SMS66

Preliminary Information

Summit Microelectronics, Inc

2070 1.0 7/16/03

2

GENERAL DESCRIPTION

The SMS66 is a highly integrated power supply

controller, monitor and sequencer. It has the ability to

control, monitor and sequence up to six power

supplies. Also, the SMS66 can monitor the VDD input,

the 12V input, two general-purpose analog inputs and

the internal temperature sensor.

The SMS66 has

three operating modes: Power-on sequencing mode,

monitor mode, and Power-off sequencing mode.

Power-on sequencing can be initiated via the

PWR_ON/OFF pin or I

SMS66 will sequence the power supply channels on in

any order by activating the PUP outputs and

monitoring the respective converter voltages to ensure

cascading of the supplies. A programmable sequence

termination timer can be set to disable all channels if

the Power-on sequence stalls. During this mode the

HEALTHY output will remain inactive and the RST

output will remain active.

Once the Power-on sequencing mode is complete, the

SMS66 enters monitor mode. In the monitor mode the

SMS66 supervises the supplies to within 5mV, and

enables the triggering of outputs by monitored fault

conditions.

The 10-bit ADC cycles through all 11 channels every

2ms and checks the conversions against the

programmed threshold limits. The results can be used

to trigger RST, HEALTHY and FAULT outputs as well

as to trigger a Power-off or a Force Shutdown

operation.

The Power-off sequencing mode can only be entered

while the SMS66 is in the monitoring mode. It can be

initiated by either bringing the PWR_ON/OFF pin

inactive, through I

exceeding its programmed thresholds. Once Power-

off is initiated it will disable the Active DC Control and

sequence the PUP outputs off in either the same or

reverse order as Power-on sequencing and monitor

the supply voltages to ensure cascading of the

supplies as they turn off. The sequence termination

timer can be programmed to immediately disable all

channels if the Power-off sequencing stalls. The RST

output will remain active throughout this mode while

the HEALTHY output remains inactive.

Figure 2 – Example Power Supply Sequencing and System Start-up Initialization using the SMS66.

Any order of supply sequencing can be applied using the SMS66 with very accurate monitoring and

supervisory functions.

2.5V

2.7V

1.8V

2.0V

1.5V

VDD (+2.7V to +5.5V)

or 12VIN ( +8V to +15V)

RST#

t

PRTO

t

DPONC

t

DPONB

t

DPOND

t

DPONE

t

DPONF

t

DPONA