MIC2594 MICREL [Micrel Semiconductor], MIC2594 Datasheet - Page 12

• Manufacturer Part Number: MIC2594
• Description: Single-Channel, Negative High-Voltage Hot Swap Power Controllers
• Manufacturer: MICREL [Micrel Semiconductor]

MIC2588/MIC2594
R1, R2, and R3 as shown in the
equations to set the trip points are shown below. For the
following example, the circuit’s UV threshold is set to V
and the OV threshold is placed at V
used in Central Office power distribution applications.
Given V
two resistor values can be found. A suggested value for R3
is that which will provide approximately 100 A of current
through the voltage divider chain at V
following as a starting point:
The closest standard 1% value for R3 = 12.4k . Solving for
R2 and R1 yields:
The closest standard 1% value for R2 = 11.8k . Next, the
value for R1 is calculated:
The closest standard 1% value for R1 = 698k .
Using standard 1% resistor values, the circuit’s nominal
UV and OV thresholds are:
Programmable UVLO Hysteresis—MIC2594
The MIC2594 has user-programmable hysteresis by means of
the ON and OFF pins. This allows setting the part 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 bus while at the same time increasing
the amount of available operating time from a loosely regulated
power supply (for example, a battery supply). Similarly to the
MIC2588, each of these pins is internally connected to an
M9999-122303
V
V
UV
OV
R3
R2 R3
R2 12.4k
R2 11.729k
R1 R3
R1 12.4k
R1 705.808k
V
V
UV
OV
= 36.5V
UV
= 71.2V
, V
V
V
V
OVH
100 A
OV
UVL
OVH
, and any one resistor value, the remaining
(typ)
V
(typ)
(typ)
V
OV
V
OV
UV
1.223V
72V – 1.223V
– 1.223V
72V
37V
12.23k
– 1
1.223V
R1+ R2 + R3
R1+ R2 + R3
R2 + R3
– 1
R3
– R2
OV
“Typical Application.”
= 72V, values commonly
DD
– R2
= V
UV
. This yields the
UV
= 37V
The
12
analog comparator with 20mV of hysteresis. The MIC2594
holds the output off until the voltage at the ON pin exceeds its
V
remain on until the voltage at the OFF pin falls below its V
threshold value, or the part turns off due to a fault. Should either
event occur, the GATE pin is immediately pulled low and will
remain low until the ON pin once again exceeds its V
threshold. The circuit’s turn-on and turn-off points are set using
the resistor divider R1, R2, and R3 as shown in the
Application.”
shown below. In the following example, the circuit’s ON thresh-
old is set to V
= 35V.
Given V
two resistor values can be readily found. A suggested value
for R3 is that which will provide approximately 100 A of
current through the voltage divider chain at V
yields the following as a starting point:
The closest standard 1% value for R3 = 12.4k .
Then, solving for R2 and R1 yields:
The closest standard 1% value for R2 = 1.78k .
The closest standard 1% value for R1 = 392k .
Using standard 1% resistor values, the circuit’s nominal
ON and OFF thresholds are:
table. Once the output has been enabled by the ON pin, it will
ONH
V
V
ON
OFF
R3 =
R2 = R3
R2 = 12.4k
R2 = 1.771k
R1= R3
R1= 12.4k
R1= 391.380k
threshold value given in the
V
V
ON
OFF
OFF
= 40.1V
= 35V
= V
V
, V
= V
ON
OFFL
100 A
The equations to establish the trip points are
ONH
ON
OFFL
= 40V and the circuit’s OFF threshold is V
V
, and any one resistor value, the remaining
(typ)
ON
(typ)
V
V
OFF
(typ)
1.223V
ON
40V – 1.223V
– 1.223V
40V
35V
1.223V
12.23k
– 1
R1 R2 R3
R1 R2 R3
– 1
R2 R3
R3
– R2
“Electrical Characteristics”
– R2
December 2003
DD
= V
OFF
“Typical
Micrel
. This
OFFL
ONH
OFF