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105 lines
2.7 KiB
105 lines
2.7 KiB
7 years ago
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#!/usr/bin/env python
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# coding: utf8
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NOMINALS = [
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1000000.0,
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750000.0,
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470000.0,
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220000.0,
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75000.0,
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47000.0,
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22000.0,
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10000.0,
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6800.0,
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2200.0,
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1000.0,
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750.0,
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470.0,
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220.0,
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100.0,
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47.0,
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22.0,
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10.0
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]
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def format_value(value, suffix=''):
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order_suffix = ''
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divider = 1.0
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orders = [
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[1000000000.0, 'G'],
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[1000000.0, 'M'],
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[1000.0, 'k'],
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[1.0, ''],
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[0.001, 'm'],
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[0.000001, u'\u00b5'],
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[0.000000001, u'n'],
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[0.000000000001, u'p'],
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]
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for suggested_divider, suggested_order_suffix in orders:
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if value >= suggested_divider:
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divider = suggested_divider
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order_suffix = suggested_order_suffix
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break
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mag_value = value / divider
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mag_value = int(mag_value * 1000)
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mod = mag_value % 1000
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if mod == 0:
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return "%i%s%s" % (mag_value / 1000.0, order_suffix, suffix)
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elif mod % 100 == 0:
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return "%.1f%s%s" % (mag_value / 1000.0, order_suffix, suffix)
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elif mod % 10 == 0:
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return "%.2f%s%s" % (mag_value / 1000.0, order_suffix, suffix)
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return "%.3f%s%s" % (mag_value / 1000.0, order_suffix, suffix)
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def choose_resistors(v_in, v_out, limits='both'):
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if v_in <= v_out:
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raise Exception("Vin should be greater than Vout")
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v_in = float(v_in)
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v_out = float(v_out)
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best_r1 = None
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best_r2 = None
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best_v_out = None
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for r1 in NOMINALS:
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for r2 in NOMINALS:
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tmp_v_out = float(v_in * r2) / (r1 + r2)
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choose_this_pair = best_v_out is None
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if limits == 'both':
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choose_this_pair = choose_this_pair or abs(tmp_v_out - v_out) < abs(best_v_out - v_out)
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elif limits == 'upper':
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choose_this_pair = choose_this_pair or v_out <= tmp_v_out < best_v_out or best_v_out < v_out
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elif limits == 'lower':
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choose_this_pair = choose_this_pair or best_v_out < tmp_v_out <= v_out or best_v_out > v_out
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if choose_this_pair:
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best_r1 = r1
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best_r2 = r2
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best_v_out = tmp_v_out
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print u"R1 %s\nR2 %s\nVout %s\nDissipation %s\nFactor %f" % (
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format_value(best_r1, u'Ω'),
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format_value(best_r2, u'Ω'),
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format_value(best_v_out, 'V'),
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format_value(v_in * v_in / best_r1, 'W'),
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best_r2 / (best_r1 + best_r2)
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)
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def main():
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print "\nPower supply UVLO divider"
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choose_resistors(30, 1.3, 'upper')
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print "\nPower supply feedback divider"
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choose_resistors(5, 1.225, 'lower')
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print "\nUnidirectional sensor"
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choose_resistors(5.1, 3.3, 'lower')
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if __name__ == '__main__':
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main()
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