VISHAY SILICONIX www.vishay.com Power MOSFETs Application Note AN917 Dual-Channel LITTLE FOOT ® 6-Pin SC-70 MOSFET Copper Leadframe Version Recommended Pad Pattern and Thermal Performance 175 °C Rated Part INTRODUCTION The new dual 6-pin SC-70 package with a copper leadframe enables improved on-resistance values and enhanced thermal performance as compared to the existing 3-pin and 6-pin packages with Alloy 42 leadframes. These devices are intended for small to medium load applications where a miniaturized package is required. Devices in this package come in a range of on-resistance values, in n-channel and p-channel versions. This technical note discusses pin-outs, package outlines, pad patterns, evaluation board layout, and thermal performance for the dual-channel version. 87 (mil) 26 (mil) 6 5 4 96 (mil) 71 (mil) 48 (mil) 23 (mil) PIN-OUT Figure 1 shows the pin-out description and pin 1 identification for the dual-channel SC-70 device in the 6-pin configuration. Both n-and p-channel devices are available in this package – the drawing example below illustrates the p-channel device. 61 (mil) 1 2 3 0.0 (mil) 8 (mil) 26 (mil) SOT-363 SC-70 (6-LEADS) 16 (mil) S1 1 6 D1 G1 2 5 G2 D2 3 4 S2 Top View Fig. 1 For package dimensions see outline drawing SC-70 (6-Leads) (www.vishay.com/doc?71154) See Application Note 826, Recommended Minimum Pad Patterns With Outline Drawing Access for Vishay Siliconix MOSFETs, (www.vishay.com/doc?72286) for the SC-70 6-pin basic pad layout and dimensions. This pad pattern is sufficient for the low-power applications for which this package is intended. Increasing the drain pad pattern (figure 2) yields a reduction in thermal resistance and is a preferred footprint. Revision: 15-Apr-13 EVALUATION BOARD FOR THE DUAL-CHANNEL SC70-6 The 6-pin SC-70 evaluation board (EVB) shown in figure 3 measures 0.6 in. by 0.5 in. The copper pad traces are the same as described in the previous section, Basic Pad Patterns. The board allows for examination from the outer pins to the 6-pin DIP connections, permitting test sockets to be used in evaluation testing. The thermal performance of the dual 6-pin SC-70 has been measured on the EVB, comparing both the copper and Alloy 42 leadframes. This test was then repeated using the 1-inch2 PCB with dual-side copper coating. A helpful way of displaying the thermal performance of the 6-pin SC-70 dual copper leadframe is to compare it to the traditional Alloy 42 version. Document Number: 75130 1 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 APPLICATION NOTE BASIC PAD PATTERNS Fig. 2 SC-70 (6 leads) Dual Application Note AN917 www.vishay.com Vishay Siliconix Dual-Channel LITTLE FOOT® 6-Pin SC-70 MOSFET Copper Leadframe Version Recommended Pad Pattern and Thermal Performance 175 °C Rated Part Front of Board SC70-6 Back of Board SC70-6 S1 D1 G1 G2 D2 S2 vishay.com SC70−6 DUAL Fig. 3 THERMAL PERFORMANCE COOPER LEADFRAME Junction-to-Foot Thermal Resistance (the Package Performance) ROOM AMBIENT 25 °C Thermal performance for the dual SC-70 6-pin package is measured as junction-to-foot thermal resistance, in which the “foot” is the drain lead of the device as it connects with the body. The junction-to-foot thermal resistance for this device is typically 80 °C/W, with a maximum thermal resistance of approximately 100 °C/W. This data compares favorably with another compact, dual-channel package - the dual TSOP-6 - which features a typical thermal resistance of 75 °C/W and a maximum of 90 °C/W. Power Dissipation for 175 °C Rated Part The typical RJA for the dual-channel 6-pin SC-70 with a copper leadframe is 224 °C/W steady-state, compared to 413 °C/W for the Alloy 42 version. All figures are based on the 1-inch2 FR4 test board. The following example shows how the thermal resistance impacts power dissipation for the dual 6-pin SC-70 package at varying ambient temperatures. Alloy 42 Leadframe ALLOY 42 LEADFRAME APPLICATION NOTE ROOM AMBIENT 25 °C PD T J(max.) - TA R JA T J(max.) - TA R JA PD T J(max.) - TA R JA PD 175 °C - 25 °C 224 °C/W PD 175 °C - 60 °C 224 °C/W PD 669 mW PD 513 mW Although they are intended for low-power applications, devices in the 6-pin SC-70 dual-channel configuration will handle power dissipation in excess of 0.5 W. TESTING To further aid the comparison of copper and Alloy 42 leadframes, Figures 4 and 5 illustrate the dual-channel 6-pin SC-70 thermal performance on two different board sizes and pad patterns. The measured steady-state values of RJA for the dual 6-pin SC-70 with varying leadframes are as follows: LITTLE FOOT 6-PIN SC-70 ELEVATED AMBIENT 60 °C PD T J(max.) - TA R JA PD 175 °C - 25 °C 413 °C/W PD 175 °C - 60 °C 413 °C/W PD 363 mW PD 278 mW Revision: 15-Apr-13 PD ELEVATED AMBIENT 60 °C 1) Minimum recommended pad pattern on the EVB board (see fig. 3). 1-inch2 2) Industry standard PCB with maximum copper both sides. ALLOY 42 COPPER 518 °C/W 344 °C/W 413 °C/W 224 °C/W The results indicate that designers can reduce thermal resistance (JA) by 34 % simply by using the copper leadframe device as opposed to the Alloy 42 version. In this example, a 174 °C/W reduction was achieved without an increase in board area. If an increase in board size is feasible, a further 120 °C/W reduction can be obtained by utilizing a 1-inch2. PCB area. Document Number: 75130 2 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000 Application Note AN917 www.vishay.com Vishay Siliconix Dual-Channel LITTLE FOOT® 6-Pin SC-70 MOSFET Copper Leadframe Version Recommended Pad Pattern and Thermal Performance 175 °C Rated Part Dual: Sx19xxEDH or Sx19xxEEH Compl.: Sx15xxEDH or Sx15xxEEH 500 500 400 400 Thermal Resistance (°C/W) Thermal Resistance (°C/W) The dual copper leadframe versions have the following suffix: 300 Alloy 42 200 Copper 100 300 Alloy 42 200 100 Copper 0 0 10-5 10-4 10-3 10-2 10-1 1 10 100 1000 Time (s) APPLICATION NOTE Fig. 4 Dual SC70-6 Thermal Performance on EVB Revision: 15-Apr-13 10-5 10-4 10-3 10-2 10-1 1 10 100 1000 Time (s) Fig. 5 Dual SC70-6 Comparison on 1-inch2 PCB Document Number: 75130 3 For technical questions, contact: [email protected] THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000