PRM48BF480T500A00 Datasheet, PDF (28/45 Pages) Vicor Corporation – PRM™ Regulator

PRM48B x 480 y 500A00
VCCINT
VTRIM
10K
TRIM
Micro
Controller
RTRIM
SGND
Figure 25: TRIM Connection
The output as a function of V_TRIM is defined by equation (1) for
1.00 V ≤ V_TRIM ≤ 2.75 V, and allows for an output voltage
ranging from 20V to 55V.
The TRIM pin is pulled up internally to V_{CC_INT} thorough a
10 kΩ resistor. V_TRIM can be actively set with a DAC that is
ground referenced to SGND. V_TRIM can be passively set by
connecting a resistor, R_TRIM, from TRIM to SGND such that the
voltage divider made with V_{CC_INT} and the 10 kΩ pull up yields
the desired V_TRIM. The formula for calculating this resistor is
provided in Equation (1a).
∙ 20
(1)
∙
∙
∙_{_}
_
_
(1a)
For 1.00 V≤ V_TRIM ≤ 2.75 V
Where V_{OUT_SET} is the desired output voltage
The output voltage tranfer function saturates for applied TRIM
voltages above approximately 2.75V as illustrated in Figure 26
to prevent the output from being driven above its rated output
voltage.
When TRIM is set lower than 1.00 V the output voltage is not
specified and stable operation is not guaranteed.
PRM V_OUT vs V_TRIM
60
60
Recommended Range
50
50
40
40
30
30
20
20
10
10
Unspecified
Operation
0
0
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
TRIM Pin Voltage (V)
Output Voltage (V)
AT Pin Resistor (KΩ)
Figure 26: PRM V_OUT vs. V_TRIM
When trim is enabled the voltage at this pin is sampled at
120 µs intervals to determine the trim level. The output can be
dynamically trimmed during normal operation, however it is not
recommended to use this pin in an external analog feedback
loop.
Refer to Table 1 for a summary of the TRIM pin functionality
and the recommended voltage/resistance that should be
applied to this pin.
TRIM PIN FUNCTION SUMMARY
Operating State
V_TRIM
R_TRIM
Detected and Latched
Remote Sense / Slave Operation
Adaptive Loop Operation
<0.45V
>0.55V_{2}
<1 kΩ
> 3 kΩ _{2}
After application of V_IN when
ENABLE first transitions high
After application of V_IN when
ENABLE first transitions high
Adaptive Loop Operation
Trim Active
V_OUT = 20* V_TRIM
1.00 V to 2.75 V
4.32 kΩ to 49.9 kΩ
At every start up when
Trim Mode
Trim Inactive
V_OUT = 48V
>3.2 V
>10 MΩ
ENABLE transitions high
Table 1: TRIM Pin Function Summary
{2} ^{It is not recommended to configure TRIM with a voltage less than 1.00V in Adaptive Loop operation}
- 28 -
Rev. 1.0
11/2012