February 2005

MIC2580A

MIC2580A

Micrel, Inc.

MIC2580A

Hot-Swap PCI Power Controller

General Description

The MIC2580A is a hot-swap controller that provides for safe
and orderly insertion and removal of PCI based adapter cards
from a PCI hot-plug compliant system backplane or
CompactPCITM system.

The MIC2580A incorporates a circuit breaker function that
protects all four supplies (+12V, +5V, +3.3V, and 12V) upon
an overcurrent fault condition. Current foldback limiting pre-
vents large transient currents caused by plugging adapter
cards into live backplanes, such as in a CompactPCI system.
A programmable slew-rate control limits high inrush currents
to all loads that occur when power is applied to large capaci-
tive loads.

Voltage supervisory functions for all four power supplies are
provided by "power good" (/PWRGD) and "overcurrent fault"
(/FAULT) diagnostic outputs. Power good and overcurrent
fault include deglitch filters to prevent nuisance tripping.
Power good is active when all four supplies are within
tolerance. Fault (/FAULT) goes active upon overcurrent or
overtemperature conditions. The on-off control input (/ON) is
used to cycle power to the adapter card.

Typical Application

12VOUT

5VGATE

3VGATE

VPCHG

12VIN

/FAULT

GND

CSTART

/LPCIRST

5VIN

3VIN

/PCIRST

/EPWRGD

/ON

CSLEW

MIC2580A

5VSENSE

3VSENSE

5VOUT

3VOUT

/POR

CRST

IRF7413

+3.3V

+5V

+12V

/PWRGD

M12VIN

M12VOUT

+12V

+5V

+3.3V

GND

12V

10m

PCH

= +1V ±20%

(PRECHARGE SUPPLY)

Data Bus

/HEALTHY

/BD_SEL

/PCI_RST

VIO

12V/1A

GND

+3.3V/8A

+5V/8A

+12V/1A

/ENUM

Data Bus

/ON

/PCIRST

/PGD

Adapter

Platf

Overcurrent
Fault

PCI

Controller

/LPCIRST

1.2k

1µF

CompactPCITM Adapter with Early Power

Features

· PCI hot-plug and CompactPCITM hot-swap support
· +12V, +5V, +3.3V, and 12V power supply control
· Circuit breaker function to protect system
· Programmable slew rate control for all supplies
· Foldback current-limiting
· +5V and +3.3V programmable current-limit thresholds
· Undervoltage and overcurrent diagnostic outputs
· Deglitch filters on diagnostic fault outputs
· Integrated +12V and 12V MOSFET switches
· Integrated high-side drivers for 3.3V and 5V external

switches

· Precharge supply for CompatPCITM I/O termination

Applications

· PCI hot-plug systems
· CompactPCITM hot-swap systems

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

CompactPCI is a trademark of the PCI Industrial Computer Manufacturer's Group.

MIC2580A

Micrel, Inc.

MIC2580A

February 2005

Pin Configuration

12VOUT

3VGATE

3VOUT

3VSENSE

3VIN

/PCIRST

/LPCIRST

/EPWRGD

/PWRGD

VPCHG

24 12VIN

5VGATE

5VOUT

5VSENSE

5VIN

/FAULT

CSTART

CSLEW

/POR

CRST

GND

/ON

M12VIN

M12VOUT

24-lead TSSOP (TS)

Pin Description

Pin Number

Pin Name

Pin Function

12VOUT

+12V Switched Supply (Output): Load carrying output.

3VGATE

3.3V Gate Drive (Output): Drives gate of external N-channel MOSFET +3V
switch. Adding capacitance will slow the slew rate of the external MOSFET
switch turn-on. (The external MOSFET's gate is charged by an internal
current source.)

3VOUT

+3.3V Output Voltage Sense (Input): Connect to source of external
N-channel MOSFET (+3V switched output) to monitor for output undervolt-
age conditions.

3VSENSE

+3.3V Current Sense (Input): Measures voltage drop across an external
sense resistor with respect to 3VIN for overcurrent detection through the
+3.3V switch.

3VIN

3V Supply (Input): +3.3V-supply input for current monitoring (reference input
for 3VSENSE). Not a load-current carrying input.

/PCIRST

PCI-Bus Reset (Input): Input from PCI bus that resets the internal logic.

Ordering Information

Part Number

Precharge

Temperature

Standard

Pb-Free

Voltage

Range

Package

MIC2580A-1.0BTS

MIC2580A-1.0YTS

40°C to +85°C

24-lead TSSOP

MIC2580A-1.6BTS

MIC2580A-1.6YTS

1.6V

40°C to +85°C

24-lead TSSOP

February 2005

MIC2580A

MIC2580A

Micrel, Inc.

Pin Number

Pin Name

Pin Function

/LPCIRST

Local PCI Reset (Open-Drain Output): Local PCI reset output to PCI
controller. Compliant to CompactPCI specification for LOCAL_PCI_RESET.

/EPWRGD

Early Power Good (Open-Drain Output): This signal goes active should
/FAULT or /PWRGD go active. No deglitch filtering is provided. This signal
satisfies PCI /RST timing for T

FAIL

per PCI Local Bus Specification, ver-

sion 2.1.

/PWRGD

Power Good (Open-Drain Output): Active-low output goes active when all
supplies are within tolerance. (A 20µs delay is inserted prior to activation to
reduce nuisance tripping.)

VPCHG

Precharge Supply (Output): (MIC2580A-1.0) +1V ±20% supply used for
precharge bias for I/O terminations (CompactPCI only).

GND

Ground

M12VIN

12V Supply (Input): Input for internal 12V switch.

M12VOUT

12V Switched Supply (Output): Switched 12V supply to PCI Hot Plug
compliant socket. Load carrying output.

/ON

On-Off Control (Input): Logic low turns on all switches; logic high turns off all
switches. Also used to reset the device from a circuit breaker condition. The
/ON pin is edge-triggered and requires a high-to-low transition once all four
supplies are above their respective thresholds.

CRST

Reset Delay (External Component): Connect to external capactior (C

RST

) to

increase power-on reset delay.

/POR

Reset (Open-Drain Output): Active-low signal remains active for a time
determined by C

RST

after all supplies are within tolerance; i.e., /PWRGD is

active. This signal may be used as a reset for logic controllers.

CSLEW

Slew (External Component): Connect to external capacitor (C

SLEW

) to

program the output slew rate of 3VGATE, 5VGATE, 12VGATE (internal) and
M12VGATE (internal).

CSTART

Start-Up Timer (External Component): Connect to external capacitor
(C

START

) to increase the filter delay used to gate the /FAULT output upon

start-up. Used to prevent nuisance tripping during turn-on of supplies.

/FAULT

Fault (Open-Drain Output/Input): This active-low output signal activated
upon overcurrent or thermal shutdown. Includes 20µs deglitch filter. Fault is
reset using /ON.
Forcing pin low turns off all switches but does not activate the circuit breaker
function.

5VIN

5V Supply (Input): +5V-supply input for current monitoring (reference
voltage for 5VSENSE). Not a load-current carrying input.

5VSENSE

+5V Current Sense (Input): Measures voltage drop across an external
sense resistor with respect to 5VIN for overcurrent detection through the +5V
switch.

5VOUT

+5V Output Voltage Sense (Input): Connect to source of external N-channel
MOSFET (+5V switched output) to monitor for output undervoltage condi-
tions.

5VGATE

5V Gate Drive (Output): Drives gate of external N-channel MOSFET +5V
switch. Adding capacitance will slow the slew rate of the external MOSFET
switch turn-on. (The external MOSFET's gate is charged by an internal
current source.)

12VIN

12V Supply (Input): MIC2580A power supply and input for internal +12
switch. Supplies power for internal circuitry.

MIC2580A

Micrel, Inc.

MIC2580A

February 2005

Absolute Maximum Ratings

(Note 1)

Supply Voltages

+12V Input (V

12VIN

) ................................................. +14V

+5V Input (V

5VIN

) ....................................................... +7V

+3.3V Input (V

3VIN

) .................................................... +7V

12V Input (V

M12VIN

) ............................................... 14V

/PWRGD, /FAULT, /POR, /EPWRGD, and /PCIRST

Output Current ........................................................... 10mA

Lead Temperature (Soldering)

Standard Package (-x.xBTS)
IR Reflow ......................................... 240°C + 0ºC/-5ºC
Lead-free Package (-x.xYTS)
IR Reflow ......................................... 260ºC + 0ºC/-5ºC

ESD Rating, Note 3

Human body model ................................................... 2kV

Operating Ratings

(Note 2)

Supply Voltages

+12V Input (V

12VIN

) ............................. +11.4V to +12.6V

12V Input (V

M12VIN

) ........................... 11.4V to 12.6V

+5V Input (V

5VIN

) ................................... +4.75V to +5.25

+3.3V Input (V

3VIN

) .............................. +3.125V to +3.5V

Temperature Range (T

) ........................... 40°C to +85°C

Junction Temperature (T

) ........................................ 150°C

Package Thermal Resistance (

)

24-Lead TSSOP .................................................. 83°C/W

Electrical Characteristics

12VIN

= 12V, V

5VIN

= 5V, V

3VIN

= 3.3V, V

M12VIN

= 12V; T

= 25°C, bold values indicate 40°C T

+85°C; unless noted

Symbol

Parameter

Condition

Min

Typ

Max

Units

12IN

Supply Current

/ON > V

2.2

5IN

3IN

0.23

0.4

12MIN

UVLO

Undervoltage Lockout

12VIN

increasing

8.9

9.8

12VIN

UVLO hysteresis

300

M12VIN

decreasing

-10.5

-8.3

M12VIN

UVLO hysteresis

100

5VIN

increasing

2.1

3.1

5VIN

UVLO hysteresis

3VIN

increasing

2.4

2.6

3VIN

UVLO hysteresis

5VGATE

5VGATE Voltage

10.5

3VGATE

3VGATE Voltage

10.5

5VGATE

5VGATE Output Current

during start-up, V

5VGATE

= 5V

µA

during turnoff; /FAULT = 0

3VGATE

3VGATE Output Current

during start-up, V

5VGATE

= 5V

µA

during turnoff; /FAULT = 0

PGTH

Power Good Threshold Voltage

12VOUT

increasing

11.4

12VOUT

Power-Good hysteresis

200

M12VOUT

decreasing

11.2

M12VOUT

Power-Good hysteresis

5VOUT

increasing

4.45

4.7

5VOUT

Power-Good hysteresis

100

3VOUT

increasing

2.90

3.10

3VOUT

Power-Good hysteresis

Input Voltage Level (/ON)

logic low

0.8

logic high

2.0

Input Leakage Currnet (/ON)

µA

February 2005

MIC2580A

MIC2580A

Micrel, Inc.

Symbol

Parameter

Condition

Min

Typ

Max

Units

Output-Low Voltage

= 2mA

0.4

(/PWRGD, /FAULT, /POR,
EPWRGD, /LPCIRST)

Overtemperature Shutdown

increasing

170

°C

Threshold

decreasing

160

°C

CRST

CRST Charge Current

during turn-on

11.5

µA

CSTART

CSTART Charge Current

during turn-on

11.5

µA

CSLEW

CSLEW Charge Current

during turn-on

µA

DS(on)12

Output MOSFET Resistance

+12V internal MOSFET, I

= 500mA

450

600

DS(on)M12

12V internal MOSFET, I

= 200mA

430

600

Output MOSFET Leakage

+12V internal MOSFET

100

µA

12V internal MOSFET

300

µA

CLTH

Current Limit Threshold Voltage

5VIN

5VSENSE

3VIN

3VSENSE

LIM12

Current-Limit

+12V internal MOSFET, ramped load

1.0

1.3

1.5

LIM12M

Threshold

12V internal MOSFET, ramped load

0.4

0.5

0.7

Short-Circuit Current

+12V internal MOSFET, V

OUT

= 0V

140

12V internal MOSFET, V

OUT

= 0V

170

POR(thr)

Power-On Reset Threshold Voltage

2.4

PCH

Precharge Bias Supply

MIC2580A-1.0, I

PCH

= 10mA

0.8

1.0

1.2

MIC2580A-1.6, I

PCH

= 10mA

1.28

1.6

1.92

START

Start-up Threshold Voltage

2.4

AC Parameters

GOOD

Early Power-Good

See Figure 4

200

Response Low

/GOOD

Early Power-Good

See Figure 4

100

Response High

Undervoltage to Power-Good Delay

µs

Current-limit to Fault Delay

µs

+5V Current-Limit-to-Off Delay

SENSE

= 10m

µs

Note 4

+3.3V Current-Limit-to-Off Delay

SENSE

= 10m

µs

Note 4

+12V Current-Limit-to-Off Delay

+12V

µs

Note 4

12V Current-Limit-to-Off Delay

12V

µs

Note 4

Note 1.

Exceeding the absolute maximum rating may damage the device.

Note 2.

The device is not guaranteed to function outside its operating rating.

Note 3.

Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF.

Note 4.

Off refers to the condition in which the circuit breaker turns all outputs off.

MIC2580A

Micrel, Inc.

MIC2580A

February 2005

Enable Into

3V Output Short Circuit

/ON

(10V/div)

CSTART

(5V/div)

3VOUT

(5V/div)

M12VOUT

(10V/div)

12VOUT

(10V/div)

3VIN

(1A/div)

5VOUT

(5V/div)

/PWRGD

(5V/div)

/POR

(5V/div)

/FAULT

(5V/div)

Time (1ms/div)

Enable Into

5V Output Short Circuit

/ON

(10V/div)

CSTART

(5V/div)

3VOUT

(5V/div)

12VOUT

(10V/div)

M12VOUT

(10V/div)

5VOUT

(5V/div)

5VIN

(200mA/div)

/PWRGD

(5V/div)

/POR

(5V/div)

/FAULT

(5V/div)

Time (1ms/div)

START

= 0.01µF

SLEW

= 0.01µF

RST

= 0.01µF

3VOUT = GND
R

12L

= 100

12L

= 1µF

M12L

= 100

M12L

= 1µF

START

= 0.01µF

SLEW

= 0.01µF

RST

= 0.01µF

12L

= 100

12L

= 1µF

M12L

= 100

M12L

= 1µF

5VOUT = GND

MIC2580A

Micrel, Inc.

MIC2580A

February 2005

Functional Description

Start-Up Sequence

The start-up sequence iniates after all four supplies are
connected to the inputs and then /ON is asserted by
transistioning from high to low. During the start-up sequence,
all four gates ramp up at a rate determined by C

SLEW

. During

this time /PWRGD is deasserted until all four supplies are
within specified levels. When /PWRGD is asserted the power-
on-reset signal /POR timer begins. The time period is defined
by C

RST

. Refer to Figure 1 for a timing diagram of the signals

during the start-up sequence.

During the start-up sequence, a current source charges
C

START

at a constant rate until a threshold voltage of 2.4V is

reached. This period of time defines an interval during which
overcurrent events are ignored. This prevents high inrush
currents that normally occur when charging capacitance
erroneously asserting /FAULT. The magnitude of the start-
up time, t

START

is defined by C

START

The MIC2580A employs foldback current limiting that en-
sures the device starts up in current limit. This minimizes high
inrush currents due to ramping a voltage into capacitance
regardless of the size of the load capacitance.

Overcurrent Detection

The MIC2580A senses overcurrent via the use of external
sense resistors for the 5V and 3.3V supply rails. When the
sense voltage across these resistors is greater than or equal
to 50mV an overcurrent condition is detected. Therefore the
overcurrent set point is determined by I

LIMIT

= 50mV/R

SENSE

For the +12V and 12V supply rails overcurrent detection is
set internally at 1.3A and 0.5A respectively.

When an overcurrent condition is detected /FAULT is as-
serted only if the overcurrent condition lasts for a minimum
time period of 10µs. This delay prevents spurious noise from
the system erroneously tripping the circuit breaker and as-
serting /FAULT. Upon /FAULT being asserted an internal
latch is set that immediately turns off all four supplies to
prevent further damage to the system. Toggling /ON will reset
the latch and initiate another start-up sequence. Figures 2
and 3 depict the timing for two fault conditions.

Thermal Shutdown

The +12V and 12V internal MOSFET switches are protected
by current limit and overtemperature shutdown circuitry.
When the die temperature exceeds 160°C, /FAULT is as-
serted and all supplies are shut off. The power dissipated in
the MIC2580A is primarily due to the sum of current flowing
through the internal MOSFET switches and, to a lesser
extent, power dissipated due to the supply current. To com-
pute the total power dissipation of the MIC2580A the follow-
ing equation is used:

D(total)

= P

D(+12V switch)

+ P

D(12V switch)

+ P

D(supplies)

where:

D(switches)

= R

DS(on)

× I

OUT

D(supplies)

= V

SUPPLY

× I

SUPPLY

To relate this to operating junction temperature:

= P

+ T

where:

= ambient temperature

= package thermal resistance

Precharge Voltage

For CompactPCI applications, the MIC2580A-1.0BSM/BTS
integrates a 1V ±20% voltage source that satisfies
CompactPCI precharge requirements. The voltage source
can provide up to 10mA. For higher current, the MIC2580A-
1.6BSM/BTS integrates a 1.6V ±20% voltage source to bias
a NPN transistor.

MIC2580A-1.6

VPCHG

DATA

BUS

I > 10mA

+5V

Figure 5. Voltage Source

Turnoff

Deasserting /ON will turn off all four supplies. Alternatively
driving /FAULT low will turn off all supplies but will not latch
the supplies off. Releasing /FAULT will initiate a new start
sequence.

February 2005

MIC2580A

MIC2580A

Micrel, Inc.

Application Information

Whenever voltage is applied to a highly capacitive load, high
inrush currents may result in voltage droop that may bring the
supply voltage out of regulation for the duration of the
transient. The MIC2580A solves this problem by specifically
controlling the current and voltage supply ramps so that the
system supply voltages are not disturbed. Very large capaci-
tive loads are easily supported with this device.

Figure 1 shows the timing during turn-on. When /ON is forced
low, all supplies are turned on at a slew rate determined by the
external capacitor, C

SLEW

Figure 2 shows the foldback characteristics for the supply
voltages. This foldback affect bounds the magnitude of the
current step when the supplies are turned on or shorted. This
specifies the compact PCI specification of 1.5A/ms, thereby
ensuring reliable operation. In discrete FET implementa-
tions, this magnitude can exceed several amps and may
cause the main supply to go out of regulation during this
transient event. This, in turn, could cause the system to
behave unpredictably. In addition, should a fault occur, the
MIC2580A will prevent system malfunctions by limiting the
current to within specifications.

MOSFET Selection

The external MOSFET should be selected to provide low
enough dc loss to satisfy the application's voltage regulation
requirements. Note that the voltage across the sense resistor

must also be added to the dc voltage drop across the
MOSFET to compute total loss. In addition to meeting the
voltage regulation specifications, thermal specifications must
also be considered. During normal operation very little power
should be dissipated in the MOSFET. DC power dissipation
of the MOSFET is easily computed as I

where I is the

drain current and R

is the specified on-resistance of the

MOSFET at the expected operating drain current. However,
during excessive drain current or short-circuit faults, the
power dissipation in the external MOSFET will increase
dramatically. To help compute the effective power dissipated
during such transients, MOSFET manufacturers provide
transient thermal impedance curves for each MOSFET.
These curves provide the effective thermal impedance of the
MOSFET under pulsed or repetitive conditions; for example,
as will be the case when enabling into a short circuit fault.
From these curves the effective rise in junction temperature
of the MOSFET for a given condition can be computed. The
equation is given as:

peak T

= PDM × Z

+ T

where PDM is the power dissipated in the MOSFET usually
computed as V

x I

DRAIN

and Z

is the thermal response

factor provided from the curves. Since the MIC2580A re-
duces the current to 30% of full scale even under severe faults
such as short-circuits the MOSFET power dissipation is held
to safe levels. This feature allows MOSFETs with smaller
packages to be used for a given application thereby reducing
cost and PCB real-estate requirements.

12VOUT

5VGATE

3VGATE

VPCHG

12VIN

/FAULT

GND

CSTART

/LPCIRST

5VIN

3VIN

/PCIRST

/EPWDGD

/ON

CSLEW

MIC2580A

5VSENSE

3VSENSE

5VOUT

3VOUT

CRST

IRF7413

3.3V

12V

/PWDGD

M12VIN

M12VOUT

+12V

+5V

+3.3V

GND

12V

Power

Supply

/CIRST

BUS EN

12V

/CIRST

Data Bus

/CIRST

12V /100mA

12V/500mA

5V/5A

3.3V/7.6A

10m

PCI Hot-Plug

Controller

Bus

Switch

Data Bus

GND

Adapter

Platf

r
m

/POR

+5V

Figure 6. Hot-Plug PCI Application

MIC2580A

Micrel, Inc.

MIC2580A

February 2005

CompactPCITM BD_SEL# Pin Tied to Ground

For applications that use system backplanes with the
BD_SEL# pin tied to ground, the MIC2580A /ON pin is edge
sensitive. Therefore, the /ON pin requires a delay circuit for
proper start-up when the board has already been inserted
into the backplane and the supplies are switched off, then
back on. The circuit, shown in the figure below, allows the
MIC2580A /ON pin to transition from high to low which is
necessary for start-up. The delay time may be increased or
decreased by changing the RC time constant in the circuit,
but the delay time must exceed the ramp time of all system
backplane supplies. The same circuit is functional for hot
swap insertion.

(3.3V or 5V)

3.3µF

/FAULT

/RESET

MIC2580A

/ON

1.2k

10k

50k

2N3904

1N914

BD_SEL#

On PCB

Figure 7. /ON Pin Assertion Delay Circuit

PCB Layout Considerations

To achieve accurate current sensing Kelvin connections are
recommended between the supply pin and the respective
sense resistor as shown in Figure 8. PCB trace length should
be kept at a minimum. 0.02 inches per ampere is a minimum
width for 1 oz. copper to prevent damage to traces carrying
high current. Keep these high-current traces as short as
possible.

VIN

pin

from

supply

SENSE

pin

to
load

sense resistor

Kelvin
connections

short-length, high-current
(wide) copper traces

Figure 8. Layout Recommendation

February 2005

MIC2580A

MIC2580A

Micrel, Inc.

Package Information

1.10 MAX (0.043)

0.15 (0.006)
0.05 (0.002)

1.00 (0.039) REF

8°
0°

6.4 BSC (0.252)

7.90 (0.311)
7.70 (0.303)

0.30 (0.012)
0.19 (0.007)

0.20 (0.008)
0.09 (0.003)

0.70 (0.028)
0.50 (0.020)

DIMENSIONS:

MM (INCH)

4.50 (0.177)
4.30 (0.169)

0.65 BSC
(0.026)

24-Lead TSSOP (TS)

MICREL INC.

2180 FORTUNE DRIVE

SAN JOSE, CA 95131

USA

TEL

+ 1 (408) 944-0800

FAX

+ 1 (408) 474-1000

WEB

http://www.micrel.com

This information furnished by Micrel in this data sheet is believed to be accurate and reliable. However no responsibility is assumed by Micrel for its use.

Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.

Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can

reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into
the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser's

use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser's own risk and Purchaser agrees to fully indemnify

Micrel for any damages resulting from such use or sale.

Ð­Ð»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MIC2580A-1.0BTS

ÐÐ»ÐµÐºÑ‚Ñ€Ð¾Ð½Ð½Ñ‹Ð¹ ÐºÐ¾Ð¼Ð¿Ð¾Ð½ÐµÐ½Ñ‚: MIC2580A-1.0BTS