CALIFORNIA MICRO DEVICES
PRELIMINARY
CM3503
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
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 (95
A typ.)
Low quiescent current when disabled (<1
A max)
Small 8-Lead SOIC package
Applications
2 USB ports 5V supply overcurrent protection
Pin Diagram
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
Simplified Electrical Schematic
SOIC-8
V
CC
EN#
GND
V
CC
V
OUT
V
OUT
OC#
V
OUT
EN#
OC#
V
OUT
V
CC
Over
current
protect
1 USB Port
V
BUS
V
BUS
1 USB Port
V
CC
EN#
GND
V
CC
V
OUT
V
OUT
OC#
V
OUT
V
CC
CALIFORNIA MICRO DEVICES
PRELIMINARY
CM3503
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
Absolute Maximum Ratings
Parameter
Rating
Unit
ESD Protection (All pins, HBM)
2000
V
V
CC
Input Voltage
+ 5.6, Gnd - 0.5
V
Storage Temperature Range
Operating Ambient
Operating Junction
-55 to +150
-40 to +85
-40 to +150*
C
Output Current Loading
Internally limited
A
Package Power Dissipation
0.5
W
*Internally limited
Operating Conditions
(unless specified otherwise)
Parameter
Range
Unit
V
CC
Input Voltage
4.5 to 5.5
V
Ambient Temperature
-40 to +85
C
I
LOAD
V
CC
0 to 1400
mA
Electrical Operating Characteristics
(over operating conditions unless specified otherwise)
Symbol Parameter
Conditions
MIN
TYP
MAX UNIT
UVLO
V
CC
voltage under which circuit
locks out - will not operate
T=25
C
2.2
2.5
V
R
SW
Switch ON-Resistance
I
LOAD
= 0 to 1400mA; V
CC
= 5V,
T = 25
C
0.07
0.1
R
SWa
Switch ON-Resistance
I
LOAD
= 0 to 1400mA; V
CC
= 5V,
T = 0 to +85
C
0.125
R
SWb
Switch ON-Resistance
I
LOAD
= 0 to 1400mA; V
CC
= 5V,
T = -40 to +85
C
0.125
V
OUT
Output Voltage
I
LOAD
= 1000mA, V
CC
= 5.0V,
EN#=0V, T=25
C
4.9
V
I
LIM
Over-current limit
V
CC
= 5V T=25
C
1400
2000
2600
mA
t
FBD
Time delay from overcurrent
detection to OC# output
indication (fault blanking delay)
10
20
30
ms
T
MAX
Temperature at which switch
turns off during overcurrent
150
C
T
MIN
Temperature at which switch
turns on, after cooling from T
MAX
125
C
I
RCC
Reverse leakage from output to
input
V
CC
= 0V, V
OUT
= 5V, EN# = high,
T=25
C
10
A
I
CC
Operating supply current
EN# = low
95
A
I
CCQ
Quiescent current
EN# = high
1
A
V
IH-EN
EN# input Logic-1 threshold
V
CC
= 5V
2
V
V
IL-EN
EN# input Logic-0 threshold
V
CC
= 5V
0.8
V
V
OL-OC
OC# output Logic-0 threshold
I
OC
= 1mA to V
CC
0.4
V
CALIFORNIA MICRO DEVICES
PRELIMINARY
CM3503
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
Pin Functions
V
CC
is the power source.
Pins 2 & 3 must be connected together externally
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.
EN#
is the active low logic input pin that is used to
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. Symbol Description
1
GND
Negative reference for all voltages.
2
V
CC
Power Primary High current Positive supply input.
3
V
CC
Power supply input connected to pin 2
4
EN#
Active low enable pin
5
OC#
Active low when V
OUT
is in overcurrent mode. External pull-up resistor required.
6
V
OUT
Output connected to pins 7 and 8
7
V
OUT
Output connected to pins 6 and 8
8
V
OUT
Output connected to pins 6 and 7
STANDARD PART ORDERING INFORMATION
Pins
Package
Ordering Part Number
1
Part Marking
8
SOIC
CM3503-02SN
CM3503-02SN
Note 1: Parts are shipped in Tape & Reel form unless otherwise specified.
CALIFORNIA MICRO DEVICES
PRELIMINARY
CM3503
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
Response to Momentary Overcurrent Fault
I
OUT
V
OUT
OC#
Temp.
>1400mA
<150'C
V
OUT
drops to reduce I
OUT
OC# goes inactive as
soon as overcurrent
condition stops
<1300mA
OC# goes active
after 10ms (min)
20ms (typ.) delay
I
OUT
V
OUT
OC#
Temp.
T
MAX
= 150'C
T
MIN
= 125'C
150'C
Response to Continuous Overcurrent Fault
V
OUT
drops to reduce I
OUT
Total powerdown when
over-temperature limit
reached
Re-powers when
temperature drops
to 125'C
OC# goes active
after 10ms (min)
20ms (typ.) delay
OC# stays low
>1400mA
CALIFORNIA MICRO DEVICES
PRELIMINARY
CM3503
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
Typical Operating characteristics
CM3503 Quiescent supply current vs. supply voltage
0
20
40
60
80
100
120
4
4.2
4.4
4.6
4.8
5
5.2
5.4
5.6
V
CC
[V]
I
CC
[uA]
OC# Fault Blanking Delay
0
10
20
30
40
50
60
3.5
4
4.5
5
5.5
6
V
CC
[V]
Delay [msec]
CM3503 V
OUT
- I
OUT
characteristic
0
1
2
3
4
5
6
0
1
2
3
4
5
6
I
OUT
[A]
V
OUT
[V]
CALIFORNIA MICRO DEVICES
PRELIMINARY
CM3503
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
6
SOIC-8 Package Dimensions
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