User Guide 012 ISL72991RHEVAL2Z Evaluation Board User Guide Description Key Features The ISL72991RHEVAL2Z platform showcases the radiation hardened ISL72991RH, a low dropout adjustable negative voltage regulator with an output voltage range of -2.25V to -26V. The device features a 1A output current capability, an adjustable current limit pin (ILIM) and a shutdown pin (SD) for easy on/off control. • Small, compact design Specifications • VIN range of -3V to -30V • VOUT adjustable from -2.25V to -26V • Convenient power connection References ISL72991RH Datasheet This board has been default configured for the following operating conditions: Ordering Information • VIN = -7V to -26V PART NUMBER • VOUT = -5V ISL72991RHEVAL2Z • IMAX = 0.8A DESCRIPTION ISL72991RHEVAL2Z Evaluation Kit • Board temperature: +25°C VIN CIN RCL VOUT VIN VOUT ILIM ISL72991RH SD ADJ GND R1 COUT R2 CC FIGURE 1. ISL72991RHEVAL2Z TYPICAL USAGE BLOCK DIAGRAM January 20, 2015 UG012.1 1 FIGURE 2. ISL72991RHEVAL2Z TOP SIDE CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2015. All Rights Reserved Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries. All other trademarks mentioned are the property of their respective owners. User Guide 012 Functional Description PCB Layout Guidelines The ISL72991RHEVAL2Z board provides a simple platform to demonstrate the features and functionality of this negative voltage regulator. Capable of being biased from -3V to -30V the ISL72991RH is ideal for generating up to 1A of load current limited by its power dissipation driven die temperature for output voltages ranging from -2.25V to -26V. This platform features adjustable voltage and current limiting along with a signalled turn-on via the SD input or turn-on as input voltage is applied. The ISL72991EVAL2Z PCB layout has been optimized for electrical and thermal performance. By default, the ISL72991RHEVAL2Z is configured for an output voltage of -5V and a 0.8A current limit and also allowing for easy adjustment of both of these operating points. The board VIN range is -3V to -30V. The board VOUT is default set to -5V by a jumper JP4 and can be changed by changing the jumper position including to the jumper position (JP1) that connects to a potentiometer for a custom voltage provided beyond jumper pin strapping. The ISL72991RHEVAL2Z provides jumper configurations for several common voltages including, -2.5V, -3.3V, -5.0V, -12V, -15V and -24V. The stability of the regulator is sensitive to layout. It is strongly recommended that a continuous copper ground plane (1 ounce or greater) be used. In addition, component lead lengths and interconnects should be minimized, but should not exceed 1/2 inch. Finally, the return lead of the compensation capacitor (CC) should be connected as close as possible to the GND pin of the IC. For optimum thermal performance, generally place a pattern of vias on the layer of the PCB directly underneath the IC and connect the vias to the plane which serves as a heatsink. In general, to ensure good thermal contact, thermal interface material such as a Sil-Pad or thermally conductive epoxy should be used to fill the gap between the vias and the bottom of the IC of the ceramic package. Quick Start Guide 1. Ensure that the board is properly connected to the negative voltage supply and loads prior to applying any power. The output current limit threshold of the regulator is set with a single external resistor (RCL) connected from ILIM to ground. 2. Connect the negative voltage input supply to VIN (-7V to -30V) The effective current limit at any single RCL value is influenced by the VIN to VOUT difference, temperature and VIN amplitude. Because of these numerous variables, there is no single formula relating RCL to ICL that will suffice for the range of likely possible operating conditions. 4. Turn input power supply ON. 3. Connect the load to VOUT and GND connectors. 5. Confirm default -5V output voltage, test ISL72991RH operation. Figures 7 through 10 provide guidance in setting the RCL value for a limited number of possible conditions. Users are advised to evaluate their specific condition for satisfactory performance. Operating Range By default, the board VIN range is -7V to -30V for a VOUT of -5V and an IOUT of up to ~0.8A, both set by jumpers. Modifying the operating conditions will change the performance results. Submit Document Feedback 2 UG012.1 January 20, 2015 TP11 -3V TO -30V U1 13 SD VOUT VOUT VOUT VOUT VOUT TP5 TP9 15 ISL72991RHVF C4 R8 TP6 J2 JP4 JP2 JP1 6.81K R11 3.74K R10 JP8 TP10 DNP 3 C5 DNP 10UF JP3 2 TP12 16 ADJ 1 3 17 GND TP4 2 18 R1 TP3 ADJ 1 237 R7 392 R6 499 R5 1.43K R4 2.61K R3 -24V -15V -12V -5.0V -3.3V -2.5V VADJ GND TP8 3 50K R2 RJ1 2 4.32K 1 TP7 User Guide 012 ILIM 14 GND ILIM SD JP9 DNP 12 26 25 24 23 22 21 20 19 R9 11 TP13 27 OPEN J1 NC NC NC NC NC NC NC NC JP7 DNP VIN NC NC NC NC NC NC NC NC 28 JP6 3 10UF 3 4 5 6 7 8 9 10 OPEN C2 C3 TP2 C1 VIN VIN JP5 VIN VIN C6 2 4.32K TP1 OPEN 1 C7 Submit Document Feedback ISL72991RHEVAL2Z Circuit Schematic UG012.1 January 20, 2015 User Guide 012 Bill of Materials ITEM QTY REFERENCE DESIGNATOR MANUFACTURER PART NUMBER MANUFACTURER DESCRIPTION 1 2 J1, J2 131-4353-00 TEKTRONIX Scope Probe Test Point PCB Mount 2 8 TP1-TP8 1514-2 KEYSTONE Test Point Turret 0.150 Pad 0.100 Thole 3 1 RJ1 3262W-1-503 BOURNS Trimmer Potentiometer 4 5 TP9-TP13 5002 KEYSTONE Miniature White Test Point 0.100 Pad 0.040 Thole 5 3 C3, C6, C7 H1045-OPEN GENERIC Multilayer Cap 6 1 R8 H2505-DNP-DNP-1 GENERIC Metal Film Chip Resistor (Do Not Populate) 7 1 R9 H2506-DNP-DNP-1 GENERIC Metal Film Chip Resistor (Do Not Populate) 8 1 R5 H2511-04990-1/16W1 GENERIC Thick Film Chip Resistor 9 2 R1, R2 H2511-04301-1/16W1 GENERIC Thick Film Chip Resistor 10 1 R6 H2511-03920-1/16W1 GENERIC Thick Film Chip Resistor 11 1 R3 H2511-02611-1/16W1 GENERIC Thick Film Chip Resistor 12 1 R7 H2511-02370-1/16W1 GENERIC Thick Film Chip Resistor 13 1 R10 H2511-03741-1/16W1 GENERIC Thick Film Chip Resistor 14 1 R4 H2511-01431-1/10W1 GENERIC Thick Film Chip Resistor 15 1 R11 H2511-06811-1/16W1 GENERIC Thick Film Chip Resistor 16 1 U1 ISL72991RHVF INTERSIL RH Negative Low Dropout Adjustable Voltage Regulator 17 2 JP8, JP9 JUMPER-3-100 GENERIC Three Pin Jumper 18 7 JP1-JP7 JUMPER2_100 GENERIC Two Pin Jumper 19 4 C1, C2, C4, C5 T491D106K050AT KEMET T491 Series Solid Tantalum Chip Cap Submit Document Feedback 4 UG012.1 January 20, 2015 User Guide 012 Board Layout - 2 Layers FIGURE 3. TOP LAYER FIGURE 4. PCB – BOTTOM LAYER (VIEWED FROM TOP) Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com Submit Document Feedback 5 UG012.1 January 20, 2015 User Guide 012 Typical Performance Curves Unless noted: VIN = -12V, VOUT = -5V, TA = +25°C 1200 VDO 1000 (VOUT = -10V) +125°C VDO (mV) 800 600 +25°C 400 200 -55°C 0 200 100 0 400 300 500 700 600 800 CONTINUOUS OUTPUT CURRENT (mA) FIGURE 6. PACKAGE TEMP AT -12VIN, -5VOUT, 0.76A, Pd = 5.3W 1.4 1.6 1.2 1.4 1.0 -55°C CURRENT LIMIT (A) CURRENT LIMIT (A) FIGURE 5. DROP-OUT VOLTAGE vs AMBIENT TEMPERATURE +25°C 0.8 0.6 +125°C 0.4 0.2 0.0 1.2 -55°C 1.0 +25°C 0.8 +125°C 0.6 0.4 0.2 2.1 3 4 5.11 6 7 8 9 0.0 10 2.1 3 4 5.11 RCL (kΩ) 6 7 8 9 10 9 10 RCL (kΩ) FIGURE 7. -7VIN, -5VOUT FIGURE 8. -12VIN, -5VOUT 1.6 2.5 2.0 1.2 CURRENT LIMIT (A) CURRENT LIMIT (A) 1.4 -55°C 1.0 +25°C 0.8 +125°C 0.6 0.4 -55°C 1.5 +25°C 1.0 +125°C 0.5 0.2 0.0 2.1 3 4 5.11 6 7 RCL (kΩ) FIGURE 9. -12VIN, -10VOUT Submit Document Feedback 6 8 9 10 0.0 2.1 3 4 5.11 6 7 8 RCL (kΩ) FIGURE 10. -20VIN, -10VOUT UG012.1 January 20, 2015 User Guide 012 Dynamic Response VOUT SD (5V/DIV) (100V/DIV) IOUT (200mA/DIV) IOUT (200A/DIV) VOUT (1V/DIV) 100ms/DIV 20µs/DIV FIGURE 11. 0.1A TO 0.7A LOAD STEP. VOUT IS AC COUPLED TO ILLUSTRATE THE EXTENT OF VOLTAGE DEFLECTION FIGURE 12. SD ENABLE ON INTO 0.76A LOAD, VIN = -12V, VOUT = -5V IOUT (200mA/DIV) IOUT (200mA/DIV) VOUT (1V/DIV) VOUT (1V/DIV) 5ms/DIV 1s/DIV FIGURE 13. POWER ON INTO 0.76A LOAD, VIN = -12V, VOUT = -5V 200 40 180 35 160 25 20 100 15 80 10 GAIN 5 60 0 40 -5 20 -10 100 1k 10k FREQUENCY (Hz) 100k FIGURE 15. GAIN/PHASE -12VIN, -5VOUT, 0.5A IOUT Submit Document Feedback 7 30 140 120 0 1M 160 PHASE GAIN (dB) PHASE 180 40 PHASE (°) GAIN (dB) 30 50 140 120 20 100 10 80 PHASE (°) 45 FIGURE 14. RECOVERY FROM OVER TEMPERATURE 60 0 40 GAIN -10 20 -20 100 1k 10k 0 1M 100k FREQUENCY (Hz) FIGURE 16. GAIN/PHASE -20VIN, -15VOUT, 0.5A IOUT UG012.1 January 20, 2015