MIC2589R-1YM Micrel Inc, MIC2589R-1YM Datasheet - Page 21

• 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
The circuit in Figure 7 consisting of M2, R5, and a
digital control signal, can be used to reset the
controller after the GATE (and output) turns off. Once
the output has been latched off, applying a low-high-
low pulse on the GATE of M2 via the System Enable
control can toggle the UV pin. System Enable is a
user-defined signal referenced to V
Sense Resistor Selection
The sense resistor is nominally valued at:
where V
breaker threshold voltage (50mV) and I
the nominal load current level necessary to trip the
internal circuit breaker.
To accommodate worse-case tolerances in the sense
resistor (for a ±1% initial tolerance, allow ±3%
tolerance for variations over time and temperature)
and circuit breaker threshold voltages, a slightly more
detailed calculation must be used to determine the
minimum and maximum hot swap load currents.
As the MIC2589’s minimum current limit threshold
voltage is 40mV, the minimum hot swap load current
is determined where the sense resistor is 3% high:
Keep in mind that the minimum hot swap load current
should be greater than the application circuit’s upper
steady-state load current boundary. Once the lower
I
HOT_SWAP(m
(Short Pin)
(Long Pin)
(Long Pin)
R
-48V RTN
-48V RTN
-48V RTN
System
SENSE(nom)
Reset
SMAT70A
TRIP(TYP)
*Optional components (See Functional Description and Applications Information for more details)
*D1
M2 is an SOT-323, B8S138W or equivalent
D2 is a 68V, 500mW Zener diode
in)
0.47µF
=
=
C1
I
is the typical (or nominal) circuit
(
HOT_SWAP(n
1.03
V
689k
1%
R1
TRIP(typ)
×
R
40mV
Figure 7. Optional Components for Added Performance/Protection
SENSE(nom)
om)
*M2
0.1µF
*C3
EE
.
12.4k
)
1%
R3
HOT_SWAP(NOM)
=
R
11.8k
R2
1%
SENSE(nom)
38.8mV
0.068µF
C
2.2µF
FILTER
C
NLD
C
47k
TIMER
R5
is
1
2
3
4
5
6
7
/PWRGD1
PGTIMER
UV
OV
CFILTER
CNLD
VEE
MIC2589-2BM
21
R
0.01
SENSE
5%
value of R
practice to check the maximum hot swap load current
(I
of tolerance build-up in the opposite direction. Here,
the worse case maximum is found using a V
threshold of 60mV and a sense resistor 3% low in
value:
In this case, the application circuit must be sturdy
enough to operate up to approximately 1.5x the
steady-state hot swap load current. For example, if an
MIC2589 circuit must pass a minimum hot swap load
current of 4A without nuisance trips, R
set to:
where the nearest 1% standard value is 10.0mΩ. At
the other tolerance extremes, I
circuit in question is then simply:
With a knowledge of the application circuit’s maximum
hot swap load current, the power dissipation rating of
the sense resistor can be determined using P = I
Here, the current is I
resistance
R
Thus, the sense resistor’s maximum power dissipation
is:
P
I
R
I
HOT_SWAP(m
HOT_SWAP(m
/PWRGD3
/PWRGD2
HOT_SWAP(MAX)
MAX
SENSE(max)
SENSE(nom)
SENSE
DRAIN
GATE
VDD
N/C
= (6.19A)
14
13
12
11
10
9
8
ZMM5266B
= (1.03)(R
SENSE
ax)
ax)
*D2
) that the circuit may let pass in the case
=
2
× (10.3mΩ) = 0.395W
40mV
=
=
4A
0.1µF
has been calculated, it is good
(
61.9mV
0.97
10mΩ
*C2
SENSE(nom)
SUM110N10-09
HOT_SWAP(max)
=
×
10mΩ
R
60mV
M1
R4
10
SENSE(nom)
=
100µF
6.19A
) = 10.3mΩ.
C5
HOT_SWAP(MAX)
= 6.19A and the
0.1µF
SENSE
)
C4
[phone]
=
M9999-120505
R
SENSE(nom)
should be
61.9mV
-48V RTN
-48V
TRIP(MAX)
for the
2
OUT
× R.