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SLDM-06D1Ax

tech.support@psbel.com

belpowersolutions.com

26. OUTPUT VOLTAGE SEQUENCING

The SLDM-06D1Ax module includes a sequencing feature, EZ-SEQUENCE that enables users to implement various types of output voltage

sequencing in their applications. This is accomplished via an additional sequencing pin. When not using the sequencing feature, leave it

unconnected.

The voltage applied to the SEQ pin should be scaled down by the same ratio as used to scale the output voltage down to the reference voltage of

the module. This is accomplished by an external resistive divider connected across the sequencing voltage before it is fed to the SEQ pin as

shown in Fig. 44. In addition, a small capacitor (suggested value 100pF) should be connected across the lower resistor R1.

For SLDM-06D1x modules, the minimum recommended delay between the ON/OFF signal and the sequencing signal is 10ms to ensure that the

module output is ramped up according to the sequencing signal. This ensures that the module soft-start routine is completed before the

sequencing signal is allowed to ramp up.

Figure 44

Circuit showing connection of the sequencing signal to the SEQ pin

When the scaled down sequencing voltage is applied to the SEQ pin, the output voltage tracks this voltage until the output reaches the set-point

voltage. The final value of the sequencing voltage must be set higher than the set-point voltage of the module. The output voltage follows the

sequencing voltage on a one-to-one basis. By connecting multiple modules together, multiple modules can track their output voltages to the

voltage applied on the SEQ pin.

The module’s output can track the SEQ pin signal with slopes of up to 0.5V/msec during power-up or power-down.

To initiate simultaneous shutdown of the modules, the SEQ pin voltage is lowered in a controlled manner. The output voltage of the modules

tracks the voltages below their set-point voltages on a one-to-one basis. A valid input voltage must be maintained until the tracking and output

voltages reach ground potential.

Note that in all digital Bel series of modules, the PMBus Output Undervoltage Fault will be tripped when sequencing is employed. This will be

detected using the STATUS_WORD and STATUS_VOUT PMBus commands. In addition, the SMBALERT# signal will be asserted low as occurs

for all faults and warnings. To avoid the module shutting down due to the Output Undervoltage Fault, the module must be set to continue

operation without interruption as the response to this fault (see the description of the PMBus command VOUT_UV_FAULT_RESPONSE for

additional information)

27. OVERCURRENT PROTECTION

To provide protection in a fault (output overload) condition, the unit is equipped with internal current-limiting circuitry and can endure current

limiting continuously. At the point of current-limit inception, the unit enters hiccup mode. The unit operates normally once the output current is

brought back into its specified range.

28. DIGITAL ADJUSTABLE OVERCURRENT WARNING

Please see the Digital Feature Descriptions section.

29. OVERTEMPERATURE PROTECTION

To provide protection in a fault condition, the unit is equipped with a thermal shutdown circuit. The unit will shut down if the overtemperature

threshold of 150oC(typ) is exceeded at the thermal reference point Tref .Once the unit goes into thermal shutdown it will then wait to cool before

attempting to restart.

100 pF

Module

R1=Rtrim

20K

SIG_GND

SEQ

SEQ

V