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Dear customer
ROHM Co., Ltd. ("ROHM"), on the 1st day of April, 2024,
has absorbed into merger with 100%-owned subsidiary of LAPIS Technology Co., Ltd.
Therefore, all references to "LAPIS Technology Co., Ltd.", "LAPIS Technology"
and/or "LAPIS" in this document shall be replaced with "ROHM Co., Ltd."
Furthermore, there are no changes to the documents relating to our products other than
the company name, the company trademark, logo, etc.
Thank you for your understanding.
ROHM Co., Ltd.
April 1, 2024
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Related Manuals for Rohm LAPIS ML7425 LSI
Summary of Contents for Rohm LAPIS ML7425 LSI
- Page 1 100%-owned subsidiary of LAPIS Technology Co., Ltd. Therefore, all references to "LAPIS Technology Co., Ltd.", "LAPIS Technology" and/or "LAPIS" in this document shall be replaced with "ROHM Co., Ltd." Furthermore, there are no changes to the documents relating to our products other than the company name, the company trademark, logo, etc.
- Page 2 FEXL7425DG-02 ML7425 LSI Design Guide Ver.1 Issue Date Mar. 19, 2024...
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Page 3: Notes
LAPIS Technology intends our Products to be used in a way indicated in this document. Please be sure to contact a ROHM sales office if you consider the use of our Products in different way from original use indicated in this document. For use of our Products in medical systems, please be sure to contact a LAPIS Technology representative and must obtain written agreement. -
Page 4: Introduction
ML7425 LSI Design Guide Introduction This Design Guide describes Notes for designing circuits using ML7425 series. (hereinafter referred to as "ML7425"). This manual contains the main RF Characteristics measurements result and condition. Target products: ML7425 Read the following manuals in addition to this Design Guide. ◼... -
Page 5: Notation
ML7425 LSI Design Guide Notation Classification Notation Description ■Numeric value 0xnn Represents a hexadecimal number. 0bnnnn Represents a binary number. ■Address 0xnnnn_nnnn Represents a hexadecimal number. (Indicates 0xnnnnnnnn) ■Unit Word, WORD 1 word = 32 bits Byte, BYTE 1 byte = 8 bits Mega, M Kilo, K (uppercase) =1024... -
Page 6: Table Of Contents
ML7425 LSI Design Guide Index Notes..............................................i Introduction ............................................ ii Notation ............................................iii Index .............................................. iv Bypass capacitor ........................................5 Crystal-oscillator circuit ....................................... 6 2.1................................7 IRCUIT CONSTANTS ON THE BOARD 2.2......................7 RECAUTIONS WHEN CONFIGURING RYSTAL OSCILLATION CIRCUIT TCXO circuit ......................................... -
Page 7: Bypass Capacitor
ML7425 LSI Design Guide Bypass capacitor Place a bypass capacitor between the power supply pin and GND as shown in Figure 1.1. Consider the following when determining the position of the bypass capacitor ⚫ For VDD and GND wires, use wires with a wider width than other signaling wires and reduce the wire resistivity. When using a via to connect to another layer, increase the via diameter, or use two vias, to reduce the resistor of the via. -
Page 8: Crystal-Oscillator Circuit
ML7425 LSI Design Guide Crystal-oscillator circuit Figure 2.1 shows an example of a typical crystal oscillator circuit. In order for the crystal oscillator circuit to oscillate stably, capacitors are required at the XIN (26) and XOUT (25) pins. When determining the final constant, please evaluate and determine the stray capacitance of your board. -
Page 9: Circuit Constants On The Board
ML7425 LSI Design Guide Circuit constants on the board 2.1. We recommend that you ask the quartz crystal manufacturer to obtain matching characteristics on your board. For reference, Table 2.1 shows the matching constants in the configuration Example of Figure 2.1 on LAPIS Technology evaluation board. -
Page 10: Tcxo Circuit
ML7425 LSI Design Guide TCXO circuit Use a TCXO that satisfies the following specifications. ⚫ Output load :10kΩ//10pF * ⚫ Output level :0.8Vpp ～ 1.4Vpp ⚫ Frequency deviation :Refer to Table 2.2 Table 3.1 Example of TCXO configuration Frequency Manufacturer Model (MHz) Kyocera... -
Page 11: Rf Matching Circuit
ML7425 LSI Design Guide RF matching circuit This section Description the instructions for designing RF matching circuit. Typical antennas have a 50Ω signal source impedance. Input impedance of RF receiver as seen from the antennae end must be converted to 50 Ω. Deviation from 50 Ω... -
Page 12: Receiving Circuit Matching Design Procedure
ML7425 LSI Design Guide Receiving circuit matching design procedure 4.1. Figure 4.2 is the measured value of the Input impedance at RXIN (18) pin. Figure 4.2 Input impedance measurement value RXIN (18) Input impedance of a pin can be expressed by an equivalent circuit (Figure 4.3) in which resistors and capacitors are connected in parallel. -
Page 13: Connect Ac Coupling Capacitance
ML7425 LSI Design Guide Table 4.1 shows the resistors and capacities of the equivalent circuit at typical frequencies. Table 4.1 Resistance and capacitance values of equivalent circuit Freq [MHz] Rona[Ω] Clan[pF] 2576 1.12 2378 1.12 2007 1.19 1513 1.23 1.43 1.44 Connect AC coupling capacitance 4.1.1. -
Page 14: Adjust The Real Part Of Input Impedance Of Lna To 50 Ω
ML7425 LSI Design Guide Adjust the real part of Input impedance of LNA to 50 Ω 4.1.2. By connecting inductor Lmatch in parallel as shown in Figure 4.5, the real part of Input impedance is adjusted to be 50 Ω. RXIN(18) Lmatch Rlna... -
Page 15: Adjust The Imaginary Part Of Input Impedance Of Lna To 0 Ω
ML7425 LSI Design Guide When an inductor is added, the impedance on the Smith chart moves to 50+jX Ω as shown in Figure 4.6. ① Connect Lmatch 50+jX ② 50-jX LNA Input impedance Figure 4.6 Impedance-Conversion by Lmatch There are actually two Latch that make the real part 50 Ω like a Figure 4.6, each of which converts Input impedance into ①50+jX Ω... -
Page 16: Antenna Path Design
ML7425 LSI Design Guide The required capacitance is given by equation (2) ⋯ ( 2 ) match �� ⋅ √ 50 ⋅ �� − 1 When the capacity is added, the impedance on the Smith chart moves to 50+ j0Ω as shown in Figure 4.8. Connect Cmatch Connect Lmatch 50+j0Ω... -
Page 17: Transmitter Circuit Matching Design Procedure
ML7425 LSI Design Guide Transmitter Circuit Matching Design Procedure 4.2. This section introduces an Example of designing transmit matching circuit. The design procedure is as follows. Output pin design 4.2.1. The transmit power circuit consists of a choke coil Lch and a matching capacity Cp as shown in Figure 4.10. Designing Lch and Cp Example is shown in Table 4.2. -
Page 18: Notch Filter Ln1//Cn1, Ln2+Cn2 Designed Example (Figure 4.11)
ML7425 LSI Design Guide Notch Filter Ln1//Cn1, Ln2+Cn2 Designed Example (Figure 4.11) 4.2.2. CAP_PA2 (15) TXOUT (16) Figure 4.11 Example of Notch Filter Design The notch filter (Ln, Cn) is calculated by the following equation, assuming that it is the transmit frequency f0. ⋯... -
Page 19: Antenna Line Design
ML7425 LSI Design Guide Antenna line design 4.2.4. Connect the antenna and matching circuit as shown in Figure 4.13 using a 50Ω characteristic impedance line. CAP_PA2(15) 50 Ω line TXOUT(16) Figure 4.13 Example of 50Ω line design 17/22 FEXL7425DG-02... -
Page 20: Selection Of Parts
ML7425 LSI Design Guide Selection of parts Antenna 5.1. We recommend an antenna that satisfies the properties shown in Table 5.1. Select the one with the best directivity according to the operating Condition, environmental conditions, and mounting Condition. Since antennae are affected by mounting Condition such as GND, external factors must be taken into account. -
Page 21: Switching Regulator
ML7425 LSI Design Guide Switching regulator 6.2. When the switching regulator (DCDC converter) operates, Large current flows alternately in the path (dotted line/solid line)shown in Figure 6.1/6.2. Consider the following points. ⚫ Depending on the board, spurious characteristics may change depending on the orientation of the inductor. We recommend using a device with known polarity and mounting it in the same direction. - Page 22 ML7425 LSI Design Guide ⚫ The diagram for connecting the power supply when the switching regulator is used and not used is shown in Figure 6.3. When not using a DCDC converter, leave the DCDC_OUT (8) pin open. Power supply Power supply VDD_ANA (13) VDD_ANA (13)
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Page 23: Others
ML7425 LSI Design Guide Others In the board design, please follow the instructions below. ⚫ PDN (31) The pin should be fixed to GND during normal operation. ⚫ When using TCXO, use XIN (26) pin in OPEN. Refer to 3. TCXO circuit for more information. 21/22 FEXL7425DG-02... -
Page 24: Revision History
ML7425 LSI Design Guide Revision history Page Document No. Issue Date Change Contents Previous Current Edition Edition FEXL7425DG-01 2023/12/1 First Edition ⅰ ⅰ FEXL7425DG-02 2024/03/19 Notice of wording change Updated Switching Regulator Description Addition of board layout reference example 22/22 FEXL7425DG-02...
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