QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 389 HIGH EFFICIENCY NOTEBOOK CPU POWER SUPPLY LTC3778 DESCRIPTION Demonstration circuit 389 is a step down controller ment. DC389 includes a dynamic load circuit for the featuring the LTC3778. It produces an output voltage convenience of the user. suitable for Intel Mobile Tualatin, Low Voltage Tualatin There are three versions of the board: and Ultra Low Voltage mobile processors. The 389A-A: Mobile Tualatin, 23A max output LTC3778 is a synchronous step-down controller. It uses valley current control architecture to deliver low 389A-B: Low Voltage Tualatin, 15A max duty cycles. 389A-C: Ultra Low Voltage Tualatin, 13A max The maximum current supported by each version of Design files for this circuit board are available. Call the DC389 conforms to Intel IMVP-II Mobile Proces- the LTC factory. sor Core Voltage Design Guide REF. NO. OR-2980. Please contact Intel to obtain this restricted docu- Table 1. Performance Summary PARAMETER CONDITION VALUE Minimum Input Voltage 7.5V Maximum Input Voltage 24 V I See Tables 2,3,4 OUT , OUT Typical Output Ripple V V = 12V, I =15A 20mV OUT IN OUT PP Nominal Switching Frequency 300kHz QUICK START PROCEDURE Demonstration circuit 389 is easy to set up to evalu- When measuring the input or output voltage ripple, ate the performance of the LTC3778. Refer to Figure 1 care must be taken to avoid a long ground lead on the for proper measurement equipment setup and follow oscilloscope probe. Measure the input or output volt- the procedure below: age ripple by touching the probe tip directly across the input or output and ground terminals. See Figure Table 2. Jumper Descriptions (See Figure 1) 2 for proper scope probe technique. JUMPER JUMPER POSITION DESCRIPTION 1. Set jumpers as shown in Figure 1. See also Table 2 NUM for jumper descriptions. PURPOSE 1-2 2-3 BER 2. With power off, connect the input power supply to Dynamic JP1 Disabled Enabled VIN and GND. Load VRON JP2 Enabled Disabled 3. Turn on the power in this sequence: Deep Sleep JP3 Disabled Enabled a. VIN (Do not exceed 24V) Deeper JP4 Enabled Disabled b. 3.3V Sleep c. 5V (Do not allow 5V to be ON without VIN ON) Perform- Performance Opti- Battery Opti- JP5 ance Mode mized Mode mized Mode d. 12V. 1GND VIN QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 389 HIGH EFFICIENCY NOTEBOOK CPU POWER SUPPLY 4. Check for the proper output voltages. See Tables 3 5. Once the proper output voltage is established, ad- to 5 for expected output voltages. just the load within the operating range and ob- serve the output voltage regulation, ripple voltage, If there is no output, temporarily disconnect the efficiency and other parameters. load to make sure that the load is not set too high. See Figures 3 to 5 for expected performance. + + + SCOPE OR + VOLTMETER LOAD JUMPER POSITIONS 3 2 1 + + Figure 2. Measuring Input or Out- Figure 1. Proper Measurement Equipment Setup put Ripple 2 + + + +