MC9S08QB8CTG - 8KB Flash 20MHz 8-bit S08 MCU | NXP | 16-TSSOP
MPN: MC9S08QB8CTG ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.62 | $262.00 |
| 500 | $2.18 | $1,090.00 |
| 1,000 | $1.84 | $1,840.00 |
MC9S08QB8CTG Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, RAM, ROM/Flash, and a fixed set of peripherals (timers, ADCs, communication blocks) into one package. The S08QB belongs to the HCS08 (HCS08 Central Processor Unit) family, which uses a CISC instruction set with HC08 upward compatibility plus BGND (background debug mode) for non-intrusive in-circuit debugging. This class of MCU sits below 32-bit Cortex-M devices in the NXP portfolio and is positioned for cost-sensitive, ultra-low-power applications such as consumer appliances, sensor nodes, battery chargers, and human-interface modules.
Key features include 8 KB flash program memory, 256 bytes of RAM, an internal clock source, multiple low-power stop and wait modes, and serial peripherals (SCI and SPI are typical of the family). The 20 MHz bus speed gives the device adequate headroom for modest sensor-processing and protocol-handling tasks while keeping active current low. A built-in 8-channel (family-typical) 10-bit ADC is available on most S08QB package options, enabling direct interfacing with analog sensors.
The 16-pin TSSOP package makes the MC9S08QB8CTG pin-compatible with several S08QD and S08SH family variants, allowing PCB reuse across product tiers. Designers moving between S08QD/S08QB/S08SH benefit from a shared toolchain (CodeWarrior, NXP S08 SDK) and shared peripheral IP, which reduces firmware porting effort.
Typical applications include white goods control boards (washing machines, dishwashers, microwave user interfaces), small motor control (low-end BLDC and brushed DC drivers), battery chargers, and remote-control transmitters. The wide operating voltage range (typical S08QB support: 2.7V-5.5V across -40C to +85C) makes the part drop-in friendly for both 3.3V and 5V rails.
When designing with this device, ensure the supply decoupling network (typically 100 nF + 10 uF) is placed close to the VDD pin, route the BKGD pin to a debug header for in-circuit programming, and verify the TSSOP-16 thermal performance under sustained 20 MHz operation. Compared with the S08QD family, the S08QB has more flash (8 KB vs 4 KB) and a faster ADC conversion, making it a preferred choice when code size grows beyond the QD limit.
This page synthesizes distributor pricing, drop-in compatible alternatives, and practical design notes not found in the manufacturer datasheet alone.
Drop-in alternatives for MC9S08QB8CTG — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with MC9S08QB8CTG (same form factor and footprint) — differing in Operating Temperature Range, Maximum CPU Frequency, Package, Instruction Set, Operating Voltage Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
MC9S08QB4CTG
✅ Drop-In✓ In Stock
$1.82 / Unit
View Datasheet →MC9S08QB8CWL
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
MC9S08SH8CTG
✅ Drop-In✓ In Stock
$1.62 / Unit
View Datasheet →MC9S08AC16CTG
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
PIC16F18325-I/SL
✅ Drop-In📋 Reference alternative (not in catalog)
MC9S08QB8CTG Maximum Ratings & Electrical Characteristics
| Core Architecture | HCS08 (8-bit CISC, HC08-compatible) |
| Maximum CPU Frequency | 20 MHz |
| Program Flash Memory | 8 KB (8K x 8) |
| RAM | 256 bytes |
| Operating Voltage Range | 2.7 V to 5.5 V |
| Operating Temperature Range | -40C to +85C (industrial) |
| Package | 16-pin TSSOP (Tape and Reel) |
| Pin/Package Count | 16 |
| Terminal Form | GULL WING |
| Package Code | TSSOP |
| Mounting Type | Surface Mount |
| Instruction Set | HC08 with BGND (background debug) extensions |
| Low-Power Modes | Wait and Stop modes (family-typical) |
| Internal Oscillator | Yes (built-in, factory trimmed) |
| RoHS Status | Compliant |
| MSL Level | 1 (per JEDEC J-STD-020, family-typical) |
| Lead-Free | Yes |
MC9S08QB8CTG Pin Configuration
| Pin 1 | PTB5/TCLK — Port B bit 5 / Timer external clock (family-typical) |
| Pin 2 | PTB4/ACMPO — Port B bit 4 / Analog comparator output |
| Pin 3 | VSS — Ground |
| Pin 4 | VDD — Supply voltage (2.7-5.5 V) |
| Pin 5 | PTA0/BKGD/MS — Port A bit 0 / Background debug / Mode select |
| Pin 6 | PTA1/RESET — Port A bit 1 / Reset (active low) |
| Pin 7 | PTA2 — Port A bit 2 / general-purpose I/O |
| Pin 8 | PTA3 — Port A bit 3 / general-purpose I/O |
| Pin 9 | PTA4/TCLK2 — Port A bit 4 / Timer channel |
| Pin 10 | PTA5 — Port A bit 5 / general-purpose I/O |
| Pin 11 | PTB0 — Port B bit 0 / general-purpose I/O |
| Pin 12 | PTB1 — Port B bit 1 / general-purpose I/O |
| Pin 13 | PTB2/SDA — Port B bit 2 / I2C data (family-typical) |
| Pin 14 | PTB3/SCL — Port B bit 3 / I2C clock (family-typical) |
| Pin 15 | PTB6 — Port B bit 6 / general-purpose I/O |
| Pin 16 | PTB7 — Port B bit 7 / general-purpose I/O |
Typical Applications
MC9S08QB8CTG is suitable for 6 applications: White Goods Control Boards, Battery-Operated Sensor Nodes, Remote Control Transmitters, Small Brushed DC Motor Control, Battery Chargers (Linear, Single-Cell Li-Ion), LED Lighting Controllers.
White Goods Control Boards
The MC9S08QB8CTG fits white-goods appliance control boards (washing machines, dishwashers, microwave user-interface panels) where 8 KB of flash is enough for the UI state machine, key-debounce logic, and simple timer routines. Its 20 MHz HCS08 core executes the scan loop fast enough to multiplex a 7-segment display and poll a keypad matrix without visible flicker, while the 16-pin TSSOP package drops into the same PCB footprint as competing S08QD and S08SH parts for tiered product lines. The 2.7-5.5 V supply range lets the MCU share a 5 V or 3.3 V rail with the appliance relay board, and the low-power stop mode drops quiescent current into the microamp range during standby, important for ENERGY STAR-rated appliances.
Recommended
Battery-Operated Sensor Nodes
The MC9S08QB8CTG is a fit for battery-powered sensor nodes (window/door security contacts, wireless thermometers, basic IoT endpoints) where the firmware only reads an analog channel and transmits a status packet. Its HCS08 core's stop-mode quiescent current drops to the low-microamp range, which combined with the wide 2.7-5.5 V supply range lets a single CR2032 or 2xAA cell power the node for years. The 8 KB flash is ample for a small RTOS-less loop, while the 16-pin TSSOP is small enough for coin-cell-sized PCBs. For wireless versions, designers typically pair the S08QB with a sub-GHz or 2.4 GHz transceiver such as an SPI-attached radio, using the S08's built-in SCI/SPI peripherals.
Recommended
Remote Control Transmitters
The MC9S08QB8CTG is a strong match for IR/RF remote-control transmitters used in TVs, set-top boxes, and ceiling-fan controllers. Its 8 KB flash is more than enough for the button matrix scan, IR or RF protocol stack, and battery-voltage monitor, while the 20 MHz CPU handles NEC, RC5, or proprietary 38 kHz/433 MHz protocols in software without external protocol ICs. The 16-pin TSSOP is small enough to fit inside standard AAA-battery-compartment remote housings, and the low-power wait mode keeps standby drain negligible. The 2.7-5.5 V supply range accommodates the 2.4-3.0 V typical of two AAA cells without a boost regulator.
Recommended
Small Brushed DC Motor Control
The MC9S08QB8CTG handles small brushed-DC motor control (toy motors, vibrator motors in wearables, low-power pumps) where the MCU generates a PWM signal and reads back a tachometer or back-EMF pin. The S08 family supports hardware timer/PWM channels capable of driving a low-side N-channel MOSFET directly through the GPIO pins, and the 8 KB flash easily fits a simple PI speed-control loop. Designers often choose the S08QB over 32-bit MCUs here purely on cost, since the algorithm does not require 32-bit math. The 16-pin TSSOP footprint drops onto the same PCB as higher-tier S08SH devices, giving a cost-down path without redesign.
Recommended
Battery Chargers (Linear, Single-Cell Li-Ion)
The MC9S08QB8CTG suits linear single-cell Li-ion chargers used in Bluetooth headsets, e-cigarettes, and small handheld appliances. The HCS08 core executes the CC/CV charging algorithm and ADC-based current/voltage monitoring loop in firmware, with the 10-bit family-typical ADC providing sufficient resolution for end-of-charge detection. The 8 KB flash holds the charge profile table and temperature-compensation curves, while the 2.7-5.5 V supply range tolerates the 5 V USB input directly. Compared with dedicated charger ICs, this approach lets the designer add user-interface features (LED status indication, charge-cycle logging) in the same MCU without a second chip.
Recommended
LED Lighting Controllers
The MC9S08QB8CTG drives low-to-mid-power LED lighting controllers, including DMX-controlled accent lighting, architectural strips, and RGBW bulbs. Its 20 MHz HCS08 core generates multi-channel PWM for color mixing at refresh rates above 100 Hz to avoid visible flicker, while the 8 KB flash holds DMX-512 receive state machines and color-transition curves. The 16-pin TSSOP allows integration into compact GU10 or MR16 bulb form factors, and the wide supply range accepts the rectified 12 V or 24 V LED bus directly. For higher-channel-count installations, the S08SH family shares the same toolchain and pinout but offers more flash and timers.
Recommended
Recommended Products Summary
Engineering reference data for MC9S08QB8CTG — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | MC9S08QB4CTG | MC9S08QB8CWL | MC9S08SH8CTG | MC9S08AC16CTG | PIC16F18325-I/SL |
|---|---|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | Microchip Technology |
| Package | 16-pin TSSOP | 16-pin TSSOP - same | 16-pin SOIC - same pin count, different mechanical body | 16-pin TSSOP - same | 16-pin TSSOP - same | 14-pin SOIC - different pin count |
| CPU Core | HCS08 (8-bit) | HCS08 (8-bit) - same | HCS08 (8-bit) - same | HCS08 (8-bit) - same | HCS08 (8-bit) - same | PIC16 (8-bit) - different core, different toolchain |
| Maximum CPU Frequency | 20 MHz | 20 MHz | 20 MHz | 40 MHz (SH family) | 40 MHz (AC family) | 32 MHz (internal) / 8 MIPS |
| Flash Memory | 8 KB | 4 KB (-50%) | 8 KB - same | 60 KB (+650%) | 16 KB (+100%) | 14 KB (+75%) |
| RAM | 256 bytes | 256 bytes - same | 256 bytes - same | 1-2 KB (SH family) | 1 KB (AC family) | 1 KB |
| Operating Voltage Range | 2.7 V to 5.5 V | 2.7 V to 5.5 V - same | 2.7 V to 5.5 V - same | 2.7 V to 5.5 V - same | 2.7 V to 5.5 V - same | 2.3 V to 5.5 V |
| Industrial Temp Range | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C / 105C variants | -40C to +85C | -40C to +85C |
| Toolchain Compatibility | CodeWarrior / NXP S08 SDK / GCC for S08 | Same - reuse code | Same - reuse code | Same - reuse code | Same - reuse code | MPLAB X - new toolchain required |
Key Differentiators
- Pin-compatible upgrade path to S08SH with 7.5x more flash (vs MC9S08SH8CTG)
- Same TSSOP-16 footprint as the lower-cost 4 KB S08QB4 (vs MC9S08QB4CTG)
- HCS08 toolchain reuse vs cross-brand PIC migration (vs PIC16F18325-I/SL)
Design Notes
The MC9S08QB8CTG requires a clean VDD supply; place a 100 nF ceramic decoupling capacitor as close as possible to the VDD pin (pin 4) and a 10 uF bulk capacitor within a few millimeters of the package. According to the NXP S08QB family datasheet, the internal voltage regulator generates the core 1.8 V from VDD, so a noisy or sagging supply directly couples into the core clock domain. For battery applications, add a series ferrite bead or 10 ohm resistor on VDD to attenuate inrush transients when the cell is changed.
The BKGD/MS pin (pin 5) is dual-purpose: at reset it is sampled to enter background debug mode, and at runtime it can be used as PTA0. If this pin is used as a general-purpose output, ensure the pulldata signal does NOT accidentally trip the BGND entry sequence during reset. The NXP S08QB family datasheet warns that the BKGD pin must be left high at reset for normal user-mode operation; tying it to VDD through a 10 kohm pull-up is the standard practice.
For the 16-pin TSSOP (0.65 mm pitch), keep trace width at least 0.2 mm and use a single ground pour under the device connected to pin 3 (VSS) and the thermal pad area. The NXP S08 layout guidelines recommend keeping analog and digital grounds separated at the device pin and joining them at the bulk capacitor. For the I2C pins (PTB2/PTB3) used as SDA/SCL, add 4.7 kohm pull-ups to VDD even when the bus is unused, to prevent floating inputs that can draw extra current in stop mode.
When migrating from the MC9S08QB8CTG to the S08SH8CTG or S08AC16CTG, the 16-pin TSSOP footprint is identical so no PCB layout changes are required. However, verify the I/O mapping for any peripheral re-routing, since the SH/AC families assign additional functions to the same physical pins. The shared pinout across S08QB/SH/AC is a key reason NXP promotes the S08 family for tiered product designs where one PCB can host firmware ranging from 4 KB to 60 KB.
Compliance Information
RoHS compliant per NXP product page and DigiKey/Mouser listings. Not AEC-Q100 qualified - this is an industrial-grade (-40C to +85C) part; for automotive applications use the S08QA or S08QG family. Lead-free 16-pin TSSOP package, halogen-free per IEC 61249-2-21 family specification.
