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سجل التغييرات الكاملالمحرّك 1.18.3

System Power Budget

Power & Regulators

Total input power, conversion loss and battery runtime across every rail on the board.

هذه الصفحة غير مترجمة بالكامل بعد. الأجزاء غير المترجمة معروضة بالإنجليزية.

المدخلات

V
The rated current of the adapter, bus or upstream regulator at Vin
A
Headroom for tolerance, ageing and loads not listed
%
Usable capacity, after cut-off and temperature derating
mAh
V
Rail / loadFed from (V)Rail V (V)Load I (A)Duty (%)ConverterEff. (%)
120 mA
60 mA
30 mA
250 mA
800 mA

النتائج

1 للمراجعة
Drawn from input Pin

بلا حكم: no supply current entered. Enter it to check this budget against the supply.

with 20 % margin: 5.179 W
4.316W
System efficiency
97.1%
Input current (with margin) Iin

at 12 V; rate the fuse and connector above this
431.6mA
كل النتائج (2)
Delivered to loads Pload
4.193W
Total conversion loss

2.9 % of input
123.6mW
LDO efficiency is below 60 % on Sensor 1V8. An LDO's efficiency is Vout/Vin, so consider a switcher ahead of it and leave the LDO a small drop.

Each row's input power is added as if drawn straight from Vin, so a row fed from another rail misses that rail's conversion loss. For an exact total, add its input current to the parent rail's load instead of giving it a row.

Totals are duty-weighted averages. Size bulk capacitance, connector and fuse for the peak: 800 mA on Motor driver.

Per-rail breakdown
RailFromVIDutyTypeηP loadP inLoss
MCU 3V312 V3.3 V120 mA100 %Buck89.0 %396 mW445 mW48.9 mW
Analog 5V12 V5 V60 mA100 %Buck91.0 %300 mW330 mW29.7 mW
Sensor 1V83.3 V1.8 V30 mA100 %LDO54.5 %54 mW99 mW45 mW
RF TX burst3.3 V3.3 V250 mA10 %Direct100.0 %82.5 mW82.5 mW0 W
Motor driver12 V12 V800 mA35 %Direct100.0 %3.36 W3.36 W0 W
Total4.193 W4.316 W123.6 mW
Where the heat goes
MCU 3V3
48.9 mW
Sensor 1V8
45 mW
Analog 5V
29.7 mW
RF TX burst
0 W
Motor driver
0 W

المسح البارامتري

غيّر مدخلاً واحداً على مدى، وشاهد الإجابة والحكم والهامش عند كل خطوة، جدولاً ومنحنى.Pro

أسوأ الحالات

أضف التفاوتات إلى المدخلات لتحصل على النطاق المضمون حول الإجابة الاسمية، لا الحالة النموذجية وحدها.Pro

المبدأ

A power budget answers four questions: how much current comes in, how much heat stays on the board, how long the battery lasts, and which part loses the most power.

Load power on a rail
Pload=Vrail⋅Iload⋅DP_{load} = V_{rail} \cdot I_{load} \cdot D
D is the load's duty. A radio on 10 % of the time adds a tenth of its power to the average, but its full peak to the decoupling design.
Switching converter
Pin=PloadηPloss=Pload(1η−1)P_{in} = \frac{P_{load}}{\eta} \qquad P_{loss} = P_{load}\left(\frac{1}{\eta}-1\right)
Linear regulator (LDO)
Pin=VinIloadPloss=(Vin−Vout) Iloadη=VoutVinP_{in} = V_{in} I_{load} \qquad P_{loss} = (V_{in}-V_{out})\,I_{load} \qquad \eta = \frac{V_{out}}{V_{in}}
The load current passes straight through, so efficiency is set by the voltage ratio alone.
System
ηsys=∑Pload∑PinIin=∑Pin⋅(1+m)Vin\eta_{sys} = \frac{\sum P_{load}}{\sum P_{in}} \qquad I_{in} = \frac{\sum P_{in}\cdot(1+m)}{V_{in}}
Battery runtime
t=CmAh⋅Vbat1000⋅Pinhourst = \frac{C_{mAh}\cdot V_{bat}}{1000 \cdot P_{in}} \quad \t{hours}
  • η\etaconverter efficiency at the actual load current
  • DDduty of the load, 0…1
  • mmdesign margin
  • CmAhC_{mAh}usable battery capacity, after cut-off and temperature derating
تفاصيل إضافية

Getting the numbers right

  • Efficiency at your load current. A buck rated 95 % may be 70 % at 10 mA.
  • Quiescent currents. Regulators, supervisors, dividers and pull-ups draw all the time. In a sleeping battery product they often dominate.
  • Average and peak. Average sets battery life and heat. Peak sets bulk capacitance, connector, fuse and trace width.
  • Inrush. Charging the bulk capacitance at power-on can far exceed the steady peak. It sets soft-start and fuse I²t.
Margin. 20 % is normal for a mature design; use 30–50 % on a first prototype.

Total loss is the heat left inside the enclosure. Compare it with what the enclosure can shed.

Workflow: budget → LDO Dissipation & Limits / Buck Converter Design for each stage → Junction Temperature & Safe Limits for each hot part → Trace Width for each high-current path.

إصدار المحرك ⁨1.18.3⁩