TM
Technical Specification
S25-48-3.3, S25-48-3.3N
48Vin 3.3Vout 7A
Protection Features
Input under voltage lockout (UVL)
80
70
60
50
40
30
20
10
0
The input voltage must be at least 35V for the
unit to turn on. Once the unit has been turned on,
it will shut off when the input voltage drops below
34V.
Output Over-Current Protection (OCP)
The unit is protected against over current or short
circuit on the output. When sensing an over
current condition, the unit will enter constant
current operation and reduce the output voltage.
Upon short-circuit condition, the unit will shut
down.
1
2
3
4
5
6
7
8
9
10
Trim-up Vout change (%)
Fig 4 Trim-up output vs. trim resistance
120
After over-current or short circuit condition is
removed, the unit will resume normal operation
automatically.
100
80
60
40
20
0
Output Over Voltage Protection (OVP)
This unit will shut down and latch off if the output
voltage exceeds the over protection point. The
over-voltage-protection latch is reset only by
another cycle of the input power.
1
2
3
4
5
6
7
8
9
10
The OVP set point is between 4.1V~4.7V.
Trim-down Vout change (%)
Over Temperature Protection (OTP)
Fig 5 Trim-down output vs. trim resistance
This unit will shut down if the case temperature
exceeds the over temperature set point. The unit
will resume normal operation automatically when
the case temperature drops down.
Table 1
resistor value
Trim Voltage
+10%
Output voltage trim vs. trim
Trim Resistor
1.84k
Trim Voltage
-10%
-9%
Trim Resistor
0.87k
The OTP set point is around 100°C.
+9%
2.74k
1.34k
+8%
3.88k
-8%
2.56k
+7%
5.29k
-7%
4.12k
+6%
7.22k
-6%
6.10k
+5%
9.90k
-5%
9.20k
+4%
+3%
+2%
+1%
14.37k
21.20k
34.37k
72.82k
-4%
-3%
-2%
-1%
13.65k
20.95k
36.20k
101.30k
Broadband TelCom Power, Inc. – 1719 S. Grand Avenue, Santa Ana, CA 92705 U.S.A. P 5 of 11
Tel.: 714-259-4888 • Fax: 714-259-0840 • www.btcpower.com • Email: sales@btcpower.com PS S25-48-3.3 Rev 3 16-1-04
BTCPOWER [ BROADBAND TELCOM POWER, INC. ]
