ADMOS AMS2027 Single power distribution switch Datasheet

Advanced
Monolithic
Systems
AMS2027
SINGLE POWER DISTRIBUTION SWITCH
PRELIMINARY INFORMATION
FEATURES
• 110mΩ
Ω Typical (5V Input) High Side MOSFET Switch
• Short Circuit Protection
• Logic Overcurrent Output Error Flag
• 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
Surges and Minimize EMI
• Undervoltage Lock-Out Guarantees the Switch is
Off At Start-up
• 100µ
µ A Maximum On-State Supply Current
• Available Active-High or Active-Low Enable
• Available in Space Saving 8 lead SOIC and 8 Lead PDIP
APPLICATIONS
• USB Power Management
• Hot Plug-In Power Supplies
• Battery-Charger Circuits
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 power 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 the 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
PACKAGE TYPE
8 LEAD SOIC
AMS2027S
8 LEAD PDIP
AMS2027P
Advanced Monolithic Systems, Inc.
PIN CONNECTIONS
OPER. TEMP
RANGE
-40°C to 85°C
8 LEAD SOIC/ 8LEAD PDIP
ENABLE
1
8 OUTPUT
ERROR
2
7
GROUND
3
6 OUTPUT
N/C
4
5 N/C
INPUT
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS2027
ABSOLUTE MAXIMUM RATINGS (Note 1)
Input Voltage Range, VI
Output Voltage Range, VO
Input Voltage Range, VI at /EN
Continuos Output Current, IO
-0.3V to 7V
-0.3V to VI(IN) +0.3V
-0.3V to 7V
Internal Power Dissipation (Note 3)
Maximum Junction Temperature
Storage Temperature
Lead Temperature (Soldering 10 sec)
Internally Limited
+125°C
-65°C to +150°C
260°C
ELECTRICAL CHARACTERISTICS
Electrical Characteristics at TJ=25°C, VI(IN) = 5.5V, IO =rated current, /EN = 0V unless otherwise specified.
AMS2027
Typ.
Max.
VI(IN) = 5.5V
75
95
mΩ
VI(IN) = 5.0V
80
95
mΩ
VI(IN) = 4.5V
90
110
mΩ
96
110
mΩ
0.01
5
µA
10
µA
PARAMETER
CONDITIONS
Min.
(Note 2)
Switch On-State Resistance
VI(IN) = 4.0V
Switch Output Leakage Current
/EN = VI
/EN = VI , -40°C ≤ TJ ≤ 85°C
Switch Output Rise Time
Switch Output Fall Time
Units
VI(IN) = 5.5V, CL = 1µF
4.0
ms
VI(IN) = 2.7V, CL = 1µF
3.8
ms
VI(IN) = 5.5V, CL = 1µF
3.9
ms
VI(IN) = 2.7V, CL = 1µF
3.5
ms
Enable High-Level Input Voltage
4.0V ≤ VI ≤ 5.5V
Enable Low-Level Input Voltage
4.0V ≤ VI ≤ 5.5V
Enable Input Current
/EN = 0V or /EN = VI
Enable Delay Time, Low-to-High
Output
Short Circuit Current
VI(IN) = 5.5V, TJ=25°C
2.4
V
.06
V
1.0
µA
CL = 1µF
20
ms
CL = 1µF
40
ms
1.2
1.8
A
0.015
10
µA
10
µA
100
µA
100
µA
-1.0
0.66
OUT Connected to GND, device enable into
short circuit
Supply Current, Low-Level
Output
Supply Current, High-Level
Output
/EN = VI , TJ=25°C
/EN = VI , -40°C ≤ TJ ≤ 85°C
/EN = 0V, TJ=25°C
73
/EN = 0V, -40°C ≤ TJ ≤ 85°C
Undervoltage lock-out Low-Level
2.0
3.0
3.2
V
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 TA = 25 °C. Above TA = 25 °C the Power Dissipation must be derated at 5.8mW/ °C (for TA =
70 °C PD = 464mW ; for TA = 125 °C PD = 145mW)
RECOMENDED OPERATING CONDITIONS:
Input Voltage, VI
Input Voltage, VI at /EN
Continuous Output Current, IO
Operating Junction Temp. Range
Advanced Monolithic Systems, Inc.
Min
4.0V
0V
0A
-40°C
Max
5.5V
5.5V
0.6A
+125°C
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS2027
PIN FUNCTIONS
Pin Name
Enable
/EN
Ground
GND
Input
IN
Error Flag
ERROR
Output
OUT
Pin No.
1
3
7
2
6,8
I/O
I
I
I
O
O
Description
Enable Input, Logic turns power switch on.
Ground.
Power switch input, also supplies IC’s internal circuitry.
Overcurrent, Over temperature, Logic output.
Power switch output.
BLOCK DIAGRAM
POWER SWITCH
OUT
IN
*
CS
1.2V
REFERENCE
CURRENT
LIMIT
GATE
DRIVER
THERMAL
SENSE
ENABLE
ERROR
ERROR
FLAG
CHARGE
PUMP
UVLO
GND
*Current Sense
FUNCTIONAL DESCRIPTION
Power Switch
The power switch is an N-channel MOSFET with a maximum onstate resistance of 140mΩ (VI(IN) = 5.0V, configured as a highside 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.
Advanced Monolithic Systems, Inc.
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.
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS2027
APPLICATION HINTS
As an initial estimate use the highest operating ambient
temperature of interest and read rON from Figure1. Power
dissipation is equal to:
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.
PD = rON X I2
Calculate the junction temperature:
TJ = PD X RθJA + TA
Where RθJA 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.
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 VI has been applied. The device senses the short and
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.
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 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 rON at the input voltage and operating
temperature.
TYPICAL APPLICATIONS
Figure 1
7
POWER SUPPLY
4.0V - 5.0V
IN
0.1µF
10k
ENABLE
ERROR FLAG
EXTERNAL LOAD
8
OUT
1µF
0.1µF
1
2
EN
ERROR
OUT
6
GND
3
Advanced Monolithic Systems, Inc.
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140
AMS2027
PACKAGE DIMENSIONS inches (millimeters) unless otherwise noted.
8 LEAD SOIC PLASTIC PACKAGE (S)
0.189-0.197*
(4.801-5.004)
8
7
6
5
0.228-0.244
(5.791-6.197)
0.150-0.157**
(3.810-3.988)
1
2
3
4
0.010-0.020
x 45°
(0.254-0.508)
0.053-0.069
(1.346-1.752)
0.004-0.010
(0.101-0.254)
0.014-0.019
(0.355-0.483)
0.008-0.010
(0.203-0.254)
0.050
(1.270)
TYP
0°-8° TYP
0.016-0.050
(0.406-1.270)
S (SO-8 ) AMS DRW# 042293
*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
8
7
6
5
1
2
3
4
0.255±0.015*
(6.477±0.381)
0.045-0.065
(1.143-1.651)
0.300-0.325
(7.620-8.255)
0.130±0.005
(3.302±0.127)
0.065
(1.651)
TYP
0.005
(0.127)
MIN
0.100±0.010
(2.540±0.254)
0.125
(3.175)
MIN
0.009-0.015
(0.229-0.381)
0.015
(0.380)
MIN
0.018±0.003
(0.457±0.076)
0.325 +0.025
-0.015
(8.255 +0.635
-0.381
)
P (8L PDIP ) AMS DRW# 042294
*DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTUSIONS.
MOLD FLASH OR PROTUSIONS SHALL NOT EXCEED 0.010" (0.254mm)
Advanced Monolithic Systems, Inc.
6680B Sierra Lane, Dublin, CA 94568 Phone (925) 556-9090 Fax (925) 556-9140