MIC2536 Micrel MIC2536 Dual USB Power Distribution Switch Final Information General Description Features The MIC2536 is a cost-effective high-side power switch, with • Compliant to USB specifications two independently controlled channels, optimized for bus- • 2.7V to 5.5V operating range powered Universal Serial Bus (USB) applications. Few exter- • 150mA minimum continuous load current per channel nal components are necessary to satisfy USB requirements. • 400mΩ typical on-resistance Each switch channel of the MIC2536 will supply up to 100mA • Fast-acting short circuit protection with as required for USB bus-powered downstream devices. Fault thermal shutdown current is limited to typically 275mA by fast-acting current- • Integrated filter eliminates limit circuitry which minimizes voltage droop on the upstream false overcurrent flag assertions port during fault conditions. A flag output with transient filter • Individual open-drain fault flag pins with transient filter indicates fault conditions to the local USB controller but will • 3V/5V-compatible enable inputs ignore short flag signals resulting from inrush current during • Active-high (-1) and active-low (-2) versions hot plug-in events. • Reverse-current blocking in off mode (no “body diode”) • Soft-start circuit Soft start eliminates the momentary voltage droop on other • 100µA maximum on-state supply current ports that may occur when the switch is enabled in bus- • <1µA typical off-state supply current powered applications. Additional features include thermal • –40°C to 85°C operation shutdown to prevent catastrophic switch failure from high- current loads and 3.3V and 5V logic compatible enable Applications inputs. • USB keyboard bus-powered hubs The MIC2536 is available in active-high and active-low ver- • USB bus-powered docking stations sions in 8-lead SOP and MSOP. • Note Book PCs • PDAs • General purpose power distribution applications • PC board hot swap • Inrush current-limiting Typical Application Ferrite Beads 10k 4.50V to 5.25V V Upstream VBUS 1.5k 10k BDU+S 100mA max. VBUS IMNIC5207O-3U.T3 3.V3IVN USB COoNn/tOroFllFer ENMAIC253O6U-2TA 63µF .01µF GNDD– PUoSrtB 1 D+ 1µF OVERCURRENT FLGA IN D– GND 0.1µF OVERCURRENT FLGB GND GND 4.7µF ON/OFF ENB OUTB VBUS D+ .01µF D– USB 63µF Port 2 GND Data Data (Two Pair) to USB Controller Typical Two-Port Bus-Powered Hub UL Recognized Component Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com March 2000 1 MIC2536

MIC2536 Micrel Ordering Information Part Number Enable Temperature Range Package MIC2536-1BM Active High –40°C to +85°C 8-Lead SOP MIC2536-2BM Active Low –40°C to +85°C 8-Lead SOP MIC2536-1BMM Active High –40°C to +85°C 8-Lead MSOP MIC2536-2BMM Active Low –40°C to +85°C 8-Lead MSOP Pin Configuration MIC2536-x ENA 1 8 OUTA FLGA 2 7 IN FLGB 3 6 GND ENB 4 5 OUTB 8-Lead SOP (M) 8-Lead MSOP (MM) Pin Description Pin Number Pin Name Pin Function 1 ENA Enable A (Input): Channel A control input. Active high (–1) or active low (–2) input. 2 FLGA Flag A: (Output): Channel A open-drain fault flag output. Indicates overcurrent or thermal shutdown conditions. Overcurrent conditions must last longer than t in order to assert FLG. D 3 FLGB Flag B (Output): Channel B open-drain fault flag output. Indicates overcur- rent or thermal shutdown conditions. Overcurrent conditions must last longer than t in order to assert FLG. D 4 ENB Enable B (Input): Channel B control input. Active high (–1) or active low (–2) input. 5 OUTB Output B: Channel B switch output. 6 GND Ground 7 IN Positive Switch and Logic Supply Input 8 OUTA Output A: Channel A switch output. MIC2536 2 March 2000

MIC2536 Micrel Absolute Maximum Ratings (Note 1) Operating Ratings (Note 2) Supply Voltage (V ) .....................................................+6V Supply Voltage (V ) ...................................+2.7V to +5.5V IN IN Fault Flag Voltage (V )..............................................+6V Ambient Operating Temperature (T )........–40°C to +85°C FLG A Fault Flag Current (I )............................................25mA Thermal Resistance FLG Output Voltage (VOUT) ..................................................+6V SOP (θJA)..........................................................160°C/W Output Current (IOUT)...............................Internally Limited MSOP (θJA).......................................................206°C/W Control Input (V )...................................–0.3V to V +2V EN IN Storage Temperature (T ) .......................–65°C to +150°C S Lead Temperature (Soldering 5 sec.) .......................260°C ESD Rating, Note 3 ......................................................1kV Electrical Characteristics V = +5V; T = 25°C, bold values indicate –40°C ≤ T ≤ +85°C; unless noted IN A A Parameter Condition Min Typ Max Units Supply Current both switches off, OUTA–B = open, Note 4 0.75 5 µA both switches on, OUTA–B = open, Note 4 60 100 µA Enable Input Threshold low-to-high transition, Note 4 1.7 2.4 V high-to-low transition, Note 4 0.8 1.5 V Enable Input Current V = 0V to 5.5V 0.01 1 µA EN Enable Input Capacitance Note 5 1 pF Switch Resistance single switch, I = 100mA 400 700 mΩ OUT Output Turn-On Delay, t R = 50Ω, C = 1µF 1.5 ms ON L L Output Turn-On Rise Time, t R = 50Ω, C = 1µF 1.4 ms R L L Output Turnoff Delay, t R = 50Ω, C = 1µF 130 µs OFF L L Output Turnoff Fall Time, t R = 50Ω, C = 1µF 115 µs F L L Output Leakage Current each output (switch off) 1 10 µA Current Limit Threshold ramped load applied to enable output 500 mA Short Circuit Current Limit each output (enabled into load), V = 0V 150 275 400 mA OUT Current Limit Response V = 0V to I = I (short applied to output), Note 5 10 µs OUT OUT LIMIT Flag Response Delay, t V = 5V, apply V = 0V until FLG low 5 13 20 ms D IN OUT V = 3.3V, apply V = 0V until FLG low 13 ms IN OUT Overtemperature Shutdown T increasing, Note 5 135 °C J Threshold T decreasing, Note 5 125 °C J Error Flag Output Resistance V = 5V, I = 10mA 10 20 Ω IN L V = 3.3V, I = 10mA 15 30 Ω IN L Error Flag Off Current V = 5V 0.01 1 µA FLAG 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, 1.5kΩ in series with 100pF. Note 4. Off is ≤ 0.8V and on is ≥ 2.4V for the MIC2536-1. Off is ≥ 2.4V and on is ≤ 0.8V for the MIC2536-2. The enable input has approximately 200mV of hysteresis. Note 5. Guaranteed by design. Not production tested. March 2000 3 MIC2536

MIC2536 Micrel Test Circuit V OUT Device Under OUT Test R C L L Functional Characteristics Test Circuit Timing Diagrams tr tf 90% 90% VOUT 10% 10% Output Rise and Fall Times 50% VEN tOFF tON 90% VOUT 10% Active-High Switch Delay Times (MIC2536-1) 50% VEN tOFF tON 90% VOUT 10% Active-Low Switch Delay Times (MIC2536-2) MIC2536 4 March 2000

MIC2536 Micrel Supply On Current Output On-Resistance Output Rise Time vs. Input Voltage vs. Input Voltage vs. Input Voltage 100 700 4 µT (A) 80 ΩM)60085°C 385°C RREN 60 NCE (45000025°C ms) 25°C CU –40°C TA –40°C E (2–40°C UPPLY ON 24002855°°CC ON RESIS123000000 TIM1 S 0 0 0 2 3 4 5 6 2 4 6 2 3 4 5 6 INPUT VOLTAGE (V) INPUT VOLTAGE (V) INPUT VOLTAGE (V) Output Fall Time Control Voltage vs. Control Voltage vs. vs. Input Voltage Input Voltage VEN Falling Input Voltage VEN Rising 120 2.0 2.5 85°C V) 118 –40°C E (2.0 1.5 G ms)116 µs) 2855°°CC OLTA1.525°C TIME (111124 25°C–40°C TIME (1.0 HOLD V1.0–40°C 110 0.5 RES0.5 H 85°C T 108 0 0 2 3 4 5 6 2 3 4 5 6 2 3 4 5 6 INPUT VOLTAGE (V) INPUT VOLTAGE (V) INPUT VOLTAGE (V) Flag Delay vs. Supply Off Current Current Limit Threshold Input Voltage vs. Input Voltage vs. Input Voltage 20 1 300 85°C 85°C µA)0.8 290 E (ms)110525°C URRENT (0.6–40°C ENT (mA)227800–2450°C°C TIM –40°C LY C0.485°C URR260 5 PP 25°C C SU0.2 250 0 0 240 2 3 4 5 6 2 3 4 5 6 2 3 4 5 6 INPUT VOLTAGE (V) INPUT VOLTAGE (V) INPUT VOLTAGE (V) Short Circuit Current Limit vs. Input Voltage 280 85°C 270 A)26025°C m250 T ( EN240–40°C R R230 U C220 210 200 2 3 4 5 6 INPUT VOLTAGE (V) March 2000 5 MIC2536

MIC2536 Micrel Functional Characteristics Turn-On / Turnoff Turn-On (MIC2536-1) (MIC2536-1) v) v) Ndi Ndi VE0V/ VE0V/ 1 1 ( ( VFLG5V/div) VFLG5V/div) ( ( UTdiv) UTdiv) VO(5V/ VO(5V/ VCIN == 54V.7µF CRL == 3150ΩµF v) IN L di IOUT(100mA/ VCIINN == 54V.7µF RCLL == 51µ0ΩF IOUT00mA/div) 1 ( Time (1ms/div) Time (1ms/div) Turnoff Turn-On (MIC2536-1) (MIC2536-1) v) v) Ndi Ndi VE0V/ VE0V/ 1 1 ( ( VFLG(5V/div) VCIN == 54V.7µF RCL == 3150ΩµF VFLG(5V/div) VCIINN == 54V.7µF RCLL == 3457ΩµF || 10µF UTdiv) IN L UTdiv) VO5V/ VO5V/ (output current limited) ( ( v) di IOUT0mA/div) IOUT(100mA/ 0 1 ( Time (1ms/div) Time (1ms/div) Turnoff Enabled Into Short Circuit (MIC2536-1) (MIC2536-1) v) v) Ndi Ndi VE0V/ VE0V/ 1 1 ( ( VFLG(5V/div) VCIINN == 54V.7µF RCLL == 3457ΩµF || 10µF VFLG(5V/div) tD UTdiv) UTdiv) VO5V/ VO5V/ ( ( v) di IOUT0mA/div) IOUT(200mA/ VCIINN == 54V.7µF OCLU =T 0= GND 0 1 ( Time (5µs/div) Time (10ms/div) MMIaCrc2h5 326000 56 MaMrcIhC 22503060

MIC2536 Micrel Ramped Into Short Circuit Inrush Current (MIC2536-1) (MIC2536-1) v) v) Ndi Ndi VE0V/ V = 5V VE0V/ (1 CIN = 4.7µF (1 IN VFLG5V/div) RL = 0Ω VFLG5V/div) C = 110µF ( ( CL = 210µF L VOUT(5V/div) CCLL == 431100µµFF VCIN == 54V.7µF Thermal Shutdown v) RIN = 35Ω di L IOUT00mA/div) IOUT(100mA/ CL = 10 2 ( Time (100ms/div) Time (5µs/div) Current-Loop Response (MIC2536-1) output = open UTdiv) output = ground VO5V/ ( V = 5V C = 47µF EN L OUTA/div) VCIINN == 54V700µF I1 ( Time (5µs/div) March 2000 7 MIC2536

MIC2536 Micrel Block Diagram FLGA DELAY OUTA ENA CHARGE GATE PUMP CONTROL CURRENT LIMIT THERMAL 1.2V OSC. IN SHUTDOWN REFERENCE CHARGE CURRENT PUMP LIMIT GATE CONTROL ENB OUTB DELAY FLGB MIC2536 GND MIC2536 8 March 2000

MIC2536 Micrel Functional Description Equations that can be used to calculate power dissipation and die temperature are found below: The MIC2536-1 and MIC2536-2 are dual high-side switches Calculation of power dissipated by each channel can be with active-high and active-low enable inputs, respectively. accomplished by the following equation: Fault conditions turn off or inhibit turn-on of one or more of the output transistors, depending upon the type of fault, and P = R × (I )2 D DS(on) OUT activate the open-drain error flag transistors making them Total power dissipation of the device will be the summation sink current to ground. of P for both channels. To relate this to junction D Input and Output temperature, the following equation can be used: IN (input) is the power supply connection to the logic circuitry T = P × θ + T j D JA A and the drain of each output MOSFET. OUTx (output) is the where: source of each respective MOSFET. In a typical circuit, T = junction temperature current flows through the switch from IN to OUTx toward the j load. If V is greater than V , current will flow from OUT T = ambient temperature OUT IN A to IN during an on-condition since the MOSFET is bidirec- θ = is the thermal resistance of the package JA tional when enabled. Current Sensing and Limiting The output MOSFET and driver circuitry are also designed to The current-limit threshold is preset internally. The preset allow the MOSFET source to be externally forced to a higher level prevents damage to the output MOSFET and external voltage than the drain (V > V ) when the output is OUTx IN load but allows a minimum current of 150mA through the disabled. In this situation, the MIC2536 prevents reverse output MOSFET of each channel. current flow. The current-limit circuit senses a portion of the output FET Thermal Shutdown switch current. The current sense resistor shown in the block Each output MOSFET has its own thermal sensor. If either or diagram is virtual and has no voltage drop. The reaction to an both channels reach 135°C, affected channel(s) will be shut overcurrent condition varies with the following three sce- down and flag(s) asserted. 10°C of hysteresis prevents the narios: switches from turning on until the die temperature drops to Switch Enabled into Short Circuit 125°C. Overtemperature detection functions only when at If a switch is enabled into a heavy load or short circuit, the least one switch is enabled. switch immediately goes into a constant-current mode, re- The MIC2536 will automatically reset its output when the die ducing the output voltage. The FLG is asserted indicating an temperature cools to approximately 125°C. The MIC2536 overcurrent condition. output and FLG signal will continue to cycle on and off until the Short Circuit Applied to Output device is disabled or the fault is removed. When a heavy load or short circuit is applied to an enabled Depending on PCB layout, package, ambient temperature, switch, a large transient current may flow until the current- etc., it may take several hundred milliseconds from the limit circuitry responds. Once this occurs, the device limits occurrence of the fault to the output MOSFET being shut off. current to less than the maximum short-circuit current-limit Delay to reach thermal shutdown will be shortest with a dead specification. short on the output. Current-Limit Response Ramped Load Current-Limit Induced Thermal Shutdown The MIC2536 current-limit profile exhibits a small foldback Internal circuitry increases the output MOSFET on-resis- effect of approximately 100mA. Once this current-limit thresh- tance until the series combination of the MOSFET on-resis- old is exceeded the device enters constant-current mode. tance and the load impedance limits output current to ap- This constant current is specified as the short-circuit current- proximately 275mA. The resulting increase in power dissipa- limit in the “Electrical Characteristics” table. It is important to tion may cause the shorted channel to go into thermal note that the MIC2536 will deliver load current up to the shutdown. In addition, even though individual channels are current-limit threshold before entering current-limited opera- thermally isolated, it is possible they may shut down when an tion. adjacent channel is shorted. When this is undesirable, ther- mal shutdown can be avoided by externally responding to the Fault Flag fault and disabling the current-limited channel before the FLGx is an open-drain N-channel MOSFET output. Fault shutdown temperature is reached. The delay between the flags are active (low) for current-limit or thermal shutdown. In flag indication of a current-limit fault and thermal shutdown the case where an overcurrent condition occurs, FLG will be will vary with ambient temperature, board layout, and load asserted only after the flag response delay time, t has D impedance, but is typically several seconds. The USB con- elapsed. This ensures that FLG is asserted only upon valid troller must therefore recognize a fault and disable the overcurrent conditions and that erroneous error reporting is appropriate channel within this time. eliminated. False overcurrent conditions can occur during Power Dissipation hot-plug events when a highly capacitive load is connected and causes a high transient inrush current that exceeds the Power dissipation depends on several factors such as the current-limit threshold. The flag response delay time is typi- load, PCB layout, ambient temperature and package type. cally 12ms. March 2000 9 MIC2536

MIC2536 Micrel Applications Information Enable Input EN must be driven logic high or logic low for a clearly defined Supply Filtering input. Floating the input may cause unpredictable operation. A 0.1µF to 1µF bypass capacitor from IN to GND, located at EN should not be allowed to go negative with respect to GND. the device, is strongly recommended to control supply tran- Printed Circuit Board Hot-Plug sients. Without a bypass capacitor, an output short may cause sufficient ringing on the input (from supply lead induc- The MIC2536 is an ideal inrush current-limiter for hot-plug tance) to damage internal control circuitry. applications. Due to the integrated charge pump, the MIC2536 presents a high impedance when off and slowly becomes a Input or output transients must not exceed the absolute low impedance as it turns on. This “soft-start” feature effec- maximum supply voltage (V = 6V) even for a short IN(max) tively isolates power supplies from highly capacitive loads by duration. reducing inrush current. Figure 2 shows how the MIC2536 V 2.7V toIN 5.5V may be used in a hot-plug card application. Overcurrent Transients MIC2536 ENA OUTA The MIC2536 incorporates an internal circuit designed to 0.1µF to 1µF prevent FLG from being asserted due to transient inrush FLGA IN current. Overcurrent events <12ms (typ.) will not assert FLG. FLGB GND In case of large capacitive loads (i.e., >430µF), the length of ENB OUTB the transient due to inrush current may exceed the delay provided by the integrated filter. Since this inrush current exceeds the current-limit delay specification, FLG will be Figure 1. Supply Bypassing asserted during this time. To prevent the logic controller from responding to FLG being asserted, an external RC filter, as shown in Figure 3, can be used to filter out transient FLG assertion. The value of the RC time constant should be selected to match the length of the transient, minus flag t . D MIC2536-2 V 1 EN OUTA 8 CC 0.1 2 FLGA IN 7 Backend to "Hot" µF Receptacle 3 FLGB GND 6 Function 4 ENB OUTB 5 GND CBULK Adaptor Card Figure 2. Hot-Plug Card Application V+ Logic Controller 10k MIC2536 1 EN OUTA 8 R OVERCURRENT 2 FLGA IN 7 C 3 FLGB GND 6 4 ENB OUTB 5 Figure 3. Transient Filter MIC2536 10 March 2000

MIC2536 Micrel Universal Serial Bus (USB) Power Distribution may not consume more than 500µA. In a nonconfigured state Applications all downstream devices will be switched off. In most cases, a The MIC2536 is ideally suited for USB (Universal Serial Bus) nonconfigured hub is not a practical state for the system. power distribution applications. For Bus-Powered hubs, USB Therefore, the 2.5mA specification is the applicable target requires that each downstream port be switched on or off specification for the suspend state. In a bus-powered hub under control by the host. Up to four downstream ports each with less than 4 ports, the hub may use the additional current capable of supplying 100mA at 4.4V minimum are allowed. In for internal functions. additon, to reduce voltage droop on the upstream bus the hub The 500µA worst case suspend current must be further must consume only 100mA max at start-up until it enumer- divided among the data port termination resistors and internal ates with the host prior to requesting more power. The same functions. The termination resistors will consume requirements apply for bus-powered peripherals that have no 3.6V ÷ (16.5KΩ – 5%) = 230µA. This leaves only 270µA for downstream ports. Figure 4 shows a two-port bus-powered internal functions. Assuming 100µA as the maximum USB hub. controller suspend current, 170µA remains for the rest of the Bus-Powered Hub Port Switching system. The MIC2536 will consume 100µA maximum, leav- ing a margin of 70µA. The USB Specification requires that bus-powered hubs imple- ment port switching on either a ganged or individual basis. USB Voltage Regulation The specific implementation must be reported via the Hub USB specifications require a minimum downstream voltage Descriptor Status Register. Individual port switching has supply of 4.40V from a bus-powered hub port (See Applica- advantages in that a fault on one port will not prevent the other tion Note 17 for details). The USB specification allows for a ports from operating correctly. In addition, a soft-start circuit 100mV drop across the hub, leaving 250mV for PCB, up- must be included in order to reduce inrush currents when the stream cable, and connector resistance. Therefore, the on- switch is enabled. To meet this requirement, the MIC2536 resistance of the switch for each port, not including PCB has been designed to slowly ramp its output. resistance, must be <100mV ÷ 100mA = 1Ω. The MIC2536 Suspend Current has a maximum on-resistance of 700mΩ, which easily satis- fies this requirement. Universal Serial Bus Specification places a maximum sus- pend current requirement of 500µA on devices. For hubs, Overcurrent Indication Universal Serial Bus Specification Revision 1.1 clarifies this The USB Specification does not require bus-powered hubs to issue. Revision 1.1, section 7.2.3, stipulates that the maxi- report overcurrent conditions to the host, since the hub is mum suspend current for a configured hub is 2.5mA. This already current-limited at the upstream port. However, if it is number is derived by allocating 500µA for up to four down- desired to report overcurrent, the Hub Descriptor Status stream ports plus 500µA for the hub’s internal functions. A Register must be programmed to indicate this. The MIC2536 nonconfigured hub is considered a low-power device and provides a flag output for this application. Ferrite Beads 10k 4.50V to 5.25V V Upstream VBUS 1.5k 10k BDU+S 100mA max. VBUS IMNIC5207O-3U.T3 3.V3IVN USB COoNn/tOroFllFer ENMAIC253O6U-2TA 63µF .01µF GNDD– PUoSrtB 1 D+ 1µF OVERCURRENT FLGA IN D– GND 0.1µF OVERCURRENT FLGB GND GND 4.7µF ON/OFF ENB OUTB VBUS D+ .01µF D– USB 63µF Port 2 GND Data Data (Two Pair) to USB Controller Figure 4. USB Two-Port Bus-Powered Hub March 2000 11 MIC2536

MIC2536 Micrel Package Information 0.026 (0.65) MAX) PIN 1 0.157 (3.99) DIMENSIONS: 0.150 (3.81) INCHES (MM) 0.020 (0.51) 0.013 (0.33) 0.050 (1.27) TYP 0.0098 (0.249) 45° 0.010 (0.25) 0.0040 (0.102) 0.007 (0.18) 0.197 (5.0) 0°–8° 0.050 (1.27) 0.064 (1.63) 0.189 (4.8) SEATING 0.016 (0.40) 0.045 (1.14) PLANE 0.244 (6.20) 0.228 (5.79) 8-Lead SOP (M) 0.122 (3.10) 0.199 (5.05) DIMENSIONS: 0.112 (2.84) 0.187 (4.74) INCH (MM) 0.120 (3.05) 0.116 (2.95) 0.036 (0.90) 0.043 (1.09) 0.032 (0.81) 0.038 (0.97) 0.007 (0.18) 0.012 (0.30) R 0.005 (0.13) 0.012 (0.03) 0.008 (0.20) 5° MAX 0.012 (0.03) R 0.004 (0.10) 0° MIN 0.0256 (0.65) TYP 0.039 (0.99) 0.035 (0.89) 0.021 (0.53) 8-Lead MSOP (MM) MIC2536 12 March 2000

MIC2536 Micrel MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc. © 2000 Micrel Incorporated March 2000 13 MIC2536

Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: M icrel: MIC2536-1YMM TR MIC2536-2YM TR M icrochip: MIC2536-2YMM MIC2536-1YMM MIC2536-1YM MIC2536-2YM MIC2536-1YMM-TR MIC2536-2YM-TR MIC2536- 1YM-TR MIC2536-2YMM-TR