SI8511-C-IM

Si85xx Si85 XX U N ID I R E C TI ON A L A C C URRENT S ENSORS Features        Single-chip ac current sensor Low loss: 175 V 1012  1.4 pF 4.0 pF Minimum Internal Gap (Internal Clearance) Tracking Resistance (Comparative Tracking Index) CTI Resistance (Input-Output)1 RIO 1 Capacitance (Input-Output) DIN IEC 60112/VDE 0303 Part 1 CIO Input Capacitance2 f = 1 MHz CI Notes: 1. To determine resistance and capacitance, the Si85xx is converted into a 2-terminal device. Pins 1–10 are shorted together to form the first terminal and pins 11–20 are shorted together to form the second terminal. The parameters are then measured between these two terminals. 2. Measured from input pin to ground. Table 4. IEC 60664-1 (VDE 0884 Part 2) Ratings Parameter Test Conditions Specification SOIC-20 Basic Isolation Group Installation Classification 6 Material Group IIIa Rated Mains Voltages < 150 VRMS I-IV Rated Mains Voltages < 300 VRMS I-IV Rated Mains Voltages < 400 VRMS I-IV Rated Mains Voltages < 600 VRMS I-IV Rated Mains Voltages < 1000 VRMS I-III Preliminary Rev. 0.4 Si85xx Table 5. IEC 60747-5-2 Insulation Characteristics* Parameter Symbol Test Condition Characteristic Unit SOIC-20 Maximum Working Insulation Voltage Input to Output Test Voltage Transient Overvoltage VIORM 1414 V peak VPR Method b1 (VIORM x 1.875 = VPR, 100% Production Test, tm = 1 sec, Partial Discharge < 5 pC) 2652 V peak VIOTM t = 60 s 8000 V peak Pollution Degree (DIN VDE 0110, Table 1) Insulation Resistance at TS, VIO = 500 V 2 >109 RS W Note: The Si85xx is suitable for basic and reinforced electrical isolation only within the safety limit data. Maintenance of the safety data is ensured by protective circuits. The Si85xx provides a climate classification of 40/125/21. Note that the Si85xx is compliant with the IEC60747-5-2 but neither certified nor inspected to IEC60747-5-2. The Si85xx is compliant, certified, and factory-inspected to IEC60950. Table 6. IEC Safety Limiting Values1 Parameter Symbol Case Temperature TS Safety Input Current IS Device Power Dissipation2 PD Test Condition JA = 85, VDD = 5.5 V, IIN to IOUT = 20 A, TJ = 150 °C, TA = 25 °C SOIC-20 Unit 150 °C 30 A 0.9 W Notes: 1. Maximum value allowed in the event of a failure. Refer to the thermal derating curve in Figure 1. 2. The Si85xx is tested with VDD = 5.5 V, TJ = 150 ºC, CL = 15 pF, and with an input current from IIN to IOUT equal to 20 Amps at 500 kHz (duty cycle = 50%). Preliminary Rev. 0.4 7 Si85xx Table 7. Thermal Characteristics Parameter Symbol Safety-Limiting Current (A) IC Junction-to-Air Thermal Resistance Test Condition JA SOIC-20 4x4 mm QFN Unit 85 55 °C/W 40 VDD = 5.5 V IIN to IOUT = 20 Amps 30 20 10 0 0 50 100 150 Case Temperature (ºC) 200 Figure 1. SOIC-20 Thermal Derating Curve, Dependence of Safety Limiting Values with Case Temperature per DIN EN 60747-5-2 Table 8. Absolute Maximum Ratings1 Parameter Symbol Min Typ Max Units TSTG –65 — +150 °C Ambient temperature under bias TA –40 — +125 °C Junction Temperature TJ — — 150 °C Supply voltage VDD — — 5.75 V Voltage on any pin with respect to ground (not including IIN, IOUT) VIN –0.5 — VDD + 0.5 V Output Current Drive LO — — 10 mA Lead solder temperature (10 s) — — 260 ºC Maximum Input Current Rate of Change — — 1000 A/µs Maximum Peak AC Input Current Limit — — 200 A Thermal Limit (DC Current)2 — — 30 A Maximum Isolation Voltage (QFN) — — 1400 VRMS Maximum Isolation Voltage (SOIC-20) — — 6000 VRMS Storage temperature ESD (CDM) JEDEC (JESD22-C101C) –1.5 +1.5 kV ESD (HBM) JEDEC (JESD22-A114E) –2500 +2500 V ESD (MM) JEDEC (JESD22-A115A) –250 + 250 V Notes: 1. Permanent device damage may occur if the absolute maximum ratings are exceeded. Functional operation should be restricted to conditions as specified in the operational sections of this data sheet. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2. Refer to “AN329: Extending the Full-Scale Range of the Si85xx” for more information. 8 Preliminary Rev. 0.4 Si85xx 2. Functional Overview The Si85xx ac current sensor family of products mimics the functionality of traditional current transformer (CT) circuits with burden resistor, diode, and output filter, but offers enhanced performance and added capabilities. These devices use inductive current sensing and onboard signal conditioning electronics to generate a 2 V full-scale output signal proportional to the ac current flowing from the IIN to the IOUT terminals. As shown in Figures 2 and 3, current flowing through the metal package slug induces a signal in the pickup coil on the Si85xx die. This signal is applied to the input of an integrator that reconstructs the ac current flowing from IIN to IOUT. Onboard circuitry provides cycle-by-cycle integrator reset and temperature and offset voltage compensation to achieve initial measurement accuracy to within ±5%. R1 IIN R2 R3 R4 Si851x RESET LOGIC MODE LOGIC MODE OUT1 METAL SLUG INTEGRATOR SIGNAL CONDITIONING OUT2 PICKUP COIL TEMP SENSOR IOUT AUTO CALIBRATION LOGIC ADC GND VDD TRST/FAULT Figure 3. Si851x (Ping Pong Output) Block Diagram R1 IIN The Si85xx is superior to other current sensing approaches and benefits the system in a number of ways: R2 Si850x VDD2 RESET LOGIC METAL SLUG INTEGRATOR SIGNAL CONDITIONING OUT   PICKUP COIL  TEMP SENSOR AUTO CALIBRATION LOGIC ADC NC  IOUT GND2 GND1 VDD1 GND3 TRST Figure 2. Si850x (Single Output) Block Diagram    Small size: With its 4x4 mm footprint and 1 mm height (QFN package option), the Si85xx is among the smallest current sensors available. Large output signal: The nominal 2.0 V full-scale output swing offers superior noise immunity versus other current sensing technologies. Low loss: The Si85xx adds only 1.3 m (at 25 °C) to the sensing path, making it one of the lowest-loss current sensors available. Low 2 nH primary series inductance is 2,000 times lower compared to a CT and results in significantly less ringing. High precision: All versions are available with an initial maximum error of ±5% of reading; one of the most accurate current sensors available. Ping-Pong output mode (Si851x): Alternately routes the current measurements from each side of a full-bridge circuit to separate output pins for comparison, which is very useful for transformer flux balancing applications. Eliminates a second CT in a full-bridge application. Leading edge noise suppression: Filters out reflected noise due to long reverse recovery time of output rectifier. Eliminates the need for external leading edge blanking circuit. High common-mode voltage: The Si85xx offers a minimum of 1,000 VRMS (for QFN package) or 5 kVRMS (for SOIC package) of common-mode voltage range (or isolation), making it useful over a very wide voltage range. Preliminary Rev. 0.4 9 Si85xx FAULT output (Si8517/8/9): Goes low when external reset timing is in error.  Ease-of-use: Other than conventional power and grounding techniques, no special board layout considerations are required. Built-in timing interface circuits allow already-available system switching signals to be used for reset with no external circuits required. 2.3. Integrator Reset and Current Measurement 2.1. Under Voltage Lockout (UVLO) To achieve the specified accuracy, the integrator capacitor must be discharged (reset) for time period tR prior to the start of every measurement cycle. This cycle-by-cycle reset is implemented by connecting existing system gate control signals to the R1–R4 inputs in a way that resets the integrator when no current is flowing from IIN to IOUT. To achieve rated accuracy, the reset cycle must be completed prior to the start of the measurement cycle. For maximum flexibility, integrator reset operation can be configured in one of two ways:  The Si85xx measures current flowing from the IIN to IOUT terminals. Current is allowed to flow in the opposite direction, but will not be measured (OUT1 and OUT 2 remain at their minimum values during reverse current flow. Reverse current flow will not damage the Si85xx). UVLO is provided to prevent erroneous operation during device start-up and shutdown or when VDD is significantly below the specified operating range. The Si85xx is in UVLO state when VDD < VUVLO (Figure 4). During UVLO, the output(s) are held at minimum value regardless of the amount of current flowing from IIN to IOUT, and signals on integrator reset inputs R1–R4 are ignored. The Si85xx exits UVLO when VDD > (VUVLO + VHYST). 2.2. Device Startup Upon exit from UVLO, the Si85xx performs a voltage offset and temperature self-calibration cycle. During this time, output(s) are held at minimum value and reset inputs (R1-R4) are ignored. The reset inputs are enabled at the end of the self-calibration cycle, and an integrator reset cycle is initiated on the first occurrence of active signals on R1–R4. A current measurement is initiated immediately after the completion of the integrator reset cycle, and the resulting current waveforms appear on the output pins. This "resetmeasure-reset" pattern repeats throughout steady-state operation. Option 1: The start and duration of reset is determined by the states of the timing signals applied to R1–R4. Option 2: The timing signals applied to R1–R4 trigger the start of reset, and the duration of the reset is determined by an onboard programmable reset timer. VUVLO + VHYST VDD SUPPLY First Positive Edge Following End of Self-Cal INTEGRATOR RESET Si85xx STATUS DON’T CARE UNDER VOLTAGE LOCKOUT STATE tRP START-UP SELF-CAL CYCLE tCAL Si85xx OUTPUT RESET tRP MEASURE CURRENT tR tR VOUTMIN OUT1, OUT2 VALID Figure 4. Si85xx Startup and Control Timing 10 Preliminary Rev. 0.4 RESET Si85xx Integrator reset Option 1 is selected by connecting TRST to VDD. In this mode, the Si85xx is held in reset as long as the signals on R1–R4 satisfy the logic equations of Table 11. It is typically used in applications where the gate drivers are external to the system controller IC (the gate driver delay ensures reset is completed prior to the start of measurement). Reset Option 2 is selected by connecting a timing resistor (RTRST in Figure 5) from the TRST input to ground. It is typically used in applications where the gate drivers are on-board the controller. In this mode, the on-chip reset timer is triggered when the signals on R1–R4 satisfy the logic equations in Table 11. Once triggered, the timer maintains integrator in reset for time duration tR as programmed by the value of resistor RTRST. The user must select the value of resistor RTRST to terminate the reset cycle prior to the start of measurement under worst-case timing conditions. Note that values of tR below the specified value in "1. Electrical Specifications" on page 4 results in increased integrator output offset error and increased output noise on VOUT. Moreover, tR’s time is summarized by the following equation (see Table 9): tR = 10 ns/k where values of RTRST that produce a reset time less than 150 ns (RTRST < 15 k) should not be used. Si85xx 2.4. Total Measurement Error The Si85xx’s absolute accuracy is affected by the following factors:  Ambient operating temperature  VDD supply voltage  Time Table 10 includes a composite of all environmental and operating conditions that can ultimately affect the absolute measurement accuracy of the Si85xx. The total worst-case accuracy at full scale can be estimated by the sum of the initial accuracy (up to ±5%) plus aging (up to ±1.5%) and supply variations (up to ±3.5%). For example, the total measurement error expected for a device operating at a given VDD supply of 5 V (±10%) is 10% if the device is operated over a temperature range of –40 to 125 °C for up to 10 years. If the temperature range is limited to 0 to 85 °C, the measurement error can be improved by up to 2%. See Figure 6 for details. Table 10. Total Measurement Error Contributors Error Contributor % Error Added Initial error @ given VDD ±10%, 25 °C ±5% Temperature variation –40 to 125 °C ±3.5% Aging (10 years) ±1.5% 2.5. Effect of Temperature on Accuracy TRST RTRST Figure 5. Programming Reset Time (tR) Table 9. Typical Reset Time vs. RTRST Resistance RTRST Reset Time (tR) 15 k 150 ns 100 k 1 µs 1 M 9 µs 2.2 M 20 µs Offset voltage present at the Si85xx output terminals (output offset voltage) is calibrated out each time VDD is applied to the Si85xx; so, its error contribution is minimized when the temperature at which calibration occurred is at or near the steady-state operating temperature of the Si85xx. For example, applying VDD at 25 °C (offset cal is performed) and operating at 85 °C will result in a larger offset error than operating at 50 °C. The effect of this error is summarized in Figure 6. The chart is referenced to 25 °C. If the Si85xx is powered up at 25 °C and then operated at 125 °C with no autocalibration performed (i.e., the power is not cycled at 125 °C, which causes an auto-calibration), a 3% measurement error can be expected. Preliminary Rev. 0.4 11 Si85xx 1.0% % Typical Error 0.5% 0.0% -0.5% -1.0% Current Sense Transformer -1.5% -2.0% -2.5% -3.0% Si8502 -3.5% 0 25 50 75 100 125 Temperature (Celcius) Figure 6. Differential Temperature Calibration Error Typical Series Resistance (mOhm) Figure 7 shows the Si85xx thermal characteristics of the on-chip sense resistance over the temperature range of –40 to +125 °C. Series inductance is constant at 2 nH (max) across this same temperature range. 2 2.7. FAULT Output 1.8 1.6 The FAULT output (Si8517/8/9) guards against Si85xx output signal errors caused by missing reset cycles. FAULT is asserted when a measurement cycle exceeds the internal watchdog timer times limit of tWD. FAULT can be used to alert a local microcontroller or digital power controller of a current sense failure or to initiate a system shutdown. To detect faults, tie a 200 k resistor from TRST/FAULT to VDD. 1.4 1.2 1 0.8 0.6 0.4 0.2 0 -20 0 20 40 60 80 100 120 Temperature (°C) Figure 7. Series Resistance Thermal Characteristics 2.6. Leading Edge Noise Suppression High-amplitude spikes on the leading edge of the primary switching waveforms can cause the PWM latch to be erroneously reset at the start of the switching cycle when operating in current mode control. To prevent this problem, leading edge blanking is commonly used to disable the current comparator during the early portion of the primary-side switching cycle. The Si85xx eliminates leading-edge noise spikes by including them in the signal integration. As shown in the output waveform of Figure 8 (Si8502 waveform measured directly on OUT pin with no external filter), noise present in the input waveform is eliminated without the use of blanking. 12 Figure 8. Leading-Edge Noise Suppression Waveforms (200 kHz, 9.3 A Load) 2.8. Safe Operating Limits The Si85xx is a very robust current sensor. Its maximum input current rate of change is limited to 1000 A/µs. The maximum peak ac input current limit is 200 A. The thermal limit or continuous dc current flow limit is 30 A. Exceeding these limits may cause long-term reliability issues. Refer to “AN329: Extending the Full-Scale Range of the Si85xx” for more information. Preliminary Rev. 0.4 Si85xx 3. Application Information Ground Plane Edge 3.1. Board Layout Ground Plane Edge Top View The Si85xx is connected in the series path of the current to be measured. The Si85xx must be located as far as possible from transformer and other magnetic field sources. Like other analog components, the Si85xx should be powered from a low-noise dc source and, preferably, to a low-noise analog ground plane. Recommended bypass capacitors are 1 µF in parallel with a 0.1 µF, positioned as close to the Si85xx as possible. When using the Si850x (single output versions), all three ground pins MUST be connected to the same ground point, and both VDD1 and VDD2 pins MUST be tied to the VDD system power supply. VDD Pin Mode Pin (Non-Ping-Pong) Current Carrying Slug VDD Fly Wire 3.5 mm Current Sensor Die Bonding Wire 3.2. Layout Requirements The Si85xx requires special layout techniques to ensure proper operation (see Figures 9 and 10). Due to the close proximity of the current-carrying slug and current sensor silicon, magnetic coupling between the currentcarrying slug and the silicon can form a ground loop causing the output voltage to be 0 V even though current is flowing through the slug. To eliminate any such coupling issues, a red fly-wire VDD trace (see Figures 9 and 10) should be implemented in the layout. For the SOIC package, the red fly-wire trace should be approximately 3.5 mm from the center edge of the package intersecting approximately in the center of the package (see Figure 9). For the QFN package, the red fly-wire should be approximately in the center of the package (see Figure 10). Standard wire thicknesses for 10 mA current-carrying capabilities should be used. Moreover, note that the fly-wire trace should be completely under the ground plane since this will also reduce coupling. Regarding isolation voltage requirements, the trace does not need to follow the lead frame and bonding traces exactly, as long as the net magnetic flux is close to zero. The goal here is to keep the magnetic coupling small and, at the same time, keep the isolation distance large. Moreover, to ensure that the layout meets the design’s required creepage and clearance requirements, the VDD trace should be placed on one of the inner layers or even the back side of the board. For example, one can lay out the return VDD trace on the other side of the PCB so the PCB itself can help to provide high isolation voltage. Gnd Pin Bypass Capacitor SOIC Package 5 V VDD Trace Figure 9. SOIC Layout Requirements Ground Plane Edge VDD Pin Mode Pin (Non-Ping-Pong) Ground Plane Edge Top View Current Carrying Slug Bonding Wires Current Sensor Die 2 mm VDD Fly Wire Bypass Capacitor Gnd Pin QFN Package 5V VDD Trace Figure 10. QFN Layout Requirements Preliminary Rev. 0.4 13 Si85xx 3.3. Device Configuration Configuring the Si85xx involves the following steps: R1 1. Selecting an output mode 2. Configuring integrator reset timing R2 3. Setting integrator reset time tR 3.3.1. Device Selection Si85xx State The Si85xx family offers three output modes: Single output (Si850x), and 2 and 4-Wire Ping Pong (Si851x). The Si851x products can be configured to operate in all three of these output modes. The Si850x products operate ONLY in Single output mode. Most half-wave and single-phase applications require only Single output mode and will typically use the Si850x. In Single output mode, output current always appears on the OUT pin (Si850x) or the OUT1 pin (Si851x). A single integrator reset signal is typically sufficient when operating in this mode. Ping-Pong mode routes the current waveform to two different output pins on alternate measurement cycles. It is useful in full-wave and push-pull topologies where external circuitry can be used to monitor and/or control transformer flux balance. (Section "3. Application Information" on page 13 shows design examples using both output modes in various power topologies.) 2-wire Ping-Pong mode is useful mainly in nonoverlapping two-phase buck converters but may also be used in full-bridge applications. In this output mode, reset inputs R1 and R2 are used, and input R3 is grounded. Measured current appears on OUT1 when R1 is high and on OUT2 when R2 is high as shown in the full-bridge timing example of Figures 11 and 12. R1 MEASURE RESET tR MEASURE RESET tR OUT1 OUT2 TIME Figure 12. Full-Bridge Timing Example B 4-Wire Ping-Pong mode is recommended for full-bridge applications over 2-wire because it uses all four inputs, making the reset function tolerant to single-point signal failures. In 4-Wire Ping-Pong mode, current appears on OUT2 when R1 is high and R2 is low, and appears on OUT1 when R3 is high and R4 is low as shown in the full-bridge timing example of Figure 13. Table 11 shows the states of the Mode and R4 inputs that select each output, and the resulting reset logic functions and truth tables. R1 R2 R3 R2 R4 Si85xx State MEASURE RESET tR MEASURE RESET tR MEASURE RESET OUT1 tR MEASURE RESET tR OUT1 OUT2 TIME Figure 11. Two-Phase Buck Timing Example A OUT2 Figure 13. Full-Bridge Timing Example C 14 Preliminary Rev. 0.4 Si85xx 3.3.2. Selecting Reset Timing Signals Reset timing signals should be chosen to meet the following conditions:  Satisfy reset time tR  Not overlap integrator reset into the desired measurement period  Not violate reset watchdog timeout period tWD 3.3.3. Configuring Integrator Reset Per Section “2. Functional Overview”, the integrator must be reset (zeroed) prior to the start of each measurement cycle to achieve specified measurement accuracy. This reset must be synchronized with the system switch timing signals to ensure that current is measured during the appropriate time; so, the Si85xx integrator reset circuitry uses system timing as its reference. Timing signals connect to reset inputs R1 through R4 where built-in logic functions allow the user to choose the conditions that cause an integrator reset event. Important Note: reset inputs R1–R4 are rated to a maximum input voltage of VDD. External resistor dividers must be used when connecting driver output signals to R1–R4 that swing beyond VDD. As shown in Table 11, the Si850x integrator reset logic is a simple XOR gate where reset is maintained (or triggered, depending on use of the TRST input) when states of reset inputs R1 and R2 are not equal. Figure 14 shows the logic for the Si851x products, where any one of three reset logic functions can cause integrator reset. The output mode (Si851x) is determined by the states of the Mode and R4 inputs, as shown in Table 11. Preliminary Rev. 0.4 15 Si85xx Table 11. Si85xx Output and Reset Mode Summary Output Mode MODE R4 R3 R2 R1 Reset State1 0 0 0 0 1 1 1 0 1 1 1 0 0 0 1 0 1 0 1 0 1 1 1 0 0 0 1 0 1 0 1 0 0 1 1 1 0 0 0 0 1 0 1 0 0 1 1 1 0 0 0 0 1 0 1 0 0 1 1 1 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 1 Reset Logic Expression 0 Single-Ended2 1 0 RESET = XOR[R1, (R2|R3)] 1 2-Wire Ping Pong 1 1 0 RESET = XNOR[R1,(R2|R3)] 0 0 1 4-Wire Ping Pong 0 RESET = (R1&R2)|(R3&R4) 0 1 1 Notes: 1. Device is in reset when Reset State = 1. 2. For Si850x devices, RESET = XOR [R1, R2]. 16 Preliminary Rev. 0.4 Si85xx As explained in Section “2.3. Integrator Reset and Current Measurement”, the signals applied to R1–R4 can control integrator reset in real time (Option 1), or they can trigger a reset event of programmable duration (Option 2). Referring to Figure 14, reset timing is exclusively a function of the signals applied to R1–R4 when TRST is tied to VDD. If not connected to VDD, the reset timer is enabled, and TRST must be connected through a resistor to ground to set the reset duration (tR). Note that the reset timer is retriggerable and generates a timed integrator discharge pulse whenever the reset logic output transitions from low to high. MODE = 1 R4 = 0 TRST = VDD TRST = R1 to GND Reset timing determined only by inputs R1–R4. Reset triggered by inputs R1–R4. Reset time (tR) set by value of resistor RTRST. Output 1 R1 R2 MODE = 1 R4 = 1 R3 Output 2 RESET TIMER TRST PGM CLK R4 OUT 1 0 + VREF MODE = 0 Output 3 SYSTEM CONTROLLER Logic level gate control signals (to Rn inputs) INTEGRATOR External Driver Internal Driver Required if driver output voltage > VDD Logic level gate control signals (to Rn inputs) Figure 14. Si851x Integrator Reset Logic Preliminary Rev. 0.4 17 Si85xx 3.3.4. Setting Reset Time tR The programmable reset timer is triggered when the states of the signals applied to R1–R4 cause the associated logic expression in Table 11 to go high (transition to the TRUE state). Because this timer is re-triggerable, R1–R4 must remain TRUE for the duration of the desired tR as shown in Figure 15. Should R1–R4 transition FALSE during tR, integrator reset will be immediately halted, resulting in lower measurement accuracy due to higher integrator offset error. CURRENT R1–R4 TRUE for programmed tR (minimum) TRUE R1–R4 STATE FALSE Programmed value of tR Si85xx STATUS 0 ns (min) RESET MEASURE Si85xx OUTPUT Figure 15. Correct tR Programming Using Resistor from TRST Input to Ground 18 Preliminary Rev. 0.4 Si85xx 3.3.5. Measurement Watchdog Timer and FAULT Output A built-in watchdog timer disables measurement and holds OUT or OUT1 and OUT2 at their minimum values when the time between integrator resets exceeds the FAULT Detect Time. The output signal from this watchdog is available on the FAULT output pin (Si8517/8/9 only). Figure 16 illustrates two means of entering a fault condition. Either fault condition 1 or 2 occurs when the reset period exceeds the FAULT Detect Time, which ranges from 30 to 80 µs due process variations. The fault condition ends when the next logic reset cycle begins. Output t Cycle Reset Reset Logic 30-80 µs FAULT Detect Time FAULT Output FAULT Condition 1 Output Reset Logic 30-80 µs FAULT Detect Time FAULT Output FAULT Condition 2 Figure 16. Measurement Watchdog Timer Operation Preliminary Rev. 0.4 19 Si85xx 3.3.6. Output Over-Range The Si85xx can be over-ranged by more than 100% with no adverse effects. For instance, if the Si8512 (a 10 A nominal full-scale device) has a 15 A peak current applied, then the output voltage (OUT) will be 3 V (assuming VDD = 5 V). If a 10 A peak current is applied, then the output returns to the nominal 2 V output. The head room of OUT is VDD–1.4 V. Figure 17 illustrates the head room limitation of the Si85xx versus supply. 5 3.6 V 4 VDD = 5 V 3 OUT (V) VDD = 2.7 V 2 1 0 50% 100% 150% 200% 250% I (Amps) Percent Nominal Full-Scale Input Figure 17. Headroom Limitation 20 Preliminary Rev. 0.4 Si85xx 3.4. Single-Phase Buck Converter Example In this example, the Si850x is configured to operate in a single-phase synchronous buck converter (Figure 18). This converter has a PWM frequency of 1 MHz and a maximum duty cycle of 80%. This is an example of a half-wave application that can be addressed with Single-Ended output mode. The PWM period is calculated to be 1/10–6 = 1.0 µs, and the worst-case value, tR, is 0.2 x 1.0 x 10–6 = 200 ns at 80% maximum duty cycle (RTRST = 20 k). In this example, the current measurement is made when the buck switch is on; so, PH2 is chosen as the reset signal by connecting PH2 to R1 and grounding R2. The PH2 signal can be obtained at the input of the driver external to the PWM controller or the output of the controller's internal driver (through a resistor divider if the driver output swings beyond the device VDD range). VDD VIN C2 1 µF C1 0.1 µF VDD1 VDD2 GND1 IIN GND2 R2 RTRST TRST R1 Si850x IOUT GND3 2 Vpp OUT Q1 PH1 L1 VOUT PWM PH2 Current I=0 I>0 RESET MEASURE C3 Q2 PH2 Si850x State 100 ns Figure 18. Si850x Single-Phase Buck Converter Preliminary Rev. 0.4 21 Si85xx 3.5. Full-Bridge Converter Example The full-bridge circuit of Figure 19 uses an Si851x configured in 4-Wire Ping-Pong output mode. The switching frequency of this phase-shifted full-bridge is 150 kHz, and the maximum control phase overlap is 70%. VIN VDD IIN VDD MODE C1 0.1 µF C2 1 µF GND OUT1 OUT1 OUT2 OUT2 Si851x PH1 VDD PH2 TRST R1 R2 R3 R4 IOUT PH3 PH4 Q1 1–4 Switches Turned ON PH1 Q2 PH2 Si85xx State MEASURE 1–2 RESET 2–3 3–4 MEASURE RESET TI OUT1 PH3 PH4 Q3 Q4 OUT2 Figure 19. Full-Bridge Converter Given the 150 kHz switching frequency (duty cycle fixed at 50%), the equivalent period is 1/150 x 103 = 6.6 µs. At 70% maximum overlap, this equates to a worst-case tR value of 0.3 x 6.6 x 10–6 = 1.98 µs. The default value for tR can, therefore, be used and is selected by connecting TRST to VDD. As shown in the timing diagram of Figure 19, integrator reset occurs when current circulates between Q1 and Q2 and between Q3 and Q4 (i.e. when current is not being sourced from VIN). The external driver delay ensures reset is complete prior to the start of measurement. 22 Preliminary Rev. 0.4 Si85xx 3.6. Push-Pull Converter Example The Push-Pull converter of Figure 20 uses 2-Wire Ping Pong output mode. As shown in the timing diagram, the integrator reset occurs when the inputs of both the PH1 and PH2 drivers are low. As shown, TRST is connected to VDD, selecting the default value of tR (250 ns). Assuming an 80% maximum duty cycle, this value of tR would deliver specified accuracy over a PWM frequency range of 50 to 400 kHz. Frequencies above 400 kHz would require the selection of a lower tR value by connecting a resistor from TRST to ground. VDD VIN C1 0.1 µF C2 1 µF VDD MODE IIN OUT1 R4 TRST Si851x OUT2 IOUT GND R3 R2 R1 Q1 PH2 PH1 PH2 T1 Si85xx Status MEASURE RESET MEASURE RESET MEASURE OUT1 PH1 Q2 OUT2 Figure 20. Push-Pull Example Using Default tR Value Preliminary Rev. 0.4 23 Si85xx R1 VDD MODE VDD1 VDD2 4. Pin Descriptions—12-Pin QFN R1 IIN IIN R2 R2 GND2 R3 Si850x GND3 Si851x R4 OUT1 IOUT IOUT TRST/FAULT OUT2 GND1 TRST NC GND OUT Figure 21. Example Pin Configurations Table 12. Si85xx Family Pin Descriptions 24 Pin# Si850x Pin Name Description Si851x Pin Name Description 1 R1 Integrator reset input 1 R1 Integrator reset input 1 2 R2 Integrator reset input 2 R2 Integrator reset input 2 3 GND2 Ground R3 Integrator reset input 3 4 GND3 R4 Integrator reset input 4 5 OUT 6 NC 7 Output OUT1 Output in single-ended output mode, or one of two outputs in Ping-Pong mode. No connect OUT2 Second of two Ping-Pong mode outputs TRST Reset time control TRST Reset time control 8 GND1 Ground GND Ground 9 IOUT Current output terminal IOUT Current output terminal 10 IIN 11 VDD1 12 VDD2 Current input terminal Power supply input IIN Current input terminal VDD Power supply input MODE Mode control input Preliminary Rev. 0.4 Si85xx 5. Pin Descriptions—20-Pin SOIC 20-Pin SOIC 20-Pin SOIC VDD1 IIN VDD IIN VDD2 IIN MODE IIN R1 IIN R1 IIN R2 IIN R2 IIN GND2 IIN R3 GND3 IOUT R4 IOUT OUT IOUT OUT1 IOUT NC IOUT OUT2 IOUT TRST IOUT TRST/FAULT IOUT GND1 IOUT GND IOUT Si850x Si851x IIN Figure 22. Example Pin Configurations Table 13. Si85xx Family Pin Descriptions Pin# Si850x Pin Name 1 VDD1 Description Si851x Pin Name Description VDD Power supply input MODE Mode control input Power supply input 2 VDD2 3 R1 Integrator reset input 1 R1 Integrator reset input 1 4 R2 Integrator reset input 2 R2 Integrator reset input 2 5 GND2 Ground R3 Integrator reset input 3 6 GND3 R4 Integrator reset input 4 7 OUT 8 NC 9 Output OUT1 Output in single-ended output mode, or one of two outputs in Ping-Pong mode. No connect OUT2 Second of two Ping-Pong mode outputs TRST Reset time control TRST Reset time control 10 GND1 Ground GND Ground 11–15 IOUT Current output terminal IOUT Current output terminal 16–20 IIN Current input terminal IIN Preliminary Rev. 0.4 Current input terminal 25 Si85xx 6. Ordering Guide New OPNs Full Scale Current (A) Si8501-C-IM 5 Si8502-C-IM 10 Si8503-C-IM 20 Initial Accuracy %1 Temp Range Pin 7 Function Isolation Rating Output Mode Package2 QFN-12 1 kVRMS Old Obsolete Old Obsolete OPNs3 (Previously Specified with ±5% Accuracy and –40C to +85 °C) OPNs3 (Previously Specified with ±20% Accuracy) Si8501-C-GM Si8504-C-IM Si8502-C-GM Si8505-C-IM Si8503-C-GM Si8506-C-IM Single Si8501-C-IS 5 Si8502-C-IS 10 Si8503-C-IS 20 Si8511-C-IM 5 Si8512-C-IM 10 Si8513-C-IM 20 5 kVRMS 5 Si8512-C-IS 10 Si8513-C-IS 20 Si8517-C-IM 5 Si8518-C-IM 10 Si8519-C-IM 20 Si8517-C-IS 5 Si8518-C-IS 10 Si8519-C-IS 20 QFN-12 1 kVRMS 5% Si8511-C-IS SOIC-20 Integrator Reset Programming Time Input –40 to 125 °C 5 kVRMS SOIC-20 PingPong 1 kVRMS New package offering Si8511-C-GM Si8514-C-IM Si8512-C-GM Si8515-C-IM Si8513-C-GM Si8516-C-IM New package offering Si8517-C-GM QFN-12 Si8518-C-GM — Si8519-C-GM FAULT Output 5 kVRMS SOIC-20 New Package Offering Notes: 1. See "2.4. Total Measurement Error" on page 11 for more information. 2. All packages are RoHS-compliant. Moisture Sensitivity level is MSL3 with peak reflow temperature of 260 °C according to the JEDEC industry classification, and peak solder temperature. 3. Since the initial accuracy for all devices is now specified as ±5%, Si8504/5/6 and Si8514/15/16 OPNs have been replaced with Si8501/2/3 and Si8511/12/13 OPNs, respectively. 26 Preliminary Rev. 0.4 Si85xx 7. Package Outline—12-Pin QFN Figure 23 illustrates the package details for the Si85xx. Table 14 lists the values for the dimensions shown in the illustration. Figure 23. 12-Pin QFN Package Diagram Table 14. QFN-12 Package Diagram Dimensions Dimension Min Nom Max A 0.80 0.85 0.90 A1 0.00 0.03 0.05 b1 0.20 0.25 0.30 b2 0.95 1.00 1.05 D 4.00 BSC. e 0.50 BSC. E 4.00 BSC. f 0.75 BSC. g 2.45 BSC. h 1.30 BSC. L1 0.35 0.40 0.45 L2 0.85 0.90 0.95 aaa 0.05 bbb 0.05 ccc 0.08 ddd 0.10 eee 0.10 Notes: 1. All dimensions shown are in millimeters (mm). 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. Preliminary Rev. 0.4 27 Si85xx 8. Recommended PCB Land Pattern (12-Pin QFN) Figure 24 illustrates the PCB land pattern details for the 12-pin QFN package. Table 15 lists the values for the dimensions shown in the illustration. Figure 24. 12-Pin QFN PCB Land Pattern Table 15. 12-Pin QFN PCB Land Pattern Dimensions Dimension mm C1 1.95 C2 1.30 D1 3.90 D2 2.45 E 0.50 X1 0.80 X2 1.00 Y1 0.30 Y2 1.10 Notes: 1. This Land Pattern Design is based on IPC-7351 design guidelines for Density Level B (Median Land Protrusion). 2. All feature sizes shown are at Maximum Material Condition (MMC) and a card fabrication tolerance of 0.05 mm is assumed. 28 Preliminary Rev. 0.4 Si85xx 9. Package Outline: Wide Body SOIC Figure 25 illustrates the package details for the wide-body SOIC package. Table 16 lists the values for the dimensions shown in the illustration. Figure 25. 20-Pin Wide Body SOIC Preliminary Rev. 0.4 29 Si85xx Table 16. 20-Pin Wide Body SOIC Package Diagram Dimensions Dimension Min Max A — 2.65 A1 0.10 0.30 A2 2.05 — b 0.31 0.51 c 0.20 0.33 D 12.80 BSC E 10.30 BSC E1 7.50 BSC e 1.27 BSC L 0.40 1.27 h 0.25 0.75 θ 0° 8° aaa — 0.10 bbb — 0.33 ccc — 0.10 ddd — 0.25 eee — 0.10 fff — 0.20 Notes: 1. All dimensions shown are in millimeters (mm) unless otherwise noted. 2. Dimensioning and Tolerancing per ANSI Y14.5M-1994. 3. This drawing conforms to JEDEC Outline MS-013, Variation AC. 4. Recommended reflow profile per JEDEC J-STD-020C specification for small body, lead-free components. 30 Preliminary Rev. 0.4 Si85xx 10. Recommended PCB Land Pattern (20-Pin SOIC) Figure 26 illustrates the PCB land pattern details for the 20-pin SOIC package. Table 17 lists the values for the dimensions shown in the illustration. Figure 26. 20-Pin SOIC PCB Land Pattern Table 17. 20-Pin SOIC PCB Land Pattern Dimensions Dimension mm C1 9.40 E 1.27 X1 0.60 Y1 1.90 Notes: 1. This Land Pattern Design is based on IPC-7351 design guidelines for Density Level B (Median Land Protrusion). 2. All feature sizes shown are at Maximum Material Condition (MMC) and a card fabrication tolerance of 0.05 mm is assumed. Preliminary Rev. 0.4 31 Si85xx 11. Top Marking (QFN) Si85XX RTTTTT YYWW Figure 27. QFN Top Marking Table 18. Top Marking Explanation Line 1 Marking: Device Part Number Si85XX: Where XX = 01, 02, 03, 11, 12, 13, 17, 18, 19 Line 2 Marking: RTTTTT = Mfg Code Manufacturing code from assembly house “R” indicates revision Line 3 Marking: Circle Bottom-Left Justified Pin 1 Identifier YY = Year WW = Work Week Corresponds to the year and work week of the assembly build date. 32 Preliminary Rev. 0.4 Si85xx 12. Top Marking (SOIC) Si85XX-IS YYWWRTTTTT TW e3 Figure 28. SOIC Top Marking Table 19. Top Marking Explanation Line 1 Marking: Device Part Number Si85XX-IS Where XX = 01, 02, 03, 11, 12, 13, 17, 18, 19 Line 2 Marking: YY = Year WW = Work Week Assigned by the Assembly House. Corresponds to the year and work week of the mold date. RTTTTT = Mfg Code Manufacturing code from assembly house “R” indicates revision Circle = 1.5 mm Diameter (Center Justified) “e3” Pb-Free Symbol Country of Origin ISO Code Abbreviation TW = Taiwan Line 3 Marking: Preliminary Rev. 0.4 33 Si85xx DOCUMENT CHANGE LIST Revision 0.1 to Revision 0.2  Updated Table 1, “Electrical Specifications,” on page 4.  Added 20-pin wide-body SOIC package option.  Updated "6. Ordering Guide" on page 26. All devices are now specified to ±5% initial accuracy. devices are now specified for operation over –40 to +125 °C temperature range. All ordering part numbers have been updated to reflect this (i.e. previous “-GM” and “-GS” part number suffixes have been replaced with “-IM” and “-IS” suffixes). All  Added sections “8. Recommended PCB Land Pattern (12-Pin QFN)” and “10. Recommended PCB Land Pattern (20-Pin SOIC)”. Revision 0.2 to Revision 0.21  Added reference to IEC61010, IEC60601 on page 1.  Updated "6. Ordering Guide" on page 26.  Added Top Marking sections. Revision 0.21 to Revision 0.3  Updated Table 2 on page 5. Production test voltage is > 6.0 kVRMS.  Added “2.5. Effect of Switching Frequency on Accuracy” on page 11.  Added Figure 6, “Full-Scale Output Accuracy vs. Frequency,” on page 11.  Updated "3.2. Layout Requirements" on page 13. Added  layout recommendations for QFN. Added Figure 10, “QFN Layout Requirements,” on page 13. Revision 0.3 to Revision 0.4  Updated Table 8 on page 8. Added junction temperature spec.  Removed Figure 6, “Full-Scale Output Accuracy vs. Frequency,” on page 11.  Updated Figures 9 and 10 on page 13.  Updated Table 11 on page 16. Updated  Added 34 notes. Updated Top Marks. revision description. Preliminary Rev. 0.4 Si85xx NOTES: Preliminary Rev. 0.4 35 Si85xx CONTACT INFORMATION Silicon Laboratories Inc. 400 West Cesar Chavez Austin, TX 78701 Tel: 1+(512) 416-8500 Fax: 1+(512) 416-9669 Toll Free: 1+(877) 444-3032 Please visit the Silicon Labs Technical Support web page: https://www.silabs.com/support/pages/contacttechnicalsupport.aspx and register to submit a technical support request. The information in this document is believed to be accurate in all respects at the time of publication but is subject to change without notice. Silicon Laboratories assumes no responsibility for errors and omissions, and disclaims responsibility for any consequences resulting from the use of information included herein. Additionally, Silicon Laboratories assumes no responsibility for the functioning of undescribed features or parameters. Silicon Laboratories reserves the right to make changes without further notice. Silicon Laboratories makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Silicon Laboratories assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. Silicon Laboratories products are not designed, intended, or authorized for use in applications intended to support or sustain life, or for any other application in which the failure of the Silicon Laboratories product could create a situation where personal injury or death may occur. Should Buyer purchase or use Silicon Laboratories products for any such unintended or unauthorized application, Buyer shall indemnify and hold Silicon Laboratories harmless against all claims and damages. Silicon Laboratories and Silicon Labs are trademarks of Silicon Laboratories Inc. Other products or brandnames mentioned herein are trademarks or registered trademarks of their respective holders. 36 Preliminary Rev. 0.4