Доброго времени.
Обьясните как определить номиналы R3 и R4 согласно схемы. В электронике не силен и с английским туго. Интересует конкретно max1676.
1. V OUT can be set to 3.3V or 5.0V by connecting the FB pin to GND (5V) or OUT (3.3V) (Figures 5 and 6). из этого я понял, что для получения 5В на выходе необходимо пин FB притянуть к земле.
2.
Low-Battery Detection
The MAX1674/MAX1675/MAX1676 contain an on-chip
comparator for low-battery detection. If the voltage at
LBI falls below the internal reference voltage (1.30V),
LBO (an open-drain output) sinks current to GND. The
low-battery monitor threshold is set by two resistors, R3
and R4 (Figures 5, 6, and 7). Since the LBI current is
less than 50nA, large resistor values (R4 ≤ 260kΩ) can
be used to minimize loading of the input supply.
Calculate R3 using the following equation:
R3 = R4 [(V TRIP / V REF ) - 1]
for V TRIP ≥ 1.3V. V TRIP is the level where the low-battery
detector output goes low, and V REF is the internal
1.30V reference. Connect a pull-up resistor of 100kΩ or
greater from LBO to OUT when driving CMOS circuits.
LBO is an open-drain output, and can be pulled as
high as 6V regardless of the voltage at OUT. When LBI
is above the threshold, the LBO output is high imped-
ance. If the low-battery comparator is not used, ground
LBI and LBO. For V TRIP less than 1.3V, configure the
comparator as shown in Figure 8. Calculate the value of
the external resistors R3 and R4 as follows:
R3 = R4(V REF - V TRIP ) / (V OUT - V REF )
Since the low-battery comparator is noninverting, exter-
nal hysteresis can be added by connecting a resistor
between LBO and LBI as shown in Figure 9. When LBO
is high, the series combination of R2 and R7 source
current into the LBI summing junction.
От номиналов R3 и R4 зависит контроль низкого уровня питания, но как конкретно их (номиналы) определить, из даташит не понял (сложновато на английском). Можно-ли вообще не использовать эти пины контроля низкого уровня?
или я вообще все неправильно понимаю?
Обьясните как определить номиналы R3 и R4 согласно схемы. В электронике не силен и с английским туго. Интересует конкретно max1676.
1. V OUT can be set to 3.3V or 5.0V by connecting the FB pin to GND (5V) or OUT (3.3V) (Figures 5 and 6). из этого я понял, что для получения 5В на выходе необходимо пин FB притянуть к земле.
2.
Low-Battery Detection
The MAX1674/MAX1675/MAX1676 contain an on-chip
comparator for low-battery detection. If the voltage at
LBI falls below the internal reference voltage (1.30V),
LBO (an open-drain output) sinks current to GND. The
low-battery monitor threshold is set by two resistors, R3
and R4 (Figures 5, 6, and 7). Since the LBI current is
less than 50nA, large resistor values (R4 ≤ 260kΩ) can
be used to minimize loading of the input supply.
Calculate R3 using the following equation:
R3 = R4 [(V TRIP / V REF ) - 1]
for V TRIP ≥ 1.3V. V TRIP is the level where the low-battery
detector output goes low, and V REF is the internal
1.30V reference. Connect a pull-up resistor of 100kΩ or
greater from LBO to OUT when driving CMOS circuits.
LBO is an open-drain output, and can be pulled as
high as 6V regardless of the voltage at OUT. When LBI
is above the threshold, the LBO output is high imped-
ance. If the low-battery comparator is not used, ground
LBI and LBO. For V TRIP less than 1.3V, configure the
comparator as shown in Figure 8. Calculate the value of
the external resistors R3 and R4 as follows:
R3 = R4(V REF - V TRIP ) / (V OUT - V REF )
Since the low-battery comparator is noninverting, exter-
nal hysteresis can be added by connecting a resistor
between LBO and LBI as shown in Figure 9. When LBO
is high, the series combination of R2 and R7 source
current into the LBI summing junction.
От номиналов R3 и R4 зависит контроль низкого уровня питания, но как конкретно их (номиналы) определить, из даташит не понял (сложновато на английском). Можно-ли вообще не использовать эти пины контроля низкого уровня?
или я вообще все неправильно понимаю?
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