TPS62736EVM-205

User's Guide SLVU819B – February 2013 – Revised August 2014 Evaluation Module for TPS62736 Ultra Low Power Buck Converter This user’s guide describes the TPS62736 evaluation module (EVM). The TPS62736 device is a highfrequency synchronous stepdown dc-dc converter optimized for ultralow-power energy harvesting applications. The converter can provide up to 50 mA of continuous current to a 1.3 V – 5.3 V output from input voltages up to 5.5 V. 1 2 3 4 Contents Introduction ................................................................................................................... 2 1.1 TPS62736EVM Schematic ........................................................................................ 3 Performance Specification Summary ..................................................................................... 3 Test Summary ................................................................................................................ 4 3.1 Recommended Equipment ........................................................................................ 4 3.2 Equipment and EVM Setup........................................................................................ 4 3.3 Tips when Measuring Efficiency .................................................................................. 5 3.4 Tips for Taking Scope Plots ....................................................................................... 5 PWR205 PCB Layout and Bill of Materials ............................................................................... 8 4.1 REV A PCB Layout (FUNCTIONAL) ............................................................................. 8 4.2 REV B PCB Layout (BEST) ....................................................................................... 9 4.3 Bill of Materials .................................................................................................... 11 List of Figures 1 TPS62730 and TPS62733 EVM Board Schematic...................................................................... 3 2 EVM Test Setup for Measuring Efficiency 3 4 5 6 7 8 9 10 11 12 13 ............................................................................... 5 Efficiency Versus Load Current, VOUT = 1.8 V ............................................................................ 6 Steady State Operation with RO = 50 Ω .................................................................................. 6 Load Transient Response .................................................................................................. 6 Ship-Mode Startup Behavior ............................................................................................... 7 Standby-Mode Startup Behavior ........................................................................................... 7 Assembly Layer .............................................................................................................. 8 Top Layer ..................................................................................................................... 8 Bottom Layer ................................................................................................................. 9 Assembly Layer .............................................................................................................. 9 Top Layer.................................................................................................................... 10 Bottom Layer ................................................................................................................ 10 SLVU819B – February 2013 – Revised August 2014 Submit Documentation Feedback Evaluation Module for TPS62736 Ultra Low Power Buck Converter Copyright © 2013–2014, Texas Instruments Incorporated 1 Introduction 1 www.ti.com Introduction TPS62736 IC Features The TPS62736 is a highly integrated ultra low power buck converter solution that is well suited for meeting the special needs of ultra low power applications such as energy harvesting. The TPS62736 provides the system with an externally programmable regulated supply in order to preserve the overall efficiency of the power management stage versus a linear step down converter. Although intended to have input power from an energy storage element such as a Li-Ion battery or super cap, the TPS62736 can accept any input voltage up to 5.5 V, while supplying the rail to low voltage electronics. The TPS62736 integrates an optimized hysteretic controller for low power applications. The internal circuitry utilizes a time based sampling system in order to reduce the average quiescent current. This allows for the quiescent current consumption to scale with output load levels. The regulated output has been optimized to provide high efficiency across low output currents (< 10 µA) to high currents (50 mA). To further assist users in the strict management of their energy budgets, the TPS62736 toggles the input good (VIN_OK) flag to signal an attached microprocessor when the voltage on the input supply has dropped below a pre-set critical level. The intent of VIN_OK is to trigger the reduction of load currents to prevent the system from entering an undervoltage condition. Two separate enable signals allow the user to enable/disable the regulated output or place IC into an ultra-low quiescent sleep state. Two separate enable signals allow the enabling or disabling of the regulated output or allow putting the IC into an ultralow quiescent sleep state. The output voltage regulation point and input good threshold are set by external resistors. In order to maximize efficiency at light load, the use of voltage level setting resistors > 1 MΩ is recommended. However, during board assembly or modification, contaminants such as solder flux and even some board cleaning agents can leave residue that may form parasitic resistors across the physical resistors and/or from one end of a resistor to ground, especially in humid, fast airflow environments. This can result in the voltage regulation and threshold levels changing significantly from those expected per the installed resistor values. Therefore, the boards must be carefully cleaned then rinsed with de-ionized water until the ionic contamination of that water. If this is not feasible, then it is recommended that the sum of the voltage setting resistors be reduced. TPS62736EVM Features 1. Input voltage range from 2.0 V to 5.5 V 2. Output voltage set to 1.8 V but adjustable from 1.3 V to 5.3 V with external resistors 3. VIN_OK threshold of 2.9 V but adjustable from VOUT to 5.3 V with external resistors 4. Easily accessible headers for IN, IN-SENSE, OUT, OUT-SENSE, GND, VIN_OK 5. Jumpers for EN1 and EN2 2 Evaluation Module for TPS62736 Ultra Low Power Buck Converter SLVU819B – February 2013 – Revised August 2014 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Introduction www.ti.com 1.1 TPS62736EVM Schematic IN J1 2.0V-5.5V, 200m A IN -SN S G N D -SN S J2 GND C1 C2 4.7uF 0.1uF 1 2 J3 3 4 5 VIN 6 HI 7 EN 1 LO JP1 J4 U1 TPS62736RG Y VIN NC NC SW NC VSS NC VO U T EN 1 VIN _O K EN 2 VO U T_SET VRD IV PG O O D _SET PW PD R3 4.32M O UT 14 L1 13 12 C3 C4 22uF 10 uH 1.3V-5.3V, 50m A J5 O U T-SN S 1 11 10 G N D -SN S 9 8 15 GND J6 R2 3.4M VIN HI J7 VIN _O K EN 2 LO R1 5.49M JP2 GND Figure 1. TPS62730 and TPS62733 EVM Board Schematic 2 Performance Specification Summary Specification Conditions MIN Input dc voltage, IN TYP 2.0 MAX 5.5 UNIT V Output dc voltage, OUT Adjustable by changing external resistors from 1.3 V to 5.3 V 1.8 V VBAT_OK threshold Adjustable by changing external resistors from OUT to 5.3 V 2.9 V Output current 0 SLVU819B – February 2013 – Revised August 2014 Submit Documentation Feedback 50 Evaluation Module for TPS62736 Ultra Low Power Buck Converter Copyright © 2013–2014, Texas Instruments Incorporated mA 3 Test Summary www.ti.com 3 Test Summary 3.1 Recommended Equipment • • • • • 3.2 Adjustable dc power supply between 2.0 V and 5.5 V with the adjustable current limit set to approximately 100 mA Load: system load or resistive load ≥ 300 Ω Two digital multimeters configured to measure voltage (equivalent or better) Two digital multimeters configured to measure current (equivalent or better). NOTE: Due to the input current pulses inherent to a hysteretically-controlled converter, the input current meter must be capable of filtering and/or averaging in order to measure the correct value. Adding a large (> 100 µF) capacitor between IN and GND may be necessary to assist with filtering. Use of a sourcemeter, configured to regulate voltage and measure current, or power, or both current and power is also recommended. Oscilloscope with up to four voltage probes Equipment and EVM Setup Table 1. Setup I/O Connections and Configuration for Measuring Efficiency of TPS62736 EVM Jack and Component (Silk Screen) Description Connect or Adjustment To: J1 (IN) Negative lead of current meter (CM#1) J2-1 (+ IN SNS) Kelvin connection to capacitance Positive lead of voltmeter (VM#1) J2-2 (- GND SNS) Kelvin connection to capacitance Negative lead of voltmeter (VM#1) J3 (GND) Power supply negative lead J4 (OUT) Positive lead of current meter (CM#2) J5-1 (+ OUT SNS) Kelvin connection to capacitance Positive lead of voltmeter (VM#2) J5-2 (- GND SNS) Kelvin connection to capacitance Negative lead of voltmeter (VM#2) J6 (GND) J7-1 (VIN_OK) Negative lead to load resistance Push-pull output of comparator that indicates the status of the input voltage J7-2 (GND) 4 n/a n/a JP1 (EN1) EN1 = HI and EN2 = x implements full standby mode. Switching converter and VIN_OK indication is off (ship mode). EN1 = LO JP2 (EN2) EN1 = LO and EN2 = HI implements full buck converter mode. EN1 = LO and EN2 = LO implements partial standby mode. Switching converter is off, but VIN_OK indication is on. EN2 = HI Evaluation Module for TPS62736 Ultra Low Power Buck Converter SLVU819B – February 2013 – Revised August 2014 Submit Documentation Feedback Copyright © 2013–2014, Texas Instruments Incorporated Test Summary www.ti.com Table 1 and Figure 2 show the test setup for measuring efficiency. CM #1