Other Parts Discussed in Thread: TPS63060, , TPS63070
Hi,
We have an application that requires multiple power signals, some are battery backed and others aren't. We use MOSFETS to disable various circuits when the external power drops.
The TPS63060 seems perfect for the application:
- It can run from the 12V when we have external power;
- It can run from a 3.7V Li-Ion when the main power has been lost;
- Looking at the datasheet, it can source 2A at 12V (page 11)
- It can source 800mA at 2.5V (page 1)
It means we can use this one part instead of two separate regulators.
So we ordered the TPS63060EVM from Farnell and immediately hit a problem - the voltage seemed to be jumping all over the place both from battery and from the external supply. The load varies but is generally between 500mA and 620mA but the output of the TPS was varying from 4.3V to 5V.
So we took it out of the circuit, hooked it up to a bench power supply and started connecting bunches of resistors across the output to simulate loads (monitored with our scope). We had the PWR Save jumper set to OFF. Our results are as follows:
| Vin | Load (Ω) | Expected Current (mA) | Expected Power (W) | PG output (V) | Vout (mean) | Vout (pk-pk) |
| 12.01 | OPEN | - | - | 4.655 | 5.11 | 400mV |
| 5.00 | OPEN | - | - | 4.655 | 5.11 | 400mV |
| 3.00 | OPEN | - | - | 4.655 | 5.11 | 400mV |
| 12.01 | 25 | 200 | 1 | 4.654 | 5.11 | 400mV |
| 5.03 | 25 | 200 | 1 | 4.654 | 5.12 | 400mV |
| 3.01 | 25 | 200 | 1 | 0 | 4.44 | 400mV |
| 4.19 | 25 | 200 | 1 | 0 | 5.01 | 400mV |
| 4.22 | 25 | 200 | 1 | 4.568 | 5.02 | 400mV |
| 12.01 | 12.5 | 400 | 2 | 4.652 | 5.11 | 400mV |
| 5.02 | 12.5 | 400 | 2 | 4.654 | 5.13 | 400mV |
| 3.00 | 12.5 | 400 | 2 | 0 | 5.03 | 400mV |
| 3.10 | 12.5 | 400 | 2 | 4.611 | 5.11 | 400mV |
| 3.03 | 12.5 | 400 | 2 | 0 | 5.01 | 400mV |
| 12.01 | 8.3 | 600 | 3 | 4.652 | 5.11 | 400mV |
| 5.02 | 8.3 | 600 | 3 | 4.654 | 5.14 | 400mV |
| 3.00 | 8.3 | 600 | 3 | 0 | 4.29 | 480mV |
| 4.00 | 8.3 | 600 | 3 | 0 | 5.01 | 400mV |
| 4.09 | 8.3 | 600 | 3 | 4.585 | 5.07 | 480mV |
We've noticed that the TPS63060EVM PCB has extra capacitors fitted across the output that are not described in the datasheet so we don't know the value.
We consider it possible that we've badly misinterpreted the datasheet but the TPS63060EVM-619 datasheet does say 5.0V, 800mA on page 9.
Thanks for your help,
Alan
