Micrel MIC2085, MIC2086 User Manual

MIC2085/2086 Micrel

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MIC2085/MIC2086

Single Channel Hot Swap Controllers

General Description

The MIC2085 and MIC2086 are single channel positive
voltage hot swap controllers designed to allow the safe
insertion of boards into live system backplanes. The MIC2085
and MIC2086 are available in 16-pin and 20-pin QSOP
packages, respectively. Using a few external components
and by controlling the gate drive of an external N-Channel
MOSFET device, the MIC2085/86 provide inrush current
limiting and output voltage slew rate control in harsh, critical
power supply environments. Additionally, a circuit breaker
function will latch the output MOSFET off if the current limit
threshold is exceeded for a programmed period of time. The
devices’ array of features provide a simplified yet robust
solution for many network applications in meeting the power
supply regulation requirements and affords protection of
critical downstream devices and components.

All support documentation can be found on Micrel’s web
site at www.micrel.com.

Features

• MIC2085: Pin for pin functional equivalent to the
LTC1642

• 2.3V to 16.5V supply voltage operation

• Surge voltage protection to 33V

• Operating temperature range –40°C to 85°C

• Active current regulation limits inrush current

independent of load capacitance

• Programmable inrush current limiting

• Analog foldback current limiting

• Electronic circuit breaker

• Dual-level overcurrent fault sensing

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

• Programmable output undervoltage detection

• Undervoltage lockout protection

• Power-on reset (MIC2085/86) and

power-good (MIC2086) status outputs

• /FAULT status output

• Driver for SCR crowbar on overvoltage

Applications

• RAID systems

• Cellular base stations

• LAN servers

• WAN servers

• InfiniBand™ Systems

• Industrial high side switching

T ypical Application

(PowerPAK

/POR

FB

283

Q1

Si7884DP

14

11
10

5

7

1

C6

0.01µF

TM

SO-8)

*R6
10Ω

R7
127kΩ
1%

R10

47kΩ

R8

16.2kΩ
1%

C7

0.033µF

µ

s

V

LOGIC

C2

0.022µF

R11
47kΩ

Q2
2N4401

**R9
180Ω

C

LOAD

220µF

Output Signal
(Power Good)

Power-On Reset

Output

Q3
TCR22-4

V

OUT

12V@5A

PWRGD

LOGIC

CONTROLLER

/RESET

34

C1

µ

F

1

16 15

4

ON

6

/FAULT

9

OV

12

COMP—

13

REF

CPOR

C4

µ

F

0.1

R

SENSE

0.007Ω
2%

12

SENSEVCC

MIC2085

GATE

COMP+

COMPOUT

CRWBR

GND

CFILTER

C5

8200pF

POR/START-UP DELAY = 60ms
Circuit-Breaker Response Time = 500
*R6 is an optional component used for noise filtering
**R9 needed when using a sensitive gate SCR

V

12V

/FAULT

GND

IN

Backplane
Connector

PCB Edge
Connector

(or Short)

Long

Pin

Short

Pin

R5

47kΩ

Medium

Pin

Long

Pin

R2

100kΩ

1%

R3

1.82kΩ
1%

R4

10kΩ

1%

Overvoltage (Input) = 13.3V
Undervoltage Lockout = 10.8V
Undervoltage (Output) &
Power-Good (Output) = 11.4V

R1

3.3Ω

C3

µ

F

0.1

InfiniBand is a trademark of InfiniBand Trade Association
PowerPAK is a trademark of Vishay Intertechnology Inc.

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 [phone] • fax + 1 [phone] • http://www.micrel.com

January 2004 1 M0235-121903

MIC2085/2086 Micrel

Ordering Information

Part Number Fast Circuit Breaker Threshold Discharge Output Package

MIC2085-xBQS x = J, 95mV NA 16-pin QSOP

x = K, 150mV*
x = L, 200mV*

x = M, Off

MIC2086-xBQS x = J, 95mV Yes 20-pin QSOP

x = K, 150mV*
x = L, 200mV*

x = M, Off

*Contact factory for availability.

Pin Configuration

CFILTER

CPOR

ON

/POR

/FAULT

FB

GND

1CRWBR

1CRWBR
2
3
4
5
6
7
8

16 VCC

SENSE

15

GATE

14

REF

13

COMP–

12

COMP+

11

COMPOUT

10

OV

9

CFILTER

PWRGD

CPOR

ON

/POR

/FAULT

FB
GND
GND

2
3
4
5
6
7
8
9

10

20 VCC

VCC

19

SENSE

18

GATE

17

REF

16

DIS

15

COMP–

14

COMP+

13

COMPOUT

12

OV

11

MIC2085

16-Pin QSOP (QS)

MIC2086

20-Pin QSOP (QS)

Pin Description

Pin Number Pin Number Pin Name Pin Function

MIC2086 MIC2085

1 1 CRWBR Overvoltage Timer and Crowbar Circuit Trigger: A capacitor connected to

this pin sets the timer duration for which an overvoltage condition will trigger
an external crowbar circuit. This timer begins when the OV input rises above
its threshold as an internal 45µA current source charges the capacitor. Once
the voltage reaches 470mV, the current increases to 1.5mA.

2 2 CFILTER Current Limit Response Timer: A capacitor connected to this pin defines the

period of time (t
fault condition and trip the circuit breaker. If no capacitor is connected, then
t

OCSLOW

OCSLOW

defaults to 5µs.

3 3 CPOR Power-On Reset Timer: A capacitor connected between this pin and ground

sets the start-up delay (t
VCC rises above the UVLO threshold, the capacitor connected to CPOR
begins to charge. When the voltage at CPOR crosses 1.24V, the start-up
threshold (V
C

POR

above V
CPOR rises above the power-on reset delay threshold (VTH), the timer

START

is immediately discharged to ground. When the voltage at FB rises

, capacitor C

FB

resets by pulling CPOR to ground, and /POR is deasserted.
If C

= 0, then t

POR

) in which an overcurrent event must last to signal a

) and the power-on reset interval (t

START

), a start cycle is initiated if ON is asserted while capacitor

begins to charge again. When the voltage at

POR

defaults to 20µs.

START

POR

). When

M0235-121903 2 January 2004

MIC2085/2086 Micrel

Pin Description (Cont.)

Pin Number Pin Number Pin Name Pin Function

MIC2086 MIC2085

4 4 ON ON Input: Active high. The ON pin, an input to a Schmitt-triggered compara-

tor used to enable/disable the controller, is compared to a VTH reference
with 100mV of hysteresis. Once a logic high is applied to the ON pin

> 1.24V), a start-up sequence is initiated as the GATE pin starts

(V

ON

ramping up towards its final operating voltage. When the ON pin receives a
low logic signal (V
high if VCC is above the UVLO threshold. ON must be low for at least 20µs
in order to initiate a start-up sequence. Additionally, toggling the ON pin
LOW to HIGH resets the circuit breaker.

5 5 /POR Power-On Reset Output: Open drain N-Channel device, active low. This pin

remains asserted during start-up until a time period t
voltage rises above the power-good threshold (V
C

determines t

POR

at the FB pin, /POR is asserted for a minimum of one timing cycle, t
/POR pin has a weak pull-up to VCC.

6 N/A PWRGD Power-Good Output: Open drain N-Channel device, active high. When the

voltage at the FB pin is lower than 1.24V, the PWRGD output is held low.
When the voltage at the FB pin is higher than 1.24V, then PWRGD is
asserted. A pull-up resistor connected to this pin and to VCC will pull the
output up to VCC. The PWRGD pin has a weak pull-up to VCC.

7 6 /FAULT Circuit Breaker Fault Status Output: Open drain N-Channel device, active

low. The /FAULT pin is asserted when the circuit breaker trips due to an
overcurrent condition. Also, this pin indicates undervoltage lockout and
overvoltage fault conditions. The /FAULT pin has a weak pull-up to VCC.

8 7 FB Power-Good Threshold Input: This input is internally compared to a 1.24V

reference with 3mV of hysteresis. An external resistive divider may be used
to set the voltage at this pin. If this input momentarily goes below 1.24V,
then /POR is activated for one timing cycle, t
undervoltage condition. The /POR signal de-asserts one timing cycle after
the FB pin exceeds the power-good threshold by 3mV. A 5µs filter on this pin
prevents glitches from inadvertently activating this signal.

9,10 8 GND Ground Connection: Tie to analog ground.

11 9 OV OV Input: When the voltage on OV exceeds its trip threshold, the GATE pin

is pulled low and the CRWBR timer starts. If OV remains above its threshold
long enough for CRWBR to reach its trip threshold, the circuit breaker is
tripped. Otherwise, the GATE pin begins to ramp up one POR timing cycle

after OV drops below its trip threshold.
12 10 COMPOUT Uncommitted Comparator’s Open Drain Output.
13 11 COMP+ Comparator’s Non-Inverting Input.
14 12 COMP- Comparator’s Inverting Input.
15 NA DIS Discharge Output: When the MIC2086 is turned off, a 550Ω internal resistor

at this output allows the discharging of any load capacitance to ground.
16 13 REF Reference Output: 1.24V nominal. Tie a 0.1µF capacitor to ground to ensure

stability.
17 14 GATE Gate Drive Output: Connects to the gate of an external N-Channel

MOSFET. An internal clamp ensures that no more than 13V is applied

between the GATE pin and the source of the external MOSFET. The GATE

pin is immediately brought low when either the circuit breaker trips or an

undervoltage lockout condition occurs.

< 1.14V), the GATE pin is grounded and /FAULT is

ON

after the FB pin

POR

). The timing capacitor

. When an output undervoltage condition is detected

POR

FB

, indicating an output

POR

POR

. The

January 2004 3 M0235-121903

MIC2085/2086 Micrel

Pin Description (Cont.)

Pin Number Pin Number Pin Name Pin Function

MIC2086 MIC2085

18 15 SENSE Circuit Breaker Sense Input: A resistor between this pin and VCC sets the

current limit threshold. Whenever the voltage across the sense resistor
exceeds the slow trip current limit threshold (V
is adjusted to ensure a constant load current. If V
exceeded for longer than time period t

OCSLOW

TRIPSLOW

, then the circuit breaker is
tripped and the GATE pin is immediately pulled low. If the voltage across the
sense resistor exceeds the fast trip circuit breaker threshold, V
any point due to fast, high amplitude power supply faults, then the GATE pin
is immediately brought low without delay. To disable the circuit breaker, the
SENSE and VCC pins can be tied together.

The default V

TRIPFAST

are available: 150mV, 200mV, or OFF(V
factory for availability of other options.

for either device is 95mV. Other fast trip thresholds

TRIPFAST

19,20 16 VCC Positive Supply Input: 2.3V to 16.5V. The GATE pin is held low by an

internal undervoltage lockout circuit until VCC exceeds a threshold of 2.18V.
If VCC exceeds 16.5V, an internal shunt regulator protects the chip from
VCC and SENSE pin voltages up to 33V.

), the GATE voltage

TRIPSLOW

(48mV) is

TRIPFAST

, at

disabled). Please contact

M0235-121903 4 January 2004

MIC2085/2086 Micrel

Absolute Maximum Ratings

(1)

(All voltages are referred to GND)

Supply Voltage (VCC) ..................................... –0.3V to 33V

SENSE Pin..........................................–0.3V to VCC + 0.3V

GATE Pin ....................................................... –0.3V to 22V

ON, DIS, /POR, PWRGD, /FAULT,

COMP+, COMP–, COMPOUT ....................... –0.3V to 20V

CRWBR, FB, OV, REF..................................... –0.3V to 6V

Maximum Currents

Digital Output Pins .....................................................10mA

(/POR, /FAULT, PWRGD, COMPOUT)

DIS Pin .......................................................................30mA

ESD Rating:

Human Body Model...................................................2kV

Machine Model........................................................200V

Operating Ratings

Supply Voltage (VCC) .................................... 2.3V to 16.5V

Operating Temperature Range .................. –40°C to +85°C

Junction Temperature (TJ) ........................................ 125°C

Package Thermal Resistance R

16-pin QSOP.....................................................112°C/W

20-pin QSOP.......................................................91°C/W

(2)

θ(J-A)

Electrical Characteristics

(3)

VCC = 5.0V, TA = 25°C unless otherwise noted. Bold indicates specifications over the full operating temperature range of –40°C to +85°C.
Symbol Parameter Condition Min Typ Max Units

V

CC

I

CC

V

UV

V

UVHYST

V

FB

V

FBHYST

V

OV

∆V

OV

V

OVHYST

I

OV

V

TH

I

CPOR

Supply Voltage 2.3 16.5 V
Supply Current 1.6 2.5 mA
Undervoltage Lockout Threshold VCC rising 2.05 2.18 2.28 V

VCC falling 1.85 2.0 2.10 V
UV Lockout Hysteresis 180 mV
FB (Power-Good) Threshold Voltage FB rising 1.19 1.24 1.29 V
FB Hysteresis 3mV
OV Pin Threshold Voltage OV pin rising 1.19 1.24 1.29 mV
OV Pin Threshold Voltage 2.3V < VCC < 16.5V 5 15 mV

Line Regulation
OV Pin Hysteresis 3mV
OV Pin Current 0.2 µA
POR Delay and Overcurrent (CFILTER) V

Timer Threshold

CPOR

, V

CFILTER

rising 1.19 1.24 1.29 V

Power-On Reset Timer Current Timer on –2.5 –2.0 –1.5 µA

Timer off 5 mA

I

TIMER

Current Limit /Overcurrent Timer on –30 –20 –15 µA
Timer Current (CFILTER) Timer off 2.5 mA

V
∆V

I

CR

V

CR

CR

TRIP

CRWBR Pin Threshold Voltage 2.3V < VCC < 16.5V 445 470 495 mV
CRWBR Pin Threshold Voltage 2.3V < VCC < 16.5V 4 15 mV

Line Regulation
CRWBR Pin Current CRWBR On, V

CRWBR On, V

CRWBR Off, V
Circuit Breaker Trip Voltage V
(Current Limit Threshold) 2.3V ≤ V

TRIP

= VCC –V

≤ 16.5V V

CC

= 0V –60 –45 –30 µA

CRWBR

= 2.1V –1.5 –1.0 mA

CRWBR

= 1.5V 3.3 mA

CRWBR

SENSE

V

TRIPSLOW
TRIPFAST

x = K 150 mV

x = J 80 95 110 mV

40 48 55 mV

x = L 200 mV

V

GS

External Gate Drive V

GATE

– V

CC

VCC < 3V 4 8 9 V
5V < VCC < 9V 11 12 13 V
9V < VCC < 15.0V 4.5 21–V

CC

13 V

January 2004 5 M0235-121903

MIC2085/2086 Micrel

Electrical Characteristics (Cont.)

Symbol Parameter Condition Min Typ Max Units

I

GATE

I

GATEOFF

V

ON

V

ONHYST

I

ON

V

START

V

OL

I

PULLUP

V

REF

∆V

LNR

∆V

LDR

I

RSC

V

COS

V

CHYST

R

DIS

GATE Pin Pull-up Current Start cycle, V

=16.5V –22 –16 –8 µA

V

CC

GATE

= 0V

VCC = 2.3V –20 –14 –8 µA

GATE Pin Sink Current /FAULT = 0, V

V

= 16.5V 25 50 mA

CC

GATE

>1V

VCC = 2.3V 12 20 mA

ON Pin Threshold Voltage ON rising 1.19 1.24 1.29 V

ON falling 1.09 1.14 1.19 V
ON Pin Hysteresis 100 mV
ON Pin Input Current VON = V
Undervoltage Start-up V

Timer Threshold
/FAULT, /POR, PWRGD Output I

Voltage (PWRGD for MIC2086 only)

OUT

CC

rising 1.19 1.24 1.29 V

CPOR

= 1.6mA 0.4 V

0.5 µA

Output Signal Pull-up Current /FAULT, /POR, PWRGD = GND –20 µA
/FAULT, /POR, PWRGD, COMPOUT (PWRGD for MIC2086 only)

Reference Output Voltage I

LOAD

= 0mA; C

= 0.1µF 1.21 1.24 1.27 V

REF

Reference Line Regulation 2.3V < VCC < 16.5V 5 10 mV
Reference Load Regulation I
Reference Short-Circuit Current V
Comparator Offset Voltage VCM = V
Comparator Hysteresis VCM = V

= 1mA 2.5 7.5 mV

OUT

= 0V 3.5 mA

REF

REF
REF

–5 5 mV

3mV

Discharge Pin Resistance ON pin toggles from HI to LOW 100 550 1000 Ω

AC Electrical Characteristics

(4)

Symbol Parameter Condition Min Typ Max Units

t

OCFAST

t

OCSLOW

t

ONDLY

t

FBDLY

Notes:

1. Exceeding the absolute maximum rating may damage the device.

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

3. Specification for packaged product only.

4. Specification for packaged product only.

Fast Overcurrent Sense to GATE VCC = 5V 1 µs
Low Trip Time V

C

–V

CC
GATE

= 100mV

SENSE

= 10nF, See Figure 1

Slow Overcurrent Sense to Gate VCC = 5V 5 µs
Low Trip Time V

CC

C

FILTER

–V

= 50mV

SENSE

= 0, See Figure 1
ON Delay Filter 20 µs
FB Delay Filter 20 µs

M0235-121903 6 January 2004

MIC2085/2086 Micrel

1V

48mV

V

GATE

t

OCSLOW

V

TRIPFAST

(VCCÐV

SENSE

)

t

OCFAST

1V

0

CFILTER

0

0

1.24V

Timing Diagrams

Figure 1. Current Limit Response

ON

CPOR

GATE

FB

FB

CPOR

/POR

0

0

0

1.24V
t

POR

Figure 2. Power-On Reset Response

t

ONDLY

1.24V

0

1.24V

0

0

0

Arm Fast Comparator

t

START

1.24V

Arm Slow Comparator

t

POR

1.24V

/POR

0

Figure 3. Power-On Start-Up Delay Timing

50

January 2004 7 M0235-121903

20

Current Limit Threshold (mV)

0

600 800 1000

400200

FB Voltage (mV)

Figure 4. Foldback Current Limit Response

MIC2085/2086 Micrel

g

Typical Characteristics

Supply Current

4.0

vs. Temperature

3.5

3.0
V

= 16.5V

CC

2.5

2.0

VCC= 5V

1.5

1.0

SUPPLY CURRENT (mA)

0.5

0.0

-40 -20 0 20 40 60 80 100

Overcurrent Timer Current

34

VCC= 2.3V

TEMPERATURE (°C)

vs. Temperature

30

26

(µA)

VCC= 16.5V

22

TIMER

I

18

VCC= 5V

14

10

-40 -20 0 20 40 60 80 100

VCC= 2.3V

TEMPERATURE (°C)

Power-On Reset Timer Current

vs. Temperature

2.6

(µA)

CPOR

I

2.4

2.2

2.0

1.8

VCC= 5V

VCC= 2.3V

VCC= 16.5V

1.6

1.4

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Overcurrent Timer (Off) Current

vs. Temperature

5

4

VCC= 16.5V

3

(mA)

2

TIMER

I

VCC= 2.3V

1

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

VCC= 5V

Power-On Reset Timer (Off) Current

10

vs. Temperature

9

(mA)

I

CPOR

8
7
6
5
4
3
2

VCC= 16.5V

VCC= 5V

VCC= 2.3V

1
0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Gate Pull-Up Current

vs. Temperature

30

25

20

VCC= 16.5V

(µA)

15

GATE

I

10

VCC= 2.3V

5

0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

VCC= 5V

Gate Pull-Up Current

vs. V

25

20

15

(A)

10

GATE

I

5

0

2 4 6 8 10 12 14 16 18

Gate Sink Current

100

vs. Temperature

CC

(V)

V

CC

90
80

(mA)

70
60

VCC= 16.5V

50

GATEOFF

40

I

VCC= 5V

30

VCC= 2.3V

20
10

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

External Gate Drive

vs. Temperature

16

VCC= 5V

14
12
10

8
6
4

VCC= 16.5V

VCC= 2.3V

(V)

GS

V

2
0

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Gate Sink Current

600

vs. Gate Volta

500

400

(mA)

300

GATEOFF

200

I

100

0

02468101214

12V

V

CC

GATE

5V

CC

(V)

External Gate Drive

vs. V

22
20
18
16
14

(V)

12

GS

10

V

8
6
4
2
0

2 4 6 8 10 12 14 16 18

POR Delay/Overcurrent

e

(mV)

V

TH

1.25

1.24

1.23

1.22

1.21

1.20

Timer Threshold
vs. Temperature

VCC= 16.5V

VCC= 5V

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

CC

(V)

V

CC

VCC= 2.3V

M0235-121903 8 January 2004

MIC2085/2086 Micrel

1.7

1.8

1.9

2.0

2.1

2.2

2.3

2.4

2.5

-40 -20 0 20 40 60 80 100

UVLO THRESHOLD (V)

TEMPERATURE (°C)

10

14

18

22

26

-40 -20 0 20 40 60 80 100

I

PULLUP

(µA)

TEMPERATURE (°C)

Output Signal Pull-Up Current

vs. Temperature

VCC= 16.5V

VCC= 2.3V

VCC= 5V

Typical Characteristics

Current Limit Threshold

(Fast Trip)

120
115
110
105

(mV)

100

TRIPFAST

V

1.30

1.25

1.20

ON THRESHOLD (V)

1.15

vs. Temperature

VCC= 2.3V

95
90

VCC= 5V

85
80

-40 -20 0 20 40 60 80 100

ON Pin Threshold (Rising)

VCC= 16.5V

VCC= 5V

-40 -20 0 20 40 60 80 100

VCC= 16.5V

TEMPERATURE (°C)

vs. Temperature

VCC= 2.3V

TEMPERATURE (°C)

Current Limit Threshold

(Slow Trip)

vs. Temperature

55

53

(mV)

51

49

TRIPSLOW

V

47

45

-40 -20 0 20 40 60 80 100

1.20

1.15

1.10

ON THRESHOLD (V)

1.05

VCC= 2.3V

VCC= 5V

TEMPERATURE (°C)

ON Pin Threshold (Falling)

vs. Temperature

VCC= 2.3V

VCC= 16.5V

-40 -20 0 20 40 60 80 100

VCC= 16.5V

VCC= 5V

TEMPERATURE (°C)

UVLO Threshold

vs. Temperature

UVLO+

UVLO–

ON Pin Input Current

vs. Temperature

40
35
30
25
20
15
10

5

ON PIN INPUT CURRENT (nA)

0

-40 -20 0 20 40 60 80 100

VCC= 16.5V

VCC= 2.3V

TEMPERATURE (°C)

VCC= 5V

FB (Power-Good) Threshold

1.30

1.25

1.20

FB THRESHOLD (V)

1.15

-40 -20 0 20 40 60 80 100

Comparator Offset Voltage

0.5

0.4

0.3

January 2004 9 M0235-121903

0.2

0.1

0.0

-40 -20 0 20 40 60 80 100

COMPARATOR OFFSET VOLTAGE (V)

vs. Temperature

VCC= 5V

TEMPERATURE (°C)

vs. Temperature

VCC= 5V

VCC= 16.5V

VCC= 2.3V

TEMPERATURE (°C)

VCC= 16.5V

VCC= 2.3V

Overvoltage Pin Threshold

1.30

1.25

1.20

1.15

OVERVOLTAGE PIN THRESHOLD (V)

1000

900
800
700

(Ω)

600

DIS

500

R

400
300
200

vs. Temperature

VCC= 16.5V

VCC= 2.3V

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)

Discharge Pin Resistance

vs. Temperature

2.3V

5V

16.5V

-40 -20 0 20 40 60 80 100

TEMPERATURE (°C)