NH020-Series Power SIPs: Data Sheet
5 Vdc Input; 1.5 Vdc to 3.3 Vdc Output; 20 W April 2000
1010 Tyco Electronics Corp.
Safety Considerations
For safety-agency approval of the system in which the
power SIP is used, the power SIP must be installed in
compliance with the spacing and separation require-
ments of the end-use safety agency standard, i.e.,
UL
1950,
CSA
C22.2 No. 950-95, and the EN60950/
IEC950.
For the converter output to be considered meeting the
requirements of safety extra-low voltage (SELV), the
input must meet SELV requirements.
The power SIP has extra-low voltage (ELV) outputs
when all inputs are ELV.
The input to these units is to be provided with a maxi-
mum 10 A normal-blow fuse in the ungrounded lead.
If an input electrolytic capacitor is to be used, it should
be selected using the design information found in the
Design Considerations section.
Feature Descriptions
Overcurrent Protection
To provide protection in a fault condition, the unit is
equipped with internal overcurrent protection. The unit
operates normally once the fault condition is removed.
Power SIP will supply up to 350% of rated current for
less than 1.25 seconds bef ore unit enters thermal shut-
down.
Remote On/Off
To turn the power SIP on and off, the user must supply
a switch to control the voltage at the on/off terminal
(Von/off). The switch can be an open collector pnp tran-
sistor connected between the on/off terminal and the VI
terminal or its equivalent (see Figure 20).
During a logic low when the ON/OFF pin is open, the
power SIP is on and the maximum Von/off generated
by the power SIP is 0.3 V. The maximum
allowable leakage current of the switch when
Von/off = 0.3 V and VI = 5.5 V (Vswitch = 5.2 V) is 50 µA.
During a logic high, when Von/off = 2.8 V to 5.5 V, the
power SIP is off and the maximum Ion/off is 10 mA. The
switch should maintain a logic high while sourcing
10 mA.
If not using the remote on/off feature, leave the
ON/OFF pin open.
The SIP has internal capacitance to reduce noise at
the ON/OFF pin. Additional capacitance is not gener-
ally needed and may degrade the start-up characteris-
tics of the SIP.
CAUTION: Never ground the on/off terminal.
Grounding the on/off terminal disables
an important safety feature and may
damage the SIP or the customer
system.
8-1175(C)
Figure 20. Remote On/Off Implementation
Output Voltage Set-Point Adjustment
(Trim)
Output voltage set-point adjustment allows the output
voltage set point to be increased or decreased by con-
necting an external resistor between the TRIM pin and
either the VO pin (decrease output voltage) or GND pin
(increase output voltage). The trim range for the
NH020F is +10%, –16%. The trim range for the
NH020G is ±10% of VO, nom. The trim range for SIPs
that produce less than 2.5 VO is +20%, –0%.
Connecting an e xternal resistor (Rtrim-down) between the
TRIM and V O pin decreases the output voltage set point
as defined in the following equation.
For the F (3.3 VO) SIP:
For the G (2.5 VO) SIP:
Note: Output voltages below 2.5 V cannot be trimmed
down.
The test results for these configurations are displayed
in Figures 21 and 22.
Vo
Vswitch Ion/off ON/OFF
VI
GND
Von/off
+
+
Rtrim-down 18.23
VOVO adj,–
------------------------------15–
kΩ=
Rtrim-down 6.975
2.498 VO adj,–
------------------------------------- 15–
kΩ=