Rainbow Electronics MAX5079 User Manual

General Description

The MAX5079 ORing MOSFET controller replaces ORing diodes in high-reliability redundant, parallel-connected power supplies. Despite their low forward-voltage drop, ORing Schottky diodes cause excessive power dissipation at high currents. The MAX5079 allows for the use of low-on-resistance n-channel power MOSFETs to replace the Schottky diodes. This results in low power dissipation, smaller size, and elimination of heatsinks in high-power applications.

The MAX5079 operates from 2.75V to 13.2V and includes a charge pump to drive the high-side n-channel MOSFET. Operation down to 1V is possible if an auxiliary voltage of at least 2.75V is available. When the controller detects a positive voltage difference between IN and BUS, the n-channel MOSFET is turned on. The MOSFET is turned off as soon as the MAX5079 sees a negative potential at IN with respect to the BUS voltage, and is automatically turned back on when the positive potential is restored. Under fault conditions, the ORing MOSFET’s gate is pulled down with a 1A current, providing an ultra-fast 200ns turn-off. The reverse voltage turn-off threshold is externally adjustable to avoid unintentional turn-off of the ORing MOSFET due to glitches at IN or BUS caused by hot plugging the power supply.

Additional features include an OVP flag to facilitate shutdown of a failed power supply due to an overvoltage condition, and a PGOOD signal that indicates if V

IN

is either below the undervoltage lockout or V

BUS

is in an overvoltage condition. The MAX5079 operates over the -40°C to +85°C temperature range and is available in a space-saving 14-pin TSSOP package.

Applications

Paralleled DC-DC Converter Modules

N+1 Redundant Power Systems

Servers

Base-Station Line Cards

RAID

Networking Line Cards

Features

♦ 2.75V to 13.2V Input ORing Voltage

♦ 1V to 13.2V Input ORing Voltage with 2.75V Aux

Voltage Present

♦ 2A MOSFET Gate Pulldown Current During Fault

Condition

♦ Ultra-Fast 200ns, MOSFET Turn-Off During Fault

Condition

♦ Supply Undervoltage and Bus Overvoltage

Detection

♦ Power-Good (PGOOD) and Overvoltage (OVP)

Outputs for Fault Detection

♦ Space-Saving 14-Pin TSSOP Package

♦ -40°C to +85°C Operating Temperature Range

MAX5079

ORing MOSFET Controller with

Ultra-Fast 200ns Turn-Off

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

PART TEMP RANGE

PIN-PACKAGE

MAX5079EUD -40°C to +85°C 14 TSSOP

19-3584; Rev 0; 2/05

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

BUS

COMMON

GATE BUSIN

POWER SUPPLY 1

(PS1)

POWER SUPPLY 2

(PS2)

1V TO 13.2V

V

OUT1

V

OUT2

UVLO

OVI

GND

U1

STH

AUXIN

>2.75V

FTH

PGOOD

V

BUS

R

STH

R

FTH

R

FTH

C

STH

R

STH

C

STH

C

EXT

C

EXT

C

BUS

N1

V

IN

C+ C-

OVP

GATE BUSIN

1V TO 13.2V

UVLO

OVI

U2

STH

AUXIN

>2.75V

PGOOD

V

BUS

N2

V

IN

C+ C-

OVP

MAX5079

GNDFTH

SUB 75N 03-04

Typical Operating Circuit

Pin Configuration appears at end of data sheet.

MAX5079

ORing MOSFET Controller with Ultra-Fast 200ns Turn-Off

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

((VIN= 2.75V to 13.2V and V

AUXIN

= 0V) or (VIN= 1V and V

AUXIN

= 2.75V to 13.2V), R

STH

= open, R

FTH

= 0, V

UVLO

= 1V, V

OVI

= 0V,

T

A

= -40°C to +85°C, unless otherwise noted. Typical values are at VIN= 12V and TA= +25°C. See the Typical Operating Circuit.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

GATE to GND ..............................................-0.3V to (VIN+ 8.5V)

All Other Pins to GND.............................................-0.3V to +15V

Continuous Current Into Any Pin ......................................±50mA

Continuous Power Dissipation (T

A

= +70°C)

14-Pin TSSOP (derate 9.1mW/°C above +70°C) ......727.3mW

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

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER SYMBOL CONDITIONS

UNITS

POWER SUPPLIES

V

IN Input Voltage Range V

IN

V

AUXIN

≥ 2.75V 1.0

V

AUXIN Input Voltage Range V

AUXIN

0

V

(V

AUXIN

- VIN) High Threshold (When GATE Connects Directly to AUXIN) (Note 2)

V

AUXIN_

THRESHOLD

V

AUXIN

rising, I

GATE

= 10µA 4.3 4.9 5.4 V

(V

AUXIN

- VIN) Hysteresis (When GATE Connects Directly To AUXIN)

V

AUXIN_

HYSTERESIS

40 mV

IN Supply Current I

IN

V

UVLO

= 1V, VIN > V

BUS

4mA

AUXIN Leakage Current I

LEAK_AUX

V

AUXIN

= 0V 20 µA

AUXIN Supply Current I

AUXIN

V

UVLO

= 1V, V

AUXIN

= 13.2V, V

AUXIN

≥

V

IN

, V

AUXIN

≥ V

BUS

4mA

BUS Leakage Current I

LEAK_BUS

VIN = 13.2V, V

BUS

= 0V 1 mA

BUS Supply Current I

BUS

V

BUS

= 13.2V, V

BUS

> VIN, V

BUS

>

V

AUXIN

3mA

IN TO AUXIN SWITCHOVER

Switchover High Threshold

(VIN - V

AUXIN

), V

AUXIN

falling -60

mV

Switchover Low Threshold V

AUXIN_LOW

(VIN - V

AUXIN

), V

AUXIN

rising

-25

mV

IN UNDERVOLTAGE LOCKOUT

Internal UVLO High Threshold

VIN rising, V

AUXIN

= 0V or V

AUXIN

rising, VIN = 0V

2.0

2.5 V

Internal UVLO Hysteresis

VIN falling, V

AUXIN

= 0V or V

AUXIN

falling, VIN = 0V

30 mV

External UVLO Threshold V

UVLO

V

UVLO

falling

0.6

V

External UVLO Hysteresis V

UVLO_HYST

60 mV

External UVLO Input Bias

I

UVLO

500 nA

MIN TYP MAX

2.75 13.20

13.2

V

AUXIN_HIGH

V

INTUVLO_HIGH

V

INTUVLO_HYST

+25 +200

-200

2.25

0.568

+50

0.632

MAX5079

ORing MOSFET Controller with

Ultra-Fast 200ns Turn-Off

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

((VIN= 2.75V to 13.2V and V

AUXIN

= 0V) or (VIN= 1V and V

AUXIN

= 2.75V to 13.2V), R

STH

= open, R

FTH

= 0, V

UVLO

= 1V, V

OVI

= 0V,

T

A

= -40°C to +85°C, unless otherwise noted. Typical values are at VIN= 12V and TA= +25°C. See the Typical Operating Circuit.) (Note 1)

PARAMETER SYMBOL CONDITIONS

ORing MOSFET CONTROL

ORing MOSFET Turn-On Time t

ON

C

GATE

= 10nF, C

EXT

= 100nF,

MOSFET gate threshold = 2V

10 25 µs

ORing MOSFET Forward Voltage Threshold (Fast Comparator)

V

DTH

(VIN - V

BUS

) rising 5

20 mV

R

FTH

= 0 -12 -24 -31

R

FTH

= 12kΩ -63

ORing MOSFET Reverse Voltage Turn-Off Threshold (Fast Comparator (V

IN

- V

BUS

))

V

FTH

R

FTH

= 27kΩ, VIN ≥ 3.5V

mV

ORing MOSFET Reverse Voltage

Blanking Time (Fast Comparator)

t

FBL

V

BUS

= 2.8V, R

FTH

= 0,

V

BUS

- VIN = 0.3V

50 ns

Slow-Comparator Output Voltage Threshold on STH

V

O_STH

1

V

R

STH

open

-12

R

STH

= 500kΩ -25

ORing MOSFET Reverse Voltage Turn-Off Threshold (Slow Comparator (V

IN

- V

BUS

))

V

STH

R

STH

= 64kΩ

mV

(VIN - V

BUS

) to I

STH

Transconductance (Slow Comparator)

G

M_STH

V

STH

= 0V

mS

STH floating 0.5 0.9 1.5

C

STH

= 0.047µF 5

ORing MOSFET Reverse Voltage Blanking Time (Slow Comparator)

t

SBL

C

STH

= 0.22µF 14

ms

ORing MOSFET DRIVER

Gate-Charge Current I

GATE

C

EXT

= 100nF 0.7 2 mA

V

GATE

≥ VIN, VIN = 5V, V

BUS

= 5V 0.9 2 5.0

1.3

Gate Discharge Current (Note 3)

3.2

A

V

BUS

= 3.5V, C

GATE

= 0.1µF

Gate Fall Time t

FGATE

V

BUS

= 3.5V, C

GATE

= 0.01µF

ns

Gate Discharge Current Delay Time (Time from V

IN

Falling from

3.7V to 3V to V

GATE

= VIN)

t

DIS_GATE

V

BUS

= 3.5V, V

FTH

= 0V,

C

GATE

= 0.1nF

70 200 ns

Gate to IN Resistance R

GATE_IN

(V

GATE

- VIN) = 100mV 900 Ω

Gate to IN Clamp Voltage

I

GATE

= 10mA, VIN ≥ V

BUS

8.5 11 V

2.7V < VIN < 13.2V 3.8

VIN = 13.2V 6.5 7 7.6

Gate-Drive Voltage (Measured with Respect to V

IN

)

VIN = 2.75V 4.5 5 5.5

V

VIN Switchover Threshold to Higher GATE Voltage (Note 4)

V

IN_SOTH+

7.4 8 8.5 V

I

GATE.DIS_MIN

V

GAT E _ IN _ C L AM P

(V

- VIN)

GATE

MIN TYP MAX UNITS

12.5

-104 -150

-126 -204 -300

0.95

-0.1

-100

0.17

V

≥ VIN, VIN = 2.75V, V

GATE

V

GATE

≥ V

IN

, VIN = 12V, V

BUS

= 3.5V

= 13.2V

600

200

1.05

-24.0

MAX5079

ORing MOSFET Controller with Ultra-Fast 200ns Turn-Off

4 _______________________________________________________________________________________

Note 1: All devices are production tested at +25°C. Limits over temperature are guaranteed by design. Note 2: Threshold is reached when charge pump turns off. Note 3: Gate discharge current is guaranteed through the testing of gate fall time. Note 4: V

IN

switchover threshold is VINat which the gate-drive voltage (V

GATE

- VIN) goes from 5V to 7V, VINrising and (VIN≥ V

BUS

).

ELECTRICAL CHARACTERISTICS (continued)

((VIN= 2.75V to 13.2V and V

AUXIN

= 0V) or (VIN= 1V and V

AUXIN

= 2.75V to 13.2V), R

STH

= open, R

FTH

= 0, V

UVLO

= 1V, V

OVI

= 0V,

T

A

= -40°C to +85°C, unless otherwise noted. Typical values are at VIN= 12V and TA= +25°C. See the Typical Operating Circuit.) (Note 1)

PARAMETER SYMBOL CONDITIONS

MIN

TYP

MAX

UNITS

VIN Switchover Hysteresis (Note 4)

V

IN_SOHYS

40 mV

External 70

Charge-Pump Frequency f

CP

Internal, VIN < 5V, V

AUXIN

< 5V

kHz

PROTECTION

OVI Input Bias Current I

OVI

500 nA

OVI Threshold V

OVI_TH

OVI rising

0.6

V

OVP Output Low Voltage V

OVP_LOW

V

OVI

= 1V, I

SINK

= 10mA 0.2 0.4 V

OVP Leakage Current I

OVP_LEAK

VIN = 2.75V, V

OVP

= 13.2V 1 µA

PGOOD Leakage Current I

PG_LEAK

V

PGOOD

= 13.2V 1 µA

PGOOD Output Low Voltage V

PG_LOW

I

SINK

= 2mA 0.2 0.4 V

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted. See the Typical Operating Circuit.)

AUXIN SUPPLY CURRENT

vs. TEMPERATURE (V

IN

= V

BUS

= 1V)

MAX5079 toc01

TEMPERATURE (°C)

I

AUXIN

(mA)

1109580655035205-10-25

1

2

3

0

-40 125

V

AUXIN

= 5V

V

AUXIN

= 10V

V

AUXIN

= 2.7V

GATE-CHARGE CURRENT vs. V

IN

MAX5079 toc02

VIN (V)

I

GATE

(mA)

14128 104 62

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

6.0

0

015

131179351

TA = +25°C

TA = -40°C

TA = +125°C

TA = +85°C

SLOW-COMPARATOR REVERSE VOLTAGE

THRESHOLD (V

STH

vs. R

STH

)

MAX5079 toc03

R

STH

(kΩ)

V

STH

(V)

100

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0

10 1000

TA = -40°C, TA = +25°C, T

A

= +85°C, TA = +125°C

1100

0.568

0.632

MAX5079

ORing MOSFET Controller with

Ultra-Fast 200ns Turn-Off

_______________________________________________________________________________________ 5

0

20

10

40

30

60

50

70

90

80

100

00.20.30.40.1 0.5 0.6 0.7 0.90.8 1.0

SLOW-COMPARATOR BLANKING TIME

t

STH

vs. C

STH

(R

STH

= 180kΩ)

MAX5079 toc04

C

STH

(µF)

t

STH

(ms)

75mV OVERDRIVE

FAST-COMPARATOR REVERSE VOLTAGE

THRESHOLD (V

FTH

vs. R

FTH)

MAX5079 toc05

R

FTH

(kΩ)

V

FTH

(V)

14012080 10040 6020

0.1

0.3

0.5

0.2

0.4

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

0

TA = +125°C

TA = +85°C

TA = -40°C

FAST-COMPARATOR RESPONSE TIME

MAX5079 toc06

TEMPERATURE (°C)

t

RESPONSE

(ns)

1109565 80-10 5 20 35 50-25

8

16

24

32

40

48

56

64

72

80

0

-40 125

VIN = 5V, V

AUXIN

= 0V

VIN = 1V, V

AUXIN

= 5V

VIN = 2.75V,

V

AUXIN

= 12V

VIN = 12V,

V

AUXIN

= 0V

CHARGE-PUMP FREQUENCY

vs. INPUT VOLTAGE

MAX5079 toc07

VIN (V)

f

CP

(kHz)

141210 11 1397 82 3 4 5 61

62

64

66

68

70

72

74

76

78

80

60

015

TA = +125°C

TA = +85°C

TA = +25°C

TA = -40°C

GATE-CHARGE CURRENT vs. C

EXT

MAX5079 toc08

C

EXT

(nF)

GATE-CHARGE CURRENT (mA)

10

0.5

1.0

1.5

2.0

2.5

3.5

4.0

4.5

5.0

6.0

0

1 100

VIN = 12V

3.0

5.5

FAULT CURRENT WAVEFORM

(IN SHORTED TO PGND)

MAX5079 toc09

VIN = 5V, V

BUS

= 5V,

V

AUXIN

= 0V, C

STH

= 0,

R

STH

= OPEN, R

FTH

= 0,

UVLO = IN

BUS 5V/div

IN 5V/div

GATE 10V/div

MOSFET REVERSE CURRENT 5A/div

400ns/div

Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted. See the Typical Operating Circuit.)

MAX5079

ORing MOSFET Controller with Ultra-Fast 200ns Turn-Off

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(TA = +25°C, unless otherwise noted. See the Typical Operating Circuit.)

FAULT CURRENT WAVEFORM

(IN SHORTED TO PGND)

MAX5079 toc13

VIN = 5V, V

BUS

= 5V,

V

AUXIN

= 5V, C

STH

= 0µF,

R

STH

= OPEN, R

FTH

= 0,

UVLO = IN

BUS 5V/div

IN 5V/div

GATE 10V/div

MOSFET REVERSE CURRENT 10A/div

1µs/div

FAULT CURRENT WAVEFORM

(IN SHORTED TO PGND)

MAX5079 toc12

VIN = 1V, V

BUS

= 1V,

V

AUXIN

= 5V, C

STH

= 0µF,

R

STH

= OPEN, R

FTH

= 0,

UVLO = IN

BUS 1V/div

IN 1V/div

GATE 5V/div

MOSFET REVERSE CURRENT 10A/div

1µs/div

FAULT CURRENT WAVEFORM

(IN SHORTED TO PGND)

MAX5079 toc10

VIN = 2.75V, V

BUS

= 2.75V,

V

AUXIN

= 0V, C

STH

= 0µF,

R

STH

= OPEN, R

FTH

= 0,

UVLO = IN

BUS 2V/div

IN 2V/div

GATE 5V/div

MOSFET REVERSE CURRENT 10A/div

1µs/div

FAULT CURRENT WAVEFORM

(IN SHORTED TO PGND)

MAX5079 toc11

VIN = 12V, V

BUS

= 12V,

V

AUXIN

= 0V, C

STH

= 0µF,

R

STH

= OPEN, R

FTH

= 0,

UVLO = IN

BUS 10V/div

IN 10V/div

GATE 20V/div

MOSFET REVERSE CURRENT 10A/div

400ns/div