Datasheet
www.recom-power.com
REV.: 1/2019 RPX-4
DC/DC Converter
RPX-2.5
Series
OUTPUT VOLTAGE SETTING
Specifications (measured @ ta= 25°C, 12Vin, 3.3Vout, full load and after warm-up unless otherwise stated, refer to test set up)
INPUT AND OUTPUT CAPACITOR
Input Capacitor
Output Capacitor
The RPX-2.5 requires a 10µF MLCC input capacitor for normal operation. For high transient load applications, an additional 47µF electrolytic capacitor
connected in parallel is recommended, rated for a ripple current of 1.25A or higher.
The RPX-2.5 requires MLCC output capacitors for normal operation (see table). Transient load reaction time can be improved by adding a speedup capacitor,
C
FF
across R
FBT
, but it is not required for normal operation or for output voltages below 2.5V.
Minimum output capacitance
Set Output Voltage
[VDC]
Ceramic
Capacitor (C
OUTn
)
[µF]
Feed Forward
Capacitor (C
FF
)
[pF]
MIN MAX
1.2 <1.5 188 (4 x 47µF) 330
1.5 <2.5 141 (3 x 47µF) 220
2.5 <3.3 94 (2 x 47µF) 100
3.3 <5 94 (2 x 47µF) 100
5 <6 47 100
V
OUT
+V
out
FB
R
FBT
open open
R
FBB
V
IN
V
IN
DNC SW
CTRL
GND
RPX-2.5
R
ULVO1
R
UVLO2
C
IN1
C
IN2
C
OUT1
C
FF
C
OUTn
. . .
R
FBB
=
V
REF
Vout
set
- d
R
FBB
=
6VDC
= 2.22kW
3.3VDC - 0.6
R
FBB
according to E96 ≈
2.21kW
Practical Example:
Calculation:
Vout
set
=
1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 [VDC]
R
FBB
(E96) ≈
10k 8k45 7k5 6k65 6k04 5k36 4k99 4k64 4k22 4k02 [W]
Vout
set
=
2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3 3.1 [VDC]
R
FBB
(E96) ≈
3k74 3k48 3k32 3k16 3k01 2k87 2k74 2k61 2k49 2k37 [W]
Vout
set
=
3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 [VDC]
R
FBB
(E96) ≈
2k32 2k21 2k15 2k05 2k 1k96 1k87 1k82 1k74 1k69 [W]
Vout
set
=
5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 6 [VDC]
R
FBB
(E96) ≈
1k3 1k27 1k24 1k22 1k2 1k18 1k15 1k13 1k1 [W]
Vout
set
=
4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5 5.1 [VDC]
R
FBB
(E96) ≈
1k65 1k62 1k58 1k54 1k5 1k47 1k43 1k4 1k37 1k33 [W]
Resistor Table:
The recommended value of R
FBT
is 10kW. The values for trim resistors shown in trim tables below are according to standard E96 values; therefore, the
specified voltage may slightly vary. For other output voltages, the value of the required R
FBB
resistor can be calculated using below equation:
Vout
nom
= nominal output voltage [VDC]
Vout
set
= trimmed output voltage [VDC]
V
REF
= reference voltage (6VDC) [VDC]
d = trim offset (0.6VDC) [VDC]
R
FBT
= Trim resistor (10kW) [kW]
R
FBB
= calculated trim resistor [kW]
V
OUT
+V
out
FB
R
FBT
open open
R
FBB
V
IN
V
IN
DNC SW
CTRL
GND
RPX-2.5
R
ULVO1
R
UVLO2
C
IN1
C
IN2
C
OUT1
C
FF
C
OUTn
. . .