Renesas RTKA214250DE0020BU User manual

Evaluation Board Manual
R16UZ0023EU0100 Rev.1.00 Page 1
Sep 23, 2021 © 2021 Renesas Electronics
The RTKA214250DE0020BU evaluation board
provides a simple platform to evaluate the 3×3mm
8 Ld DFN and SOIC version of the RAA214250 on the
same board.
The RAA214250 is a low-dropout linear voltage
regulator that operates from 2.5V to 20V and provides
up to 500mA of output current with a typical dropout
of 269mV. The output voltage is adjustable with
external feedback resistors anywhere from 1.224V to
18V.
Features
▪Wide input voltage range: 2.5V to 20V
▪Adjustable output voltage range: 1.224 to 18V with
±2% accuracy
▪Excellent line and load regulation
▪Stable with MLCC output capacitor as low as 2.2µF
▪Integrated Fault protections including thermal
shutdown and short-circuit current limit with
foldback
▪3mm×3mmDFN and SOIC can be evaluated on
the same board
Specifications
This board is specified for the following operating
conditions:
▪VIN supply: 2.5V to 20V
▪VOUT adjustable by changing the feedback resistor
divider.
▪Low Dropout of 269mV at 500mA
▪Short Circuit Current Limit Protection with fold-back
at higher input voltages
Figure 1. Block Diagram - SOIC
Figure 2. Block Diagram - DFN
VIN VO UT
RAA214250
VE N
NCGND
VIN VO UT
ADJ
R1
100kΩ
R2
57.6kΩ
C1
10µF
C2
1µF
C5
4.7µF
VOUT
3.3V,
IOUT ( MAX )
500mA
VIN
2.5V – 20V C6
22pF
(opti onal )
VEN
2.5V – 20V
VIN VO UT
RAA214250
VE N
NCGND
VIN VO UT
ADJ
R3
100kΩ
R4
57.6kΩ
C3
10µF
C4
1µF
C7
4.7µF
V
OUT
3.3V,
I
OUT( MAX)
500mA
V
IN
2.5V – 20V C8
22pF
(optional)
V
EN
2.5V – 20V
RTKA214250DE0020BU

R16UZ0023EU0100 Rev.1.00 Page 2
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RTKA214250DE0020BU Evaluation Board Manual
Contents
1. Functional Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Adjusting The Output Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Using the Feed-Forward Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.3 Enabling and Disabling the Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.4 Quick Start Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2. Board Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1 Layout Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Schematic Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.3 Bill of Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.4 Board Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
3. Typical Performance Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
4. Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5. Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

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Sep 23, 2021
RTKA214250DE0020BU Evaluation Board Manual
1. Functional Description
The RTKA214250DE0010BU evaluation board provides a simple platform to evaluate the features of the
RAA214250 LDO and help characterize important critical performance parameters. The evaluation board is
functionally optimized to allow efficient operation up to the maximum output current of 500mA.
1.1 Adjusting The Output Voltage
The RAA214250 output voltage (VOUT) can be programmed down to 1.224V and up to 18V using the feedback
(FB) resistors, R1and R2for the SOIC package (Figure 3) or R3and R4for the DFN package (Figure 4).
To simplify the explanation for how to change the output voltage R1and R2is referred to as RF, and R2and R3is
referred to as RGas shown in Figure 5.
VOUT is calculated using Equation 1.
Figure 3. RAA214250 SOIC Simplified Application Schematic
Figure 4. RAA214250 DFN Simplified Application Schematic
Figure 5. RAA214250 Simplified Application Schematic
(EQ. 1)
VIN VO UT
RAA214250
VE N
GND
ADJ R
1
R
2
C
IN
C
OUT
C
6
C
FF
(optional)
VIN VO UT
RAA214250
VE N
GND
ADJ R
3
R
4
C
IN
C
OUT
C
8
C
FF
(optional)
VIN VO UT
RAA214250
VE N
GND
ADJ R
F
R
G
C
IN
C
OUT
C
FF
(optional)
VOUT 1.224V 1
RF
RG
--------
+



=

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Sep 23, 2021
RTKA214250DE0020BU Evaluation Board Manual
Similarly, the RFand RGresistors are calculated for any target output voltage by rearranging Equation 1 to get
Equation 2 and solving for RF.
Table 1 suggests the FB resistor values to get some common voltage rails with 0.1% error. These resistors are
commercially available in 0.1% tolerances. This table is not exhaustive and there may be other RFand RGresistor
combinations that can provide better accuracy. These resistor values also only require the user to change the RG
resistor instead of both resistors.
1.2 Using the Feed-Forward Capacitor
A Feed-Forward Capacitor (CFF) in parallel with the RFresistor as shown in Figure 5 can be used to improve the
transient, noise, start-up, and PSRR performance. However, it is not necessary to use one to achieve stability.
Table 2 lists some recommended RFand RGresistors and feed-forward capacitor combinations for typical voltage
rails. Keep in mind that the RFand RGresistor values listed can be used without a feed-forward capacitor as well.
When using the feed-forward capacitor it is generally better to keep RGconstant which is why Table 2 shows
different RFand RGvalues than Tabl e 1 .
(EQ. 2)
Table 1. Recommended RFand RGFeedback Resistor Values for Common Voltage Rails
VOUT(TARGET) (V) RF(kΩ)R
G(kΩ) Error (%)
1.224 0 None 0.0
1.5 100 442 -0.1
1.8 100 210 -0.4
1.9 100 180 -0.2
2.5 100 95.3 -0.3
3 100 68.1 -0.7
3.3 100 59 0.0
4.2 100 41.2 0.1
4.5 100 37.4 0.1
5 100 32.4 0.0
9 100 15.8 0.3
12 100 11.3 -0.5
18 100 7.32 0.3
Table 2. Recommended RFand RGFeedback Resistor Values for Common Voltage Rails
VOUT(TARGET) (V) RF (kΩ)R
G(kΩ)C FF (pF) Error (%)
1.224 None 0 47 0.0
1.5 13 57.6 43 0.0
1.8 27 57.6 39 0.1
1.9 31.6 57.6 37 0.2
2.5 60.4 57.6 30 -0.3
3 84.5 57.6 25 -0.7
3.3 97.6 57.6 22 0.1
RFRG
VOUT TARGET
1.224V
-------------------------------------------- 1–


=

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RTKA214250DE0020BU Evaluation Board Manual
1.3 Enabling and Disabling the Device
The evaluation board has a test point connected to the device EN pin for both the SOIC and DFN package
options, which means this pin is floating. Do not let this pin float. Instead, to ENABLE the device, connect the
same power supply powering VIN to the EN_U1 or EN_U2 test points depending on the package option. This sets
the part to automatically ENABLE when the VIN supply is powered up. To DISABLE the device, connect the
EN_U1 or EN_U2 test points to Ground somewhere on the board such as GND_U1_IN1 or GND_U2_IN2.
To control the EN pin independent of VIN, a separate power supply or signal generator can be connected between
EN_U1 and GND_U1_IN1 for the DFN package or EN_U2 and GND_U2_IN1 for the SOIC package.
1.4 Quick Start Guide
Complete the following steps if using the 3x3mm 8-Ld DFN package.
1. Connect the input supply to the terminals marked VIN_U1 and GND_U1_IN1.
2. For automatic enabling, connect the same input supply’s positive terminal to EN_U1. If powering EN with a
separate power supply or signal generator connect the leads to EN_U1 and GND_U1_IN1.
3. Connect the load to the output terminals VOUT_U1 and GND_U1_OUT1
4. After setting the input voltage and load conditions turn on the input supply followed by the load if applicable.
5. Observe the output voltage.
Complete the following steps if using the 8-Ld SOIC package.
1. Connect the input supply to the terminals marked VIN_U2 and GND_U2_IN1.
2. For automatic enabling, connect the same input supply’s positive terminal to EN_U2. If powering EN with a
separate power supply or signal generator connect the leads to EN_U2 and GND_U2_IN1.
3. Connect the load to the output terminals VOUT_U1 and GND_U1_OUT2
4. After setting the input voltage and load conditions turn on the input supply followed by the load if applicable.
5. Observe the output voltage.
4.2 140 57.6 17 0.0
4.5 154 57.6 16 0.1
5 178 57.6 15 -0.1
9 365 57.6 DNP 0.2
12 511 57.6 DNP -0.7
18 787 57.6 DNP 0.3
Table 2. Recommended RFand RGFeedback Resistor Values for Common Voltage Rails (Cont.)
VOUT(TARGET) (V) RF (kΩ)R
G(kΩ)C FF (pF) Error (%)

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RTKA214250DE0020BU Evaluation Board Manual
2. Board Design
2.1 Layout Guidelines
A proper PCB layout is important to achieve expected performance. Consideration should be taken when placing
the components and routing the trace to minimize the ground impedance, and keep the parasitic inductance low.
The input and output capacitors should have a good ground connection and be placed as close to the IC as
possible. The feedback resistors should be placed as close to the IC as possible. If using a feed-forward capacitor
make sure it is also close to the RF resistor. The trace for FB must be away from noisy planes and traces.
Figure 6. RTKA214250DE0020BU Evaluation Board

R16UZ0023EU0100 Rev.1.00 Page 7 Sep 23, 2021 RTKA214250DE0020BU Evaluation Board Manual
2.2 Schematic Diagrams
Figure 7. RTKA214250DE0020BU Schematic
S1
S1 S1
S1
S1 S1
S1
S1
S1
S1
S1
S1
C2
1UF
C5
4.7UF
GND_U1_OUT1
GND_U2_IN1
VIN_U1
C6
22PF
VOUT_U1
VIN_U2
VIN_IN_TP2
R4
57.6K
EN_U1
R3
100K
R2
57.6K
VIN
VIN
EN
GND NC
ADJ
VOUT
VOUT
PAD
U2
RAA214250GSP
1
2
3
45
6
7
8
9
VOUT_U2_TP2
C3
10UF
R1
100K
C1
10UF
GND_U2_OUT1
GND_IN_TP1
GND_IN_TP2
VIN_IN_TP1
VOUT_U2
C7
4.7UF
GND_U1_IN1
VIN
VIN
EN
GND NC
ADJ
VOUT
VOUT
PAD
U1
RAA214250GNP
1
2
3
45
6
7
8
9
C4
1UF
C8
22PF
VOUT_U1_TP1
EN_U2
UNNAMED_3_RAA214250_I515_2
UNNAMED_3_RAA214250_I515_3UNNAMED_3_RAA214250_I 515_6
UNNAMED_3_RAA214250_I 515_7
UNNAMED_3_RAA2 14250_I518_1
UNNAMED_3_RAA2 14250_I518_3UNNAMED_3_RAA2 14250_I518_6
UNNAMED_3_RAA2 14250_I518_7

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RTKA214250DE0020BU Evaluation Board Manual
2.3 Bill of Materials
Qty Reference Designator Description Manufacturer Manufacturer Part
1PWB-PCB,
RTKA214250DE0020BU,
REVA, ROHS
Imagineering Inc RTKA214250DE0020BURVAPCB
2 C6, C8 CAP, SMD, 0603, 22pF, 50V,
10%, X7R, ROHS
Various Generic
2 C2, C4 CAP, SMD, 0805, 1.0µF, 50V,
10%, X7R, ROHS
Murata GRM21BR71H105KA12L
2 C1, C3 CAP, SMD, 1210, 10µF, 50V,
10%, X5R, ROHS
Murata GRM32ER71H106KA12L
2 C5, C7 CAP, SMD, 1210, 4.7µF, 50V,
10%, X7R, ROHS
Venkel C1210X7R500-475KNE
10 EN_U1, EN_U2, VIN_U1,
VIN_U2, VOUT_U1,
VOUT_U2, GND_U1_IN,
GND_U2_IN,
GND_U1_OUT,
GND_U2_OUT
CONN-TURRET, TERMINAL
POST, TH, ROHS
Keystone 1514-2
2 VOUT_U1_TP1,
VOUT_U2_TP2
CONN-MINI TEST PT,
VERTICAL, RED, ROHS
Keystone 5000
2 GND_IN_TP1, GND_IN_TP2 CONN-MINI TEST PT,
VERTICAL, BLK, ROHS
Keystone 5001
2 VIN_IN_TP1, VIN_IN_TP2 CONN-MINI TEST POINT,
VERTICAL, WHITE, ROHS
Keystone 5002
1 U1 IC-20V, 500mA LDO
REGULATOR, 8P, DFN, ROHS
Renesas Electronics RAA2142504GNP#AA0
1 U2 IC-20V, 500mA LDO
REGULATOR, 8P, SOIC, ROHS
Renesas Electronics RAA2142504GSP#HA0
2 R1, R3 RES, SMD, 0603, 100k, 1/10W,
1%, TF, ROHS
Various Generic
2 R2, R4 RES, SMD, 0603, 57.6k, 1/10W,
1%, TF, ROHS
Various Generic
4 Bottom four corners BUMPONS,0.44inWx0.20inH,
CYLINDRICAL DOME, BLK,
ROHS
3M SJ-5003 (BLACK)

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RTKA214250DE0020BU Evaluation Board Manual
2.4 Board Layout
Figure 8. Top Layer Silkscreen Figure 9. Top Layer
Figure 10. Bottom Layer

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RTKA214250DE0020BU Evaluation Board Manual
3. Typical Performance Graphs
4. Ordering Information
5. Revision History
Figure 11. Dropout Voltage vs Input Voltage for Various
Junction Temperatures (IOUT = 500mA)
Figure 12. Ground Current vs Input Voltage for Various
IOUT (VEN = 5V, VOUT = VADJ)
Figure 13. Load Transient Response for Various
Junction Temperatures (VIN = 4.3V, VOUT = 3.3V,
COUT = 2.2µF, CFF = 22pF, ∆IOUT = 1mA to 500mA at
100mA/µs)
Figure 14. Start-Up Time for Various Junction
Temperatures (VIN = 4.3V, VOUT = 3.3V, IOUT = 500mA,
CFF = 22pF, COUT = 2.2µF)
Part Number Description
RTKA214250DE0020BU RAA214250 DFN and SOIC package evaluation board
Revision Date Description
1.00 Sep 23, 2021 Initial release
100
150
200
250
300
350
400
450
2.5 5.0 7.5 10.0 12.5 15.0 17.5
20.0
Dropout Voltage (mv)
Input Voltage (V)
-40°C 0°C 25°C
85°C 125°C
0
20
40
60
80
100
120
140
160
180
200
2.5 5 7.5 1012.51517.5
20
Ground Current (µA)
Input Voltage (V)
0mA 10mA 50mA
100mA 300mA 500mA
Time (100µs/div)
-40°C 0°C 25°C 85°C 125°C
IOUT (250mA/div)
VOUT (50mV/div)
Time (20µs/div)
-40°C 0°C 25°C 85°C 125°C
VEN (2V/div)
VOUT (1V/div)