LTM8029 36VIN, 600mA Step-Down µModule Converter with 5µA Quiescent Current Description Features n n n n n n n n n n n Complete Switch Mode Power Supply Low Quiescent Current Burst Mode® Operation 5μA IQ at 12VIN to 3.3VOUT 600mA Output Current Wide Input Voltage Range: 4.5V to 36V (40VMAX) Output Voltage: 1.2V to 18V Excellent Dropout Performance Can Be Used As an Inverter Adjustable Switching Frequency: 200kHz to 2.2MHz Current Mode Control (e1) RoHS Compliant Package Tiny, Low Profile (11.25mm × 6.25mm × 3.42mm) Surface Mount BGA Package Applications n n n n n Automotive Battery Regulation Power for Portable Products Distributed Supply Regulation Industrial Supplies Wall Transformer Regulation The LTM®8029 is a 36VIN, 600mA step-down µModule® converter with 5µA quiescent current. It is an adjustable frequency buck switching regulator that consumes only 5μA of quiescent current. The LTM8029 can accept an input as high as 36VIN and operates at low input voltages due to its off-time skipping capability. Burst Mode operation maintains high efficiency at low output currents while keeping the output ripple low. The RUN pin features an accurate threshold and the shutdown current is 0.9μA. A power good flag signals when VOUT reaches 90% of the programmed output voltage. The LTM8029 is packaged in a thermally enhanced, compact (11.25mm × 6.25mm) and low profile (3.42mm) overmolded ball grid array (BGA) package suitable for automated assembly by standard surface mount equipment. The LTM8029 is RoHS compliant. L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode and µModule are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical Application Low Quiescent Current, 5VOUT, 600mA µModule Regulator Minimum Input Voltage vs Output Current 5.8 VIN 5.6V TO 36V 1µF VIN VOUT RUN BIAS PGOOD RT GND 158k f = 800kHz FB 309k 22µF VOUT 5V 600mA INPUT VOLTAGE (V) LTM8029 5.7 5.6 5.5 8029 TA01a 5.4 0 100 400 300 500 200 OUTPUT CURRENT (mA) 600 8029 TA01b 8029f 1 LTM8029 Absolute Maximum Ratings Pin Configuration (Notes 1, 2) VIN, RUN ...................................................................40V VOUT, BIAS.................................................................20V VIN + BIAS..................................................................55V PGOOD , FB, RT...........................................................6V Maximum Internal Temperature............................ 125°C Solder Temperature................................................ 260°C TOP VIEW VIN 5 VOUT BANK 1 4 BANK 3 3 BIAS FB PGOOD GND 2 RUN RT A B BANK 2 1 C D E F G H BGA PACKAGE 35-LEAD (11.25mm × 6.25mm × 3.42mm) TJMAX = 125°C, θJA = 13.8°C/W, θJCtop = 17.2°C/W, θJCbottom = 3.9°C/W, θJCB = 9.0°C/W WEIGHT = 0.6g Order Information LEAD FREE FINISH TRAY PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTM8029EY#PBF LTM8029EY#PBF LTM8029Y 35-Lead (11.25mm × 6.25mm × 3.42mm) BGA –40°C to 125°C LTM8029IY#PBF LTM8029IY#PBF LTM8029Y 35-Lead (11.25mm × 6.25mm × 3.42mm) BGA –40°C to 125°C LTM8029MPY#PBF LTM8029MPY#PBF LTM8029Y 35-Lead (11.25mm × 6.25mm × 3.42mm) BGA –55°C to 125°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ This product is only offered in trays. For more information go to: http://www.linear.com/packaging/ 8029f 2 LTM8029 Electrical Characteristics The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 12V, RUN = 12V unless otherwise noted (Note 2). PARAMETER CONDITIONS MIN Minimum Input Voltage Output DC Voltage TYP 4.5 l IOUT ≤ 0.6A, RFB Open IOUT ≤ 0.6A, RFB = 576k Output DC Current 3.3VOUT Quiescent Current Into VIN RUN = 0V No Load No Load MAX 1.2 3.3 10 0.9 5 l UNITS V V V 600 mA 9 µA µA µA BIAS Current 600mA Load VIN = 32V, VOUT = 20V at 100mA Load 3.6 4.7 mA mA Line Regulation 5.5V < VIN < 36V, IOUT = 600mA 0.3 % Load Regulation 10mA < IOUT < 600mA 0.4 % Output RMS Voltage Ripple IOUT = 600mA 10 mV Switching Frequency RT = 41.2k RT = 124k RT = 768k 2.2 1 200 MHz MHz kHz Voltage at FB Pin l 1.185 1.175 Internal Feedback Resistor 1.215 1.225 1 Minimum BIAS Voltage for Proper Operation RUN Pin Current 1.20 1.20 l RUN = 2.5V RUN Threshold Voltage l RUN Voltage Hysteresis MΩ 1.7 2.25 V 1 30 nA 0.95 1.3 30 PGOOD Threshold (at FB) VOUT Rising 1.1 PGOOD Leakage Current PGOOD = 6V 0.1 PGOOD Sink Current PGOOD = 0.4V 100 Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LTM8029E is guaranteed to meet performance specifications from 0°C to 125°C internal. Specifications over the full –40°C to 125°C internal operating temperature range are assured by design, characterization and correlation with statistical process controls. V V V mV V 1 µA µA The LTM8029I is guaranteed to meet specifications over the full –40°C to 125°C internal operating temperature range. The LTM8029MP is guaranteed to meet specifications over the full –55°C to 125°C internal operating temperature range. Note that the maximum internal temperature is determined by specific operating conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors. 8029f 3 LTM8029 Typical Performance Characteristics TA = 25°C, unless otherwise noted. Configured per Table 1, where applicable. 3.3VOUT Efficiency vs Output Current, BIAS = 5V 90 85 85 80 80 75 70 65 60 55 50 0 100 200 300 400 85 75 70 65 5VIN 12VIN 24VIN 36VIN 55 50 600 500 90 60 5VIN 12VIN 24VIN 36VIN 5VOUT Efficiency vs Output Current, BIAS = 5V EFFICIENCY (%) 90 EFFICIENCY (%) EFFICIENCY (%) 2.5VOUT Efficiency vs Output Current, BIAS = 5V 0 100 OUTPUT CURRENT (mA) 200 300 400 80 12VIN 24VIN 36VIN 300 400 90 85 80 70 0 100 200 300 400 500 150 100 300 400 86 24VIN 36VIN 0 100 500 600 OUTPUT CURRENT (mA) 300 400 400 300 200 0 600 500 Input Current vs Output Current, 5VOUT, BIAS = 5V 12VIN 24VIN 36VIN 300 250 200 150 100 50 0 100 200 300 400 500 600 0 0 100 200 300 400 500 600 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 8029 G07 200 8029 G06 350 100 50 200 88 OUTPUT CURRENT (mA) INPUT CURRENT (mA) 200 100 90 80 600 5VIN 12VIN 24VIN 36VIN 500 INPUT CURRENT (mA) INPUT CURRENT (mA) 600 250 0 92 82 Input Current vs Output Current, 3.3VOUT, BIAS = 5V 300 0 94 8029 G05 Input Current vs Output Current, 2.5VOUT, BIAS = 5V 600 84 24VIN 36VIN 8029 G04 350 500 96 OUTPUT CURRENT (mA) 5VIN 12VIN 24VIN 36VIN 400 98 OUTPUT CURRENT (mA) 400 300 100 75 600 500 200 18VOUT Efficiency vs Output Current, BIAS = 5V EFFICIENCY (%) EFFICIENCY (%) EFFICIENCY (%) 85 200 100 8029 G03 95 100 0 OUTPUT CURRENT (mA) 100 90 450 60 12VOUT Efficiency vs Output Current, BIAS = 5V 95 0 12VIN 24VIN 36VIN 8029 G02 8VOUT Efficiency vs Output Current, BIAS = 5V 70 70 OUTPUT CURRENT (mA) 8029 G01 75 75 65 600 500 80 8029 G08 8029 G09 8029f 4 LTM8029 Typical Performance Characteristics TA = 25°C, unless otherwise noted. Configured per Table 1, where applicable. 350 300 250 200 150 100 200 150 100 0 0 100 200 300 400 500 600 0 100 200 300 400 500 0 OUTPUT CURRENT (mA) INPUT CURRENT (mA) VIN (V) 300 250 f = 800kHz 200 150 0 20 f = 400kHz 0 20 10 40 30 8 7 8 20 10 400 500 600 IOUT (mA) 6 IBIAS (mA) 6 5 4 0 5 4 3 2 1 0 100 200 300 400 500 600 0 0 100 200 300 400 500 600 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 8029 G16 40 30 12VIN 24VIN 36VIN 7 1 300 0 8029 G15 5VIN 12VIN 24VIN 36VIN 9 IBIAS (mA) IBIAS (mA) 10 1 200 1000 IBIAS vs Output Current, 5VOUT, BIAS = 5V 2 100 f = 400kHz 1200 IBIAS vs Output Current, 3.3VOUT, BIAS = 5V 3 0 1300 8029 G14 5VIN 12VIN 24VIN 36VIN 2 0 1400 VIN (V) 8029 G13 IBIAS vs IOUT, 2.5VOUT, BIAS = 5V 600 f = 800kHz 1500 VIN (V) 3 500 1100 VOUT (V) 4 400 1600 50 5 300 1700 100 5 15 200 8029 G12 450 10 6 100 Output Short-Circuit Current, BIAS = 5V 350 7 0 OUTPUT CURRENT (mA) Input Current vs VIN, Output Short, BIAS = 5V 15 8 150 600 400 10 200 8029 G11 20 5 250 OUTPUT CURRENT (mA) Minimum VIN vs VOUT, IOUT = 600mA, BIAS = 5V 0 300 50 8029 G10 0 350 100 OUTPUT CURRENT (mA) 25 24VIN 36VIN 400 250 50 Input Current vs Output Current, 18VOUT, BIAS = 5V 450 300 50 0 500 24VIN 36VIN 350 INPUT CURRENT (mA) 400 INPUT CURRENT (mA) 400 12VIN 24VIN 36VIN 450 Input Current vs Output Current, 12VOUT, BIAS = 5V INPUT CURRENT (mA) 500 Input Current vs Output Current, 8VOUT, BIAS = 5V 8029 G17 8029 G18 8029f 5 LTM8029 Typical Performance Characteristics TA = 25°C, unless otherwise noted. Configured per Table 1, where applicable. 8 12VIN 24VIN 36VIN 9 8 6 5 4 3 10 8 5 4 3 2 0 100 200 400 300 0 600 500 0 100 OUTPUT CURRENT (mA) 200 300 400 0 600 500 Minimum VIN vs Output Current, –3.3VOUT, BIAS = GND 300 400 12 600 500 8029 G21 Minimum VIN vs Output Current, –5VOUT, BIAS = GND 20 Minimum VIN vs Output Current, –8VOUT, BIAS = GND 18 10 16 VIN (V) 4 3 6 TO START 4 RUNNING 2 14 8 TO START VIN (V) 5 VIN (V) 200 OUTPUT CURRENT (mA) 6 12 10 8 6 RUNNING TO START 4 2 1 RUNNING 2 0 100 200 300 400 500 600 0 700 0 100 OUTPUT CURRENT (mA) 200 300 400 500 20 18 TO START RUNNING 14 VIN (V) 10 12 10 8 6 TO START 4 RUNNING 200 400 500 OUTPUT CURRENT (mA) 0 0 50 100 150 200 250 300 350 OUTPUT CURRENT (mA) 8029 G25 400 500 600 12VIN 24VIN 36VIN 14 12 10 8 6 4 2 2 300 300 Temperature Rise vs Output Current, 2.5VOUT 16 16 15 200 8029 G24 TEMPERATURE RISE (°C) 20 100 100 OUTPUT CURRENT (mA) Minimum VIN vs Output Current, –18VOUT, BIAS = GND 18 0 0 8029 G23 Minimum VIN vs Output Current, –12VOUT, BIAS = GND 5 0 600 OUTPUT CURRENT (mA) 8029 G22 VIN (V) 100 8029 G20 7 0 0 OUTPUT CURRENT (mA) 8029 G19 25 6 4 1 1 0 24VIN 36VIN 2 2 8 IBIAS vs Output Current, 18VOUT, BIAS = 5V 6 IBIAS (mA) IBIAS (mA) 12 24VIN 36VIN 7 7 0 IBIAS vs Output Current, 12VOUT, BIAS = 5V IBIAS (mA) 10 IBIAS vs Output Current, 8VOUT, BIAS = 5V 0 0 100 200 300 400 500 600 OUTPUT CURRENT (mA) 8029 G26 8029 G27 8029f 6 LTM8029 Typical Performance Characteristics TA = 25°C, unless otherwise noted. Configured per Table 1, where applicable. 16 14 TEMPERATURE RISE (°C) TEMPERATURE RISE (°C) 25 12VIN 24VIN 36VIN 12 10 8 6 4 Temperature Rise vs Output Current, 5VOUT 25 12VIN 24VIN 36VIN 20 TEMPERATURE RISE (°C) 18 Temperature Rise vs Output Current, 3.3VOUT 15 10 5 Temperature Rise vs Output Current, 8VOUT 12VIN 24VIN 36VIN 20 15 10 5 2 0 0 100 200 300 400 500 0 600 0 100 200 300 400 500 10 5 20 15 10 5 100 200 300 400 500 0 600 0 100 OUTPUT CURRENT (mA) 200 300 400 500 10 5 0 100 200 300 400 15 10 5 0 500 600 OUTPUT CURRENT (mA) 35 200 300 400 500 25 20 15 10 0 600 Temperature Rise vs Output Current, –12VOUT 12VIN 24VIN 30 25 20 15 10 5 0 100 200 300 400 500 600 OUTPUT CURRENT (mA) 8029 G34 100 8029 G33 12VIN 24VIN 5 0 12VIN 24VIN OUTPUT CURRENT (mA) TEMPERATURE RISE (°C) 15 600 20 0 600 Temperature Rise vs Output Current, –8VOUT 30 TEMPERATURE RISE (°C) TEMPERATURE RISE (°C) 35 12VIN 24VIN 20 500 8029 G32 Temperature Rise vs Output Current, –5VOUT 25 400 Temperature Rise vs Output Current, –3.3VOUT OUTPUT CURRENT (mA) 8029 G31 30 25 24VIN 36VIN TEMPERATURE RISE (°C) 15 300 8029 G30 Temperature Rise vs Output Current, 18VOUT 25 TEMPERATURE RISE (°C) TEMPERATURE RISE (°C) 30 24VIN 36VIN 20 200 8029 G29 Temperature Rise vs Output Current, 12VOUT 0 100 OUTPUT CURRENT (mA) 8029 G28 0 0 OUTPUT CURRENT (mA) OUTPUT CURRENT (mA) 25 0 600 0 0 100 200 300 400 500 OUTPUT CURRENT (mA) 8029 G35 8029 G36 8029f 7 LTM8029 Pin Functions VIN (Bank 1): The VIN pins supply current to the LTM8029’s internal regulator and to the internal power switch. This pin must be locally bypassed with an external, low ESR capacitor; see Table 1 for recommended values. FB (Pin A2): The LTM8029 regulates its FB pin to 1.2V. Connect the output feedback resistor from this pin to ground. The value of RFB is given by the equation RFB = 1200/(VOUT – 1.2), where RFB is in kΩ. VOUT (Bank 3): Power Output Pins. Apply the output filter capacitor and the output load between these pins and GND pins. RT (Pin B1): The RT pin is used to program the switching frequency of the LTM8029 by connecting a resistor from this pin to ground. The Applications Information section of the data sheet includes a table to determine the resistance value based on the desired switching frequency. GND (Bank 2): Tie these GND pins to a local ground plane below the LTM8029 and the circuit components. In most applications the bulk of the heat flow out of the LTM8029 is through these pads, so the printed circuit design has a large impact on the thermal performance of the part. See the PCB Layout and Thermal Considerations sections for more details. Return the feedback resistor (RFB) to this net. RUN (Pin A1): Pull the RUN pin below 0.95V to shut down the LTM8029. Tie to 1.3V or more for normal operation. If the shutdown feature is not used, tie this pin to VIN. PGOOD (Pin B2): The PGOOD pin is the open-collector output of an internal comparator that monitors the FB pin. PGOOD remains low until the FB pin is within 10% of the final regulation voltage. PGOOD output is valid when VIN is above 4.5V and RUN is high. If this function is not used, leave this pin floating. BIAS (Pin H3): The BIAS pin powers internal circuitry. Connect to a power source greater than 2.25V and less than 20V. If the output is greater than 2.25V, connect this pin there. Also, make sure that BIAS + VIN is less than 55V. Block Diagram 22µH VIN 0.1µF VOUT 47pF 1M 1µF BIAS RUN CURRENT MODE CONTROLLER GND RT PGOOD FB 8029 BD 8029f 8 LTM8029 Operation The LTM8029 is a standalone non-isolated step-down switching DC/DC power supply that can deliver up to 600mA of output current. This device features a very low quiescent current and provides a precisely regulated output voltage from 1.2V to 18V. The input voltage range is 4.5V to 36V. Given that the LTM8029 is a step-down converter, make sure that the input voltage is high enough to support the desired output voltage and load current. As shown in the Block Diagram, the LTM8029 contains a current mode controller, power switching element, power inductor, power Schottky diode and a modest amount of input and output capacitance. The LTM8029 is a fixed frequency PWM regulator. The switching frequency is set by simply connecting the appropriate resistor value from the RT pin to GND. An internal regulator provides power to the control circuitry. The internal regulator normally draws power from the VIN pin, but if the BIAS pin is connected to an external voltage higher than 2.25V, bias power will be drawn from the external source (typically the regulated output voltage). This improves efficiency. The RUN pin is used to place the LTM8029 in shutdown. To optimize efficiency, the LTM8029 automatically switches to Burst Mode operation in light load situations. Between bursts, all circuitry associated with controlling the output switch is shut down reducing the input supply current to typically 5μA at no load and 12VIN. Since the LTM8029 is mostly shut down between bursts, the effective switching frequency will be lower than that programmed at the RT pin. For the same reason, the output ripple will be different than when the part is running at the full programmed frequency. The LTM8029 contains a power good comparator which trips when the FB pin is at roughly 90% of its regulated value. The PGOOD output is an open-collector transistor that is off when the output is in regulation, allowing an external resistor to pull the PGOOD pin high. Power good is valid when the LTM8029 is enabled and VIN is above 4.5V. The LTM8029 features the ability to skip the off-time in switching cycles when the input voltage approaches the target output. This allows the LTM8029 to operate at input voltages lower than other step-down regulators. In an overload or short-circuit condition, the LTM8029 will protect itself by limiting its peak switching current and decreasing the operating frequency to reduce overall power consumption. The LTM8029 is also equipped with a thermal shutdown that will inhibit power switching at high junction temperatures. The activation threshold of this function, however, is above 125°C to avoid interfering with normal operation. Thus, prolonged or repetitive operation under a condition in which the thermal shutdown activates may damage or impair the reliability of the device. 8029f 9 LTM8029 Applications Information For most applications, the design process is straight forward, summarized as follows: 1. Look at Table 1 and find the row that has the desired input range and output voltage. 2. Apply the recommended CIN, COUT, RFB and RT values. 3. Connect BIAS as indicated. While these component combinations have been tested for proper operation, it is incumbent upon the user to verify proper operation over the intended system’s line, load and environmental conditions. Bear in mind that the maximum output current is limited by junction temperature, the relationship between the input and output voltage magnitude and polarity and other factors. Please refer to the graphs in the Typical Performance Characteristics section for guidance. The maximum frequency (and attendant RT value) at which the LTM8029 should be allowed to switch is given in Table 1 in the fMAX column, while the recommended frequency (and RT value) for optimal efficiency over the given input condition is given in the fOPTIMAL column. The LTM8029 is capable of operating at low input voltages by skipping off-times to maintain regulation. This results in a lower operating frequency than that programmed by the RT pin, so it may be necessary to use larger input and output capacitors, depending upon the system requirements. The recommended components and VIN range listed in Table 1 reflect an operation where off-times are not skipped. Capacitor Selection Considerations The CIN and COUT capacitor values in Table 1 are the minimum recommended values for the associated operating conditions. Applying capacitor values below those indicated in Table 1 is not recommended, and may result in undesirable operation. Using larger values is generally acceptable, and can yield improved dynamic response, if it is necessary. It is incumbent upon the user to verify proper operation over the intended system’s line, load and environmental conditions. Ceramic capacitors are small, robust and have very low ESR. However, not all ceramic capacitors are suitable. X5R and X7R types are stable over temperature and applied voltage and give dependable service. Other types, including Y5V and Z5U have very large temperature and voltage coefficients of capacitance. In an application circuit they may have only a small fraction of their nominal capacitance resulting in much higher output voltage ripple than expected. Ceramic capacitors are also piezoelectric. In Burst Mode operation, the LTM8029’s switching frequency depends on the load current, and can excite a ceramic capacitor at audio frequencies, generating audible noise. Since the LTM8029 operates at a lower current limit during Burst Mode operation, the noise is typically very quiet to a casual ear. If this audible noise is unacceptable, use a high performance electrolytic capacitor at the output. It may also be a parallel combination of a ceramic capacitor and a low cost electrolytic capacitor. A final precaution regarding ceramic capacitors concerns the maximum input voltage rating of the LTM8029. A ceramic input capacitor combined with trace or cable inductance forms a high Q (under damped) tank circuit. If the LTM8029 circuit is plugged into a live supply, the input voltage can ring to twice its nominal value, possibly exceeding the device’s rating. This situation is easily avoided; see the Hot-Plugging Safety section. 8029f 10 LTM8029 Applications Information Table 1. Recommended Component Values and Configuration VIN (V)* VOUT (V) CIN COUT BIAS RFB fOPT RT(OPT) fMAX RT(MIN) 4.5-36 1.2 4.7µF 50V 1206 X5R 100µF 6.3V 1206 X5R 2.1V-20V Open 270kHz 536k 510kHz 267k 4.5-36 1.5 4.7µF 50V 1206 X5R 100µF 6.3V 1206 X5R 2.1V-20V 4.02M 310kHz 475k 600kHz 220k 4.5-36 1.8 4.7µF 50V 1206 X5R 100µF 6.3V 1206 X5R 2.1V-20V 2M 350kHz 402k 750kHz 169k 4.5-36 2 4.7µF 50V 1206 X5R 100µF 6.3V 1206 X5R 2.1V-20V 1.5M 380kHz 374k 780kHz 162k 4.5-36 2.2 1µF 50V 1206 X5R 47µF 6.3V 1206 X5R 2.1V-20V 1.21M 450kHz 309k 840kHz 147k 4.5-36 2.5 1µF 50V 0805 X5R 47µF 6.3V 1206 X5R 2.1V-20V 931k 490kHz 280k 950kHz 127k 4.8-36 3.3 1µF 50V 0805 X5R 22µF 6.3V 1206 X5R VOUT 576k 615kHz 215k 1.2MHz 93.1k 7.8-36 5 1µF 50V 0805 X5R 22µF 6.3V 1206 X5R VOUT 309k 800kHz 158k 1.6MHz 61.9k 12-36 8 2.2µF 50V 1206 X5R 22µF 10V 1210 X5R 2.1V-20V 174k 830kHz 150k 2.2MHz 41.2k 17-36 12 2.2µF 50V 1206 X5R 10µF 50V 1210 X5R 2.1V-20V 110k 880kHz 137k 2.2MHz 41.2k 24.5-36 18 2.2µF 50V 1206 X5R 10µF 50V 1210 X5R 2.1V-20V 71.5k 880kHz 137k 2.2MHz 41.2k 10-33 –3.3 1µF 50V 0805 X5R 22µF 6.3V 1206 X5R GND 576k 615kHz 215k 1.2MHz 93.1k 5.5-33 –3.3 4.7µF 50V 1206 X5R 100µF 6.3V 1206 X5R GND 576k 615kHz 215k 1.2MHz 93.1k 8-31 –5 2.2µF 50V 1206 X5R 47µF 6.3V 1206 X5R GND 309k 800kHz 158k 1.6MHz 61.9k 7-28 –8 2.2µF 50V 1206 X5R 22µF 10V 1210 X5R GND 174k 830kHz 150k 2.2MHz 41.2k 7-24 –12 2.2µF 50V 1206 X5R 22µF 16V 1210 X5R GND 110k 880kHz 137k 2.2MHz 41.2k 4.5-24 1.2 2.2µF 50V 0805 X7R 47µF 6.3V 1206 X5R 2.1V-20V Open 400kHz 348k 750kHz 169k 4.5-24 1.5 2.2µF 50V 0805 X7R 47µF 6.3V 1206 X5R 2.1V-20V 4.02M 430kHz 324k 930kHz 130k 4.5-24 1.8 2.2µF 50V 0805 X7R 47µF 6.3V 1206 X5R 2.1V-20V 2M 450kHz 309k 1MHz 124k 4.5-24 2 2.2µF 50V 0805 X7R 47µF 6.3V 1206 X5R 2.1V-20V 1.5M 480kHz 287k 1.2MHz 93.1k 4.5-24 2.2 1µF 50V 0805 X5R 47µF 6.3V 1206 X5R 2.1V-20V 1.21M 545kHz 249k 1.3MHz 82.5k 4.5-24 2.5 1µF 50V 0805 X5R 47µF 6.3V 1206 X5R 2.1V-20V 931k 580kHz 232k 1.4MHz 73.2k 1.8-24 3.3 1µF 25V 0603 X5R 22µF 6.3V 1206 X5R VOUT 576k 615kHz 215k 2.2MHz 41.2k 7.8-24 5 1µF 25V 0603 X5R 22µF 6.3V 1206 X5R VOUT 309k 800kHz 158k 2.2MHz 41.2k 12-24 8 2.2µF 50V 1206 X5R 22µF 10V 1210 X5R 2.1V-20V 174k 830kHz 150k 2.2MHz 41.2k 17-24 12 2.2µF 50V 1206 X5R 10µF 50V 1210 X5R 2.1V-20V 110k 880kHz 137k 2.2MHz 41.2k 9-15 1.2 2.2µF 50V 0805 X7R 47µF 6.3V 1206 X5R 2.1V-20V Open 400kHz 348k 1.3MHz 84.5k 9-15 1.5 2.2µF 50V 0805 X7R 47µF 6.3V 1206 X5R 2.1V-20V 4.02M 430kHz 324k 1.5MHz 66.5k 9-15 1.8 2.2µF 50V 0805 X7R 47µF 6.3V 1206 X5R 2.1V-20V 2M 450kHz 309k 1.7MHz 57.6k 9-15 2 2.2µF 50V 0805 X7R 47µF 6.3V 1206 X5R 2.1V-20V 1.5M 480kHz 287k 1.9MHz 49.9k 9-15 2.2 1µF 50V 0805 X5R 47µF 6.3V 1206 X5R 2.1V-20V 1.21M 545kHz 249k 2MHz 46.4k 9-15 2.5 1µF 50V 0805 X5R 47µF 6.3V 1206 X5R 2.1V-20V 931k 580kHz 232k 2.2MHz 41.2k 9-15 3.3 1µF 25V 0603 X5R 22µF 6.3V 1206 X5R VOUT 576k 615kHz 215k 2.2MHz 41.2k 9-15 5 1µF 25V 0603 X5R 22µF 6.3V 1206 X5R VOUT 309k 800kHz 158k 2.2MHz 41.2k 12-15 8 2.2µF 50V 1206 X5R 22µF 10V 1210 X5R 2.1V-20V 174k 830kHz 150k 2.2MHz 41.2k Notes: An input bulk capacitor is required. Do not allow VIN + BIAS to exceed 55V. The minimum input operating voltage may be lower than given in the table. Refer to the Applications Information section for details. 8029f 11 LTM8029 Applications Information Frequency Selection BIAS Pin Considerations The LTM8029 uses a constant frequency PWM architecture that can be programmed to switch from 200kHz to 2.2MHz by using a resistor tied from the RT pin to ground. Table 2 provides a list of RT resistor values and their resultant frequencies. The BIAS pin is used to provide drive power for the internal power switching stage and operate other internal circuitry. For proper operation, it must be powered by at least 2.25V. If the output voltage is programmed to 2.25V or higher, BIAS may be simply tied to VOUT. If VOUT is less than 2.25V, BIAS can be tied to VIN or some other voltage source. If the BIAS pin voltage is too high, the efficiency of the LTM8029 may suffer. The optimum BIAS voltage is dependent upon many factors, such as load current, input voltage, output voltage and switching frequency, but 4V to 5V works well in many applications. In all cases, ensure that the maximum voltage at the BIAS pin is less than 25V and that the sum of VIN and BIAS is less than 55V. If BIAS power is applied from a remote or noisy voltage source, it may be necessary to apply a decoupling capacitor locally to the pin. Table 2. Frequency vs RT Value FREQUENCY (MHz) RT (k) 0.2 768 0.4 348 0.6 220 0.8 158 1.0 124 1.2 93.1 1.4 73.2 1.6 61.9 1.8 52.3 2.0 46.4 Burst Mode Operation 2.2 41.2 To enhance efficiency at light loads, the LTM8029 automatically switches to Burst Mode operation which keeps the output capacitor charged to the proper voltage while minimizing the input quiescent current. During Burst Mode operation, the LTM8029 delivers single cycle bursts of current to the output capacitor followed by sleep periods where the output power is delivered to the load by the output capacitor. Since the LTM8029 is mostly shut down between bursts, the effective switching frequency will be lower than that programmed at the RT pin. For the same reason, the output ripple will be different than when the part is running at the full programmed frequency. In addition, VIN and BIAS quiescent currents are each greatly reduced to during the sleep time. As the load current decreases towards a no load condition, the percentage of time that the LTM8029 operates in sleep mode increases and the average input current is greatly reduced, resulting in higher efficiency. Operating Frequency Trade-offs It is recommended that the user apply the optimal RT resistor value given in Table 1 for the input and output operating condition. System level or other considerations, however, may necessitate another operating frequency. While the LTM8029 is flexible enough to accommodate a wide range of operating frequencies, a haphazardly chosen one may result in undesirable operation under certain operating or fault conditions. A frequency that is too high can reduce efficiency, generate excessive heat or even damage the LTM8029 if the output is overloaded or short-circuited. A frequency that is too low can result in a final design that has too much output ripple or too large of an output capacitor. In addition, as shown in the Typical Performance Characteristics section, the operating frequency affects the amount of current that may be delivered during a short-circuit condition. 8029f 12 LTM8029 Applications Information RUN The LTM8029 is in shutdown when the RUN pin is low and active when the pin is high. The rising threshold of the RUN comparator is typically 1.15V, with a 30mV hysteresis. This threshold is accurate when VIN is above 4.5V. Adding a resistor divider from VIN to RUN programs the LTM8029 to operate only when VIN is above a desired voltage (see Figure 1). This rising threshold voltage, VIN(RUN), can be adjusted by setting the values R3 and R4 such that they satisfy the following equation: VIN(RUN) = R3 + R4 • 1.15V R4 where the LTM8029 should not start until VIN is above VIN(RUN). Note that due to the RUN pin’s hysteresis, operation will not stop until the input falls slightly below VIN(RUN). LTM8029 VIN VIN R3 RUN R4 8029 F01 It also means that the effective frequency during this mode of operation will be lower than the one programmed by the resistor connected to the RT pin, so it may be necessary to use larger input and output capacitors, depending upon the system requirements. Shorted Input Protection Care needs to be taken in systems where the output will be held high when the input to the LTM8029 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 LTM8029’s output. If the VIN pin is allowed to float and the RUN pin is held high (either by a logic signal or because it is tied to VIN), then the LTM8029’s internal circuitry will pull its quiescent current through its internal power switch. This is fine if your system can tolerate a few milliamps in this state. If you ground the RUN pin, the input current will drop to essentially zero. However, if the VIN pin is grounded while the output is held high, then parasitic diodes inside the LTM8029 can pull large currents from the output through the VIN pin. Figure 2 shows a circuit that will run only when the input voltage is present and that protects against a shorted or reversed input. Figure 1. R3 and R4 Set the Minimum Operating Threshold Voltage Minimum Input Voltage The LTM8029 is a step-down converter, so a minimum amount of headroom is required to keep the output in regulation. Curves detailing the minimum input voltage of the LTM8029 for various load conditions are included in the Typical Performance Characteristics section. The LTM8029 features the ability to skip the off-time in switching cycle when the input voltage approaches the target output. This allows the LTM8029 to operate an input voltages lower than other step-down regulators. Graphs of minimum input voltage versus output voltage and load are given in the Typical Performance Characteristics section. LTM8029 VIN VIN VOUT RUN BIAS RT GND VOUT FB 8029 F02 Figure 2. The Input Diode Prevents Shorted Input from Discharging a Backup Battery Tied to the Output. It Also Protects the Circuit from a Reversed Input. The LTM8029 Runs Only When the Input is Present 8029f 13 LTM8029 Applications Information Power Good The PGOOD pin is the open-collector output of an internal comparator that monitors the voltage at the FB pin. It is used to indicate whether the output is near or within regulation. Specifically, PGOOD is low unless the FB pin is within 10% of the final regulation voltage. PGOOD output is valid when VIN is above 4.5V and RUN is high. If this function is not used, leave this pin floating. Hot-Plugging Safely The small size, robustness and low impedance of ceramic capacitors make them an attractive option for the input bypass capacitor of LTM8029. However, these capacitors can cause problems if the LTM8029 is hot-plugged into a live supply (see Application Note 88 for a complete discussion). The low loss ceramic capacitor combined with stray inductance in series with the power source forms an underdamped tank circuit, and the voltage at the VIN pin of the LTM8029 can ring to more than twice the nominal input voltage, possibly exceeding the LTM8029’s rating and damaging the part. If the input supply is poorly controlled or the user will be hot-plugging the LTM8029 into an energized supply, the input network should be designed to prevent this overshoot. This can be accomplished by installing a small resistor in series to VIN, but the most popular method of controlling input voltage overshoot is to add an electrolytic bulk capacitor to the VIN net. This capacitor’s relatively high equivalent series resistance usually damps the circuit and eliminates the voltage overshoot. The extra capacitor improves low frequency ripple filtering and can slightly improve the efficiency of the circuit, though it is likely to be the largest component in the circuit. 1. Place the RFB and RT resistors as close as possible to their respective pins. 2. Place the CIN capacitor as close as possible to the VIN and GND connection of the LTM8029. 3. Place the COUT capacitor as close as possible to the VOUT and GND connection of the LTM8029. 4. Place the CIN and COUT capacitors such that their ground currents flow directly adjacent or underneath the LTM8029. 5. Connect all of the GND connections to as large a copper pour or plane area as possible on the top layer. Avoid breaking the ground connection between the external components and the LTM8029. 6. For good heat sinking, use vias to connect the GND copper area to the board’s internal ground planes. Liberally distribute these GND vias to provide both a good ground connection and thermal path to the internal planes of the printed circuit board. Pay attention to the location and density of the thermal vias in Figure 3. The LTM8029 can benefit from the heat sinking afforded by vias that connect to internal GND planes at these locations, due to their proximity to internal power handling components. The optimum number of thermal vias depends upon the printed circuit board design. For example, a board might use very small via holes. It should employ more thermal vias than a board that uses larger holes. VIN VOUT CIN GND PCB Layout Most of the headaches associated with PCB layout have been alleviated or even eliminated by the high level of integration of the LTM8029. The LTM8029 is nevertheless a switching power supply, and care must be taken to minimize EMI and ensure proper operation. Even with the high level of integration, you may fail to achieve specified operation with a haphazard or poor layout. See Figure 3 for a suggested layout. Ensure that the grounding and heat sinking are acceptable. BIAS PGOOD RUN COUT GND RFB RT THERMAL VIAS 8029 F03 Figure 3. Layout Showing Suggested External Components, GND Plane and Thermal Vias 8029f 14 LTM8029 Applications Information Thermal Considerations The LTM8029 output current may need to be derated if it is required to operate in a high ambient temperature or deliver a large amount of continuous power. The amount of current derating is dependent upon the input voltage, output power and ambient temperature. The temperature rise curves given in the Typical Performance Characteristics section can be used as a guide. These curves were generated by a LTM8029 mounted to a 40cm2 4-layer FR4 printed circuit board. Boards of other sizes and layer count can exhibit different thermal behavior, so it is incumbent upon the user to verify proper operation over the intended system’s line, load and environmental operating conditions. The thermal resistance numbers listed in the Pin Configuration are based on modeling the µModule package mounted on a test board specified per JESD 51-9 (“Test Boards for Area Array Surface Mount Package Thermal Measurements”). The thermal coefficients provided in this page are based on JESD 51-12 (“Guidelines for Reporting and Using Electronic Package Thermal Information”). For increased accuracy and fidelity to the actual application, many designers use FEA to predict thermal performance. To that end, the Pin Configuration section typically gives four thermal coefficients: • θJA – Thermal resistance from junction to ambient • θJCbottom – Thermal resistance from junction to the bottom of the product case • θJCtop – Thermal resistance from junction to top of the product case • θJB – Thermal resistance from junction to the printed circuit board While the meaning of each of these coefficients may seem to be intuitive, JEDEC has defined each to avoid confusion and inconsistency. These definitions are given in JESD 51-12, and are quoted or paraphrased below: • θJA is the natural convection junction-to-ambient air thermal resistance measured in a one cubic foot sealed enclosure. This environment is sometimes referred to as “still air” although natural convection causes the air to move. This value is determined with the part mounted to a JESD 51-9 defined test board, which does not reflect an actual application or viable operating condition. • θJCbottom is the thermal resistance between the junction and bottom of the package with all of the component power dissipation flowing through the bottom of the package. In the typical µModule converter, the bulk of the heat flows out the bottom of the package, but there is always heat flow out into the ambient environment. As a result, this thermal resistance value may be useful for comparing packages but the test conditions don’t generally match the user’s application. • θJCtop is determined with nearly all of the component power dissipation flowing through the top of the package. As the electrical connections of the typical µModule converter are on the bottom of the package, it is rare for an application to operate such that most of the heat flows from the junction to the top of the part. As in the case of θJCbottom, this value may be useful for comparing packages but the test conditions don’t generally match the user’s application. • θJB is the junction-to-board thermal resistance where almost all of the heat flows through the bottom of the µModule converter and into the board, and is really the sum of the θJCbottom and the thermal resistance of the bottom of the part through the solder joints and through a portion of the board. The board temperature is measured a specified distance from the package, using a two sided, two layer board. This board is described in JESD 51-9. 8029f 15 LTM8029 Applications Information Given these definitions, it should now be apparent that none of these thermal coefficients reflects an actual physical operating condition of a µModule converter. Thus, none of them can be individually used to accurately predict the thermal performance of the product. Likewise, it would be inappropriate to attempt to use any one coefficient to correlate to the junction temperature vs load graphs given in the product’s data sheet. The only appropriate way to use the coefficients is when running a detailed thermal analysis, such as FEA, which considers all of the thermal resistances simultaneously. A graphical representation of these thermal resistances is given in Figure 4. The blue resistances are contained within the µModule converter, and the green are outside. The die temperature of the LTM8029 must be lower than the maximum rating of 125°C, so care should be taken in the layout of the circuit to ensure good heat sinking of the LTM8029. The bulk of the heat flow out of the LTM8029 is through the bottom of the μModule converter and the BGA pads into the printed circuit board. Consequently a poor printed circuit board design can cause excessive heating, resulting in impaired performance or reliability. Please refer to the PCB Layout section for printed circuit board design suggestions. JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD) JUNCTION-TO-CASE (TOP) RESISTANCE JUNCTION JUNCTION-TO-BOARD RESISTANCE JUNCTION-TO-CASE CASE (BOTTOM)-TO-BOARD (BOTTOM) RESISTANCE RESISTANCE µMODULE DEVICE CASE (TOP)-TO-AMBIENT RESISTANCE AMBIENT BOARD-TO-AMBIENT RESISTANCE 8029 F04 Figure 4. Graphical Representation of JESD 51-12 Thermal Coefficients 8029f 16 LTM8029 Applications Information 1.2V Step-Down Converter 2.5V Step-Down Converter LTM8029 VIN 4.5V TO 12V VIN 2.2µF LTM8029 VOUT RUN 47µF BIAS VIN 4.5V TO 36V VOUT 1.2V 600mA VIN VOUT RUN 1µF BIAS PGOOD RT GND 47µF VOUT 2.5V 600mA PGOOD FB RT 8029 TA02 309k GND FB 280k 8029 TA03 931k 5V Step-Down Converter LTM8029 VIN 7.8V TO 36V VIN VOUT RUN 1µF BIAS 22µF VOUT 5V 600mA PGOOD RT GND 158k FB 8029 TA04 309k –5V Inverting Output Converter Minimum VIN vs Output Current 12 LTM8029 2.2µF RUN BIAS PGOOD RT 10 VOUT VIN GND 8 VIN (V) VIN 4.5V TO 31V 47µF FB 6 TO START 4 158k 309k 8029 TA05 VOUT –5V RUNNING 2 0 0 100 200 300 400 500 600 OUTPUT CURRENT (mA) 8029 TA06 8029f 17 LTM8029 Package Description Table 3. Pin Assignment Table (Arranged by Pin Number) PIN FUNCTION PIN FUNCTION PIN FUNCTION PIN FUNCTION A1 RUN B1 RT C1 GND D1 GND A2 FB B2 PGOOD C2 GND D2 GND A3 – B3 – C3 – D3 GND A4 VIN B4 VIN C4 – D4 GND A5 VIN B5 VIN C5 – D5 GND PIN FUNCTION PIN FUNCTION PIN FUNCTION PIN FUNCTION E1 GND F1 GND G1 GND H1 GND E2 GND F2 GND G2 GND H2 GND E3 GND F3 VOUT G3 VOUT H3 BIAS E4 GND F4 VOUT G4 VOUT H4 VOUT E5 GND F5 VOUT G5 VOUT H5 VOUT 8029f 18 3.4925 2.8575 4 4.445 3.175 1.905 0.635 0.000 0.635 1.905 3.175 4.445 0.3175 1.270 2.540 SUGGESTED PCB LAYOUT TOP VIEW 0.3175 0.000 PACKAGE TOP VIEW 1.270 PIN “A1” CORNER E 2.540 Y D X aaa Z 2.45 – 2.55 SYMBOL A A1 A2 b b1 D E e F G aaa bbb ccc ddd eee Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights. MIN 3.22 0.50 2.72 0.71 0.60 NOM 3.42 0.60 2.82 0.78 0.63 11.25 6.25 1.27 8.89 5.08 DIMENSIONS A A2 0.15 0.10 0.20 0.30 0.15 MAX 3.62 0.70 2.92 0.85 0.66 NOTES DETAIL B PACKAGE SIDE VIEW TOTAL NUMBER OF BALLS: 35 DETAIL A b1 0.27 – 0.37 SUBSTRATE A1 ddd M Z X Y eee M Z DETAIL B MOLD CAP ccc Z Øb (35 PLACES) // bbb Z aaa Z Z F e 4 3 2 1 DETAIL A PACKAGE BOTTOM VIEW 5 G H G F E D C B A PIN 1 DETAILS OF PIN #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PIN #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE 4 TRAY PIN 1 BEVEL COMPONENT PIN “A1” BGA 35 0510 REV Ø PACKAGE IN TRAY LOADING ORIENTATION LTMXXXXXX µModule 5. PRIMARY DATUM -Z- IS SEATING PLANE BALL DESIGNATION PER JESD MS-028 AND JEP95 3 2. ALL DIMENSIONS ARE IN MILLIMETERS NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 b 3 SEE NOTES LTM8029 Package Description BGA Package 35-Lead (11.25mm × 6.25mm × 3.42mm) (Reference LTC DWG # 05-08-1878 Rev Ø) 8029f 19 LTM8029 Typical Application –12V Inverting Output Converter Minimum VIN vs Output Current, –12VOUT, BIAS = GND 25 LTM8029 VIN 4.5V TO 31V 2.2µF VIN VOUT RUN BIAS 20 PGOOD GND 137k VIN (V) RT 22µF FB 110k 8029 TA07a VOUT –12V 15 10 TO START 5 RUNNING 0 0 100 200 300 400 500 OUTPUT CURRENT (mA) 8029 TA07b Package Photo 11.25mm 3.42mm 6.25mm Related Parts PART NUMBER DESCRIPTION COMMENTS LTM8020 36V, 200mA µModule Regulator 4V ≤ VIN ≤ 36V, 1.25V ≤ VOUT ≤ 5V LTM8021 36V, 500mA µModule Regulator 3V ≤ VIN ≤ 36V, 0.8V ≤ VOUT ≤ 5V LTM8022 36V, 1A µModule Regulator 3.6V ≤ VIN ≤ 36V, 0.8V ≤ VOUT ≤ 10V LTM8023 36V, 2A µModule Regulator 3.6V ≤ VIN ≤ 36V, 0.8V ≤ VOUT ≤ 10V LTM8048 Isolated µModule Regulator 725VDC Isolation, 3.1V ≤ VIN ≤ 32V, 300mA 8029f 20 Linear Technology Corporation LT 0312 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2012