SC18IS602BIPW/S8HP: Technical Guide to ADI I²C-to-SPI Bridge IC

Introduction

The SC18IS602BIPW/S8HP is an I²C-to-SPI bridge interface IC manufactured by Analog Devices Inc, enabling I²C bus masters to communicate with SPI peripheral devices through simple register-based commands, supporting up to 1.7 MHz SPI clock, 4 chip select lines, and wide voltage operation (1.8-3.6V) for microcontroller systems, sensor networks, and embedded applications requiring protocol translation between incompatible interfaces.

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Technical Overview

Core Specifications

Parameter	Specification
Function	I²C-to-SPI protocol bridge
I²C Speed	Up to 400 kHz (Fast-mode)
SPI Speed	Up to 1.7 MHz clock
Chip Selects	4 independent SS lines
Buffer Size	200-byte internal FIFO
Supply Voltage	1.8V - 3.6V
Package	TSSOP-16 (S8HP variant)
Operating Temp	-40°C to +85°C

Part Number Decoder

SC18IS602BIPW/S8HP:

• SC18IS602B = I²C-to-SPI bridge, 4 chip selects
• I = Industrial temperature grade
• PW = TSSOP package (standard)
• /S8HP = Alternative package code

Key Features

Protocol Translation:

• I²C slave (address: 0x28-0x2B configurable)
• SPI master (modes 0-3 supported)
• Automatic data transfer via buffer
• No CPU intervention needed

Flexible Configuration:

• SPI clock: 58 kHz to 1.7 MHz (8 settings)
• SPI modes: CPOL/CPHA configurable
• MSB/LSB first bit order
• 4 independent chip select outputs

Internal Buffer:

• 200-byte bidirectional FIFO
• Reduces I²C overhead
• Supports burst transfers
• Status flags for buffer full/empty

Low Power:

• Active: ~1 mA @ 3.3V
• Standby: <10 µA
• I²C wake-up support

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Complete Specifications

I²C Interface

Parameter	Specification
I²C Address	0x28, 0x29, 0x2A, 0x2B (pin selectable)
Speed	Standard (100 kHz), Fast (400 kHz)
SCL/SDA Voltage	1.8V - 3.6V (level compatible)
Input Capacitance	<10 pF

SPI Interface

Parameter	Options/Range
Clock Frequency	58 kHz, 115 kHz, 230 kHz, 460 kHz, 920 kHz, 1.7 MHz
SPI Mode	Mode 0, 1, 2, 3 (CPOL/CPHA)
Data Order	MSB first, LSB first
Chip Selects	SS0, SS1, SS2, SS3 (active low)

Electrical Specifications

Parameter	Min	Typ	Max	Unit
VDD	1.8	3.3	3.6	V
IDD (active)	-	1.0	2.0	mA
IDD (standby)	-	5	10	µA
Output Drive	-	4	-	mA

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Applications

Microcontroller Interface Expansion

I²C MCU with SPI Peripherals:

I²C-Only MCU (STM32L0, ESP8266)
    ↓ I²C Bus
SC18IS602BIPW (Bridge)
    ↓ SPI Bus
SPI Peripherals: SD Card, LCD, ADC, DAC

Benefits:

• Add SPI devices to I²C-only systems
• Reduce MCU pin count (2 I²C vs 4+ SPI)
• Software control of SPI parameters

Sensor Networks

Multi-Sensor I²C Bus:

• I²C bus with multiple sensors
• SC18IS602B adds SPI sensor support
• Temperature, pressure, accelerometer (SPI)
• Centralized I²C master (Raspberry Pi, Arduino)

Display Controllers

SPI Display on I²C Bus:

• OLED/LCD displays (SPI interface)
• Connect via SC18IS602B bridge
• I²C command sequences control display
• Reduces wiring in space-constrained PCBs

Industrial Automation

PLC/SCADA Systems:

• I²C fieldbus communication
• SPI peripheral modules (I/O, ADC)
• Isolated SPI interfaces
• Distributed control systems

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Implementation Guide

Hardware Connection

Basic Circuit:

I²C Master (MCU)
  SDA ──────────┐
  SCL ──────────┤
               │
           SC18IS602BIPW
               │
  MISO ────────┤
  MOSI ────────┤  SPI Peripherals
  SCLK ────────┤  (SD Card, Sensor)
  SS0-3 ───────┘

Pin Configuration:

• VDD: 1.8V - 3.6V supply
• SDA/SCL: I²C data/clock (pull-up resistors required: 4.7kΩ)
• MISO/MOSI/SCLK: SPI signals (connect to peripherals)
• SS0-SS3: Chip select outputs (active low)
• A0/A1: I²C address selection (GND = 0x28)

Register Configuration

Function ID Register (0xF0):

I²C Write: [Address] [0xF0] [Config Byte]

Config Byte bits:
[7:6] - SPI Mode (00=Mode0, 01=Mode1, 10=Mode2, 11=Mode3)
[5:3] - Clock Rate (000=1.7MHz ... 111=58kHz)
[2]   - LSB First (1=LSB, 0=MSB)
[1:0] - Order (reserved)

Example: Configure SPI Mode 0, 1.7 MHz, MSB first:

Write to 0xF0: 0x00

Data Transfer Sequence

Write to SPI Device:

1. I²C Start
2. Write SC18IS602 address + W bit (0x50 for 0x28)
3. Write SS number (0x01 = SS0, 0x02 = SS1, etc.)
4. Write data bytes (up to 200)
5. I²C Stop
→ SC18IS602 automatically transfers via SPI

Read from SPI Device:

1. I²C Write: [Address] [SS] [Dummy Bytes]
2. I²C Start (repeated)
3. I²C Read: [Address + R] [Read Data]
→ Returns SPI response from buffer

Example Code (Arduino)

#include <Wire.h>

#define SC18IS602_ADDR 0x28
#define SPI_CONFIG 0xF0
#define SS0 0x01

void setup() {
  Wire.begin();
  
  // Configure: SPI Mode 0, 1.7 MHz, MSB first
  Wire.beginTransmission(SC18IS602_ADDR);
  Wire.write(SPI_CONFIG);
  Wire.write(0x00);
  Wire.endTransmission();
}

void spiWrite(uint8_t data) {
  Wire.beginTransmission(SC18IS602_ADDR);
  Wire.write(SS0);  // Select SS0
  Wire.write(data); // Data to send
  Wire.endTransmission();
  delay(1); // Allow SPI transfer
}

uint8_t spiRead() {
  // Write dummy byte to clock data
  Wire.beginTransmission(SC18IS602_ADDR);
  Wire.write(SS0);
  Wire.write(0xFF); // Dummy
  Wire.endTransmission();
  
  delay(1);
  
  // Read response
  Wire.requestFrom(SC18IS602_ADDR, 1);
  return Wire.read();
}

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Comparison & Alternatives

vs SC18IS600 (2 Chip Selects)

Feature	SC18IS602B	SC18IS600
Chip Selects	4	2
Buffer	200 bytes	96 bytes
SPI Speed	1.7 MHz max	1.7 MHz max
Use Case	Multi-device	Simple bridge

vs Software Bit-Banging

Approach	SC18IS602B (Hardware)	Bit-Bang (Software)
CPU Load	Low (automatic)	High (manual)
Timing	Precise	Variable
Speed	Up to 1.7 MHz	Limited (~100 kHz)
Code Size	Small	Large
Cost	+$1-2 component	$0 (code only)

Conclusion

The SC18IS602BIPW/S8HP provides seamless I²C-to-SPI protocol translation with 4 chip selects, 1.7 MHz SPI speed, 200-byte buffer, and wide voltage operation (1.8-3.6V), enabling I²C-only microcontrollers to interface with SPI peripherals through simple register-based commands, ideal for sensor networks, display controllers, storage interfaces, and pin-constrained embedded systems requiring protocol bridge functionality.

Key Advantages:

✅ I²C-to-SPI Bridge: Protocol translation in hardware
✅ 4 Chip Selects: Support multiple SPI devices
✅ 1.7 MHz SPI: Adequate for most peripherals
✅ 200-Byte Buffer: Efficient burst transfers
✅ Low Power: <10 µA standby, ~1 mA active
✅ Wide Voltage: 1.8-3.6V operation
✅ Simple Integration: Minimal external components

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Written by Jack Elliott from AIChipLink.

 

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