Rainbow Electronics DS4560 User Manual

General Description

The DS4560 is a self-contained hot-plug switch intend­ed to be used on +12V power buses to limit through
current and to control the power-up output-voltage
ramp. The device contains an on-board 25mΩ n-chan­nel power MOSFET that is actively closed-loop con­trolled to ensure that an adjustable current limit is not
exceeded. The maximum allowable current through the
device is determined by an external resistor connected
to the ILIM pin.

The DS4560 also contains the ability to control the
power-up output-voltage ramp. A capacitor connected
to the VRAMP pin sets the desired voltage ramp rate.
The output voltage is unconditionally clamped to keep
input overvoltage stresses from harming the load. The
DS4560 also contains an adjustable power-up timer. A
capacitor connected to the TIMER pin determines how
long after power-on reset the DS4560 should wait
before starting to apply power to the load. The TIMER
pin can also be driven with a digital logic output to cre­ate a device-enable function.

The DS4560 contains an on-board temperature sensor
with hysteresis. If operating conditions cause the
device to exceed an internal thermal limit, the DS4560
either unconditionally shuts down and latches off await­ing a power-on reset (DS4560S-LO), or it waits until the
device has cooled by the hysteresis amount and then
restarts (DS4560S-AR).

Applications

Features

♦ On-Board 25mΩ Power MOSFET

♦ Adjustable Short-Circuit Current and Overload

Current Limit

♦ Adjustable Output-Voltage Slew Rate

♦ Adjustable Power-Up Timer with External Enable

Capability

♦ Output Overvoltage Limiting

♦ On-Board Thermal Protection

♦ On-Board Charge Pump

♦ Latchoff and Autoretry Versions Available

♦ 9.0V to 13.2V Supply Operation

♦ 8-Pin SO (150 mils) Pb-Free Package

DS4560

12V Hot-Plug Switch

________________________________________________________________

Maxim Integrated Products

1

Pin Configuration

Ordering Information

Rev 1; 9/08

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

+

Denotes a lead-free/RoHS-compliant package.

T = Tape and reel.

PART

THER MAL

SHUTDOWN

PIN-PACKAGE

DS4560S-LO+ Latchoff 8 SO

DS4560S-LO+T Latchoff 8 SO

DS4560S-AR+ Autoretry 8 SO

DS4560S-AR+T Autoretry 8 SO

Pin Description

PIN NAME FUNCTION

1 GND

Ground. This is a lso a heat sink for the
device.

2 VRAMP Output-Voltage Ramp Adjustment

3 TIMER Power-Up Timer/Enable

4 ILIM Current-Limit Adju stment

5, 6, 7 LOAD Output Load Connection (MOSFET Source)

8 VCC Input Supply Voltage (MOSFET Drain)

PCI Express is a registered trademark of PCI-SIG Corp.

InfiniBand is a trademark and service mark of the InfiniBand Trade Association.

RAID/Hard Drives

Servers/Routers

PCI/PCI Express

®

InfiniBand

SM

Base Stations

TOP VIEW

+

18V

GND

2 7 LOADVRAMP

DS4560

TIMER 3 6

45

SO (150 mils)

CC

LOAD

LOADILIM

DS4560

12V Hot-Plug Switch

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

RECOMMENDED OPERATING CONDITIONS

(TJ= -40°C to +135°C.)

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.

Voltage Range on VCCand LOAD Relative to GND

Continuous .........................................................-0.3V to +18V

1ms Maximum ....................................................-0.3V to +22V

Voltage Range on ILIM and VRAMP

Relative to GND.....................................-0.3V to (V

CC

+ 0.3V),

but not to exceed +18V

Voltage Range on TIMER Relative to GND ...........-0.3V to +5.0V

Drain Current

Continuous ...........................................................................4A

Peak ...................................................................................15A

Operating Junction Temperature Range...........-40°C to +135°C

Storage Temperature Range .............................-55°C to +135°C

Soldering Temperature...........................Refer to the IPC/JEDEC

J-STD-020 Specification.

ELECTRICAL CHARACTERISTICS

(VCC= +12V, TJ= +25°C, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage VCC (Notes 1, 2) 9.0 13.2 V

R

Value R

ILIM

C

C

TIMER Turn-On Voltage VON 2.6 5 V

TIMER Turn-Off Voltage V

Value C

VRAMP

Value C

TIMER

20 400 

ILIM

0.04 5.00 μF

VRAMP

0.04 5.00 μF

TIMER

-0.3 +2.0 V

OFF

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Current ICC (Note 3) 1.1 2.00 mA

UVLO Ri sing V

UVLO Falling V

UVLO Hysteresis V

On-Resistance RON 25 32 m

MOSFET Output Capacitance C

LOAD Voltage During Off State V

Dela y Time from Enable to
Beginning of Conduction

Gate-Charging Time from
Conduction to 90% of V

Shutdown Junction Temperature T

Thermal Hysteresis T

TIMER Charging Current I

Overvoltage Clamp V

OUT

7.5 8.0 8.5 V

UVLOR

6.5 7.0 7.5 V

UVLOF

1 V

UVLOH

500 pF

OUT

(Note 4) 200 mV

LOFF

t

C

POND

t

C

GCT

(Note 5) 120 135 150 °C

SHDN

(Note 5) 40 °C

HYS

70 80 92 μA

TIMER

13.5 15.0 16.5 V

OVC

= 1μF 5 ms

VRAMP

VRAMP

= 1μF, C

= 1000μF 48 66 80 ms

LOAD

DS4560

12V Hot-Plug Switch

_______________________________________________________________________________________ 3

Note 1: All voltages are referenced to ground. Currents entering the IC are specified positive and currents exiting the IC are negative.
Note 2: This supply range guarantees that the LOAD voltage is not clamped by the overvoltage limit.
Note 3: Supply current specified with no load on the LOAD pin.
Note 4: V

LOFF

voltage specified with a 2.5mA load applied to LOAD.

Note 5: Not production tested. Guaranteed by design.
Note 6: I

SCL

is the current limit when the output voltage is initially ramping up.

Note 7: I

OVL

is the current limit after the output voltage ramping is complete.

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +12V, TJ= +25°C, unless otherwise noted.)

Typical Operating Characteristics

(V

CC

= 12V, TA = +25°C, R

ILIM

= 56Ω, VCC= 12V, C

TIMER

= 0.1µF, C

VRAMP

= 0.1µF, unless otherwise noted.)

Short-Circuit Limit I

Overload Limit I

LOAD Voltage Slew Rate SR

VRAMP Charging Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

R

SCL

R

OVL

C

LOAD

70 80 92 μA

VRAMP

= 56 (Note 6) 2.0 2.5 3.0 A

ILIM

= 56 (Note 7) 3.5 4.4 5.9 A

ILIM

= 1μF 0.13 0.15 0.18 V/ms

VRAMP

CURRENT LIMIT vs. R

10

1

CURRENT LIMIT (A)

ILIM

I

OVL

I

SCL

DS4560 toc01

CURRENT LIMIT (A)

CURRENT LIMIT vs. TEMPERATURE

7

6

5

4

3

2

1

I

OVL

I

SCL

OVERVOLTAGE CLAMP vs. TEMPERATURE

16.4

16.2

DS4560 toc02

16.0

15.8

15.6

15.4

OVERVOLTAGE CLAMP (V)

15.2

NO LOAD

10Ω LOAD

DS4560 toc03

0.1
100

R

(Ω)

ILIM

ON-RESISTANCE vs. TEMPERATURE

45

40

35

(mΩ)

ON

R

30

25

20

-40 140
TEMPERATURE (°C)

0

100010

-40 140
TEMPERATURE (°C)

12010080604020-20 0

15.0

-40 140
TEMPERATURE (°C)

12010080604020-20 0

TYPICAL DS4560 TURN-ON WAVEFORMS

SUPPLY CURRENT vs. TEMPERATURE

2.00

1.75

DS4560 toc04

1.50

1.25

(mA)

1.00

CC

I

0.75

0.50

0.25

0

120100806040200-20

-40 140
TEMPERATURE (°C)

DS4560 toc05

5V/div

0V

120100-20 0 20 6040 80

= 18V, 10Ω RESISTIVE LOAD

V

CC

V

CC

TIMER

LOAD

2ms/div

DS4560 toc06

VRAMP

DS4560

12V Hot-Plug Switch

4 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(V

CC

= 12V, TA = +25°C, R

ILIM

= 56Ω, VCC= 12V, C

TIMER

= 0.1µF, C

VRAMP

= 0.1µF, unless otherwise noted.)

TURN-ON WAVEFORMS

10Ω RESISTIVE LOAD

DS4560 toc07

V

CC

LOAD

LOAD CURRENT

2V/div

0V

0mA

500mA/div

5ms/div

TURN-ON WAVEFORMS

3300μF CAPACITIVE LOAD

DS4560 toc08

V

CC

LOAD

LOAD CURRENT

2V/div

0V

0mA

500mA/div

5ms/div

TURN-ON WAVEFORMS

V

CC

= 18V, 10Ω RESISTIVE LOAD

DS4560 toc09

V

CC

LOAD

LOAD CURRENT

5V/div

0V

0mA

500mA/div

5ms

THERMAL SHUTDOWN WITH AUTORETRY

DS4560S-AR+, V

CC

= 18V, 10Ω RESISTIVE LOAD

DS4560 toc10

V

CC

LOAD

LOAD CURRENT

5V/div

0V

500mA/div

0mA

500ms/div

DS4560

THERMAL

LIMIT

EXTERNAL DISABLE

TIMER

C

TIMER

+5V

2.5V

UVLO

CURRENT

LIMIT

CHARGE

PUMP

LOAD

+5V

VREG

OVERVOLTAGE

LIMIT

GND

R

R

R

ILIM

LOAD

ILIM

+12V

V

CC

VRAMP

V

CC

80μA

80μA

C

VRAMP

Block Diagram/Typical Application Circuit

DS4560

12V Hot-Plug Switch

_______________________________________________________________________________________ 5

Detailed Description

The DS4560 begins to operate when VCCexceeds the
undervoltage lockout level, V

UVLOR

. At this level, the
enable circuit and TIMER pin become active. Once the
device has been enabled, a gate voltage is applied to
the power MOSFET, allowing current to begin flowing
from VCCto LOAD. The speed of the output-voltage
ramp is controlled by the capacitance placed at the
VRAMP pin. The load current is continuously monitored
during the initial voltage ramping (I

SCL

) and during nor-

mal operation (I

OVL

). If the current exceeds the current
limit that is set by the external resistance at ILIM, the
gate voltage of the power MOSFET is decreased,
reducing the output current to the set current limit.

Current is limited by the DS4560 comparing the voltage
difference between the LOAD and ILIM pins to an inter­nal reference voltage. If the output current exceeds the
limit that is set by the R

ILIM

resistor, the gate voltage of
the power MOSFET is decreased, which reduces the
output current to the load.

When the output power is initially ramping up, the current
limit is I

SCL

. Once the voltage ramping is complete, the

current limit is I

OVL

. The lower I

SCL

current limit protects

the source if there is a dead short on initial power-up.

The DS4560 acts as a fuse and automatically disables
the current flowing to the load when the temperature of
the power MOSFET has exceeded the shutdown junc­tion temperature, T

SHDN

.

DS4560

12V Hot-Plug Switch

6 _______________________________________________________________________________________

Enable/Timer

The voltage level of the TIMER pin is compared to an
internal source (see the

Block Diagram)

. When the level
on the pin exceeds VON, the comparator outputs a low
level. This then turns on the voltage ramp circuit,
enabling the device’s output. This TIMER pin can be
configured into one of four different modes of operation
listed in Table 1. The TIMER pin was designed to work
with most logic families. The TIMER pin will have at
least 250mV of hysteresis between V

ON

and V

OFF

. It is
recommended that any logic gate used to drive the
TIMER pin be tested to ensure proper operation.

Once the device has been enabled, there is a delay
(t

POND

) until conduction begins from VCCto LOAD.
This delay is the time required for the charge pump to
bring the gate voltage of the power MOSFET above its
threshold level. Once the gate is above the threshold
level, conduction begins and the output voltage begins
ramping.

Automatic Enable Mode

When VCCexceeds V

UVLOR

, the gate holding the
TIMER node low is released. The internal current
source brings the node to a level greater than VON,
enabling the device.

Delayed Automatic Enable Mode

When VCCexceeds V

UVLOR

, the gate holding the
TIMER node low is released. The internal current
source (I

TIMER

) then begins charging C

TIMER

. When

C

TIMER

is charged to a level greater than VON, the

device turns on. The equation for the delay time is:

t

DELAY

= (C

TIMER

x VON)/I

TIMER

Enable/Disable Mode

A logic gate or open-collector device can be connect­ed to the TIMER pin to enable or disable the device.
When the TIMER pin is held low, the device is disabled.
When an open-collector device is used to drive the
TIMER pin, the DS4560 is enabled when the open col­lector is in its high-impedance state by the internal cur­rent source bringing the TIMER node high. The TIMER
pin is also compatible with most logic families if the out-

put high voltage level of the gate exceeds the V

ON

level, and the gate can sink the I

TIMER

current.

Enable with Delay/Disable Mode

An open-collector device is connected in parallel with
C

TIMER

. When the pin is held low, the DS4560 is dis­abled. When the open-collector driver is high imped­ance, the internal current source begins to charge
C

TIMER

as in the delayed mode.

Output-Voltage Ramp

The voltage ramp circuit uses an operational amplifier
to control the gate bias of the n-channel power
MOSFET. When the timer/enable circuit is disabled, a
FET is used to keep C

VRAMP

discharged, which forces
the output voltage to GND. Once the enable/timer cir­cuit has been enabled, an internal current source,
I

VRAMP

, begins to charge the external capacitor,

C

VRAMP

, connected to the VRAMP pin. The amplifier
controls the gate of the power MOSFET so that the
LOAD output voltage divided by two tracks the rising
voltage level of C

VRAMP

. The output voltage continues

to ramp until it reaches either the input V

CC

level or the
overvoltage clamp limits. The equation for the output­voltage ramp function is:

dV

LOAD

/dt = 2 x (I

VRAMP/CVRAMP

)

Thermal Shutdown

The DS4560 enters a thermal shutdown state when the
temperature of the power MOSFET reaches or exceeds
T

SHDN

, approximately +135°C. When T

SHDN

is exceed­ed, the thermal-limiting circuitry disables the DS4560
using the enable circuitry. The DS4560 is offered in two
different versions: an autoretry version and a latchoff
version.

Autoretry Version (DS4560S-AR)

The autoretry verson continually monitors the tempera­ture once it has entered thermal shutdown. If the junc­tion temperature falls below approximately +95°C
(T

SHDN

- T

HYS

), the power MOSFET is re-enabled. See
the THERMAL SHUTDOWN WITH AUTORETRY graph
for details.

Table 1. TIMER Pin Modes

MODE OF OPERATION TIMER PIN SETUP

Automatic Enable No connection to TIMER pin.

Delayed Automatic Enable Capacitor C

Enable/Disable Open-collector device.

Enable with Delay/Disable Open-collector device and C

connected to TIMER.

TIMER

TIMER

.

DS4560

12V Hot-Plug Switch

_______________________________________________________________________________________ 7

Latchoff Version (DS4560S-LO)

Once the latchoff version has entered thermal shut­down, it does not attempt to turn back on. The only way
to turn this device back on is to cycle the power to the
device. When power is reapplied to V

CC

, the junction

temperature needs to be less than T

SHDN

for the

device to be enabled.

Overvoltage Limit

The overvoltage-limiting clamp monitors the VRAMP
level compared to an internal voltage reference. When
the voltage on VRAMP exceeds V

OVC

/2, the gate volt­age of the n-channel power MOSFET is reduced, limit­ing the voltage on LOAD to V

OVC

even as V

CC

increases. If the device is in overvoltage for an extend­ed period of time, the device may overheat and enter
thermal shutdown. This is caused by the power created
by the voltage drop across the power MOSFET and the
load current. See the THERMAL SHUTDOWN WITH
AUTORETRY graph for details.

Applications Information

The GND pin of the DS4560 is also a heat sink for the
device. This pin should be connected to a large trace
or plane capable of dissipating heat from the device.

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

8 SO —

21-0041

Package Information

For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages

.

DS4560

12V Hot-Plug Switch

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

8

_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

Revision History

REVISION

NUMBER

0 6/08 Initial release. —

1 9/08

REVISION

DATE

In the Recommended Operating Conditions, changed the TIMER Turn-On Voltage

) maximum specification from “VCC + 0.3V” to “5V.”

(V

ON

DESCRIPTION

PAGES

CHANGED

2