MIC2595-2BM Micrel Inc, MIC2595-2BM Datasheet - Page 19

• Manufacturer Part Number: MIC2595-2BM
• Description: IC CTRLR HOT SWAP NEG HV 14-SOIC
• Manufacturer: Micrel Inc
• Type: Hot-Swap Controllerr

Specifications of MIC2595-2BM

• 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)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

December 2005
following as a starting point:
The closest standard 1% value for R3 = 12.4kΩ.
Solving for R2 and R1 yields:
The closest standard 1% values for R2 = 11.8kΩ.
Lastly, the value for R1 is calculated:
The closest standard 1% value for R1 = 698kΩ.
Using standard 1% resistor values, the circuit’s
nominal UV and OV thresholds are:
V
V
Good general engineering design practices must
consider
parameters, including but not limited to, power supply
tolerance, undervoltage and overvoltage threshold
tolerances, and the tolerances of the external passive
components.
Programmable UVLO Hysteresis (MIC2595 and
MIC2595R)
The MIC2595 and the MIC2595R devices have user-
programmable hysteresis by means of the ON and
OFF pins (Pins 4 and 3, respectively). This allows
setting the MIC2595/MIC2595R to turn on at a voltage
V1, and not turn off until a second voltage V2, where
V2 < V1. This can significantly simplify dealing with
source impedances in the supply buss while at the
same time increasing the amount of available
operating time from a loosely regulated power rail (for
example, a battery supply). The MIC2595/MIC2595R
holds the output off until the voltage at the ON pin is
above its V
Characteristics” table. Once the output has been
enabled by the ON pin, it will remain on until the
voltage at the OFF pin falls below its respective V
threshold value, or the part turns off due to an external
R3
R2
R2
R1
R1
R1
UV
OV
=
=
=
=
=
=
= 36.5V
= 71.2V
R3
12.4kΩ
705.81kΩ
R3
12.4kΩ
V
OVH
100µA
×
×
⎡
⎢
⎣
⎡
⎢
⎢
⎣
the
⎛
⎜
⎜
⎝
(
ONH
(typ)
V
V
V
×
×
OV
OV
UV
⎡
⎢
⎣
⎡
⎢
⎣
1.223V
threshold value given in the “Electrical
⎛
⎜
⎝
(
72V
tolerances
=
72V
37V
−
⎞
⎟
⎟
⎠
1.223V
1.223V
−
100µA
1.223V
1
−
⎞
⎟
⎠
⎤
⎥
⎥
⎦
1.223V
−
1
⎤
⎥
⎦
)
⎤
⎥
⎦
=
=
−
12.23kΩ
11.73kΩ
associated
)
R2
⎤
⎥
⎦
−
1
1
8 .
kΩ
with
these
OFFL
19
fault condition. Should either event occur, the GATE
pin is immediately pulled low and will remain low until
the ON pin voltage once again rises above its V
threshold. The circuit’s turn-on and turn-off voltage
levels are set using the resistor divider R1, R2, and
R3 similar to the “Typical Application” circuit and the
equations to set the trip points are shown below. For
the following example, the circuit’s ON threshold is set
to V
V
Given V
the remaining two resistor values can be readily
determined. A suggested value for R3 is selected to
provide approximately 100µA (or more) of current
through the voltage divider chain at V
yields the following as a starting point:
The closest standard 1% value for R3 = 12.4kΩ.
Solving for R2 and R1 yields:
The closest standard 1% value for R2 = 1.78kΩ.
Lastly, the value for R1 is calculated:
The closest standard 1% value for R1 = 392kΩ.
Using standard 1% resistor values, the circuit’s
nominal ON and OFF thresholds are:
V
V
Good general engineering design practices must
consider
parameters, including but not limited to, power supply
tolerance, undervoltage and overvoltage threshold
tolerances, and the tolerances of the external passive
components.
R3
R2
R2
R1
R1
R1
V
V
OFF
ON
OFF
ON
OFF
=
=
=
=
=
=
ON
= 40.1V
= 35V.
= 35V
R3
12.4kΩ
391.38kΩ
=
R3
12.4kΩ
V
=
= 40V and the circuit’s OFF threshold is set to
OFFL
V
100µA
OFF
V
×
×
ONH
OFFL
(
⎡
⎢
⎢
⎣
the
, V
V
⎛
⎜
⎜
⎝
(typ)
ON
V
×
×
(typ)
V
ON
OFF
1.223V
ON
40V
(typ)
⎡
⎢
⎣
⎛
⎜
⎝
−
, and any one of the resistor values,
tolerances
40V
35V
=
1.223V
1.223V
×
−
−
×
1.223V
(
100µA
R1
1
1.223V
(
⎞
⎟
⎟
⎠
−
R1
⎤
⎥
⎥
⎦
+
1
R2
⎞
⎟
⎠
)
R2
+
R3
⎤
⎥
⎦
−
R2
=
+
=
R2
+
1.77kΩ
−
associated
R3
12.23kΩ
R3
+
1.78kΩ
R3
)
)
DD
[phone]
M9999-120505
= V
with
OFF
. This
these
ONH