
instruction latches into the instruction register, the
MAX16046/MAX16048 resets and immediately begins
the boot-up sequence.
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 EEPROM depending on the configuration of
the Critical Fault Log Control register (r47h).
SETEXTRAM: This is an extension to the standard
IEEE 1149.1 instruction set that allows access to the
extended page. Extended registers include ADC con-
version results, DACOUT enables, and GPIO input/out-
put data.
RSTEXTRAM: This is an extension to the standard IEEE
1149.1 instruction set. Use RSTEXTRAM to return to the
default page and disable access to the extended page.
SETEEPADD: This is an extension to the standard IEEE
1149.1 instruction set that allows access to the EEPROM
page. Once the SETEEPADD command has been sent,
all addresses are recognized as EEPROM addresses
only. When accessing any EEPROM location, set the
address to the desired location, perform a dummy
READ DATA operation, and then set the address back
to the desired location. This primes the device for a
subsequent series of READ DATA operations.
RSTEEPADD: This is an extension to the standard IEEE
1149.1 instruction set. Use RSTEEPADD to return to the
default page and disable access to the EEPROM.
Applications Information
Unprogrammed Device Behavior
When the EEPROM has not been programmed using
the JTAG or I2C interface, the default configuration of
the EN_OUT_ outputs is open-drain active-low. If it is
necessary to hold an EN_OUT_ high or low to prevent
premature startup of a power supply before the
EEPROM is programmed, connect a resistor to ground
or the supply voltage. Avoid connecting a resistor to
ground if the output is to be configured as open-drain
with a separate pullup resistor.
Device Behavior at Power-Up
When VCC is ramped from 0V, the RESET output is high
impedance until VCC reaches 1.4V, at which point it is
driven low. All other outputs are high impedance until
VCC reaches 2.85V, when the EEPROM contents are
copied into register memory, and after which the out-
puts assume their programmed states.
Margining Power Supplies
The MAX16046/MAX16048 can margin or shift the volt-
ages on external power supplies to facilitate prototyp-
ing or manufacturing tests. There are several different
ways to margin power supplies: One method feeds a
current into the feedback node of a DC-DC converter or
LDO, and another method feeds a current into the trim
input on a DC-DC module.
Feedback Method
See Figure 15 for the connections of the MAX16046/
MAX16048 to a power supply using the feedback node
method. The output voltage, VOUT, can be calculated
using the following formula:
where VREF is the internal reference voltage of the
power supply and VDACOUT_ is the output voltage of
the MAX16046/MAX16048 DACOUT_ output.
Select R1and R2to obtain the desired output voltage
with no trim in effect (VDACOUT_ = VREF). Set the DAC
range bits such that VREF falls approximately halfway
within the DACOUT_ output range (see the
DAC
Outputs
section). The resistor, R3, varies the amount of
control that the DACOUT_ voltage has on the output
voltage of the power supply. Large values of R3corre-
spond to a higher degree of resolution control over the
output voltage, and small values of R3correspond to a
lesser degree of resolution control.