APPLICATION NOTES
PIN FUNCTIONS
V
IN
-
This pin provides power to all internal circuitry in-
cluding bias, start-up, thermal limit and overcurrent latch.
Input voltage range is 2.9V to 6.5V.
GND -
Internally connected to ground, this pin should be
connected externally by the user to the circuit ground.
SHUTDOWN -
There are two functions to the SHUTDOWN
pin. It may be used to disable the output voltage or to
reset a current latch condition. To activate the shutdown/
reset functions the user must apply a voltage greater than
1.6V to the SHUTDOWN pin. The output voltage will turn
on when the SHUTDOWN pin is pulled below the thresh-
old voltage. If the SHUTDOWN pin is not used, it should
be connected to ground. It should be noted that with the
shutdown pin tied to ground, a current latch condition
can only be reset by cycling power off, then on.
V
OUT
-
This is the output pin for the device.
FIGURE 1
OVERCURRENT LATCH
Overcurrent protection is provided by the MSK 5920RH
series through the use of a timed latch off circuit. The
internal latch timeout is triggered by an overcurrent con-
dition. To allow for start up surge currents, the timeout is
approximately 5.5mS at 25°C. If the overcurrent condi-
tion remains at the end of the timeout cycle, the regulator
will latch off until the latch is reset. The latch condition
can be reset by pulling the shutdown pin high or cycling
V
IN
off then back on. A thermal limit condition will trigger
the latch with no time out delay.
CURRENT LIMIT AND SOA
The MSK 5920RH current limit function is directly af-
fected by the input and output voltages. Figure 1 illus-
trates the relationship between V
IN
and I
CL
for various
output voltages. It is very important for the user to con-
sult the SOA curve when using input voltages which re-
sult in current limit conditions beyond 4.5 Amps. When
using input voltages which result in current limit above
4.5 Amps, the user must maintain output current within
the SOA curve to avoid damage to the device. Note that 5
Amp maximum is due to current carrying capability of the
internal wirebonds.
INPUT POWER SUPPLY BYPASSING
To maximize transient response and minimize power sup-
ply transients it is recommended that a 100µF tantalum
capacitor is connected between V
IN
and ground. A 0.1µF
ceramic capacitor should also be used for high frequency
bypassing.
REPLACING THE OMR9601/IRUH33P253AIM
When the MSK 5920-2.5RH is used as a replacement
for the IR OMR9601 or IRUH33P253AIM, the user should
recognize that the MSK 5920-2.5RH does not contain in-
ternal tantalum capacitors on the input and output. MSK
does not typically use tantalum capacitors in space level
standard products of this nature.
OUTPUT CAPACITOR SELECTION
Output capacitors are required to maintain regulation
and stability. A 220µF surface mount tantalum capacitor
in parallel with a 1.0µF ceramic capacitor from the output
to ground should suffice under most conditions. If the
user finds that tighter voltage regulation is needed during
output transients, more capacitance may be added. If more
capacitance is added to the output, the bandwidth may
suffer. ESR of the output capacitors should be maintained
at 0.1Ω to 1Ω.
3
Rev. G
1/06
MSK [ M.S. KENNEDY CORPORATION ]
