Datasheet AMS2027 Datasheet (ROHS)

http://www.BDTIC.com/AMS

Advanced AMS2027

Monolithic SINGLE POWER DISTRIBUTION SWITCH
Systems

RoHS compliant

PRELIMINARY INFORMATION

FEATURES

• 110mΩ Typical (5V Input) High Side MOSFET Switch • 100µA Maximum On-State Supply Current

• Short Circuit Protection • Available Active-High or Active-Low Enable

• Logic Overcurrent Output Error Flag • Available in Space Saving 8 lead SOIC and 8 Lead PDIP

• Logic Undervoltage Output Error Flag

• Logic Overheat Output Error Flag

• Enable Input Compatible With 3V and 5V Logic

• Controlled Rise and Fall Times Limit Current • USB Power Management

Surges and Minimize EMI

• Undervoltage Lock-Out Guarantees the Switch is • Battery-Charger Circuits
Off At Start-up

PRODUCT DESCRIPTION

The AMS2027 is a power distribution switch intended for application where heavy capacitive loads and short-circuits are
likely to be encountered. The high-side switch is a 110mΩ N-channel MOSFET. The switch is controlled by a logic enable
input compatible with 3V and 5V logic and is available in active-high or active-low enable. The internal charge pump,
designed to control the power switch rise and fall time to minimize current surges during switching, also provides the gate
drive. Requiring no external components the charge pump allows operation from supplies as low as 3.3V. When an overload
or a short circuit is encountered the AMS2027 limits the output current to a safe level by switching into a constant-current
mode and the overcurrent logic output error flag is set to a low. The po wer dissipation in the switch will be increased by
continuous heavy overloads and short circuits; this will cause the junction temperature to rise. The thermal protection circuit
shuts the power switch off to prevent damage. Once the device has cooled sufficiently, it will turn on automatic. An under
voltage lock-out is provided to insure that the power switch is in th e Off state at start-up.

The AMS2027 is offered in the 8 lead SOIC package and the 8 lead PDIP package and is rated operational over a -40°C to
85°C temperature range.

ORDERING INFORMATION PIN CONNECTIONS

PACKAGE TYPE OPER. TEMP

8 LEAD SOIC 8 LEAD PDIP

AMS2027S AMS2027P

RANGE

-40°C to 85°C

APPLICATIONS

• Hot Plug-In Power Supplies

8 LEAD SOIC/ 8LEAD PDIP

ENABLE

ERROR

GROUND

N/C

1
2
3
4

8

OUTPUT

7

INPUT
6 OUTPUT
5

N/C

Advanced Monolithic Systems, Inc.

http://www.BDTIC.com/AMS

AMS2027

ABSOLUTE MAXIMUM RATINGS (Note 1)

Input Voltage Range, VI -0.3V to 7V Internal Power Dissipation (Note 3) Internally Limited
Output Voltage Range, V

-0.3V to V

O

+0.3V
Input Voltage Range, V
Continuos Output Current, I

at /EN -0.3V to 7V Storage Temperature

I

Lead Temperature (Soldering 25 sec)

O

ELECTRICAL CHARACTERISTICS

Electrical Characteristics at TJ=25°C, V

PARAMETER

Switch On-State Resistance V
V
V
V
Switch Output Leakage Current /EN = VI 0.01 5

Switch Output Rise Time

Switch Output Fall Time

= 5.5V 75 95

I(IN)

= 5.0V 80 95

I(IN)

= 4.5V 90 110

I(IN)

= 4.0V 96 110

I(IN)

/EN = V

= 5.5V, CL = 1µF

V

I(IN)

= 2.7V, CL = 1µF

V

I(IN)

= 5.5V, CL = 1µF

V

I(IN)

= 5.5V, IO =rated current, /EN = 0V unless otherwise specified.

I(IN)

CONDITIONS

(Note 2)

, -40°C ≤ TJ ≤ 85°C

I

Maximum Junction Temperature

I(IN)

Min.

10

4.0 ms

3.8 ms

3.9 ms

AMS2027

Typ.

+125°C

-65°C to +150°C
265°C

Units

Max.

mΩ
mΩ
mΩ
mΩ

µA
µA

Enable High-Level Input
Voltage

Enable Low-Level Input Voltage

Enable Input Current /EN = 0V or /EN = VI -1.0 1.0

Enable Delay Time, Low-to­High Output

Short Circuit Current V

Supply Current, Low-Level
Output

Supply Current, High-Level
Output

Undervoltage lock-out Low­Level Input Voltage

Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. For guaranteed performance limits and associated test
conditions, see the Electrical Characteristics tables.

Note 2: To ensure constant junction temperature, low duty cycle pulse testing is used; thermal effects must be taken in consideration separately.
Note 3: The Power Dissipation for the SO-8 package is 725mW at T

= 70 °C P

= 464mW ; for TA = 125 °C PD = 145mW)

D

= 2.7V, CL = 1µF

V

I(IN)

4.0V ≤ V

4.0V ≤ V

C
C

OUT Connected to GND, device enable into
short circuit

/EN = VI , TJ=25°C
/EN = V
/EN = 0V, TJ=25°C
/EN = 0V, -40°C ≤ T

2.0 3.0 3.2 V

≤ 5.5V

I

≤ 5.5V

I

= 1µF

L

= 1µF

L

= 5.5V, TJ=25°C

I(IN)

, -40°C ≤ TJ ≤ 85°C

I

≤ 85°C

J

= 25 °C. Above TA = 25 °C the Power Dissipation must be derated at 5.8mW/ °C (for TA

A

3.5 ms

2.4 V

.06 V

µA

20

40

0.66 1.2 1.8 A

0.015 10
10

73 100

100

ms
ms

µA
µA
µA
µA

RECOMENDED OPERATING CONDITIONS:
Min Max

Input Voltage, VI 4.0V 5.5V
Input Voltage, VI at /EN 0V 5.5V
Continuous Output Current, IO 0A 0.6A
Operating Junction Temp. Range -40°C +125°C

Advanced Monolithic Systems, Inc.

http://www.BDTIC.com/AMS

PIN FUNCTIONS

Pin Name Pin No. I / O Description

Enable /EN 1 I Enable Input, Logic turns power switch on.
Ground GND 3 I Ground.
Input IN 7 I Power switch input, also supplies IC’s internal circuitry.
Error Flag ERROR 2 O Overcurrent, Over temperature, Logic output.
Output OUT 6,8 O Power switch output.

AMS2027

BLOCK DIAGRAM

*Current Sense

OUT

ENABLE

ERROR

GND

*

CS

CURRENT

LIMIT

ERROR

FLAG

POWER SWITCH

GATE

DRIVER

CHARGE

PUMP

UVLO

FUNCTIONAL DESCRIPTION

Power Switch

The power switch is an N-channel MOSFET with a maximum on­state resistance of 140mΩ (V
switch.

Charge Pump

An internal 100kHz charge pump supplies the power to the driver
circuit and provides the required voltage to pull the gate of the
MOSFET above the source. The charge pump requires very little
supply current and operates from input voltages as low as 3.3V.

Gate Driver
The driver controls the gate voltage of the power switch. The

driver incorporates circuitry that controls the rise and fall times of
the output voltage, as a result it limits large current surges and
reduces the associated electromagnetic interference (EMI)
produced. The rise and fall times of the output voltage are
typically in the 2ms to 4ms range instead of the microsecond or
nanosecond range for a standard FET.

Enable
A logic high on the /EN input turns off the power switch and the

bias for the charge pump, driver, and other circuitry to reduce the
supply current to less than 10µA. A logic zero input restore bias to
the drive and control circuits and turns the power on. The enable
input is compatible with both TTL and CMOS logic levels.

) = 5.0V, configured as a high-side

I(IN

Error Flag

The error flag output, is an open drain logic output that is active
low when output current exceeds current limit. Until the fault
condition is removed the output will remain active low.

Current Limit

A sense FET monitors the current supplied to the load. In case of
an overload or short circuit, the current limit circuitry sends a
signal to the driver. The driver will then reduce the gate voltage
and drive the power FET into its linear region, which switches the
output into a constant current mode and holds the current constant
while varying the voltage on the load.

Thermal Shutdown
The internal thermal shutdown circuit will shut the power switch

off when the junction temperature rises to approx. 180°C.
Hysterisis is build into the thermal sense circuitry, and after the
junction temperature has dropped about 20°C, the switch turns
back on. Until the fault is removed the switch will continue to
cycle off and on.

Undervoltage Lock-out
An internal voltage sense monitors the input voltage. When the

input voltage is below 3.2V nominal, the switch is turned off by a
control signal. The typical fall time range due to the sense of a
low voltage is 250µs to 750µs.

IN

1.2V

REFERENCE

THERMAL

SENSE

Advanced Monolithic Systems, Inc.

http://www.BDTIC.com/AMS

APPLICATION HINTS

Power Supply Considerations

A 0.047µF ceramic bypass capacitor close to the device, between
input and ground is recommended. When the output load is heavy
or has large paralleled capacitors, a high value electrolytic
capacitor should be used. To improve the immunity of the device
to ESD, use a 0.1µF ceramic capacitor to bypass the output.

Current Limit

A sense FET monitors overcurrent conditions. When an
overcurrent condition is detected the device maintains a constant
output current and decreases the voltage accordingly. If the
condition is present long enough to activate the thermal limiting
the result is the shutdown of the device.
There are three situation in which overload can occur. In the first
case, the output has been shorted before the device is enabled or
before V
switches into a constant-current output.
In the second case, the short occurs while the device is enabled.
When this happens, very high currents flow for a short time before
the current-limit circuit can react. After the current-limit circuit
has tripped, the device limits normally.
In the third case, the load has been gradually increased beyond the
recommended operating current. The current will rise until the
current-limit threshold is reached. The AMS2027 is able to deliver
current up to the current-limit threshold without damage. When
the threshold has been reached the device switches into the
constant current mode. When over current condition is detected
the error flag logic output remains low until the condition is
removed.

Power Dissipation and Junction Temperature

The thermal resistance of the surface-mount packages such as
SOIC is high compared to that of power packages. The use of the
N-cannel MOSFET which has low on-resistance, makes it possible
for small surface-mount packages to pass large currents. To
determine the power dissipation and junction temperature the first
step is to find r

TYPICAL APPLICATIONS

has been applied. The device senses the short and

I

at the input voltage and operating temperature.

ON

Figure 1

AMS2027

As an initial estimate use the highest operating ambient
temperature of interest and read r

from Figure1. Power

ON

dissipation is equal to:
PD = rON X I

2

Calculate the junction temperature:
TJ = PD X R
Where R

θJA

+ TA

θJA

is the thermal resistance and is 172°C/W for the SOIC
package. Compare the calculated junction temperature with the
initial estimate and if they don’t mach within a few degrees,
repeat the calculations using the calculated value as the new
estimate. A few repetitions will be sufficient to give a reasonable
answer.

Thermal Protection

Thermal protection prevents damage to the device when over load
or short circuits conditions are present for extended periods of
time. These conditions force the AMS2027 into the constant
current mode. As a result the voltage across the high-side switch
will increase. Under short-circuit conditions the voltage across the
switch is equal to the input voltage. Continuous heavy over loads
and short circuits increase the power dissipation in the switch and
causes the junction temperature to rise to dangerously high levels.
The protection circuit shuts off the switch when it senses the high
junction temperature. The switch remains off until the device has
cooled about 20°C. The switch continues to cycle off and on until
the fault is removed.

Undervoltage Lock-out

An undervoltage lock-out is provided to insure that the switch is
in the off state at start-up. When the input voltage falls below

3.2V the switch will be turned off immediately. This will make it
easy for designers of hot plug-in systems that may not be able to
turn the switch off before removing the input power. In such cases
when the device is reinserted, the turn on will have a controlled
rise time to reduce EMI and voltage overshoots.

POWER SUPPLY

4.0V - 5.0V

ENABLE

ERROR FLAG

Advanced Monolithic Systems, Inc.

10k

7

IN

0.1µF1µF

1

EN

2

ERROR

GND

3

OUT

OUT

8

6

µ

F

0.1

EXTERNAL LOAD

http://www.BDTIC.com/AMS

PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted.

8 LEAD SOIC PLASTIC PACKAGE (S)

0.189-0.197*

(4.801-5.004)

87 65

AMS2027

0.050

(1.270)

TYP

0.150-0.157**

(3.810-3.988)

0.004-0.010

(0.101-0.254)

0.008-0.010

(0.203-0.254)

0.010-0.020
(0.254-0.508)

0.016-0.050

(0.406-1.270)

x 45°

0°-8° TYP

S (SO-8 ) AMS DRW# 042293

0.228-0.244

(5.791-6.197)

12 34

0.053-0.069

(1.346-1.752)

0.014-0.019

(0.355-0.483)

*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE

**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE

8 LEAD PLASTIC DIP PACKAGE (P)

0.400*

(10.160)

MAX

87 65

0.255±0.015*

(6.477±0.381)

1234

0.045-0.065

(1.143-1.651)

0.065

(1.651)

TYP

0.005

(0.127)

MIN

0.100±0.010

(2.540±0.254)

*DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTUSIONS.
MOLD FLASH OR PROTUSIONS SHALL NOT EXCEED 0.010" (0.254mm)

Advanced Monolithic Systems, Inc.

0.130±0.005

(3.302±0.127)

0.125
(3.175)

0.018±0.003

(0.457±0.076)

MIN

0.015

(0.380)

MIN

0.300-0.325

(7.620-8.255)

0.009-0.015

(0.229-0.381)

+0.025

0.325

-0.015

+0.635

(

8.255

-0.381

)

P (8L PDIP ) AMS DRW# 042294