BD2222G Datasheet, PDF (17/30 Pages) Rohm – 1ch Adjustable Current Limit High Side Switch ICs

BD2222G BD2242G BD2243G
Application Circuit Example
Controller
Datasheet
10kΩ to
100kΩ
CIN
5V (Typ)
IN
GND
EN
OUT
ILIM
/OC
RLIM
+
CL
-
Figure 50. Application Circuit Example
Application Information
Ringing may cause bad influences on IC operations. In order to avoid this case, connect a bypass capacitor across IN
terminal and GND terminal of IC. 1µF or higher is recommended. When excessive current flows due to output short-circuit
or so, ringing occurs because of inductance between power source line to IC may exert a bad influence upon IC. In order to
decrease voltage fluctuations from power source line to IC, connect a low ESR capacitor in parallel with CIN. 10µF to 100µF
or higher is effective.
Pull up /OC output via resistance value of 10kΩ to 100kΩ.
Set up a value for CL which satisfies the application.
This system connection diagram does not guarantee operation as the intended application.
When using the circuit with changes to the external circuit values, make sure to leave an adequate margin for external
components including static and transitional characteristics as well as the design tolerance of the IC.
Functional Description
1. Switch Operation
IN terminal and OUT terminal are connected to the drain and the source of switch MOSFET respectively. The IN terminal
is also used as power source input to internal control circuit.
When the switch is turned on from EN control input, the IN terminal and OUT terminal are connected by a 89mΩ(Typ)
switch. In ON status, the switch is bidirectional. Therefore, when the potential of OUT terminal is higher than that of the IN
terminal, current flows from OUT terminal to IN terminal.
Since a parasitic diode between the drain and the source of switch MOSFET is canceled, current flow from OUT to IN is
prevented during off state.
2. Thermal Shutdown Circuit (TSD)
If over-current would continue, the temperature of the IC would increase drastically. If the junction temperature were
beyond 120℃(Typ) in the condition of over-current detection, thermal shutdown circuit operates and makes power switch
turn off and outputs fault flag (/OC). Then, when the junction temperature decreases lower than 110℃(Typ), power switch
is turned on and fault flag (/OC) is cancelled. Also, regardless of over-current condition, if the junction temperature were
beyond 160℃(Typ), thermal shutdown circuit makes power switch turn off and outputs fault flag (/OC).When junction
temperature decreases lower than 140℃(Typ), power switch is turned on and fault flag (/OC) is cancelled. Unless the fact
of the increasing chips temperature is removed or the output of power switch is turned off, this operation repeats. Fault
flag (/OC) is output without delay time at thermal shutdown.
The thermal shutdown circuit operates when the switch is on (EN signal is active).
3. Over-Current Detection (OCD)
The over current detection circuit (OCD) limits current and outputs error flag (/OC) when current flowing in each switch
MOSFET exceeds a specified value. There are three cases when the OCD is activated. The OCD operates when the
switch is on (EN signal is active).
(1). When the switch is turned on while the output is in short-circuit status, the switch gets in current limit status
immediately. (See figure 42)
(2). When the output short-circuits or when high current load is connected while the switch is on, very large current
flows until the over current limit circuit reacts. When this happens, the over-current limit circuit is activated and the
current limitation is carried out. (See figure 48)
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TSZ02201-0E3E0H300280-1-2
9.JUN.2014 Rev.004