LT8609AEMSE16#TRPBF

LT8609/LT8609A/LT8609B 42V, 3A Synchronous Step-Down Regulator with 2.5µA Quiescent Current DESCRIPTION FEATURES Wide Input Voltage Range: 3.0V to 42V n Ultralow Quiescent Current Burst Mode® Operation: n 0.5), a minimum inductance is required to avoid sub-harmonic oscillation. See Application Note 19. twice its nominal value, possibly exceeding the LT8609/ LT8609A/LT8609B’s voltage rating. This situation is easily avoided (see Analog Devices Application Note 88). Output Capacitor and Output Ripple The output capacitor has two essential functions. Along with the inductor, it filters the square wave generated by the LT8609/LT8609A/LT8609B to produce the DC output. In this role it determines the output ripple, thus low impedance at the switching frequency is important. The second function is to store energy in order to satisfy transient loads and stabilize the LT8609/LT8609A/LT8609B’s control loop. Ceramic capacitors have very low equivalent series resistance (ESR) and provide the best ripple performance. A good starting value is: Input Capacitor Bypass the input of the LT8609/LT8609A/LT8609B circuit with a ceramic capacitor of X7R or X5R type. Y5V types have poor performance over temperature and applied voltage, and should not be used. A 4.7μF to 10μF ceramic capacitor is adequate to bypass the LT8609/LT8609A/LT8609B and will easily handle the ripple current. Note that larger input capacitance is required when a lower switching frequency is used. If the input power source has high impedance, or there is significant inductance due to long wires or cables, additional bulk capacitance may be necessary. This can be provided with a low performance electrolytic capacitor. Step-down regulators draw current from the input supply in pulses with very fast rise and fall times. The input capacitor is required to reduce the resulting voltage ripple at the LT8609/LT8609A/LT8609B and to force this very high frequency switching current into a tight local loop, minimizing EMI. A 4.7μF capacitor is capable of this task, but only if it is placed close to the LT8609/LT8609A/ LT8609B (see the PCB Layout section). A second precaution regarding the ceramic input capacitor concerns the maximum input voltage rating of the LT8609/LT8609A/ LT8609B. A ceramic input capacitor combined with trace or cable inductance forms a high quality (under damped) tank circuit. If the LT8609/LT8609A/LT8609B circuit is plugged into a live supply, the input voltage can ring to COUT = 100 VOUT • fSW where fSW is in MHz, and COUT is the recommended output capacitance in μF. Use X5R or X7R types. This choice will provide low output ripple and good transient response. Transient performance of adjustable output parts can be improved with a higher value output capacitor and the addition of a feedforward capacitor placed between VOUT and FB. Increasing the output capacitance will also decrease the output voltage ripple. A lower value of output capacitor can be used to save space and cost but transient performance will suffer and may cause loop instability. See the Typical Applications in this data sheet for suggested capacitor values. When choosing a capacitor, special attention should be given to the data sheet to calculate the effective capacitance under the relevant operating conditions of voltage bias and temperature. A physically larger capacitor or one with a higher voltage rating may be required. Ceramic Capacitors Ceramic capacitors are small, robust and have very low ESR. However, ceramic capacitors can cause problems when used with the LT8609/LT8609A/LT8609B due to their piezoelectric nature. When in Burst Mode operation, the LT8609/LT8609A/LT8609B’s switching frequency depends on the load current, and at very Rev. J For more information www.analog.com 17 LT8609/LT8609A/LT8609B APPLICATIONS INFORMATION light loads the LT8609/LT8609A/LT8609B can excite the ceramic capacitor at audio frequencies, generating audible noise. Since the LT8609/LT8609A/LT8609B operates at a lower current limit during Burst Mode operation, the noise is typically very quiet to a casual ear. If this is unacceptable, use a high performance tantalum or electrolytic capacitor at the output. A final precaution regarding ceramic capacitors concerns the maximum input voltage rating of the LT8609/LT8609A/ LT8609B. As previously mentioned, a ceramic input capacitor combined with trace or cable inductance forms a high quality (under damped) tank circuit. If the LT8609/ LT8609A/LT8609B circuit is plugged into a live supply, the input voltage can ring to twice its nominal value, possibly exceeding the LT8609/LT8609A/LT8609B’s rating. This situation is easily avoided (see Application Note 88). Enable Pin The LT8609/LT8609A/LT8609B is in shutdown when the EN pin is low and active when the pin is high. The rising threshold of the EN comparator is 1.05V, with 50mV of hysteresis. The EN pin can be tied to VIN if the shutdown feature is not used, or tied to a logic level if shutdown control is required. Adding a resistor divider from VIN to EN programs the LT8609/LT8609A/LT8609B to regulate the output only when VIN is above a desired voltage (see Block Diagram). Typically, this threshold, VIN(EN), is used in situations where the input supply is current limited, or has a relatively high source resistance. A switching regulator draws constant power from the source, so source current increases as source voltage drops. This looks like a negative resistance load to the source and can cause the source to current limit or latch low under low source voltage conditions. The VIN(EN) threshold prevents the regulator from operating at source voltages where the problems might occur. This threshold can be adjusted by setting the values R3 and R4 such that they satisfy the following equation: ⎛ R3 ⎞ VIN(EN) = ⎜ +1⎟ •1V ⎝ R4 ⎠ 18 where the LT8609/LT8609A/LT8609B will remain off until VIN is above VIN(EN). Due to the comparator’s hysteresis, switching will not stop until the input falls slightly below VIN(EN). When in Burst Mode operation for light-load currents, the current through the VIN(EN) resistor network can easily be greater than the supply current consumed by the LT8609/LT8609A/LT8609B. Therefore, the VIN(EN) resistors should be large to minimize their effect on efficiency at low loads. INTVCC Regulator An internal low dropout (LDO) regulator produces the 3.5V supply from VIN that powers the drivers and the internal bias circuitry. The INTVCC can supply enough current for the LT8609/LT8609A/LT8609B’s circuitry and must be bypassed to ground with a minimum of 1μF ceramic capacitor. Good bypassing is necessary to supply the high transient currents required by the power MOSFET gate drivers. Applications with high input voltage and high switching frequency will increase die temperature because of the higher power dissipation across the LDO. Do not connect an external load to the INTVCC pin. Output Voltage Tracking and Soft-Start The LT8609/LT8609A/LT8609B allows the user to program its output voltage ramp rate by means of the TR/SS pin. An internal 2μA pulls up the TR/SS pin to INTVCC. Putting an external capacitor on TR/ SS enables soft-starting the output to prevent current surge on the input supply. During the soft-start ramp the output voltage will proportionally track the TR/SS pin voltage. For output tracking applications, TR/ SS can be externally driven by another voltage source. From 0V to 0.782V, the TR/SS voltage will override the internal 0.782V reference input to the error amplifier, thus regulating the FB pin voltage to that of TR/SS pin. In the LT8609A-3.3 and LT8609A-5 fixed output voltage options the output voltage will track the TR/SS pin voltage based on a factor set by the internal feedback resistor divider. The 3.3V output options will track to a voltage 4.2 times that of the TR/SS pin, while the 5V output options will track to a voltage 6.39 times that of the TR/SS pin. When Rev. J For more information www.analog.com LT8609/LT8609A/LT8609B APPLICATIONS INFORMATION TR/SS is above 0.782V, tracking is disabled and the feedback voltage will regulate to the internal reference voltage. An active pull-down circuit is connected to the TR/SS pin which will discharge the external soft-start capacitor in the case of fault conditions and restart the ramp when the faults are cleared. Fault conditions that clear the soft-start capacitor are the EN/UV pin transitioning low, VIN voltage falling too low, or thermal shutdown. Output Power Good When the LT8609/LT8609A/LT8609B’s adjustable output voltage is within the ±8.5% window of the regulation point, which is a VFB voltage in the range of 0.716V to 0.849V (typical), the output voltage is considered good and the open-drain PG pin goes high impedance and is typically pulled high with an external resistor. Otherwise, the internal drain pull-down device will pull the PG pin low. To prevent glitching both the upper and lower thresholds include 0.5% of hysteresis. The LT8609A-3.3 and LT8609A-5 use a ±7.5% power good window around the regulation point, which for the 3.3V output version corresponds to a 3.0525V to 3.5475V range (typical) and for the 5V output version corresponds to a 4.625V to 5.375V range (typical). The PG pin is also actively pulled low during several fault conditions: EN/UV pin is below 1V, INTVCC has fallen too low, VIN is too low, or thermal shutdown. Synchronization To select low ripple Burst Mode operation, tie the SYNC pin below 0.4V (this can be ground or a logic low output). To synchronize the LT8609/LT8609A oscillator to an external frequency connect a square wave (with 20% to 80% duty cycle) to the SYNC pin. The square wave amplitude should have valleys that are below 0.9V and peaks above 2.7V (up to 5V). The LT8609/LT8609A will not enter Burst Mode operation at low output loads while synchronized to an external clock, but instead will pulse skip to maintain regulation. The LT8609/LT8609A may be synchronized over a 200kHz to 2.2MHz range. The RT resistor should be chosen to set the LT8609/LT8609A switching frequency equal to or below the lowest synchronization input. For example, if the synchronization signal will be 500kHz and higher, the RT should be selected for 500kHz. The slope compensation is set by the RT value, while the minimum slope compensation required to avoid subharmonic oscillations is established by the inductor size, input voltage, and output voltage. Since the synchronization frequency will not change the slopes of the inductor current waveform, if the inductor is large enough to avoid subharmonic oscillations at the frequency set by RT, then the slope compensation will be sufficient for all synchronization frequencies. For some applications, it is desirable for the LT8609/ LT8609A to operate in pulse-skipping mode, which is the only mode available to the LT8609B. Pulse-skipping mode offers two major differences from Burst Mode operation. First is the clock stays awake at all times and all switching cycles are aligned to the clock. Second is that full switching frequency is reached at lower output load than in Burst Mode operation as shown in Figure 1b in an earlier section. These two differences come at the expense of increased quiescent current. To enable pulse-skipping mode the SYNC pin is floated. For some applications, reduced EMI operation may be desirable, which can be achieved through spread spectrum modulation. This mode operates similar to pulse skipping mode operation, with the key difference that the switching frequency is modulated up and down by a 3kHz triangle wave. The modulation has the frequency set by RT as the low frequency, and modulates up to approximately 20% higher than the frequency set by RT. To enable spread spectrum mode, tie SYNC to INTVCC or drive to a voltage between 3.2V and 5V. The LT8609/LT8609A/LT8609B does not operate in forced continuous mode regardless of SYNC signal. Shorted and Reversed Input Protection The LT8609/LT8609A/LT8609B will tolerate a shorted output. Several features are used for protection during output short-circuit and brownout conditions. The first is the switching frequency will be folded back while the output is lower than the set point to maintain inductor current control. Second, the bottom switch current is monitored such that if inductor current is beyond safe levels For more information www.analog.com Rev. J 19 LT8609/LT8609A/LT8609B APPLICATIONS INFORMATION switching of the top switch will be delayed until such time as the inductor current falls to safe levels. This allows for tailoring the LT8609/LT8609A/LT8609B to individual applications and limiting thermal dissipation during short circuit conditions. Frequency foldback behavior depends on the state of the SYNC pin: If the SYNC pin is low or high, or floated the switching frequency will slow while the output voltage is lower than the programmed level. If the SYNC pin is connected to a clock source, the LT8609/LT8609A/LT8609B will stay at the programmed frequency without foldback and only slow switching if the inductor current exceeds safe levels. There is another situation to consider in systems where the output will be held high when the input to the LT8609/ LT8609A/LT8609B is absent. This may occur in battery charging applications or in battery backup systems where a battery or some other supply is diode ORed with the LT8609/LT8609A/LT8609B’s output. If the VIN pin is allowed to float and the EN pin is held high (either by a logic signal or because it is tied to VIN), then the LT8609/ LT8609A/LT8609B’s internal circuitry will pull its quiescent current through its SW pin. This is acceptable if the system can tolerate several μA in this state. If the EN pin is grounded the SW pin current will drop to near 0.7µA. However, if the VIN pin is grounded while the output is held high, regardless of EN, parasitic body diodes inside the LT8609/LT8609A/LT8609B can pull current from the output through the SW pin and the VIN pin. Figure 3 shows a connection of the VIN and EN/UV pins that will allow the LT8609/LT8609A/LT8609B to run only when the input voltage is present and that protects against a shorted or reversed input. D1 VIN VIN LT8609 EN/UV GND 8609 F03 Figure 3. Reverse VIN Protection 20 PCB Layout For proper operation and minimum EMI, care must be taken during printed circuit board layout. Figure 4 shows the recommended component placement with trace, ground plane and via locations. Note that large, switched currents flow in the LT8609/LT8609A/LT8609B’s VIN pins, GND pins, and the input capacitor (CIN). The loop formed by the input capacitor should be as small as possible by placing the capacitor adjacent to the VIN and GND pins. When using a physically large input capacitor the resulting loop may become too large in which case using a small case/value capacitor placed close to the VIN and GND pins plus a larger capacitor further away is preferred. These components, along with the inductor and output capacitor, should be placed on the same side of the circuit board, and their connections should be made on that layer. Place a local, unbroken ground plane under the application circuit on the layer closest to the surface layer. The SW and BOOST nodes should be as small as possible. Finally, keep the FB and RT nodes small so that the ground traces will shield them from the SW and BOOST nodes. The exposed pad on the bottom of the package must be soldered to ground so that the pad is connected to ground electrically and also acts as a heat sink thermally. To keep thermal resistance low, extend the ground plane as much as possible, and add thermal vias under and near the LT8609/LT8609A/ LT8609B to additional ground planes within the circuit board and on the bottom side. Thermal Considerations and Peak Current Output For higher ambient temperatures, care should be taken in the layout of the PCB to ensure good heat sinking of the LT8609/LT8609A/LT8609B. The exposed pad on the bottom of the package must be soldered to a ground plane. This ground should be tied to large copper layers below with thermal vias; these layers will spread heat dissipated by the LT8609/LT8609A/LT8609B. Placing additional vias can reduce thermal resistance further. The maximum load current should be derated as the ambient temperature approaches the maximum junction rating. Rev. J For more information www.analog.com LT8609/LT8609A/LT8609B APPLICATIONS INFORMATION GROUND PLANE ON LAYER 2 COUT L CIN CBST 1 CVCC CIN(OPT) RT RPG R4 R3 R1 CFF GND VIA VIN VIA VOUT VIA EN/UV VIA R2 CSS OTHER SIGNAL VIA 8609 F04 Figure 4. PCB Layout Power dissipation within the LT8609/LT8609A/LT8609B can be estimated by calculating the total power loss from an efficiency measurement and subtracting the inductor loss. The die temperature is calculated by multiplying the LT8609/LT8609A/LT8609B power dissipation by the thermal resistance from junction to ambient. The LT8609/ LT8609A/LT8609B will stop switching and indicate a fault condition if safe junction temperature is exceeded. Temperature rise of the LT8609/LT8609A/LT8609B is worst when operating at high load, high VIN, and high switching frequency. If the case temperature is too high for a given application, then either VIN, switching frequency or load current can be decreased to reduce the temperature to an acceptable level. Figure 5 shows how case temperature rise can be managed by reducing VIN. Figure  6 shows an example of how case temperature rise changes with the duty cycle of a 10Hz pulsed 3A load. Junction temperature will be higher than case temperature. Rev. J For more information www.analog.com 21 LT8609/LT8609A/LT8609B APPLICATIONS INFORMATION 60 VIN=12V VIN=24V 50 STANDBY LOAD = 50mA PULSED LOAD = 3A VOUT = 5V 40 f = 2MHz SW CASE TEMPERATURE RISE (°C) CASE TEMPERATURE RISE (°C) 60 30 20 10 0 0 VIN=12V VIN=24V 50 STANDBY LOAD = 50mA PULSED LOAD = 3A VOUT = 5V 40 f = 2MHz SW 30 20 10 0 10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%) 0 10 20 30 40 50 60 70 80 90 100 DUTY CYCLE (%) 8609 F06 8609 F06 Figure 5. Case Temperature Rise vs Load Current Figure 6. Case Temperature Rise vs 3A Pulsed Load TYPICAL APPLICATIONS 3.3V Step-Down VIN 4.3V TO 42V C2 4.7µF C1 0.1µF VIN EN/UV BST SYNC SW L1 2.2µH R4 100k LT8609A INTVCC C3 1µF C6 10nF R1 18.2k PG C5 10pF TR/SS RT FB GND fSW = 2MHz R3 309k R2 1M L1 = COILCRAFT XFL4020-222ME VOUT 3.3V 3A POWER GOOD C4 22µF 1206 8609 TA02 5V Step-Down VIN 6V TO 42V C2 4.7µF C1 0.1µF VIN EN/UV BST SYNC SW L1 2.2µH R4 100k LT8609A INTVCC C3 1µF C6 10nF R1 18.2k fSW = 2MHz 22 PG C5 10pF TR/SS RT GND FB R3 187k R2 1M L1 = COILCRAFT XFL4020-222ME VOUT 5V 3A POWER GOOD C4 22µF 1206 8609 TA03 Rev. J For more information www.analog.com LT8609/LT8609A/LT8609B TYPICAL APPLICATIONS 12V Step-Down VIN 13V TO 42V C1 0.1µF VIN C2 4.7µF EN/UV BST SYNC SW L1 10µH R4 100k LT8609 INTVCC C3 1µF C6 10nF R1 40.2k PG C5 10pF TR/SS RT FB GND FSW = 1MHz R3 69.8k R2 1M L1 = COILCRAFT XAL4040-103ME VOUT 12V 3A POWER GOOD C4 22µF 1210 8609 TA04 1.8V 2MHz Step-Down Converter VIN 2.8V TO 20V (42V TRANSIENT) C1 0.1µF VIN C2 4.7µF BST EN/UV SW SYNC C6 10nF M1 NFET R1 18.2k R4 100k LT8609 INTVCC C3 1µF PSKIP L1 2.2µH PG C5 10pF TR/SS RT FB GND fSW = 2MHz R3 768k R2 1M L1 = COILCRAFT XFL4020-222ME VOUT 1.8V 3A POWER GOOD C4 47µF 1210 8609 TA05 3.3V 2MHz Step-Down Converter VIN 4.3V TO 42V C2 4.7µF C1 0.1µF VIN BST EN/UV LT8609A-3.3 SW SYNC INTVCC C3 1µF C6 10nF R1 18.2k fSW = 2MHz L1 2.2µH PG R4 100k VOUT 3.3V 3A POWER GOOD TR/SS RT GND VOUT L1 = COILCRAFT XFL4020-222ME C4 47µF 1206 8609 TA08 Rev. J For more information www.analog.com 23 LT8609/LT8609A/LT8609B TYPICAL APPLICATIONS 5V 2MHz Step-Down Converter VIN 6V TO 42V C1 0.1µF VIN C2 4.7µF BST EN/UV LT8609A-5 L1 2.2µH SW R4 100k SYNC INTVCC C3 1µF PG VOUT 5V 3A POWER GOOD TR/SS C6 10nF R1 18.2k RT GND fSW = 2MHz VOUT C4 47µF 1206 L1 = COILCRAFT XFL4020-222ME 8609 TA09 Ultralow EMI 5V 2A Step-Down Converter VIN 6V TO 40V FB1 BEAD L3 4.7µH C8 4.7µF C7 4.7µF C9 33μF VIN C2 4.7µF BST EN/UV SYNC SW C1 0.1µF L1 8.2µH R4 100K LT8609A PG INTVCC C5 10pF TR/SS C3 1µF C6 10nF fSW = 400kHz 24 FB RT R1 110k GND R3 301k R2 1M L1 = COILCRAFT XAL4040-822 FB1 = TDK MPZ2012S221AT000 C9 = OS-CON 63SXV33M VOUT 3.3V 3A POWER GOOD C4 47µF 1210 8609 TA06 Rev. J For more information www.analog.com LT8609/LT8609A/LT8609B PACKAGE DESCRIPTION MSE Package 10-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1664 Rev I) BOTTOM VIEW OF EXPOSED PAD OPTION 1.88 ±0.102 (.074 ±.004) 5.10 (.201) MIN 1 0.889 ±0.127 (.035 ±.005) 1.68 ±0.102 (.066 ±.004) 0.05 REF 10 0.305 ± 0.038 (.0120 ±.0015) TYP RECOMMENDED SOLDER PAD LAYOUT 3.00 ±0.102 (.118 ±.004) (NOTE 3) DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY NO MEASUREMENT PURPOSE 10 9 8 7 6 DETAIL “A” 0° – 6° TYP 1 2 3 4 5 GAUGE PLANE 0.53 ±0.152 (.021 ±.006) DETAIL “A” 0.18 (.007) 0.497 ±0.076 (.0196 ±.003) REF 3.00 ±0.102 (.118 ±.004) (NOTE 4) 4.90 ±0.152 (.193 ±.006) 0.254 (.010) 0.29 REF 1.68 (.066) 3.20 – 3.45 (.126 – .136) 0.50 (.0197) BSC 1.88 (.074) SEATING PLANE 1.10 (.043) MAX 0.17 – 0.27 (.007 – .011) TYP 0.50 (.0197) NOTE: BSC 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL NOT EXCEED 0.254mm (.010") PER SIDE. 0.86 (.034) REF 0.1016 ±0.0508 (.004 ±.002) MSOP (MSE) 0213 REV I Rev. J For more information www.analog.com 25 LT8609/LT8609A/LT8609B PACKAGE DESCRIPTION MSE Package 16-Lead Plastic MSOP, Exposed Die Pad (Reference LTC DWG # 05-08-1667 Rev F) BOTTOM VIEW OF EXPOSED PAD OPTION 2.845 ±0.102 (.112 ±.004) 5.10 (.201) MIN 2.845 ±0.102 (.112 ±.004) 0.889 ±0.127 (.035 ±.005) 8 1 1.651 ±0.102 (.065 ±.004) 1.651 ±0.102 3.20 – 3.45 (.065 ±.004) (.126 – .136) 0.305 ±0.038 (.0120 ±.0015) TYP 16 0.50 (.0197) BSC 4.039 ±0.102 (.159 ±.004) (NOTE 3) RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 0.35 REF 0.12 REF DETAIL “B” CORNER TAIL IS PART OF DETAIL “B” THE LEADFRAME FEATURE. FOR REFERENCE ONLY 9 NO MEASUREMENT PURPOSE 0.280 ±0.076 (.011 ±.003) REF 16151413121110 9 DETAIL “A” 0° – 6° TYP 3.00 ±0.102 (.118 ±.004) (NOTE 4) 4.90 ±0.152 (.193 ±.006) GAUGE PLANE 0.53 ±0.152 (.021 ±.006) DETAIL “A” 1.10 (.043) MAX 0.18 (.007) SEATING PLANE 0.17 – 0.27 (.007 – .011) TYP 1234567 8 0.50 (.0197) BSC NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 6. EXPOSED PAD DIMENSION DOES INCLUDE MOLD FLASH. MOLD FLASH ON E-PAD SHALL NOT EXCEED 0.254mm (.010") PER SIDE. 26 0.86 (.034) REF 0.1016 ±0.0508 (.004 ±.002) MSOP (MSE16) 0213 REV F Rev. J For more information www.analog.com LT8609/LT8609A/LT8609B PACKAGE DESCRIPTION DDM Package 10-Lead Plastic Side Wettable DFN (3mm × 3mm) (Reference LTC DWG # 05-08-1647 Rev Ø) R = 0.125 TYP 6 0.40 ±0.10 10 1.65 ±0.10 (2 SIDES) 3.00 ±0.10 (4 SIDES) PIN 1 NOTCH R = 0.20 OR 0.35 × 45° CHAMFER PIN 1 TOP MARK (SEE NOTE 5) 5 0.200 REF 1 0.75 ±0.05 DETAIL A 0.00 – 0.05 NOTE: 1. DRAWING NOT TO SCALE 2. ALL DIMENSIONS ARE IN MILLIMETERS 3. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 4. EXPOSED PAD SHALL BE SOLDER PLATED 5. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE (DDM) DFN REV Ø 0518 0.25 ±0.05 0.50 BSC 2.40 ±0.10 (2 SIDES) BOTTOM VIEW—EXPOSED PAD DETAIL A TERMINAL LENGTH 0.40 ± 0.10 0.10 REF 0.05 REF 0.203 REF TERMINAL THICKNESS PLATED AREA 0.70 ±0.05 3.55 ±0.05 1.65 ±0.05 2.15 ±0.05 (2 SIDES) PACKAGE OUTLINE 0.25 ±0.05 0.50 BSC 2.40 ±0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS Rev. J For more information www.analog.com 27 LT8609/LT8609A/LT8609B REVISION HISTORY REV DATE DESCRIPTION A 01/16 Added the LT8609A Version to Header PAGE NUMBER All Added the LT8609A Version to Description 1 Clarified Description 1 Clarified Electrical Specifications 3 Clarified Load Regulation, Line Regulation, No-Load Supply Current vs Temperature, Minimum On-Time vs Temperature Graphs, Frequency Foldback and Soft-Start vs Temperature Graphs 5, 6, 7, 8 Clarified Block Diagram with Optional Input Resistors 10 Replaced Figure 1 with Table 1 in text 12 Clarified CIN Capacitor in Text and PCB Layout 18 Clarified Typical Application 24 6 B 06/16 Clarified Switch Drop vs Switch Current Graph axis units Clarified Switching Waveforms conditions 8 C 10/16 Added LT8609B Option All Added LT8609B Option to Absolute Maximum Ratings, Added LT8609B Package Drawing and Ordering Information 2 Clarified Electrical Parameters and Notes for LT8609B Option 3 Clarified Top FET Current Limit vs Temperature Graph 6 Clarified Pin Functions to Include LT8609B 10 Clarified Operation Section to Include LT8609B 12 Clarified Applications Information Section to Include LT8609B Clarified Graphs in Figure 5 and 6 13 – 20 20 Clarified Typical Applications Schematics 21, 22, 23, 24 D 01/17 Clarified Graphs 6, 7, 20 Clarified Schematics 23, 26 E 06/17 Add H-grade to the A version 2, 4 Modified application circuits 21, 22, 23 F G 11/17 01/18 Clarified Oscillator Frequency RT Conditions 3 Clarified Minimum Off Time 3 Clarified Efficiency Graph 5 Clarified Frequency Foldback Graph 8 Clarified Block Diagram 11 Clarified Maximum Duty Cycle 14 Clarified Figure 4 19 Added MSOP-16E Package option 1, 2, 24 Clarified the Pin Functions 28 10 Rev. J For more information www.analog.com LT8609/LT8609A/LT8609B REVISION HISTORY REV DATE DESCRIPTION H 02/19 Changed 2A/3A to 3A. Replaced all graphs with IOUT to 3A. 01/20 08/21 1, 5, 6, 7, 8 2 Eliminated “The internal circuitry…” paragraph. 15 Clarified Figure 4 PCB Layout. 19 Clarified Figure 5. 20 20 Updated Typical Applications. 21, 22 Added DFN version parts and J Grades. 1, 2, 3 Clarified parametric table. 4, 5 Added fixed output graphs. 6, 7 ,8 Clarified Pin Functions. 11 Clarified Block Diagram. 12 Clarified Operation to include fixed output options. 13 Added text for fixed output options. 15 Added text in Output Capacitor and Output Ripple for fixed output options. 17 Added text in Output Voltage Tracking section for fixed output options. 18 Added text in Output Power Good section for fixed output options. 19 Clarified Typical Applications. J 1 Added LT8609AJMSE16 and LT8609AJMSE options. Eliminated “The LT8609/LT8609A/LT8609B’s…” paragraph. I PAGE NUMBER Clarified Output Reference Voltage for LT8609A-3.3 and Line Regulations under Electrical Characteristics table. 22-25 4 Rev. J Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications moreby information www.analog.com subject to change without notice. No license For is granted implication or otherwise under any patent or patent rights of Analog Devices. 29 LT8609/LT8609A/LT8609B TYPICAL APPLICATION Tracking 3.3V and 1.8V 2MHz Converters VIN 4.3V TO 20V (42V TRANSIENT) C2 4.7µF C1 0.1µF VIN BST EN/UV R1 18.2k R4 100k LT8609 INTVCC C6 10nF VOUT 3.3V, 3A SW SYNC C3 1µF L1 2.2µH PG C5 10pF TR/SS RT GND FB R3 309k R2 1M POWER GOOD C4 47µF 1210 fSW = 2MHz C8 4.7µF R9 10k BST EN/UV SYNC R8 100k LT8609 PG C11 10pF TR/SS R10 31.6k R5 18.2k L2 2.2µH SW INTVCC C12 1µF C7 0.1µF VIN RT GND FB R7 768k R6 1M fSW = 2MHz VOUT 1.8V 3A POWER GOOD C10 47µF 1210 8609 TA07 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT8610A/ LT8610AB 42V, 3.5A, 96% Efficiency, 2.2MHz Synchronous MicroPower Step-Down VIN = 3.4V to 42V, VOUT(MIN) = 0.97V, IQ = 2.5µA, ISD