CALIFORNIA MICRO DEVICES
USB 5V Single 1.4A Overcurrent Switch
Features
•
•
•
•
•
•
•
•
•
•
High-side high current switch with active low Enable
Very low on-resistance switch (0.07
?
typ.)
Up to 1.4A continuous current on the output
Over-current limits at 1.4A min
10msec min fault blanking delay on OC# output
prevents false overcurrent alarms
Prevents backdrive current when host powered off
Low operating current (95µA typ.)
Low quiescent current when disabled (<1µA max)
Small 8-Lead SOIC package
PRELIMINARY
CM3503
Pin Diagram
GND
V
CC
V
CC
EN#
SOIC-8
V
OUT
V
OUT
V
OUT
OC#
Applications
2 USB ports 5V supply overcurrent protection
Product Description
California Micro Devices’ CM3503 is a USB
overcurrent power switch that provides power to two
USB ports. The device has a very low on-resistance
power switch that provides the V
BUS
voltage at the
USB output ports with minimal voltage drop. When
the EN# pin is logic low, the power switch is ON,
and V
CC
is connected to the output V
OUT
. When the
EN# pin is logic high, the power switch is OFF, and
no power is available at the output.
The power switch has full over-current protection.
Whenever the current limit of the switch is
exceeded, the device enters a constant-current
mode, where the output voltage is progressively
reduced to prevent the current from increasing
further. The OC# output becomes active low only if
the overcurrent condition exceeds at least 10ms.
This fault blanking delay prevents false alarms from
being reported to the host USB controller.
If the overcurrent condition is severe enough that
the part heats up to the thermal limit T
MAX
, then the
switch will be turned off and the temperature cools
down. At T
MIN
the switch then turns on again, and
the device heats up again, and so on, until the fault
is removed.
The CM3503 also prevents backdrive current
flowing into the host from the connected peripheral.
This can occur when V
CC
is removed as the host
powers down, and the peripheral still has normal
power applied. The 5V from the peripheral can
therefore be linked to the host’s V
BUS
, potentially
causing backdrive current into the host and
overloading the peripheral power supply.
Typical Application Circuit
GND
V
CC
V
CC
V
CC
EN#
V
OUT
V
OUT
V
OUT
OC#
V
BUS
V
BUS
1 USB Port
1 USB Port
Simplified Electrical Schematic
EN#
V
CC
Over
current
protect
V
OUT
OC#
© 2003 California Micro Devices Corp. All rights reserved.
C0970500
09/10/03
430 N. McCarthy Blvd, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
1
CALIFORNIA MICRO DEVICES
Absolute Maximum Ratings
Parameter
Rating
ESD Protection (All pins, HBM)
±
2000
V
CC
Input Voltage
+ 5.6, Gnd - 0.5
Storage Temperature Range
-55 to +150
Operating Ambient
-40 to +85
Operating Junction
-40 to +150*
Output Current Loading
Internally limited
Package Power Dissipation
0.5
*Internally limited
PRELIMINARY
CM3503
Unit
V
V
°C
A
W
Operating Conditions
(unless specified otherwise)
Parameter
Range
V
CC
Input Voltage
4.5 to 5.5
Ambient Temperature
-40 to +85
I
LOAD
V
CC
0 to 1400
Unit
V
°C
mA
Symbol
UVLO
R
SW
R
SWa
R
SWb
V
OUT
I
LIM
t
FBD
T
MAX
T
MIN
I
RCC
I
CC
I
CCQ
V
IH-EN
V
IL-EN
V
OL-OC
Electrical Operating Characteristics
(over operating conditions unless specified otherwise)
Parameter
Conditions
MIN
TYP
MAX
V
CC
voltage under which circuit
2.2
2.5
T=25°C
locks out - will not operate
Switch ON-Resistance
I
LOAD
= 0 to 1400mA; V
CC
= 5V,
0.07
0.1
T = 25°C
Switch ON-Resistance
I
LOAD
= 0 to 1400mA; V
CC
= 5V,
0.125
T =
0 to +85°C
Switch ON-Resistance
I
LOAD
= 0 to 1400mA; V
CC
= 5V,
0.125
T =
-40 to +85°C
Output Voltage
I
LOAD
= 1000mA, V
CC
= 5.0V,
4.9
EN#=0V, T=25°C
Over-current limit
1400 2000 2600
V
CC
= 5V T=25°C
10
20
30
Time delay from overcurrent
detection to OC# output
indication (fault blanking delay)
Temperature at which switch
150
turns off during overcurrent
Temperature at which switch
125
turns on, after cooling from T
MAX
Reverse leakage from output to V
CC
= 0V, V
OUT
= 5V, EN# = high,
10
input
T=25°C
Operating supply current
EN# = low
95
Quiescent current
EN# = high
1
EN# input Logic-1 threshold
V
CC
= 5V
2
EN# input Logic-0 threshold
V
CC
= 5V
0.8
OC# output Logic-0 threshold
I
OC
= 1mA to V
CC
0.4
UNIT
V
Ω
Ω
Ω
V
mA
ms
°C
°C
µA
µA
µA
V
V
V
Note: This is a preliminary datasheet only. Data subject to change at any time.
© 2003 California Micro Devices Corp. All rights reserved
09/10/03
430 N. McCarthy Blvd, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
2
CALIFORNIA MICRO DEVICES
Pin Functions
V
CC
is the power source.
Pins 2 & 3 must be connected together externally
PRELIMINARY
CM3503
EN#
is the active low logic input pin that is used to
V
OUT
provides the power for the loads. The internal
MOSFET switch is designed for very low voltage drops
from the voltage input pins at the full rated current.
Pins 6, 7 & 8 must be connected together externally.
Current loads of up to 1.4A are allowed. Current loads
above 1.4A may cause the constant-current limiting
circuit to operate – reducing the output voltage.
Continuous over-current loads will cause the part’s
internal temperature to rise. If the internal temperature
exceeds 150’C then the switch immediately turns off.
Once the part has cooled to 125’C then the switch
automatically turns on again.
During the cold-start interval when the input is initially
applied, internal circuitry provides a soft turn-on for the
switch, which limits peak in-rush current.
control the power switch. Set EN# high (>2V) to
deselect V
OUT
, and set EN# low (<0.8V) to select
V
OUT
.
OC#
is an active low open-drain output voltage,
indicating an overcurrent fault condition has been
detected at V
OUT
. There is a built-in 10msec (min.)
fault blanking delay after the overcurrent fault
condition has been detected, before this output
becomes active low. The OC# output deasserts only
when both the overcurrent condition stops and when
the voltage drop across the switch is less than 1V. An
external pull-up resistor of 10k - 100k is required if
the OC# output is used.
GND
is the negative reference for all voltages.
Pin Descriptions
Pin No.
1
2
3
4
5
6
7
8
Symbol
GND
V
CC
V
CC
EN#
OC#
V
OUT
V
OUT
V
OUT
Description
Negative reference for all voltages.
Power Primary High current Positive supply input.
Power supply input connected to pin 2
Active low enable pin
Active low when V
OUT
is in overcurrent mode. External pull-up resistor required.
Output connected to pins 7 and 8
Output connected to pins 6 and 8
Output connected to pins 6 and 7
STANDARD PART ORDERING INFORMATION
Pins
8
Package
SOIC
Ordering Part Number
CM3503-02SN
1
Part Marking
CM3503-02SN
Note 1: Parts are shipped in Tape & Reel form unless otherwise specified.
Note: This is a preliminary datasheet only. Data subject to change at any time.
© 2003 California Micro Devices Corp. All rights reserved
09/10/03
430 N. McCarthy Blvd, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
3
CALIFORNIA MICRO DEVICES
Response to Momentary Overcurrent Fault
>1400mA
PRELIMINARY
CM3503
<1300mA
I
OUT
V
OUT
drops to reduce I
OUT
V
OUT
OC#
OC# goes active
after 10ms (min)
20ms (typ.) delay
OC# goes inactive as
soon as overcurrent
condition stops
<150’C
Temp.
Response to Continuous Overcurrent Fault
>1400mA
I
OUT
V
OUT
drops to reduce I
OUT
V
OUT
Total powerdown when
over-temperature limit
reached
Re-powers when
temperature drops
to 125’C
OC#
OC# goes active
after 10ms (min)
20ms (typ.) delay
OC# stays low
T
MAX
= 150’C
150’C
Temp.
T
MIN
= 125’C
Note: This is a preliminary datasheet only. Data subject to change at any time.
© 2003 California Micro Devices Corp. All rights reserved
09/10/03
430 N. McCarthy Blvd, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
4
CALIFORNIA MICRO DEVICES
Typical Operating characteristics
CM3503 Quiescent supply current vs. supply voltage
120
100
80
I
CC
[uA]
PRELIMINARY
CM3503
60
40
20
0
4
4.2
4.4
4.6
4.8
V
CC
[V]
5
5.2
5.4
5.6
OC# Fault Blanking Delay
60
50
40
Delay [msec]
30
20
10
0
3.5
4
4.5
V
CC
[V]
5
5.5
6
CM3503 V
OUT
- I
OUT
characteristic
6
5
4
V
OUT
[V]
3
2
1
0
0
1
2
3
I
OUT
[A]
4
5
6
Note: This is a preliminary datasheet only. Data subject to change at any time.
© 2003 California Micro Devices Corp. All rights reserved
09/10/03
430 N. McCarthy Blvd, Milpitas, California 95035
Tel: (408) 263-3214
Fax: (408) 263-7846
www.calmicro.com
5
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