Figure 3. 12V input to 1.8V output, 2.5A regulator with digital output current monitoring
Figure 4. 5V Input to 2.5V output at 1MHz synchronized frequency with input current monitor and 475mA input current limit
current to 475mA while producing an output voltage of 2.5V from a 5V input voltage.
Temperature monitoring The LTC3626 produces an estimate of the on-die temperature at the TMON pin. This feature can be used to determine the quality of the ground connection to the QFN exposed pad made
though the on-die temperature may be far too high for reliable, long-term part operation. Measurement of the TMON pin however gives the user insight into the exposed pad connection and hence the internal part operating environment.
Figure 5. It is easy to determine the quality of the exposed pad connection by examining temperature measurements made by the LTC3626.
during assembly. The exposed pad for the QFN is intended to provide a low impedance electrical connection to the board as well as good thermal contact. Visual inspection of this critical connection can be difficult, and a poor exposed pad connection may not be apparent by simple observation of the regulated output voltage even
As an example, Figure 5 shows data taken on two parts, one with a good exposed pad connection to the PCB, the other with a poor exposed pad connection. Though both parts regulate to the expected output voltage, it is clear from the internal temperature measurement that the internal operating environment is very different between the two parts. If placed in a system with an ambient operating temperature of say 70ºC, the device with the poor exposed pad connection will clearly exceed the maximum allowed junction temperature of 125ºC and will thus have compromised long-term reliability. The continuous push for higher performance and power density faced by today’s system designers require small, flexible, and efficient point-of-load converters to maximize overall power chain efficiency. The LTC3626’s combination of wide input voltage range, output current capability, flexible feature set, and very small form factor make it ideal for many of today’s point-of-load regulator applications.
Linear Technology |
wwww.linear.com
Keith Bassett, Design Engineering Section Leader, Linear Technology
May 2013 CIE Power Supplement
7
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64