PRELIMINARY
µRAM2xxx
Ripple Attenuation @ 28V (Room Temp.)
Ripple Attenuation @ 5V (Room Temp.)
20.00
0.00
20.00
0.00
-20.00
-40.00
-60.00
-20.00
-40.00
-60.00
-80.00
-80.00
10
100
1,000
10,000
100,000
1,000,000
10,000,000
10
100
1,000
10,000
100,000
1,000,000
10,000,000
Freq. (Hz)
Freq. (Hz)
10A, 100uF Vref
10A, No Vref Cap
10A, 100uF Vref
10A, No Vref Cap
Figure 3a, 3b—Curves demonstrating the small signal attenuation performance as measured on a network analyzer with a typical
module at (a) 28V and 10A output and (b) 5V and 10A. The low frequency attenuation can be enhanced by connecting a 100µF
capacitor, CHR, to the VREF pin as shown in Figures 1 and 2.
-0
-25
-50
-75
-0
Rhr=260k (Vheadroom=90mV)
250k (100mV)
Rhr=28k (Vheadroom=90mV)
Vout=3V Iload=20A
100 degrees baseplate temperature
Vout=28V Iload=20A
100 degrees baseplate temperature
27k (100mV)
26k (110mV)
25k (122mV)
24k (135mV)
23k (150mV)
240k (110mV)
230k (122mV)
220k (135mV)
210k (150mV)
200k (160mV)
-25
-50
-75
22k (160mV)
150k (260mV)
160k (240mV)
170k (217mV)
17k (260mV)
18k (240mV)
19k (217mV)
180k (197mV)
190k (180mV)
20k (197mV)
21k (180mV)
10Hz
100Hz
... DB(V(VOUT))
1.0KHz
10KHz
100KHz
1.0MHz
10Hz
100Hz
... DB(V(VOUT))
1.0KHz
10KHz
100KHz
1.0MHz
Frequency
Frequency
Figure 4a-4b—Simulated graphs demonstrating the tradeoff of attenuation versus headroom setting at 20 Amps and an equivalent
100°C baseplate temperature at 3V and 28V.
28V 20A
-10
-20
-30
-40
-50
-60
-70
-10
-20
-30
-40
-50
-60
-70
Rhr=260k
250k
100khz 28V
500khz 28V
1Mhz 28V
100khz 3V
500khz 3V
1Mhz 3V
Rhr=28k
27k
240k
230k
26k
25k
220k
210k
24k
200k
23k
190k
22k
180k
21k
170k
20k
160k
19k
150k
18k
17k
3.0
3.5
4.0
4.5
5.0
5.5
6.0
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Watts
Watts
Figure 4c-4d—MicroRam attenuation vs. power dissipation at 3V 20A, and 28V 20A.
Notes:The measurements in Figures 8-16 were taken with a µRAM2C21 and standard scope probes with a 20MHz bandwidth scope setting. The criteria for transient current
capability was as follows: The transient load current step was incremented from 10A to the peak value indicated, then stepped back to 10A until the resulting output peak to
peak was around 40mV.
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715
MicroRAM
Rev. 1.1
Page 5 of 8
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