MIC2588 Ver la hoja de datos (PDF) - Micrel

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componentes Descripción

Fabricante

MIC2588

Single-Channel, Negative High-Voltage Hot Swap Power Controllers

Micrel 

MIC2588/MIC2594

the OFF pin falls below its VOFFL 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 VONH threshold. The circuit’s

turn-on and turn-off points are set using the resistor divider

R1, R2, and R3 as shown in the “Typical Application.” The

equations to establish the trip points are shown below. In the

following example, the circuit’s nominal ON threshold is set to

VON = 40V and the circuit’s nominal OFF threshold is

VOFF = 35V.

VON

= VONH(typ) 

R1 R2  R3

R3

VOFF

= VOFFL(typ) 

R1 R2  R3

R2  R3

Given VOFF, VON, and any one resistor value, the remaining

two resistor values can be readily found. A suggested value

for R3 is that which will provide a minimum of 100µA of cur-

rent through the voltage divider chain at VDD = VOFF. This

yields the following as a starting point:

R3 = VOFFL(typ)  12.23k

100A

The closest standard 1% value for R3 = 12.4kΩ.

solving for R2 and R1 yields:

R2

=

R3







VON

VOFF





–



1



Micrel

R2

=

12.4k





40V

35V



–

1

R2 = 1.771k

The closest standard 1% value for R2 = 1.78kΩ.

  R1= R3  VON –1.223V – R2

1.223V

R1= 12.4k  40V – 1.223V – 1.78kΩ

1.223V

R1= 391.380k

The closest standard 1% value for R1 = 392kΩ.

Using standard 1% resistor values, the circuit’s nominal

ON and OFF thresholds are:

VON = 40.1V

VOFF = 35V

Good general engineering design practices must consider

the tolerances associated with these parameters, including

but not limited to, power supply tolerance, undervoltgae

and overvoltage tolerances, and the tolerances of the

external passive components.

M9999-083005

13

September 2005

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