September 2005

1

M9999-083005

MIC2588/MIC2594

Micrel

MIC2588/MIC2594

Single-Channel, Negative High-Voltage Hot

Swap Power Controllers

General Description

The MIC2588 and the MIC2594 are single-channel, nega-

tive-voltage hot swap controllers designed to address the

need for safe insertion and removal of circuit boards into

“live” high-voltage system backplanes, while using very few

external components. The MIC2588 and the MIC2594 are

each available in an 8-pin SOIC package and work in con-

junction with an external N-Channel MOSFET for which the

gate drive is controlled to provide inrush current limiting and

output voltage slew-rate control. Overcurrent fault protection

is also provided and includes a programmable overcurrent

threshold. During an output overload condition, a constant-

current regulation loop is engaged to ensure that the system

powersupplymaintainsregulation.Ifafaultconditionexceeds

a built-in 400µs nuisance-trip delay, the MIC2588 and the

MIC2594 will latch the circuit breaker’s output off and will

remain in the off state until reset by cycling either the UV/OFF

pin or the power to the IC. A master Power-Good signal is

provided to indicate that the output voltage of the soft-start

circuit is within its valid output range. This signal can be used

to enable one or more DC-DC converter modules.

All support documentation can be found on Micrel’s web site

at www.micrel.com.

Typical Application

/PWRGD

DRAIN

UV

OV

VDD

SENSE

GATE

VEE

1

8

7

6

5

4

3

2

R1

698kΩ

1%

R3

12.4kΩ

1%

R2

11.8kΩ

1%

C1

1uF

0.01Ω

5%

*D1

SMAT70A

100V

M1

SUM110N10-09

15kΩ

C3

0.22uF

6.8nF

100V

R4

10Ω

-48V RTN

C5

100uF

C4

0.1uF

(Long Pin)

-48V RTN

(Long Pin)

*C6

0.33uF

MIC2588-2BM

-48V RTN

(Short Pin)

DC-DC

CONVERTER

IN-

IN+

OUT+

OUT-

+2.5V RTN

VDD

*C2

22nF

Nominal Undervoltage and Overvoltage Thresholds:

* Optional components (See Applications Information for more details)

# An external pull-up resistor for the power-good signal is necessary for DC-DC supplies

(and all other load modules) not equipped with internal pull-up impedence

Features

• MIC2588:

Pin-for-pin functional equivalent to the

LT1640/LT1640A/LT4250

• Provides safe insertion and removal from live –48V

(nominal) backplanes

• Operates from –19V to –80V

• Electronic circuit breaker function

• Regulated maximum output current into faults

• Programmable inrush current limiting

• Fast response to short circuit conditions (<1µs)

• Programmable undervoltage and overvoltage lockouts

(MIC2588-xBM)

• Programmable UVLO hysteresis (MIC2594-xBM)

• Fault reporting:

Active-HIGH (-1BM) and Active-LOW (-2BM)

Power-Good output signal

Applications

• Central office switching

• –48V power distribution

• Distributed power systems

• Server Networks

Micrel, Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com