BD2046AFJ_14 Datasheet, PDF (17/27 Pages) Rohm – 0.5A Current Limit High Side Switch ICs

BD2046AFJ BD2056AFJ
Datasheet
3. Over Current Detection (OCD)
The over current detection circuit limits current (ISC) and outputs an error flag (/OC) when current flowing in each switch
MOSFET exceeds a specified value. There are three types of response against over current. The over current detection
circuit works when the switch is on (EN, /EN signal is active).
(1) When the switch is turned on while the output is in short-circuit status, the switch goes into current limit status
immediately.
(2) When the output short-circuits or high-current load is connected while the switch is on, very large current flows until
the over current limit circuit reacts. When the current detection and limit circuit works, current limitation is carried out.
(3) When the output current increases gradually, current limitation does not work until the output current exceeds the
over current detection value. When it exceeds the detection value, current limitation is carried out.
4. Under Voltage Lockout (UVLO)
UVLO circuit prevents the switch from turning on until the VIN exceeds 2.3V (Typ). If VIN drops below 2.2V (Typ) while
the switch is still ON, then UVLO shuts off the switch. UVLO has a hysteresis of 100mV (Typ).
Note: Under voltage lockout circuit works when the switch of either OUT1 or OUT2 is on (EN, /EN signal is active).
5. Error Flag (/OC) Output
Error flag output is N-MOS open drain output. At over current and/or thermal shutdown detection, the output level is low.
Over current detection has a delay filter. This delay filter prevents current detection flags from being sent during
instantaneous events such as surge current at switch on or hot plug. If fault flag output is unused, /OC pin should be
connected to open or ground line.
V/EN
VOUT
IOUT
V/OC
Output Short Circuit
Thermal Shutdown
/OC Delay Time
Figure 40. Over Current Detection, Thermal Shutdown Timing
(BD2046AFJ)
VEN
VOUT
IOUT
V/OC
Output Short Circuit
Thermal Shutdown
/OC Delay Time
Figure 41. Over Current Detection, Thermal Shutdown Timing
(BD2056AFJ)
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