||NAVSO P-3641A: More Power For The Dollar
B. Design Review Checklists for Power Systems and Power Supplies
- Have requests been initiated for approval of
- Have tolerance effects, including those due to environment, been
considered on all critical component parameters?
- Are all components applied within their derated electrical and
- Have transient effects been considered?
- Are there any storage life limited components used and, if so, can they be
eliminated or their effect minimized?
- Have any components been overspecified, e.g., can less qualified
- ;Have adjustments been eliminated wherever possible?
- Have circuit stability, race conditions and/or areas of critical timing
been identified and analyzed?
- Do all components have a second source of supply?
- Are the capacitors properly derated with respect to working voltage,
ripple current and case temperature?
- Are the capacitors adequately protected against surge voltages which
exceed the rated operating voltage?
- Have the effects of AC ripple current on "hot-spot" temperature been
- Have temperature-compensating or low-temperature-coefficient capacitors
(mica or ceramic) been used wherever high stability is required?
- Are tantalum capacitors bypassed with ceramics for frequencies above 100
- Are the resistors properly derated with respect to power dissipation,
voltage, and temperature?
- Has the rated wattage been adjusted in cases where short mounting leads
- Can any potentiometers be replaced by fixed resistors?
- Have noninductive types been used in high-frequency applications?
- Has peak current capability been considered with respect to wire wound
resistor fusing current?
- Are linear devices properly derated with respect to output current, input
voltage, power supply voltage and temperature?
- Are digital devices properly derated with respect to fan-out, power supply
voltage and temperature?
- Has adequate power supply decoupling been employed?
- Has the effect of operating frequency and switch speed on digital device
power dissipation been considered?
- Have unused logic inputs been properly terminated by grounding or through
a pull-up resistor?
- Have effects of wiring and connectors on propagation delay been
- Have adequate precautions been taken against electrostatic discharge (ESD)
- Are the devices adequately derated with respect to voltage, current, power
dissipation and temperature?
- Does transistor operation approach any absolute rating including Safe
Operating Area (SOA) under any unusual variations of supply voltage or load?
- Will the circuit perform satisfactorily with randomly selected
- Is power gain a critical consideration in this application?
- Is noise figure a critical consideration in this application?
- How much leakage current is expected over the operating ambient
- Are devices adequately derated with respect to voltage, current, power
dissipation and temperature?
- How much reverse recovery time do the diodes require?
- How much reverse current can be tolerated and how much reverse current
will flow at the operating ambient temperature range?
- Does the circuit perform satisfactorily with randomly selected
diodes? Is snubbing required?
- What zener voltage reference is required, compared with the zener
reference voltage expected at the actual operating current levels?
Transformers, Chokes and Coils
- Are the units adequately derated for voltage, current, flux density and
- Is Q a critical consideration in this circuit application?
- How close is the highest operating frequency to the resonant frequency of
the chokes or coils?
- Has a shielding requirement been established? (Faraday Shield)
- Where a hum problem exists, has special consideration been given to core
Connectors and Plugs
- Does the number of active pins per connector conform to the recommended
limit (unused spares requirement)?
- Are a sufficient number of spare pins available on each connector?
- Is it necessary to parallel connector pins to obtain adequate
current-carrying capacity? (Do not depend on equal current-sharing.)
- Has consideration been given to the current rating of wire?
- Has the current rating of wire been reduced in cases where voltage drop is
- Is wire color-coding required, and if so, is it in accordance with the
proper standards or specifications?
- Has the placement of components on printed wiring boards been considered
from the crosstalk point of view?
- Does a heat dissipation problem exist on printed wiring boards?
- Is a keying scheme employed to prevent interchanging printed wiring
- Are integrated circuits, transistors, diodes, and polarized capacitors
properly oriented on printed wiring boards?
- Do any large potential gradients exist between adjacent pins or connectors
on printed wiring boards?