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CALIFORNIA MICRO DEVICES
PRELIMINARY CM3502
Dual USB Overcurrent 750mA Switches with Independent Controls
Features
* * * * * * * * * * * Dual switches, each with independent over-current protection and an indicator, for 2 USB ports Two active low Enable controls, one per channel Low ON-resistance switches Up to 750mA continuous current on each channel Over-current limits at 750mA min 10msec min fault blanking delay on OC# outputs prevents false overcurrent alarms Prevents backdrive current when host powered off Low operating current (95A typ.) Low quiescent current when disabled (<1A max) Small 8-Lead SOIC package The CM3502 also prevents backdrive current flowing into the host from the connected peripheral. This can occur when VCC 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 VBUS, potentially causing backdrive current into the host and overloading the peripheral power supply.
Pin Diagram
GND VCC EN1#
OC1# VOUT1 VOUT2 OC2# SOIC-8
Applications
PC's, notebooks, STBs with USB ports (i.e., can use a CM3502 for 2 ports or 2 CM3502s for 4 ports, etc) EN2#
Product Description
California Micro Devices CM3502 is a dual channel USB overcurrent power switch that provides 5V power to two independent USB ports. The device has two low on-resistance power switches that provide the VBUS voltage at each USB output port with minimal voltage drop. When either of the EN# inputs is at logic low, the corresponding power switch is ON and VCC is connected to the corresponding output through the switch. When either of the EN# inputs is at logic high, the corresponding power switch is OFF, and no power is available at the output. Both of the power switches have full over-current protection. Whenever the current limit out of either switch is exceeded, the device enters a constantcurrent mode, and the output voltage is progressively reduced to prevent the current from increasing further. Each switch is independent of the other, so if a switch is on but is not in overcurrent mode then it will remain switched on. The OC# output becomes active low only if the overcurrent condition exceeds a minimum continuous duration of 10ms. This fault blanking delay prevents false alarms being reported to the host USB controller. If the overcurrent condition is severe enough that the part heats up to the thermal limit TMAX, then that switch will be turned off and the device temperature cools down. At TMIN the switch then turns on again, and the device heats up again to TMAX, and so on, until the fault is removed.
Typical Application Circuit
GND VCC VCC EN1# EN2#
OC1# VOUT1 VOUT2
OC2#
VBUS
1 USB Port 1 USB Port
VBUS
Simplified Electrical Schematic
EN1# Over current protect EN2# VCC Over current protect
VOUT2 OC2# OC1# VOUT1
(c) 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
PRELIMINARY CM3502
Absolute Maximum Ratings Parameter Rating ESD Protection (All pins, HBM) 2000 VCC 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
Unit V V C A W
Operating Conditions (unless specified otherwise) Parameter Range VCC Input Voltage 4.5 to 5.5 Ambient Temperature -40 to +85 ILOAD per portB 0 to 750 00
Unit V C mA
Symbol UVLO RSW VOUT1, VOUT2 ILIM tFBD
TMAX TMIN
IR CC ICC ICCQ VIH-EN VIL-EN VOL-OC
Electrical Operating Characteristics (over operating conditions unless specified otherwise) Parameter Conditions MIN TYP MAX VCC voltage under which circuit 2.2 2.5 T=25C locks out - will not operate Switch ON-Resistance ILOAD = 0 to 750mA; VCC = 5V, 0.13 0.2 T= 25C Output Voltage ILOAD = 500mA, VCC = 5.0V, 4.9 EN# = 0V, T = 25C Over-current limit 750 VCC = 5V, T = 25C 10 20 Time delay from overcurrent detection to OC output indication (fault blanking delay) Temperature at which hot switch 150 turns off during overcurrent 125 Temperature at which cool switch turns on, after cooling from TMAX Reverse leakage from outputs VCC = 0V, VOUT1,2 = 5V, 1 to input EN# =high, T=25C Operating supply current EN# = low 95 Quiescent current EN# = high 1 EN# input Logic-1 threshold VCC = 5V 2 EN# input Logic-0 threshold VCC = 5V 0.8 OC# output Logic-0 threshold IOC = 1mA to VCC 0.4
UNIT V V mA ms C C A A A V V V
(c) 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 VCC is the power source. VOUT1 provides the power for the first load. The internal
MOSFET switches are designed for very low voltage drops from the voltage input pins at their full rated currents.
PRELIMINARY CM3502
EN1#, EN2# are the active low logic input pins that
are used to control the power switches. Both switches are independent. Set EN1# and EN2# high (to >2V) to deselect VOUT1 and VOUT2 respectively, and set EN1# and EN2# low (to <0.8V) to select VOUT1 and VOUT2 respectively.
VOUT2 provides the power for the second load. The internal
MOSFET switches are designed for very low voltage drops from the voltage input pins at their full rated currents. Current loads of up to 750mA are allowed. Current loads above 750mA may cause the constant-current limiting circuit to operate, thereby 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. 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. Pin Functions Description Negative reference for all voltages. Power supply input. Active low Enable pin for VOUT1. Active low Enable pin for VOUT2.
OC1#, OC2# are independent active low opendrain outputs, indicating an overcurrent fault condition has been detected at VOUT1 or VOUT2. There is a builtin 10msec (min.) fault blanking delay after the overcurrent fault condition has been detected, before these outputs become active. The OC# outputs become inactive 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 No. 1 2 3 4 5 6 7 8
Symbol GND VCC EN1# EN2# OC2# VOUT2 VOUT1 OC1#
Active low when VOUT2 is in overcurrent mode. Output voltage #2. Output voltage #1. Active low when VOUT1 is in overcurrent mode.
STANDARD PART ORDERING INFORMATION Pins 8 Package SOIC Ordering Part Number CM3502-02SN
1
Part Marking CM3502-02SN
Note 1: Parts are shipped in Tape & Reel form unless otherwise specified.
(c) 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 CM3502
Response to Momentary Overcurrent Fault
>750mA
<700mA
IOUT
VOUT drops to reduce I OUT
VOUT
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
>750mA IOUT
VOUT drops to reduce IOUT VOUT 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 TMAX = 150'C 150'C
Temp.
TMIN = 125'C Note: The other port stays on (unless it is also in current limit.)
(c) 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
CM3502 V OUT -IOUT characteristic (EN#=0V)
6
PRELIMINARY CM3502
5
4 V OUT [V]
3
2
1
0 0 0.5 1 1.5 IOUT [A] 2 2.5 3 3.5
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
CM3502 Quiescent supply current vs . supply voltage 120 100
80 ICC [uA] 60 40
20 0 4 4.2 4.4 4.6 4.8 V CC [V] 5 5.2 5.4 5.6
(c) 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
CALIFORNIA MICRO DEVICES
PRELIMINARY CM3502
SOIC-8 Package Dimensions
(c) 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

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