CALIFORNIA MICRO DEVICES
PRELIMINARY
CM3501
Dual USB Overcurrent Switch 750mA (V
CC
) / 100mA (V
SBY
)
Features
•
•
•
•
•
•
•
•
•
•
•
Dual outputs, each with independent over-current
protection circuitry and indicator
Supports standby mode in PCs so that a peripheral
can ramp down safely to a current <100mA
Low ON-resistance switches
Up to 750mA (V
CC
) / 100mA (V
SBY
) continuous
current on each output
Over-current limits at 750mA / 100mA respectively
10msec min fault blanking delay on OC# outputs
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
PC motherboards with USB ports (i.e., can use a
CM3501 for 2 ports or 2 CM3501s for 4 ports, etc)
The CM3501 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.
Pin Diagram
GND
V
CC
V
SBY
SEL
SOIC-8
OC1#
V
OUT1
V
OUT2
OC2#
Applications
Typical Application Circuit
Product Description
California Micro Devices’ CM3501 is a dual port
USB overcurrent power switch that selects between
two independent 5V inputs available on a PC,
depending on the state of a logic input (SEL). The
device has two pairs of power switches, and each
pair is an analog “OR” function, providing a
continuous voltage at both outputs during power
transfer beween inputs.
V
CC
is the main 5V supply, which can be disabled in
a PC, and V
SBY
is the 5V standby supply which is
powered up whenever the PC has power. When the
‘SEL’ pin is at logic high, V
CC
is the assigned input
power supply. When ‘SEL’ is at logic low, V
SBY
is
used to power the output, and no current is taken
from V
CC
. Both switches can be deselected and
switched off by not driving (floating) the ‘SEL’ input,
which places the chip in low power mode.
Both pairs of switches have over-current protection.
Depending on whether ‘SEL’ is high or low, a current
over 750mA or 100mA respectively out of either
output causes the device to enter a constant-current
mode, where the output voltage is progressively
reduced to prevent the current from increasing
further. Each output is independent of the other, so if
one of the switches is switched on but is not in
overcurrent mode then it will remain switched on.
The OC# output becomes active only if the
overcurrent condition exceeds a minimum
continuous duration of 10ms.
If the overcurrent condition is severe enough that
the part heats up to the thermal limit T
MAX
, the switch
turns off and the temperature cools down to T
MIN
.
The switch then turns on again, and the device
heats up again, and so on, until the fault is removed.
© 2002 California Micro Devices Corp. All rights reserved.
GND
5V V
CC
5V V
SBY
Select V
CC
V
CC
V
SBY
SEL
OC1#
V
OUT1
V
OUT2
V
BUS
OC2#
V
BUS
1 USB Port
1 USB Port
Simplified Electrical Schematic
V
CC
SEL
V
SBY
750mA
Over
current
100mA
Over
current
750mA
Over
current
100mA
Over
current
OC1#
V
OUT1
OC2#
V
OUT2
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
, V
SBY
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
CM3501
Unit
V
V
°C
A
W
Operating Conditions
(unless specified otherwise)
Parameter
Range
V
CC
, V
SBY
Input Voltage
4.5 to 5.5
Ambient Temperature
-40 to +85
0 to 750
I
LOAD
per port
V
CC
0 to 100
V
SBY
Unit
V
°C
mA
Symbol
UVLO
V
OUT1
,
V
OUT2
R
SW1
R
SW2
I
LIM VCC
I
LIM VSBY
t
FBD
T
MAX
T
MIN
I
R CC
I
R SBY
I
CC ON
I
SBY OFF
I
SBY ON
I
CC H Q
I
SBY L Q
I
CC L Q
I
SBY H Q
V
IH-EN
V
IL-EN
V
OL-OC
Nte –
Electrical Operating Characteristics
(over operating conditions unless specified otherwise)
Parameter
Conditions
MIN
TYP
MAX
V
CC
/V
SBY
voltage under which
2.2
2.5
T=25°C
circuit locks out - will not operate
Output Voltage
I
LOAD
= 500mA, V
CC
= 5.0V,
4.9
SEL = 5V, T = 25°C
V
CC
Switch ON-Resistance
I
LOAD
= 0 to 750mA; V
CC
= 5V
0.13
0.20
T=25°C
V
SBY
Switch ON-Resistance
I
LOAD
= 0 to 100mA; V
SBY
= 5V
1.4
T = 25°C
V
CC
over-current limit
V
CC
= 5V
750
V
SBY
over-current limit
V
SBY
= 5V
100
Time delay from overcurrent
10
20
detection to OC output indication
(fault blanking delay)
Temperature at which hot switch
150
turns off during overcurrent
Temperature at which cool
125
switch turns on, after cooling
from T
MAX
Reverse leakage from outputs
V
CC
= 0V, V
OUT
= 5V, SEL floating
1
V
SBY
= 0V, V
OUT
= 5V, SEL floating
to inputs – backdrive current
1
V
CC
operating supply current
V
CC
= 5V, SEL = high, I
LOAD
= 0mA
95
V
SBY
standby supply current
V
SBY
= 5V, SEL=high, I
LOAD
= 0mA
1
V
SBY
operating supply current
V
SBY
= 5V, SEL = low, I
LOAD
= 0mA
95
V
CC
higher, quiescent current
V
CC
= 5V, V
SBY
< V
CC
, SEL floating
40
V
SBY
lower, quiescent current
V
CC
= 5V, V
SBY
< V
CC
, SEL floating
1
V
CC
lower, quiescent current
V
CC
= 5V, V
SBY
>V
CC
, SEL floating
1
V
SBY
higher, quiescent current
V
CC
= 5V, V
SBY
>V
CC
, SEL floating
40
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
V
Ω
Ω
mA
mA
ms
°C
°C
µA
µA
µA
µA
µA
µA
µA
µA
V
V
V
The “H” version has a higher ON-resistance. All other functions are identical to the regular version.
© 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 higher current power source. Whenever the
SEL pin is above 2V it will be selected, and V
SBY
will be
deselected.
PRELIMINARY
CM3501
During the cold-start interval when the input is initially
applied, internal circuitry provides a soft turn-on for
the switches, which limits peak in-rush current.
V
SBY
is the lower current power source. Whenever the
SEL pin is below 0.8V it will be selected, and V
CC
will
be deselected. The two V
SBY
power switches can only
supply 100mA.
V
SB
V
OUT1
provides the power for a USB port. The internal
MOSFET switches are designed for low voltage drops
from the voltage input pins at their full rated currents.
SEL
is the 3-level logic input pin that is used to
control which of the power switch pairs are turned on.
Set SEL high to select V
CC
, set SEL low to select
V
SBY
, or allow SEL to float to deselect both power
switches. The external device driving the SEL pin
must able to source and sink 100µA while
maintaining the proper V
IL
/V
IH
levels.
V
OUT2
provides the power for a second USB port. The
internal MOSFET switches are designed for low voltage
drops from the voltage input pins at their full rated
currents.
Current loads of up to 750mA are allowed (from Vcc).
Current loads above 750mA 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 any switch that is in overcurrent
mode will be immediately turned off. Any switch that is
not in overcurrent mode will remain on – it will not be
affected by the over-temperature detection. Once the
part has cooled to 125’C then the switch or switches
that were in overcurrent mode will be automatically
turned on again.
OC1#, OC2#
are independent, active low open-
drain outputs, indicating an overcurrent fault condition
has been detected at V
OUT1
or V
OUT2
. There is a built-
in 10msec (min.) fault blanking period after the
overcurrent fault condition has been detected, before
these outputs become active. The OC# outputs
become deasserted only when both the overcurrent
condition stops and when the voltage drop across the
switch is less than 1V. External pull-up resistors of
10k - 100k are required if the OC# outputs are used.
GND
is the negative reference for all voltages.
Pin Functions
Pin No.
1
2
3
4
5
6
7
8
Symbol
GND
V
CC
V
SBY
SEL
OC2#
V
OUT2
V
OUT1
OC1#
Description
Negative reference for all voltages.
High current positive supply input.
Standby positive supply input. Also provides internal power.
3-level logic input. High = V
CC
, Low = V
SBY
, Floating = both off
Active low when
V
OUT2
is in overcurrent mode.
Output voltage internally switched to either V
CC
or V
SBY
input source.
Output voltage internally switched to either V
CC
or V
SBY
input source.
Active low when
V
OUT1
is in overcurrent mode.
STANDARD PART ORDERING INFORMATION
Pins
8
Package
SOIC
Ordering Part Number
CM3501-02SN
1
Part Marking
CM3501-02SN
Note 1: Parts are shipped in Tape & Reel form unless otherwise specified.
© 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
PRELIMINARY
CM3501
OC# Response to Momentary Overcurrent Fault
>750mA
<700mA
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
DieTemp.
OC# Response to
Continuous Overcurrent Fault
>750mA
I
OUT
V
OUT
drops to reduce I
OUT
Re-powers when
temperature drops
to 125’C
Total powerdown when
over-temperature limit
reached
V
OUT
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: The other port stays on (unless it is also in current limit.)
© 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
CM3501 I
CC
vs. V
CC
120
110
100
90
80
I
CC
[uA]
70
60
50
40
30
20
4
4.2
4.4
4.6
4.8
V
CC
[V]
5
5.2
5.4
5.6
PRELIMINARY
CM3501
Idd(SEL=Vdd)
Idd(SEL=floats )
CM3501 Vout-Iout characteristic (SEL=0V, Vsby active)
6
5
4
V
OUT
[V]
3
2
1
0
0
0.1
0.2
0.3
I
OUT
[A]
0.4
0.5
0.6
© 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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