Tyco Electronics Corp. 11
Data Sheet
December 1999 18 Vdc to 36 Vdc or 36 Vdc to 75 Vdc Inputs, 5 W
LC/LW005-Series Power Modules:
Feature Descriptions
Overcurrent Protection
To provide protection in a fault (output overload) condi-
tion, the unit is equipped with internal current-limiting
circuitry and can endure current limiting for an unlim-
ited duration. At the point of current-limit inception, the
unit shifts from voltage control to current control. If the
output voltage is pulled very low during a severe f ault,
the current-limit cir cuit can exhibit either foldback or
tailout characteristics (output-current decrease or
increase). The unit operates normally once the output
current is brought back into its specified range.
Output Overvoltage Protection
The output overvoltage clamp consists of control cir-
cuitry, almost entirely independent of the secondary
regulation circuitry, that monitors the voltage on the
output terminals. This control loop has a higher voltage
set point than the primary loop (see Feature Specifica-
tions table). In a fault condition, the overvoltage clamp
ensures that the output voltage does not exceed
VO, clamp, max. This provides a redundant voltage-
control that reduces the risk of output overvoltage.
If totally redundant overvoltage protection is needed in
the user application, it is recommended that an exter-
nal ov ervoltage protection circuitry be used on the user
application board assembly for additional protection.
F or e x ternal ov ervoltage protection circuit suggestions,
contact technical support.
Input Undervoltage Lockout
At input voltages below the input undervoltage lockout
limit, the module operation is disabled. The module will
begin to operate at an input voltage between the under-
voltage lockout limit and the minimum operating input
voltage.
Remote On/Off (Optional)
Positive logic, device code suffix “4,” remote on/off
turns the module on during a logic-high voltage on the
REMOTE ON/OFF pin, and off during a logic low.
To turn the power module on and off, the user must
supply a switch to control the voltage between the
on/off terminal and the VI(–) ter mi nal (Von/off). The
switch may be an open collector or equivalent
(see Figure 19). A logic low is Von/off = –0.7 V to 1.2 V.
The maximum Ion/off during a logic low is 10 mA. The
s witch should maintain a logic-low v oltage while sinking
10 mA.
During a logic high, the maximum Von/off generated by
the power module is 15 V. The maximum allowable
leakage current of the switch at Von/off = 15 V is 50 µA.
8-758(C).a
Figure 19. Remote On/Off Implementation
Synchronization (Optional)
With external circuitry, the unit is capable of synchroni-
zation at 300 kHz from an independent time base with
a s witching rate of 600 kHz. The synchronization signal
should be applied when the unit is operating to ensure
the unit functions properly.
8-2712(C)
Figure 20. Synchronization Information
+
Ion/off
-
Von/off
REMOTE
ON/OFF
VI(+)
VI(-)
ISYNC SYNC
VI(-)
348 Ω
BAS16
ISYNC =
1.67 µs
9 mA ± 1 mA
0 mA
ISYNC = 25% DUTY CYCLE, 600 kHz
A 600 kHz SYNCHRONIZATION SIGNAL
WILL CAUSE THE POWER MODULE TO
HAVE A SWITCHING FREQUENCY OF
300 kHz.
OR
EQUIVALENT