RTQ2104GSP-QA

® RTQ2104-QA 36VIN, 3A, High Efficiency, 2.1MHz, Synchronous StepDown Converter with Low Quiescent Current General Description Features The RTQ2104 is a 3A, high-efficiency, current mode synchronous step-down converter which is optimized for automotive applications. The device operates with input voltages from 3V to 36V and is protected from load dump transients up to 42V, eases input surge protection design. The device can program the output voltage between 0.8V to VIN. The low quiescent current design with the integrated low RDS(ON) power MOSFETs achieves high efficiency over the wide load range. The peak current mode control with simple internal compensation allows the use of small inductors and results in fast transient response and good loop stability.  The ultra-low minimum on-time enable constant-frequency operation even at very high step down ratios. The build-in spread-spectrum frequency modulation further helping systems designers with better EMC management.             The RTQ2104 provides complete protection functions such as input under voltage lockout, output under voltage protection, over current protection, and thermal shutdown. Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. The RTQ2104 is available in SOP8 (Exposed Pad) package.     AEC-Q100 Grade 1 Qualified Wide Input Voltage Range  4V to 36V  3V to 36V (Soft-start is finished) Wide Output Voltage Range : 0.8V to VIN Maximum Output Current : 3A Peak Current Mode Control Integrated 80mΩ Ω Switch and 80mΩ Ω Synchronous Rectifier μA Low Quiescent Current : 40μ Fast 60ns Minimum Switch On-Time Ultra-Short 65ns Minimum Switch Off-Time Fixed Switching Frequency : 2.1MHz PSM/FPWM at Light Load by Part Number Option Built-In Spread-Spectrum Frequency Modulation for Low EMI Power Good Indication Enable Control 0.8V ±1.5% Reference Accuracy Adjacent Pin-Short Protection Built-In UVLO, OCP, UVP, OTP Pin Configuration (TOP VIEW) Applications       Automotive Systems Car Camera Module and Car Cockpit Systems Connected Car Systems Point of Load Regulator in Distributed Power Systems Digital Set Top Boxes Broadband Communications Copyright © 2019 Richtek Technology Corporation. All rights reserved. DSQ2104-QA-02 June 2019 SW GND 2 PGOOD FB 3 4 PAD 9 8 VIN 7 BOOT 6 VCC 5 EN SOP-8 (Exposed Pad) is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RTQ2104-QA Ordering Information Marking Information RTQ2104GSP-QA -QA RTQ2104 Grade QA : AEC-Q100 Qualified and Screened by High Temperature Package Type SP : SOP-8 (Exposed Pad-Option 2) Lead Plating System G : Green (Halogen Free and Pb Free) PWM Operation Mode : Default : Automatic PSM B : Forced PWM RTQ2104GSPQA : Product Number RTQ2104 GSPQAYMDNN YMDNN : Date Code RTQ2104BGSP-QA RTQ2104BGSP-QA : Product Number RTQ2104B GSP-QAYMDNN YMDNN : Date Code Note : Richtek products are :  RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.  Suitable for use in SnPb or Pb-free soldering processes. Functional Pin Description Pin No. Pin Name Pin Function 1 SW Switch node. SW is the switching node that supplies power to the output and connect the output LC filter from SW to the output load. 2 GND Ground. Provide the ground return path for the control circuitry and low-side power MOSFET. Connect this pin to the negative terminals of the input capacitor and output capacitor. 3 PGOOD Open-drain power-good indication output. Once soft-start is finished, PGOOD will be pulled low to ground if any internal protection is triggered. 4 FB Feedback voltage input. Connect this pin to the midpoint of the external feedback resistive divider to set the output voltage of the converter to the desired regulation level. The device regulates the FB voltage at a feedback reference voltage, typically 0.8V. 5 EN Enable control input. A logic-high enables the converter; a logic-low forces the device into shutdown mode. 6 VCC Linear regulator output. VCC is the output of the internal 5V linear regulator powered by VIN. Decouple with a 10F, X7R ceramic capacitor from VCC to ground for normal operation. 7 BOOT Bootstrap capacitor connection node to supply the high-side gate driver. Connect a 0.1F, X7R ceramic capacitor in series with a 10 resistance between this pin and SW pin. 8 VIN Power input. The input voltage range is from 3V to 36V after soft-start is finished. Connect input capacitors between this pin and GND. It is recommended to use a 4.7F, X7R and a 0.1F, X7R capacitors. 9 (Exposed Pad) PAD Exposed pad. The exposed pad is internally unconnected and must be soldered to a large GND plane. Connect this GND plane to other layers with thermal vias to help dissipate heat from the device. Copyright © 2019 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 is a registered trademark of Richtek Technology Corporation. DSQ2104-QA-02 June 2019 RTQ2104-QA Functional Block Diagram PGOOD EN + Enable Threshold UVLO Enable Comparator Logic & PGOOD Comparator Protection Control UV + Threshold UV Comparator FB 0.8V SS Oscillator Copyright © 2019 Richtek Technology Corporation. All rights reserved. Current Sense BOOT Power Stage & Dead-time Control HS Switch Current Comparator + EA + DSQ2104-QA-02 June 2019 Internal Regulator BOOT UVLO + PGOOD Threshold VCC VIN Slope Compensation SW LS Switch Current Comparator Current Sense GND is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RTQ2104-QA Operation Control Loop until the IL reaches its minimum peak current level (1A at The RTQ2104 is a high efficiency step down converter utilizes the peak current mode control. An internal oscillator initiates turn-on the high-side MOSFET switch. At the beginning of each clock cycle, the internal highside MOSFET switch turns on, allowing current to rampup in the inductor. The inductor current is internally monitored during each switching cycle. The output voltage is sensed on the FB pin via the resistor divider, R1 and R2, and compared with the internal reference voltage (VREF) to generate a compensation signal (VCOMP). A VIN = 12V, typically) to ensure that IC can provide sufficiency output current with each switching pulse. control signal derived from the inductor current is compared to the VCOMP, derived from the feedback voltage. When the inductor current reaches its threshold, the highside MOSFET switch is turned off and inductor current ramps-down. While the high-side MOSFET switch is off, inductor current is supplied through the low-side MOSFET switch. This cycle repeats at the next clock cycle. In this way, duty-cycle and output voltage are controlled by regulating inductor current. Light Load Operation The RTQ2104GSP-QA operates in power saving mode (PSM) at light load and offers higher light load efficiency. In power saving mode (PSM) at low load current, the inductor current can drop to zero. This is detected by internal zero-current-detect circuitry which utilizing the low-side MOSFET switch RDS(ON)_L to sense the inductor current. The low-side MOSFET switch is turned off when the inductor current drops to zero, resulting in discontinuous inductor current operation (DCM). Both power MOSFETs will remain off with the output capacitor supplying the load current until the VFB is lower than PSM threshold ( VREF x 1.005, typically). DCM operation maintains high efficiency at light load and most of the internal circuit is shut down, and the supply current drops to quiescent current (typically, 40μA) to reduce the quiescent power consumption during non-switching period. In PSM, IC starts to switch when VFB is lower than PSM threshold ( VREF x 1.005, typically) and stops switching when VFB is high enough. IC detects the peak inductor current (IL_PEAK) and keeps high-side MOSFET switch on Copyright © 2019 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 If the tight voltage regulation accuracy requirement is necessary, the RTQ2104BGSP-QA is offered to operate in Forced-PWM Mode (FPWM). The inductor current maintains in continuous operation (CCM) even at light load. This mode trades off reduced light load efficiency for low output voltage ripple, tight output voltage regulation, and constant switching frequency. Furthermore, this feature ensures that the switching frequency stays away from the AM frequency band, while operating between the minimum and maximum duty cycle limits. Input Voltage Range The minimum on-time, tON_MIN, is the smallest duration of time in which the high-side MOSFET switch can be in its “on” state. Considering the minimum on-time, the allowed maximum input voltage, VIN_MAX, is calculated by : VOUT VIN_MAX  tON_MIN  fSW where the minimum on-time of the RTQ2104 is 60ns (typically) ; fSW is the maximum operating frequency. The maximum operating frequency of the RTQ2104 is 2.45MHz considering the built-in spread-spectrum frequency modulation. In contrast, the minimum off-time determines the allowed minimum operating input voltage, VIN_MIN, to maintain the the fixed frequency operation. The minimum off-time, tOFF_MIN, is the smallest amount of time that the RTQ2104 is capable of turning on the low-side MOSFET switch, tripping the current comparator and turning the MOSFET switch back off. Below shows minimum off-time calculation that considers the loss terms,   VOUT + IOUT_MAX  RDS(ON)_L + DCR VIN_MIN   1 tOFF_MIN  fSW    + IOUT_MAX  RDS(ON)_H  RDS(ON)_L      is a registered trademark of Richtek Technology Corporation. DSQ2104-QA-02 June 2019 RTQ2104-QA where the minimum off-time of the RTQ2104 is 65ns (typically) ; RDS(ON)_H is the on resistance of the high-side MOSFET switch; RDS(ON)_L is the on resistance of the low-side MOSFET switch; DCR is the DC resistance of inductor. Maximum Duty Cycle Operation The RTQ2104 is designed to operate in dropout at the high duty cycle approaching 100%. If the operational duty cycle is large and the required off-time becomes smaller than minimum off-time, the RTQ2104 starts to enable skip off-time function and keeps high-side MOSFET switch on continuously. The RTQ2104 implements skip off-time function to achieve high duty approaching 100%. Therefore, the maximum output voltage is near the minimum input supply voltage of the application. The input voltage at which the devices enter dropout changes depending on the input voltage, output voltage, switching frequency, load current, and the efficiency of the design. BOOT UVLO The BOOT UVLO circuit is implemented to ensure a sufficient voltage of BOOT capacitor for turning on the highside MOSFET switch at any condition. The BOOT UVLO usually actives at extremely high conversion ratio or the higher VOUT application operates at very light load. For extremely high conversion ratio condition after soft-start is finished or higher VOUT application operates at very light load and PSM, the low-side MOSFET switch may not have sufficient turn-on time to charge the BOOT capacitor. The device monitors BOOT pin capacitor voltage and force to turn on the low-side MOSFET switch when the BOOT to SW voltage falls below VBOOT_UVLO_L (typically, 2.3V). Meanwhile, the minimum off-time is extended to 150ns (typically) hence prolong the BOOT capacitor charging time. The BOOT UVLO is sustained until the VBOOT−SW is higher than VBOOT_UVLO_H (typically, 2.4V). Internal Regulator The device integrates a 5V linear regulator (VCC) that is supplied by VIN and provides power to the internal circuitry. The internal regulator operates in low dropout mode when VIN is below 5V. The VCC can be used as the PGOOD Copyright © 2019 Richtek Technology Corporation. All rights reserved. DSQ2104-QA-02 June 2019 pull-up supply but it is “NOT” allowed to power other device or circuitry. The VCC pin must be bypassed to ground with a minimum value of effective VCC capacitance is 3μF. In many applications, a 10μF, X7R is recommended and it needs to be placed as close as possible to the VCC pin. Be careful to account for the voltage coefficient of ceramic capacitors when choosing the value and case size. Many ceramic capacitors lose 50% or more of their rated value when used near their rated voltage. Enable Control The RTQ2104 provides an EN pin, as an external chip enable control, to enable or disable the device. If VEN is held below a logic-low threshold voltage (VENL), switching is inhibited even if the VIN voltage is above VIN undervoltage lockout threshold (VUVLOH). If VEN is held below 0.4V, the converter will enter into shutdown mode, that is, the converter is disabled. During shutdown mode, the supply current can be reduced to ISHDN (5μA or below). If the EN voltage rises above the logic-high threshold voltage (VENH) while the VIN voltage is higher than VUVLOH, the device will be turned on, that is, switching being enabled and soft-start sequence being initiated. The current source of EN typically sinks 1.2μA. Soft-Start The soft-start function is used to prevent large inrush currents while the converter is being powered up. The RTQ2104 provides an internal soft-start feature for inrush currents control. During the start-up sequence, the internal soft-start capacitor is charged by an internal current source (ISS) to generate a soft-start ramp voltage as a reference voltage to the PWM comparator. If the output is for some reasons pre-biased to a certain voltage during start-up, the device will not start switching until the voltage difference between internal soft-start voltage and FB pin is larger than 400mV ( i.e. VSS − VFB > 400mV, typically). And only when the internal soft-start ramp voltage is higher than the feedback voltage VFB, the switching will be resumed. The output voltage can then ramp up smoothly to its targeted regulation voltage, and the converter can have a monotonic smooth start-up. The PGOOD pin will be in high impedance and VPGOOD will be held high in the is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RTQ2104-QA 1.6ms (typically). The typical start-up waveform shown in Figure 1 indicate the sequence and timing between the output voltage and related voltage. VIN = 12V started-up, if any internal protection is triggered, PGOOD will be pulled low to GND. The internal open-drain pulldown device (10Ω, typically) will pull the PGOOD pin low. The power good indication profile is shown in Figure 2. VIN VCC = 5V VTH_PGHL1 VTH_PGLH2 VCC VTH_PGLH1 EN VTH_PGHL2 VOUT VFB PGOO D 1.6ms 2ms 1.6ms Figure 1. Start-Up Sequence Power Good Indication The RTQ2104 features an open-drain power-good output (PGOOD) to monitor the output voltage status. The output delay of comparator prevents false flag operation for short excursions in the output voltage, such as during line and load transients. Pull-up PGOOD with a resistor to VCC or an external voltage below 5.5V. The power-good function is activated after soft start is finished and is controlled by a comparator connected to the feedback signal VFB. If VFB rises above a power-good high threshold (VTH_PGLH1) (typically 90% of the reference voltage), the PGOOD pin will be in high impedance and VPGOOD will be held high after a certain delay elapsed. When V FB exceeds VTH_PGHL1 (typically 120% of the reference voltage), the PGOOD pin will be pulled low, moreover, IC turns off highside MOSFET switch and turns on low side MOSFET switch until the inductor current reaches ISK_L if MODE pin is set high. If the VFB is still higher than VTH_PGHL1, the high-side MOSFET switch remains prohibited and the lowside MOSFET switch will turn-on again at next cycle. If MODE pin is set low, IC turns off low side MOSFET switch once the inductor current reaches zero current unless VBOOT−SW is too low. For VFB higher than VTH_PGHL1, VPGOOD can be pulled high again if VFB drops back by a power-good high threshold (VTH_PGLH2) (typically 117% of the reference voltage). When VFB fall short of power-good low threshold (VTH_PGHL2) (typically 85% of the reference voltage), the PGOOD pin will be pulled low. Once being Copyright © 2019 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 VPGOOD Figure 2. The Logic of PGOOD Spread-Spectrum Operation Due to the periodicity of the switching signals, the energy concentrates in one particular frequency and also in its harmonics. These levels or energy is radiated and therefore this is where a potential EMI issue arises. The RTQ2104 build-in spread-spectrum frequency modulation further helping systems designers with better EMC management. The spread spectrum can be active when soft-start is finished and zero-current is not detected. The spreadspectrum is implemented by a pseudo random sequence and uses +6% spread of the switching frequency, that is, the frequency will vary from 2.1MHz to 2.226MHz. Therefore, the RTQ2104 still guarantees that the 2.1MHz switching frequency does not drop into the AM band limit of 1.8MHz. Input Under-Voltage Lockout In addition to the EN pin, the RTQ2104 also provides enable control through the VIN pin. If VEN rises above VENH first, switching will still be inhibited until the VIN voltage rises above VUVLOH. It is to ensure that the internal regulator is ready so that operation with not-fully-enhanced internal MOSFET switches can be prevented. After the device is powered up, if the VIN voltage goes below the UVLO falling threshold voltage (VUVLOL), this switching will be inhibited; if VIN voltage rises above the UVLO rising threshold (VUVLOH), the device will resume switching. Note that VIN = 3V is only designed for cold crank requirement, normal input voltage should be larger than VUVLOH. is a registered trademark of Richtek Technology Corporation. DSQ2104-QA-02 June 2019 RTQ2104-QA High-Side Switch Peak Current-Limit Protection Output Under-Voltage Protection The RTQ2104 includes a cycle-by-cycle high-side switch peak current-limit protection against the condition that the inductor current increasing abnormally, even over the inductor saturation current rating. The high-side MOSFET switch peak current limit of the RTQ2104 is 5A (typically). The inductor current through the high-side MOSFET switch will be measured after a certain amount of delay when the high-side MOSFET switch being turned on. If an over-current condition occurs, the converter will immediately turn off the high-side MOSFET switch and turn on the low-side MOSFET switch to prevent the inductor current exceeding the high-side MOSFET switch peak current limit (ILIM_H). The RTQ2104 includes output under-voltage protection (UVP) against over-load or short-circuited condition by constantly monitoring the feedback voltage (VFB). If VFB drops below the under-voltage protection trip threshold (typically 50% of the internal reference voltage), the UV comparator will go high to turn off the high-side MOSFET switch and then turn off the low-side MOSFET switch when the inductor current drop to zero. If the output under-voltage condition continues for a period of time, the RTQ2104 enters output under-voltage protection with hiccup mode and discharges the internal VSS. During hiccup mode, the device remains shut down. After the internal VSS is discharged to less than 150mV (typically), the RT2104 attempts to re-start up again. The high-side MOSFET switch will start switching when voltage difference between internal VSS and VFB is larger than 400mV ( i.e. VSS − VFB > 400mV, typically). If the fault condition is not removed, the high-side MOSFET switch stop switching when the voltage difference between internal VSS and VFB is 700mV ( i.e. VSS − VFB = 700mV, typically). Upon completion of the soft-start sequence, if the fault condition is removed, the converter will resume normal operation; otherwise, such cycle for auto-recovery will be repeated until the fault condition is cleared. Hiccup mode allows the circuit to operate safely with low input current and power dissipation, and then resume normal operation as soon as the overload or short-circuit condition is removed. A short circuit protection and recovery profile is shown in Figure 3. Low-Side Switch Current-Limit Protection The RTQ2104GSP-QA not only implements the high-side MOSFET switch peak current limit but also provides the sourcing current limit for low-side MOSFET switch. Besides, the RTQ2104BGSP-QA further provides sinking current limit for low-side MOSFET switch. With these current protections, the IC can easily control inductor current at both side MOSFET switch and avoid current runaway for short-circuit condition. For the low-side MOSFET switch sourcing current limit, there is a specific comparator in internal circuitry to compare the low-side MOSFET switch sourcing current to the low-side MOSFET switch sourcing current limit at the end of every clock cycle. When the low-side MOSFET switch sourcing current is higher than the low-side MOSFET switch sourcing current limit which is high-side MOSFET switch current limit (ILIM_H) multiplied by 0.95 (typically), the new switching cycle is not initiated until inductor current drops below the low-side MOSFET switch sourcing current limit. For the low-side MOSFET switch sinking current limit protection, it is implemented by detecting the voltage across the low-side MOSFET switch. If the low-side MOSFET switch sinking current exceeds the low-side MOSFET switch sinking current limit (ISK_L) (typically, 2A), the converter will immediately turn off the low-side MOSFET switch and turn on the high-side MOSFET switch. Copyright © 2019 Richtek Technology Corporation. All rights reserved. DSQ2104-QA-02 June 2019 VOUT, 2V/Div Output Short Short Removed VPGOOD 4V/Div ISW, 2A/Div Figure 3. Short Circuit Protection and Recovery is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RTQ2104-QA Over-Temperature Protection The RTQ2104 includes an over temperature protection (OTP) circuitry to prevent overheating due to excessive power dissipation. The OTP will shut down switching operation when junction temperature exceeds a thermal shutdown threshold TSD. Once the junction temperature cools down by a thermal shutdown hysteresis (ΔTSD), the IC will resume normal operation with a complete soft-start. Pin-Short Protection The RTQ2104 provides pin-short protection for neighbor pins. The internal protection fuse will be burned out to prevent IC smoke, fire and spark when BOOT pin is shorted to VIN pin. The hiccup mode protection will be triggered to avoid IC burn-out when SW pin is shorted to ground during internal high-side MOSFET turns on. Copyright © 2019 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 is a registered trademark of Richtek Technology Corporation. DSQ2104-QA-02 June 2019 RTQ2104-QA Absolute Maximum Ratings (Note 1) Supply Input Voltage, VIN ---------------------------------------------------------------------------------------Switch Voltage, SW ----------------------------------------------------------------------------------------------