STSR2P STMicroelectronics, STSR2P Datasheet - Page 6

• Manufacturer Part Number: STSR2P
• Description: FORWARD SYNCHRONOUS RECTIFIERS SMART DRIVERS
• Manufacturer: STMicroelectronics

Specifications of STSR2P

• Supply Voltage Range: 4.5V TO 5.5V
• Typical Peak Output Current: SOURCE -2A, SINK 3.5A
• Operating Frequency: 20 TO 750 KHZ

STSR2P/STSR2PM
EXAMPLE OF COMPONENTS SELECTION FOR A FORWARD CONVERTER
Forward Specification:
V
V
n=Np/Ns=4.5
R
secondary winding is 36/4.5=8V. Choosing R
R
This value is below the maximum allowable current flowing into the CK pin (10mA). If the 10mA value is
exceeded an external diode connected to V
R
R
The RC group composed by R
signal on Inhibit comparator. This delay must be lower than 200ns. This condition imposes a maximum
value for R
In general a suggested value for R
current flowing into Inhibit pin is 16V/10k =1.6mA which is below the maximum allowable current for the
pin (10mA). If the 10mA value is exceeded an external diode (D2) connected to V
The maximum negative voltage of –0.6V must be guaranteed for the Inhibit pin. If this negative voltage is
exceeded the current must be limited to 50mA. If necessary, a diode (D1) connected to SGLGND can be
added to satisfy this specification.
INHIBIT OPERATION OF OUT
6/12
IN
OUT
3
4
1
1
=1k
=R
and R
=36-72V
and R
=3.3V
2
=10k , t
is chosen. At 72V input the current at CK pin is calculated as:
4
2
are calculated assuring a minimum voltage of 2.8V at CK pin. At 36V input, the voltage on the
5
I
of about 20k .
CK
values set the anticipation time for OUT
R
ANT2
4
=
--------------------------------------------------------------- -
V
V
---------------------------------------------------- -
=150ns; for R
IN
IN max
–
I
CK 2.8
V
CK
R
–
3
V
CC
GATE2
5
R
1
R
and the parasitic capacitance of Inhibit pin (typically 5pF) delays the
5
3
–
=0 and R
3
is 10k . At 72V input, the secondary voltage is 16V, so the maximum
0.3
–
IN DISCONTINUOUS CONDUCTION MODE
V
CK
=
16 5
----------------------------- -
CC
2
=
= , t
3
1.5k
–
=1.5K , R
1k
must be added (D3).
–
ANT2
0.3
------------------------------------------------------------------------- -
8 V 220 A
=225ns.
=
GATE2
4
–
7.13mA
results to be:
2.8V
. For R
1.5 k
1.5 k
1
=
–
and R
2.8V
CC
=
2
=0, t
must be added.
862
ANT2
=75ns; for