MIC2589R-1YM Micrel Inc, MIC2589R-1YM Datasheet - Page 25

• Manufacturer Part Number: MIC2589R-1YM
• Description: Negative Voltage Hot-swap Controller -
• Manufacturer: Micrel Inc
• Type: Hot-Swap Controllerr

Specifications of MIC2589R-1YM

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: -19 V ~ -80 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (0.154", 3.90mm Width)
• Family Name: MIC2589
• Package Type: SOIC
• Operating Supply Voltage (min): -19V
• Operating Supply Voltage (max): -80V
• Operating Temperature (min): -40C
• Operating Temperature (max): 85C
• Operating Temperature Classification: Industrial
• Product Depth (mm): 3.9mm
• Product Height (mm): 1.45mm
• Mounting: Surface Mount
• Pin Count: 14
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

December 2005
PCB Layout Considerations
4-Wire Kelvin Sensing
Because of the low value typically required for the
sense resistor, special care must be used to measure
accurately the voltage drop across it. Specifically, the
measurement technique across each R
employ 4-wire Kelvin sensing. This is simply a means
of making sure that any voltage drops in the power
traces connecting to the resistors are not picked up by
the signal conductors measuring the voltages across
the sense resistors.
Figure 9 illustrates how to implement 4-wire Kelvin
sensing. As the figure shows, all the high current in
the circuit (from V
source of the output MOSFET) flows directly through
the power PCB traces and R
resulting across R
the high currents through the power traces will not
introduce any parasitic voltage drops in the sense
leads. It is recommended to connect the hot swap
controller’s sense leads directly to the sense resistor’s
metalized contact pads.
Other Layout Considerations
Figure 10 is a suggested PCB layout diagram for the
MIC2589/MIC2595. Many hot swap applications will
require load currents of several amperes. Therefore,
SENSE
EE
through R
is sampled in such a way that
SENSE
SENSE
. The voltage drop
, and then to the
SENSE
must
25
the power (V
be wide enough to allow the current to flow while the
rise in temperature for a given copper plate (e.g., 1oz.
or 2oz.) is kept to a maximum of 10°C to 25°C. The
return (or power ground) trace should be the same
width as the positive voltage power traces (input/load)
and isolated from any ground and signal planes so
that the controller’s power is common mode. Also,
these traces should be as short as possible in order to
minimize the IR drops between the input and the load.
Finally, the use of plated-through vias will be
necessary to make circuit connections to the power,
ground and signal planes of multi-layer PCBs.
PCB Track Width:
Figure 9.
R
0.03" per Ampere
SENSE
using 1oz Cu
Power Trace
From V
to MIC2589/MIC2595 V
4-Wire Kelvin Sense Connections for
EE
EE
and Return) trace widths (W) need to
Signal Trace
Note: Each SENSE lead trace shall be
balanced for best performance with equal
length/equal aspect ratio.
EE
Pin
R
SENSE
contact pads
R
metalized
SENSE
Signal Trace
to MIC2589/MIC2595 SENSE Pin
To MOSFET Source
[phone]
M9999-120505
Power Trace