Powering CoolRunner™ -II CPLDs

Quick Start Training Agenda Regulator Overview – Linear vs. Switching – Linear Regulators – Switching Regulators CoolRunner-II Power-Up Recommendations Regulator Application Examples Our Favorite Regulators

Quick Start Training Linear vs. Switching Two main categories of regulators: – Linear: Most basic Easy to use Inexpensive – Switching: High efficiency Can create output voltages that are higher than input voltages Can produce multiple output voltages from a single input source

Quick Start Training Linear Regulators Linear Regulators use a voltage-controlled current source to force voltage to appear at the output terminal The design specification of the current source defines the maximum load current that the regulator can supply Dropout voltage is defined as the minimum voltage drop required across the regulator in order to maintain proper output regulation

Quick Start Training Linear Regulator Types Dropout Voltages of approximately 1.5V to 2.2V Best suited for AC-Powered applications, where dropout voltage is not a big concern Dropout Voltages of approximately 100 mV to 500 mV Lower dropout = highest efficiency LDO Regulators are ideal for battery powered applications Have additional features and have better output voltage precision Low-Dropout (LDO) Regulators: Standard Linear Regulators:

Quick Start Training Switching Regulators Switching regulators use Pulse Width Modulation (PWM) to control output voltage Total power consumed is proportional to duty cycle of PWM output. Therefore switching regulators are more power efficient than Linear Regulators These regulators require external inductors and capacitors to form an L-C network. This network filters the PWM output and provides DC output voltage

Quick Start Training Switching Regulator Types Used to down convert a higher DC voltage to a lower DC voltage Switching Buck Regulators are almost always more efficient than LDO Regulators Useful in battery-powered applications where a single battery or series of batteries is not quite enough to reach full rail Boost regulation can only be accomplished by switching regulators Boost Converters: Buck Converters:

Quick Start Training CoolRunner-II Power-Up Recommendations 1) Vcc Ramp should be monotonic 2) Vcc Rise time should be as fast as possible (< 4 ms) 3) Vccint/Vccio power-up sequence – Ramp Vccint before Vccio 4) Choose a regulator with sufficient current 5) Use proper decoupling capacitor techniques

Quick Start Training Regulator Application Examples

Quick Start Training Micrel Semiconductor MIC221X Dual Output LDO Regulator Key Features Multiple output voltages Vout1 = 150 mA Vout2 = 300 mA Low Dropout Voltage ( mA) Low Noise Available in 3mm x 3mm MLF Package

Quick Start Training Micrel Semiconductor MIC5211 Dual Output LDO Regulator Key Features Similar to MIC221X family More cost efficient solution Higher dropout voltage and lower output current than MIC221X family 80 mA Output Current 500 mV Dropout Voltage 2.5V - 16V input voltage specification

Quick Start Training Micrel Semiconductor MIC5247 LDO Regulator Key Features 2.7V to 6V input voltage specification 150 mA output current 150 mV Dropout Voltage

Quick Start Training Texas Instruments TPS72118 Low-Dropout Linear Regulator Key Features Capable of 150 mA load current mV Dropout 150 mA load 1.8V to 5.5V input voltage specification Requires only 0.1 uF capacitors

Quick Start Training National Semiconductor LP3964 Low-Dropout Linear Regulator Key Features Capable of 800 mA load current 240 mV Dropout 80 mA load 2.5V - 7.0V input voltage specification

Quick Start Training ON Semiconductor NCP1400A Switching Boost Regulator Key Features Capable of 100 mA load current Start-up at 0.8V and can remain in regulation down to less than 0.2V Available w/ 1.8V fixed output voltage

Quick Start Training LM317 Standard Linear Regulator Key Features Capable of A load current Adjustable output voltage 2.5V Dropout 1.5A Many manufacturers: Linear Technology, National Semiconductor, Fairchild

Quick Start Training Our Favorite Regulators

Quick Start Training Our Favorite Regulators

Quick Start Training Our Favorite Regulators

Quick Start Training Summary For further reading get – XAPP389: Powering CoolRunner-II CPLDs Questions?