per the instructions raised the ‘pwm offset’ parameter from original 1.0v setting. i found that...

7
Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that. The test load here is similar to SSD actual loads, but not exactly same. I chose the setpoint 2.900V to have about 7.5V terminal voltage with my maximum load (which is 5/4 Ω in today’s simple setup). The cable here is 20AWG 100feet. Actual SSD cable is 18AWG 100feet + inner cable. With the new setting there is no evidence of current limiting either static or in transient load tests.

Upload: magnus-roberts

Post on 04-Jan-2016

212 views

Category:

Documents


0 download

TRANSCRIPT

Page 1: Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that

Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that.The test load here is similar to SSD actual loads, but not exactly same. I chose the setpoint 2.900V to have about 7.5V terminal voltage with my maximum load (which is 5/4 Ω in today’s simple setup).The cable here is 20AWG 100feet. Actual SSD cable is 18AWG 100feet + inner cable.

With the new setting there is no evidence of current limiting either static or in transient load tests.

Page 2: Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that

1.74A to 2.33A

2.33A to 1.74A

Load capacitance: 2x470uF(TAJD477K006RNJ)

Load switched mechanically by tapping on/off the 4th resistor lead. Some glitches probably occur in this process, I generally rejected and retook measurements that were obviously glitchy.

Page 3: Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that

2.33A to 1.74A

1.74A to 2.33ALoad capacitance: 1x470uF(TAJD477K006RNJ)

Page 4: Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that

1.74A to 2.33A

2.33A to 1.74A

Load capacitance: ~10uF Y5V ceramicNOTE SCALE CHANGE

Page 5: Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that

1.74A to 2.33A

2.33A to 1.74A

Load capacitance: NONE

Page 6: Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that

Summary is that it is stable under all those conditions and no current limiting is seen in the transient response. All good!

The SSD group internally needs to quantify what transient loads will actually be expected, and then evaluate if the resulting voltage excursions are tolerable. If not, then point-of-load regulation needs to be added/modified.

I believe the response we see from this power supply on 100 feet cable is reasonably optimal, no complaints.

All this focussed on the “medium” loop gain control setting. I did confirm that “fast” control is unstable (as advertised/expected), and that “slow” is a real extreme slow loop and of no utility with any transient load situation.

Page 7: Per the instructions raised the ‘PWM Offset’ parameter from original 1.0V setting. I found that 5.0V worked, and so set 6.0V to have some margin over that

Ripple/noise: Nothing detectable at load with simple measurement (500MHz BW, P6139A 10x atten. probe). Good.

At load At PS terminals