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SDC_DSQ_DAQ_DCQ0150V2.A04.D02 Page 14 of 25

DSQ/DAQ/DCQ Series

600W Quarter Brick

DOSA Digital PMBus Interface

Input Under-Voltage Shutdown and Start-Up Threshold

Converters will not begin to fully regulate until the rising input voltage exceeds and

remains at the Start-Up Threshold Voltage (see Specifications). Once operating,

converters will not turn off until the input voltage drops below the Under-Voltage

Shutdown Limit. Subsequent restart will not occur until the input voltage rises

again above the Start-Up Threshold. This built-in hysteresis prevents any unstable

on/off operation at a single input voltage. The over/under-voltage fault level and

fault response and hysteresis can be configured via the PMBus interface. See

commands 0x55 (VIN_OV_FAULT_LIMIT) and 0x59 (VIN_UV_FAULT_LIMIT) in the

PMBus command list for additional details

Start-Up Time

Turn-on time (see Specifications) is the time interval between the point when the

rising input voltage crosses the Start-Up Threshold and the output voltage rises to

within 10% of regulation point.

These converters include a soft start circuit to control Vout ramp time, thereby

limiting the input inrush current.

The On/Off Remote Control interval from On command to Vout (final ±10%)

assumes that the converter already has its input voltage stabilized above the

Start-Up Threshold before the On command. The interval is measured from the On

command until the output enters and remains within its specified accuracy band.

See PMBus command 0x60 (TON_DELAY) for additional configuration details

Recommended Input Filtering

The user must assure that the input source has low AC impedance to provide

dynamic stability and that the input supply has little or no inductive content, includ-

ing long distributed wiring to a remote power supply. The converter will operate

with no additional external capacitance if these conditions are met.

For best performance, we recommend installing a low-ESR capacitor imme-

diately adjacent to the converter’s input terminals. The capacitor should be a

ceramic type such as the Murata GRM32 series or a polymer type. More input bulk

capacitance may be added in parallel (either electrolytic or tantalum) if needed.

Recommended Output Filtering

This series achieves it’s rated output ripple and noise without additional external

capacitance. However, the user may install external output capacitance to further

improve ripple or for improved dynamic response, however low-ESR ceramic

(Murata GRM32 series) or polymer capacitors must be used and mounted close to

the converter using only as much capacitance as required to achieve your ripple

and noise objectives. Excessive capacitance may make step load recovery sluggish

and/or introduce instability. Never exceed the maximum rated output capacitance

listed in the specifications.

Input Ripple Current and Output Noise

All models in this converter series are tested and specified for input reflected ripple

current and output noise using designated external input/output components,

circuits and layout as shown in the figures below. The Cbus and Lbus components

simulate a typical DC voltage bus.

+Vin

-Vin

Vin

Cbus

Lbus

Cin

To

Oscilloscope

Current

Probe

Cin = 220uF, ESR < 700mΩ @ 100kHz

Cbus = 220uF, ESR < 100mΩ @ 100kHz

Lbus = 12uH

Figure 14. Measuring Input Ripple Current

C1

C2

+Vout

-Vout

Rload

SCOPE

C1 = 1uF; C2 = 10uF

LOAD 2-3 INCHES(51-76mm) FROM MODULE

Figure 15. Measuring Output Ripple and Noise (PARD)

Minimum Output Loading Requirements

All models regulate within specification and are stable under no load to full load

conditions.

Thermal Shutdown (OTP)

This series includes thermal sense and shutdown circuitry that protects itself from

overtemperature conditions. Upon detection of overtemperature condition defined

by PMBus command 0x4F “OT_FAULT_LIMIT”, the module enters OTP and shuts

down. Once the temperature falls below restart threshold, as defined in PMBus

command list, (OT_FAULT_LIMIT, 0x4F and MFR_OT_ FAULT_HYS, 0xEA), the

module automatically restarts. OTP fault limit and recovery hysteresis are configu-

rable via PMBus.

CAUTION: If you operate too close to the thermal limits, the converter may shut

down suddenly without warning. Be sure to thoroughly test your application to

avoid unplanned thermal shutdown.

Temperature Derating Curves

The graphs in this data sheet illustrate typical operation under a variety of condi-

tions. The Derating curves show the maximum continuous ambient air temperature

and decreasing maximum output current which is acceptable under increasing