MB3841 Просмотр технического описания (PDF) - Fujitsu

Номер в каталоге

Компоненты Описание

производитель

MB3841

Power Management Switch IC

Fujitsu 

MB3841

s FUNCTIONAL DESCRIPTION

Current Limit Setting

The MB3841 provides highly accurate switching current setting, in the range 100 mA to 2 A ±20% (with limit

setting current at 2 A) by placing resistance between the CURRENT and GND pins.

Because the setting is dependent on the VIN voltage, it is important that the appropriate resistance be connected

to the VIN pin.

The following approximation formula (1) may be used to calculate the limit setting when VIN = 5V.

For details, see “RLIM vs. Limit Current Characteristics” on p. 9.

ISW = 7450 [A] .... (1)

(RLIM[Ω])1.1

When the switch limit level is exceeded, the switch turns off and then latch is set to protect the device.

At the same time the O.C output signal goes to “L” level to notify external systems.

When a “L” level signal is applied to the CONTROL switch, the latch is released, so that normal operation is

resumed at the next “H” level signal to the CONTROL switch.

Thermal Shutdown

The MB3841 has a thermal shutdown function which turns the switch off and sets the latch to protect the device

when junction temperature exceeds 125°C.

At the same time the O.C output signal goes to “L” level to notify external systems.

When a “L” level signal is applied to the CONTROL switch, the latch is released,so that normal operation is

resumed at the next “H” level signal to the CONTROL switch.

Slow Start

The on/off switching time of the MB3841 can be delayed by applying capacitance between the SS and GND

pins. Controlling the on time can soften surge current to the load side capacitance when power is turned on.

(tON, tOff are measured at 90% of VOUT.)

The following approximation formula (2) may be used to set on time when VIN = 5 V.

For details, see “Css vs. tON (SS) Characteristics” on p. 9.

tON = 0.87 × 10–3 × CSS[pF] + 0.3 [ms] .... (2)

DISCHARGE

The MB3841 has a DISCHARGE pin function that immediately discharges electric charge on the load side when

the switch is turned off.

11

Share Link: