SMM605
Preliminary Information
APPLICATIONS INFORMATION (CONTINUED)
WRITE PROTECTION
MARGINING
Write protection for the SMM605 is located in a volatile
register where the power-on state is defaulted to write
protect. There are separate write protect modes for the
configuration registers and memory. In order to
remove write protection, the code 55HEX is written to
the write protection register. Other codes will enable
write protection. For example, writing 59HEX will allow
writes to the configuration register but not to the
memory, while writing 35HEX will allow writes to the
memory but not to the configuration registers. In
addition, there is a configuration register lock bit
which, once programmed, does not allow the
configuration registers to be changed.
The SMM605 has two additional Active DC Output
Control voltage settings: margin high and margin low.
The margin high and margin low settings can be as
much as ±10% of the nominal setting depending on
the manufacturer. The SMM605 range can be as
large as 0.35V to VDD. These settings are stored in
the configuration registers and are loaded into the
Active DC Output Control voltage setting by margin
commands issued via the I2C bus. The device must
be enabled for Active DC Output Control in order to
enable margining.
The margin command registers contain two bits that
decode the commands to margin high, margin low, or
control to the nominal setting. Once the SMM605
receives the command to margin the supply voltage, it
begins adjusting the supply voltage to move toward
the desired setting. When this voltage setting is
reached, a bit is set in the margin status registers and
the READY signal becomes active. (Figure 2, 5 and 6)
Note: Configuration writes or reads of registers 00HEX
to 03HEX should not be performed while the SMM605 is
margining.
Figure 5 - Margin High Waveforms
Figure 6 - Margin Low Waveforms
Time/Horizontal division = 200mS
Time/Horizontal division = 400mS
Ch 1 (1V/Div) = 3.3V DC-DC converter output (Yellow trace)
Ch 2 (500mV/Div) = 2.5VDC-DC converter output (Blue trace)
Ch 3 (500mV/Div) = 1.8V DC-DC converter output (Purple trace)
Ch 4 (500mV/Div) = 1.5V DC-DC converter output (Green trace)
Ch 1 (1V/Div) = 3.3V DC-DC converter output (Yellow trace)
Ch 2 (500mV/Div) = 2.5V DC-DC converter output (Blue trace)
Ch 3 (500mV/Div) = 1.8V DC-DC converter output (Purple trace)
Ch 4 (500mV/Div) = 1.5V DC-DC converter output (Green trace)
Summit Microelectronics, Inc
2064 1.1 09/16/03
10
SUMMIT [ SUMMIT MICROELECTRONICS, INC. ]
