Power Management Switch ICs for PCs and Digital Consumer Products
1ch Small Package
High Side Switch ICs
for USB Devices and Memory Cards
BD2232G, BD2233G
●Description
BD2232G and BD2233G are low on-resistance N-channel MOSFET high-side power switches, optimized for Universal
Serial Bus (USB) applications. BD2232G and BD2233G are equipped with the function of over-current detection, thermal
shutdown, under-voltage lockout and soft-start.
VIN terminal and VOUT terminal are connected to the drain and the source of switch MOSFET respectively. And the VIN
terminal is used also as power source input to internal control circuit.
When the switch is turned on from EN,/EN control input, VIN terminal and VOUT terminal are connected by a
100mΩ(Typ.) switch. In on status, the switch is bidirectional. Therefore, when the potential of VOUT terminal is higher
than that of VIN terminal, current flows from VOUT terminal to VIN terminal.
2. Thermal Shutdown Circuit (TSD)
If over-current would continue, the temperature of the IC would increase drastically. If the junction temperature were
beyond 135℃(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 115℃(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.
The thermal shutdown circuit operates when the switch is on (EN,/EN signal is active).
3. Over-Current Detection (OCD)
The over-current detection circuit limits current (I
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).
3-1. When the switch is turned on while the output is in shortcircuit status
When the switch is turned on while the output is in shortcircuit status or so, the switch gets in current limit status
soon.
3-2. When the output shortcircuits while the switch is on
When the output shortcircuits or large capacity is connected while the switch is on, very large current flows until the
over-current limit circuit reacts. When the current detection, limit circuit works, current limitation is carried out.
3-3. When the output current increases gradually
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 the VIN drops below 2.2V(Typ.)
while the switch turns on, then UVLO shuts off the power switch. UVLO has hysteresis of a 100mV(Typ).
Under-voltage lockout circuit works when the switch is on (EN,/EN signal is active).
5. Fault Flag (/OC) Output
Fault flag output is N-MOS open drain output. At detection of over-current, thermal shutdown, low level is output.
Over-current detection has delay filter. This delay filter prevents instantaneous current detection such as inrush current at
switch on, hot plug from being informed to outside.
) and outputs fault flag (/OC) when current flowing in each switch
When excessive current flows owing to output shortcircuit or so, ringing occurs by inductance of power source line to IC,
and may cause bad influences upon IC actions. In order to avoid this case, connect a bypath capacitor C
IN by VIN terminal
and GND terminal of IC. 1μF or higher is recommended. In order to decrease voltage fluctuations of power source line to IC,
connect a low ESR capacitor in parallel with CIN. 10μF ~ 100μF or higher is effective.
Pull up /OC output by resistance 10kΩ ~ 100kΩ.
Set up value which satisfies the application as CL and Ferrite Beads.
This system connection diagram doesn’t guarantee operating as the application.
When using the circuit with changes to the external circuit constants, make sure to leave an adequate margin for external
components including static and transitional characteristics as well as dispersion of the IC.
An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc., can
break down devices, thus making impossible to identify breaking mode such as a short circuit or an open circuit. If any
special mode exceeding the absolute maximum ratings is assumed, consideration should be given to take physical safety
measures including the use of fuses, etc.
(2) Operating conditions
These conditions represent a range within which characteristics can be provided approximately as expected. The
electrical characteristics are guaranteed under the conditions of each parameter.
(3) Reverse connection of power supply connector
The reverse connection of power supply connector can break down ICs. Take protective measures against the
breakdown due to the reverse connection, such as mounting an external diode between the power supply and the IC’s
power supply terminal.
(4) Power supply line
Design PCB pattern to provide low impedance for the wiring between the power supply and the GND lines. In this regard,
for the digital block power supply and the analog block power supply, even though these power supplies has the same
level of potential, separate the power supply pattern for the digital block from that for the analog block, thus suppressing
the diffraction of digital noises to the analog block power supply resulting from impedance common to the wiring patterns.
For the GND line, give consideration to design the patterns in a similar manner.
Furthermore, for all power supply terminals to ICs, mount a capacitor between the power supply and the GND terminal. At
the same time, in order to use an electrolytic capacitor, thoroughly check to be sure the characteristics of the capacitor to be
used present no problem including the occurrence of capacity dropout at a low temperature, thus determining the constant.
(5) GND voltage
Make setting of the potential of the GND terminal so that it will be maintained at the minimum in any operating state.
Furthermore, check to be sure no terminals are at a potential lower than the GND voltage including an actual electric transient.
(6) Short circuit between terminals and erroneous mounting
In order to mount ICs on a set PCB, pay thorough attention to the direction and offset of the ICs. Erroneous mounting can
break down the ICs. Furthermore, if a short circuit occurs due to foreign matters entering between terminals or between
the terminal and the power supply or the GND terminal, the ICs can break down.
(7) Operation in strong electromagnetic field
Be noted that using ICs in the strong electromagnetic field can malfunction them.
(8) Inspection with set PCB
On the inspection with the set PCB, if a capacitor is connected to a low-impedance IC terminal, the IC can suffer stress.
Therefore, be sure to discharge from the set PCB by each process. Furthermore, in order to mount or dismount the set
PCB to/from the jig for the inspection process, be sure to turn OFF the power supply and then mount the set PCB to the
jig. After the completion of the inspection, be sure to turn OFF the power supply and then dismount it from the jig. In
addition, for protection against static electricity, establish a ground for the assembly process and pay thorough attention
to the transportation and the storage of the set PCB.
(9) Input terminals
In terms of the construction of IC, parasitic elements are inevitably formed in relation to potential. The operation of the
parasitic element can cause interference with circuit operation, thus resulting in a malfunction and then breakdown of the
input terminal. Therefore, pay thorough attention not to handle the input terminals, such as to apply to the input terminals
a voltage lower than the GND respectively, so that any parasitic element will operate. Furthermore, do not apply a voltage
to the input terminals when no power supply voltage is applied to the IC. In addition, even if the power supply voltage is
applied, apply to the input terminals a voltage lower than the power supply voltage or within the guaranteed value of
electrical characteristics.
(10) Ground wiring pattern
If small-signal GND and large-current GND are provided, It will be recommended to separate the large-current GND
pattern from the small-signal GND pattern and establish a single ground at the reference point of the set PCB so that
resistance to the wiring pattern and voltage fluctuations due to a large current will cause no fluctuations in voltages of the
small-signal GND. Pay attention not to cause fluctuations in the GND wiring pattern of external parts as well.
(11) External capacitor
In order to us
degradation in the nominal capacitance due to DC bias and changes in the capacitance due to temperature, etc.
(12) Thermal shutdown circuit (TSD)
When junction temperatures become detected temperatures or higher, the thermal shutdown circuit operates and turns a
switch OFF. The thermal shutdown circuit is aimed at isolating the LSI from thermal runaway as much as possible. Do not
continuously use the LSI with this circuit operating or use the LSI assuming its operation.
(13) Thermal design
Perform thermal design in which there are adequate margins by taking into account the power dissipation (Pd) in actual
states of use.
e a ceramic capacitor as the external capacitor, determine the constant with consideration given to a
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