L5993 STMicroelectronics, L5993 Datasheet - Page 14

• Manufacturer Part Number: L5993
• Description: Switching Converters, Regulators & Controllers Prog Current Mode
• Manufacturer: STMicroelectronics

Specifications of L5993

• Mounting Style: Through Hole
• Package / Case: PDIP-16
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

L5993
pends both on the mains voltage range and the
synchronization frequency range.
An additional ”fine tuning” can be achieved by
adding a small DC offset (in the ten mV) on the
current sense pin (13, ISEN).
For wide range mains applications it is anyway
recommended to compensate the propagationde-
lay of the current sense path (PWM comparator +
latch + driver) with the circuit shown in the ”Appli-
cation Ideas” section, fig. 41.
Layout hints
Generally speaking a proper circuitboard layout is
vital for correct operation but is not an easy task.
Careful component placing, correct traces routing,
appropriate traces widths and, in case of high
voltages, compliance with isolation distances are
the major issues. The L5993 eases this task by
putting two pins at disposal for separate current
returns of bias (SGND) and switch drive currents
(PGND) The matter is complex and only few im-
portant points will be here reminded.
1) All current returns (signal ground, power
14/22
ground, shielding, etc.) should be routed sepa-
2) Noise coupling can be reduced by minimizing
3) For high current paths, the traces should be
4) Magnetic field radiation (and stray inductance)
5) In general, traces carrying signal currents
6) Provide adequate filtering of some crucial
rately and should be connected only at a single
ground point.
the area circumscribed by current loops. This
applies particularly to loops where high pulsed
currents flow.
doubled on the other side of the PCB whenever
possible: this will reduce both the resistance
and the inductance of the wiring.
can be reduced by keeping all traces carrying
switched currents as short as possible.
should run far from traces carrying pulsed cur-
rents or with quickly swinging voltages. From
this viewpoint, particular care should be taken
of the high impedance points (current sense in-
put, feedback input, ...). It could be a good idea
to route signal traces on one PCB side and
power traces on the other side.
points of the circuit, such as voltage references,
IC’s supply pins, etc.