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| CM2026 DUAL USB POWER CONTROL SWITCH GENERAL DESCRIPTION The CM2026 is a dual integrated high-side power switch with independent enable and flag functions, optimized for self-powered and bus-powered Universal Serial Bus (USB) applications. Few external components are necessary to satisfy USB requirements. The CM2026 satisfies the following USB requirements: each switch channel supplies up to 500mA as required by USB downstream devices; the switch's low on-resistance meets USB voltage drop requirements; fault current is limited to typically 750mA, well below the UL 25VA safety requirements; and a flag output is available to indicate fault conditions to the local USB controller. Soft start eliminates the momentary voltage drop on the upstream port that may occur when the switch is enabled in bus-powered applications. Additional features include thermal shutdown to prevent catastrophic switch failure from high-current loads, undervoltage lockout (UVLO) to ensure that the device remains off unless there is a valid input voltage present, and 3.3V and 5V logic compatible enable inputs. The CM2026 is available in active-high version in 8-pin DIP and SOIC packages. FEATURES Compliant to USB specifications UL Recognized Component 2 independent switches 3V to 5.5V input 500mA minimum continuous load current per port 140m maximum on-resistance 1.25A maximum short circuit current limit Individual open-drain fault flag pins 110uA typical on-state supply current 1uA typical off-state supply current Output can be forced higher than input (off-state) Thermal shutdown 2.4V typical undervoltage lockout (UVLO) 1ms turn-on (soft-start) and fast turnoff Active-high enable version 8-pin SOIC and DIP packages APPLICATIONS USB host and self-powered hubs USB bus-powered hubs Hot plug-in power supplies Battery-charger circuit PIN CONFIGURATION PDIP-08/SOP-08 (Top View) 1 2 3 4 EN1 FLG1 FLG2 EN2 OUT1 IN GND OUT2 8 7 6 5 2002/05/29 Rev. 2 Champion Microelectronic Corporation Page 1 CM2026 DUAL USB POWER CONTROL SWITCH PIN DESCRIPTION Pin No. 1,4 EN(1/2) Symbol 1. 2. 2,3 6 7 8,5 FLG(1/2) GND IN OUT(1/2) Description VIN = 3.3V, Enable (Input): Logic-compatible enable input. High input > 2.1V typical. Low input < 1.9V typical. Do not float. VIN = 5V, Enable (Input): Logic-compatible enable input. High input > 3.5V typical. Low input < 3.3V typical. Do not float. Fault Flag (Output): open-drain output. Indicates overcurrent, UVLO, and thermal shutdown. Ground: Supply return. Supply Input: Output MOSFET drain. Also supplies IC's internal circuitry. Connect to positive supply. Switch Output: Output MOSFET source. Typically connect to switched side of load. BLOCK DIAGRAM 5V R3 R2 47K R1 47K U1 CM2026 VIN ON/OFF 1 2 4.5~5V 3 4 3 2 1 4 FLG2 EN2 GND OUT2 6 5 J2 1 2 3 4 USBPORT1 J3 1 2 3 4 USBPORT1 EN1 FLG1 OUT1 IN 8 7 C1 0.1U CM1085 3.3V 10K R4 10K ON/OFF usb mcu 3.3 USB CPU ORDERING INFORMATION Part Number CM2026IS CM2026IP Enable Active High Active High Temperature Range -40 to +85 -40 to +85 Package 8-Pin SOIC (S08) 8-Pin PDIP (P08) 2002/05/29 Rev. 2 Champion Microelectronic Corporation Page 2 CM2026 DUAL USB POWER CONTROL SWITCH ABSOLUTE MAXIMUM RATINGS (Note 1) OPERATING RATINGS (Note 2) Supply Voltage (VIN) ........................................ +6V Fault Flag Voltage (VFLG) ................................. +6V Fault Flag Current (IFLG) .................................. 50mA Output Voltage (VOUT) ..................................... +6V Output Current (IOUT) ...................... Internally Limited Control Input (VEN) ................................. -0.3V to 12V Storage Temperature (TS) ................... -65 to +150 Lead Temperature (Soldering 5 sec.) .................. 260 ESD Rating, Note 3 ........................................... 2kV Supply Voltage (VIN) .............................. +3V to +5.5V Ambient Operating Temperature (TA) ..... -40 to +85 Thermal Resistance SOIC (JA) ..........................................120/W DIP (JA) .............................................130/W ELECTRICAL CHARACTERISTICS VIN = +5V; TA = +25; unless noted Parameter Supply Current Test Conditions Note 4, switch off, OUT = open Note 4, all switches on, OUT = open Low-to-high transition Enable Input Threshold High-to-low transition, Note4 Enable input Current Enable Input Capacitance Switch Resistance Output Turn-On Delay Output Turn-On Rise Time Output Turn-Off Delay Output Turn-Off Fall Time Output Leakage Current Continuous Load Current Short-Circuit Current Limit Current-Limit Threshold Overtemperature Shutdown Threshold Error Flag Output Resistance Error Flag Off Current UVLO Threshold VIN = 5V, IOUT = 500mA, each switch VIN = 3.3V, IOUT = 500mA, each switch RL = 10 each output RL = 10 each output RL = 10 each output RL = 10 each output Each output (output disabled0 Each output Each output (enable into load), VOUT = 4.0V Ramped load applied to enabled output, VOUT4.0V, Note 5 TJ increasing TJ decreasing VIN = 5V, IL = 10mA VIN = 3.3V, IL = 10mA VFLG = 5V VIN = increasing VIN = decreasing 0.5 0.5 0.75 1.6 135 125 10 15 0.01 2.5 2.3 25 40 1 1.25 2.2 VEN = 0V to 5.5V VIN = 3.3V VIN = 5V VIN = 3.3V VIN = 5V -1 CM2026 Min. Typ. 0.75 110 2.1 3.5 1.9 3.3 0.01 1 100 140 0.5 1 1 1 20 20 10 140 180 1 Max. 5 160 Unit A A V V A PF m m ms ms s s A A A A A V V Note 1. Exceeding the absolute maximum rating may damage the device. Note 2. The device is not guaranteed to function outside its operating rating. Note 3. Devices are ESD sensitive. Handling precautions recommended. Human body model, 1.5k in series with 100pF. Note 4. Off is 0.8V and on is 2.4V. The enable input has approximately 200mV of hysteresis. See control threshold charts. Note 5. See "Functional Characteristics: Current-Limit Response" photo. 2002/05/29 Rev. 2 Champion Microelectronic Corporation Page 3 CM2026 DUAL USB POWER CONTROL SWITCH FUNCTIONAL DESCRIPTION The CM2026 is dual high-side switch with active-high enable inputs, respectively. Fault conditions turn off or inhibit turn-on of one or more of the output transistors, depending upon the type of fault, and activate the open-drain error flag transistors making them sink current to ground. Input and Output IN (input) is the power supply connection to the logic circuitry and the drain of the output MOSFET. OUTx (output) is the source of its respective MOSFET. In a typical circuit, current flows through the switch from IN to OUT toward the load. If VOUT is greater than VIN when a switch is enabled, current will flow from OUT to IN since the MOSFET is bi-directional when on. The output MOSFET and driver circuitry are also designed to allow the MOSFET source to be externally forced to a higher voltage than drain (VOUT > VIN) when the output is off. In this situation, the CM2026 avoids undesirable current flow from OUT to IN. If VIN < 2.5V, UVLO disables both switches. Thermal Shutdown Thermal shutdown shuts off the affected output MOSFETs and signals all fault flags if the die temperature exceeds 135 . 10 of hysteresis prevents the switch from turning on until the die temperature drops to 125. Overtemperature detection functions only when at least one switch is enabled. Current Limit Induced Thermal Shutdown Internal circuitry increases the output MOSFET on-resistance until the series combination of the MOSFET on-resistance and the load impedance limit current to typically 850mA. The increase in power dissipation, in most cases, will cause the CM2026 to go into thermal shutdown, disabling affected channels. When this is undesirable, thermal shutdown can be avoided by externally responding to the fault and disabling the current limited channel before the shutdown temperature is reached. The delay between the flag indication of a current limit fault and thermal shutdown will vary with ambient temperature, board layout, and load impedance, but is typically several hundred milliseconds, The USB controller must therefore recognize a fault and disable the appropriate channel with this time. If the fault is not removed or the switch is not disabled with the time, then the device will enter into a thermal oscillation of about 2Hz. This does not cause any damage to the device. Refer to "Functional Characteristics: Thermal Shutdown Response." Undervoltage Lockout UVLO (undervoltage lockout) prevents the output MOSFET from turning on until VIN exceeds approximately 2.5V. In the undervoltage state, the FLAG will be low. After the switch turns on, if the voltage drops below approximately 2.3V, UVLO shuts off the output MOSFET and signals fault flag. Undervoltage detection functions only when at least one switch is enabled. Current Sensing and Limiting The current-limit threshold is preset internally. The preset level prevents damage to the output MOSFET and external load but allows a minimum current of 0.5A through the output MOSFET of each channel. The current-limit circuit senses a portion of the output FET switch current. The current sense resistor shown in the block diagram is virtual and has no voltage drop. The reaction to an overcurrent condition varies with three scenarios: Switch Enabled into Short Circuit If a switch is powered on or enabled into a heavy load or short circuit, the switch immediately goes into a constant current mode, reducing the output voltage. The fault flag goes low until the load is reduced. Short Circuit Applied to Output When a heavy load is applied, a large transient current may flow until the current limit circuitry will respond. Once this occurs, the device limits current to less than the short-circuit current limit specification. Current-Limit Response The CM2026 current-limit profile exhibits a small foldback effect of approximately 500mA. Once this current-limit threshold is exceeded the device enters constant current mode. Fault Flag FLG is an N-channel, open-drain MOSFET output. The fault flag is active (low) for one or more of the following conditions: undervoltage (while 2V Rev. 2 Champion Microelectronic Corporation Page 4 CM2026 DUAL USB POWER CONTROL SWITCH APPLICATIONS INFORMATION Supply Filtering A 0.1F to 0.1F bypass capacitor from IN to GND, located at the device, is strongly recommended to control supply transients. Without a bypass capacitor, an output short may cause sufficient ringing on the input (from supply lead inductance) to damage internal control circuitry. Input or output transients must not exceed the absolute maximum supply voltage (VIN max = 6V) even for a short duration. Transient Overcurrent Filter When the CM2026 is enabled, large values of capacitance at the output of the device will cause inrush current to exceed the short circuit current-limit threshold of the device and assert the flag. The duration of this time will depend on the size of the output capacitance. Refer to the "Functional Characteristics" turn-on and turnoff behaviors for details. During the capacitance charging time, the device enters into constant-current mode. As the capacitance is charged, the current decreases below the short circuit current-limit threshold old, and the flag will then be deserted. In USB applications, it is required that output bulk capacitance is utilized to support hot-plug events. When the CM2026 is enabled, the flag may go active for about 1ms due to inrush current exceeding the current-limit setpoint. Additionally, during hot-plug events, inrush currents may also cause the flag to go active for 30uS. Since these conditions are not valid overcurrent faults, the USB controller must ignore the flag during these events. To prevent this erroneous overcurrent reporting, a 1ms RC filter as shown in Figure 4 may be programmed into the USB logic controller, eliminating the need for the RC filter. Enable Input EN must be driven logic high or logic low for a clearly defined input. Floating the input may cause unpredictable operation. EN should not be allowed to go negative with respect to GND. Soft Start The CM2026 presents a high impedance when off, and slowly becomes a low impedance as it turns on. This reduces inrush current and related voltage drop that results from charging a capacitive load, satisfying the USB voltage droop requirements for bus-powered applications as shown in Figure 2. The soft start circuit shown in Figure 3 can be utilized to meet USB transient regulation specifications with large load capacitances (CBULK > 10uF). The CM2026 will provide inrush current limiting for these applications. 2002/05/29 Rev. 2 Champion Microelectronic Corporation Page 5 CM2026 DUAL USB POWER CONTROL SWITCH PACKAGE DIMENSION 8-PIN PDIP (P08) PIN 1 ID 8-PIN SOP (S08) PIN 1 ID 2002/05/29 Rev. 2 Champion Microelectronic Corporation Page 6 CM2026 DUAL USB POWER CONTROL SWITCH IMPORTANT NOTICE Champion Microelectronic Corporation (CMC) reserves the right to make changes to its products or to discontinue any integrated circuit product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe property or environmental damage. CMC integrated circuit products are not designed, intended, authorized, or warranted to be suitable for use in life-support applications, devices or systems or other critical applications. Use of CMC products in such applications is understood to be fully at the risk of the customer. In order to minimize risks associated with the customer's applications, the customer should provide adequate design and operating safeguards. HsinChu Headquarter 5F, No. 11, Park Avenue II, Science-Based Industrial Park, HsinChu City, Taiwan T E L : +886-3-567 9979 F A X : +886-3-567 9909 Sales & Marketing 11F, No. 306-3, SEC. 1, Ta Tung Road, Hsichih, Taipei Hsien 221, Taiwan T E L : +886-2-8692 1591 F A X : +886-2-8692 1596 2002/05/29 Rev. 2 Champion Microelectronic Corporation Page 7 |
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