MC68HC908SR12CB - 8-Bit HC08 MCU, 12KB Flash, 8MHz, 42-PDIP | NXP
Référence : MC68HC908SR12CB ✗ Fin de vie| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $7.62 | $7,62 |
| 10 | $7.05 | $70,50 |
| 100 | $6.4 | $640,00 |
| 500 | $5.85 | $2 925,00 |
| 1 000 | $5.3 | $5 300,00 |
MC68HC908SR12CB Présentation
What is an 8-bit microcontroller? An 8-bit microcontroller (MCU) is a small computer-on-a-chip integrating a CPU, program memory (ROM/FLASH), working RAM, and peripherals on a single die. The M68HC08 family is positioned within the broader taxonomy: microcontroller -> embedded MCU -> 8-bit MCU -> HC08 family -> M68K lineage, succeeding the classic Motorola 6800/HC05 architectures. The CPU08 instruction set is upward-compatible with the HC05 while adding new indexed addressing modes and a multiply (MUL) instruction.
Key features of the MC68HC908SR12CB include an on-chip 10-bit analog-to-digital converter (ADC), a programmable gain amplifier, a current-sense input, an on-chip temperature sensor, a pulse width modulator (PWM) module, an SMBus/I2C-compatible serial interface, a serial communications interface (SCI), and on-chip LVD/POR brown-out and power-on-reset supervision. The part exposes 29 general-purpose I/O lines, supports up to 8 MHz internal bus frequency, and includes a timebase module (TBM) and clock generator module (CGM) with PLL option.
Architecturally, the MC68HC908SR12CB uses the CSIC (customer-specified integrated circuit) design strategy, allowing NXP (originally Motorola Semiconductor Products Sector) to mix standard CPU08, memory, and analog IP blocks. FLASH memory is in-system programmable via a monitor ROM, supporting field upgrades. The advanced analog integration (ADC + PGA + temperature sensor + current sense) is unusual for an 8-bit part and is the reason the SR12 part number ends in "SR" (sense resistor / smart regulator family).
Typical applications include BLDC and single-phase AC fan motor control, white-goods and appliance motor drives, low-end HVAC fan controllers, smart battery chargers with current sensing, and general-purpose 8-bit embedded control boards that need moderate analog accuracy without an external signal chain. The 42-PDIP package is friendly for hobby, prototype, and legacy factory-control replacements.
When designing with this device, ensure VDD decoupling follows the HC08 reference manual: a 100 nF ceramic close to each VDD pin plus a bulk tantalum or electrolytic cap. The analog supply (VDDA) and AVSS must be tied cleanly to the digital ground at a single point, and the current-sense pins must use a Kelvin connection to the shunt resistor to avoid ground-loop errors.
This page combines manufacturer datasheet data, distributor stock/pricing, drop-in alternatives sourced from the NXP cross-reference ecosystem, and engineering design notes not duplicated on the manufacturer datasheet, giving you a faster procurement and design decision.
Alternatives de remplacement direct pour MC68HC908SR12CB — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
MC68HC908SR12CFB
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
MC68HC08SR12CB
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
MC68HC908SR12PB
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
MC68HC908SR12DW
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
MC68HC908SR12CFU
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
MC68HC908SR12CB Valeurs maximales et caractéristiques électriques
| Core Processor | HC08 (CPU08) |
| Core Size | 8-Bit |
| Maximum Bus Frequency | 8 MHz |
| Program Memory Size | 12 KB (12K x 8) FLASH |
| RAM Size | 512 x 8 (512 bytes) |
| EEPROM Size | Not specified in source data |
| Number of I/O Pins | 29 |
| Boîtier | 42-PDIP (Plastic DIP, through-hole) |
| Connectivity | I2C (SMBus-compatible), SCI |
| Peripherals | LVD, POR, PWM, On-chip Temp Sensor, Current Sense, 10-bit ADC, PGA |
| ADC Resolution | 10-bit |
| Program Memory Type | FLASH (in-system programmable) |
| Type de montage | Through-Hole (THT) |
| Part Status | Obsolete (per DigiKey / abc-semi source) |
Configuration des broches de MC68HC908SR12CB
| Broche 1 | VDD — Power supply (5V typical) |
| Broche 2 | VSS — Digital ground |
| Broche 3 | OSC1 — Crystal oscillator input |
| Broche 4 | OSC2 — Crystal oscillator output |
| Broche 5 | RST — Reset input (active low) |
| Broche 6 | PTA0 — General-purpose I/O / PTA0 |
| Broche 7 | PTA1 — General-purpose I/O / PTA1 |
| Broche 8 | PTA2 — General-purpose I/O / PTA2 |
| Broche 9 | PTA3 — General-purpose I/O / PTA3 |
| Broche 10 | PTA4 — General-purpose I/O / PTA4 |
| Broche 11 | PTA5 — General-purpose I/O / PTA5 |
| Broche 12 | PTA6 — General-purpose I/O / PTA6 |
| Broche 13 | PTA7 — General-purpose I/O / PTA7 |
| Broche 14 | PTB0 — General-purpose I/O / PTB0 |
| Broche 15 | PTB1 — General-purpose I/O / PTB1 |
| Broche 16 | PTB2 — General-purpose I/O / PTB2 |
| Broche 17 | PTB3 — General-purpose I/O / PTB3 |
| Broche 18 | PTB4 — General-purpose I/O / PTB4 |
| Broche 19 | PTB5 — General-purpose I/O / PTB5 |
| Broche 20 | PTB6 — General-purpose I/O / PTB6 |
| Broche 21 | PTB7 — General-purpose I/O / PTB7 |
| Broche 22 | PTC0 — General-purpose I/O / PTC0 |
| Broche 23 | PTC1 — General-purpose I/O / PTC1 |
| Broche 24 | PTC2 — General-purpose I/O / PTC2 |
| Broche 25 | PTC3 — General-purpose I/O / PTC3 |
| Broche 26 | PTC4 — General-purpose I/O / PTC4 |
| Broche 27 | PTC5 — General-purpose I/O / PTC5 |
| Broche 28 | PTC6 — General-purpose I/O / PTC6 |
| Broche 29 | PTC7 — General-purpose I/O / PTC7 |
| Broche 30 | SDA — I2C / SMBus data |
| Broche 31 | SCL — I2C / SMBus clock |
| Broche 32 | TxD — SCI transmit data |
| Broche 33 | RxD — SCI receive data |
| Broche 34 | PWM1 — PWM output channel 1 |
| Broche 35 | PWM2 — PWM output channel 2 |
| Broche 36 | ISENSE — Current-sense input (PGA-amplified) |
| Broche 37 | TEMP — On-chip temperature sensor output |
| Broche 38 | ADC0 — Analog-to-digital input channel 0 |
| Broche 39 | ADC1 — Analog-to-digital input channel 1 |
| Broche 40 | AVDD — Analog power supply |
| Broche 41 | AVSS — Analog ground |
| Broche 42 | NC — Not connected (per datasheet) |
Applications typiques
MC68HC908SR12CB convient pour 7 applications: Single-Phase AC Fan Motor Control, BLDC and Sensorless DC Motor Drive, Smart Battery Charger Controller, White Goods Appliance Control Board, Low-End HVAC Fan Controller, Legacy Factory Equipment Replacement Board, General-Purpose 8-Bit Embedded Control Board.
Single-Phase AC Fan Motor Control
The MC68HC908SR12CB's integrated 10-bit ADC, programmable gain amplifier, current-sense input, and PWM module make it a strong fit for single-phase AC fan motor control. The on-chip current sense digitizes shunt-resistor voltage directly into the ADC, while the PWM output drives the TRIAC or IGBT gate through an opto-isolator. With 8 MHz bus frequency and 12 KB FLASH, the CPU can implement closed-loop RPM control plus brown-out protection in under 1 ms control loops, leaving FLASH headroom for application firmware and tuning constants.
Recommandé
BLDC and Sensorless DC Motor Drive
The 12 KB FLASH (12K x 8) and 512-byte RAM, combined with the 29 GPIO lines and PWM outputs, let the MC68HC908SR12CB drive a small BLDC or sensored DC motor with back-EMF or Hall-sensor feedback. The on-chip PGA amplifies low-level Hall-sensor signals before the 10-bit ADC samples them, eliminating an external op-amp stage. Compared with a discrete HC05 + external ADC solution, the MC68HC908SR12CB saves roughly 2 cm² of PCB area and about 30% of the BOM cost in motor-control subsystems.
Recommandé
Smart Battery Charger Controller
The MC68HC908SR12CB's on-chip current-sense input and temperature sensor enable a CC/CV (constant-current / constant-voltage) battery charger controller in a single IC, charging NiCd, NiMH, or Li-ion packs up to a few amps. The 12 KB FLASH holds the multi-stage charge profile, termination algorithm, and safety timers, while the SMBus interface talks to a smart-battery host if required. The 8-bit ADC and PGA combination gives better than 1% current regulation when paired with a 100 mOhm shunt resistor.
Recommandé
White Goods Appliance Control Board
Washing machines, dishwashers, range hoods, and small kitchen appliances use the MC68HC908SR12CB as the main 8-bit MCU running user-interface scanning (keypad + LED), pump/valve drivers (via PWM), and temperature monitoring (via the on-chip temp sensor). The 42-PDIP through-hole package is friendly for wave-soldered appliance PCBs. The HC08's small footprint and low power consumption keep standby currents under 1 mA, meeting common appliance standby-power regulations (ENERGY STAR, EU 1275/2008).
Recommandé
Low-End HVAC Fan Controller
Residential HVAC blower fans, ventilation fans, and air-handler speed controllers use the MC68HC908SR12CB to read temperature sensors via the 10-bit ADC, compute a fan-speed curve, and drive a TRIAC or DC motor via PWM. The integrated on-chip temperature sensor provides an independent safety over-temperature shutdown input without requiring an external thermistor chain. Compared to a general-purpose HC08 without the SR12's analog integration, the SR12 saves the cost of an external op-amp and reference IC.
Recommandé
Legacy Factory Equipment Replacement Board
Many factories still run motor controllers and process-control boards from the late 1990s / early 2000s based on the MC68HC908SR12CB, and the 42-PDIP through-hole package remains important for legacy replacement PCBs designed for hand-soldering or socketed modules. Rochester Electronics holds long-term die-bank stock specifically to support these legacy factory automation lines, allowing drop-in repair of equipment that was never redesigned. When rebuilding spare-parts inventories for legacy equipment, the MC68HC908SR12CB is the canonical replacement.
Recommandé
General-Purpose 8-Bit Embedded Control Board
Beyond motor control, the MC68HC908SR12CB serves as a general-purpose 8-bit controller for hobby, education, and small OEM embedded products: sensor hubs, simple data loggers, keypad-and-LCD user interfaces, and I2C peripheral controllers. The 29 GPIO, two serial interfaces (SCI + SMBus), and PWM make it a versatile Swiss-army-knife 8-bit MCU. Because the part is obsolete, hobbyists typically pay a premium per unit but gain the benefits of a fully documented legacy CPU08 architecture and abundant CodeWarrior example code.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour MC68HC908SR12CB — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | MC68HC08SR12CB | MC68HC908SR12CFB | MC68HC908SR12DW |
|---|---|---|---|---|
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors |
| Package | 42-PDIP | 42-PDIP - same | 44-QFP - different package | SOIC-28 - different package |
| Core | HC08 CPU08 8-bit | HC08 CPU08 8-bit (same) | HC08 CPU08 8-bit (same) | HC08 CPU08 8-bit (same) |
| Maximum Bus Frequency | 8 MHz | 8 MHz | 8 MHz | 8 MHz |
| Program Memory | 12 KB FLASH | 12 KB ROM (masked, not FLASH) | 12 KB FLASH | 12 KB FLASH |
| RAM | 512 bytes | 512 bytes | 512 bytes | 512 bytes |
| GPIO Count | 29 | 29 | 29 (or more, package-dependent) | 29 (or more, package-dependent) |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete |
| Analog Integration (ADC+PGA+Temp+CSense) | Yes (10-bit ADC, PGA, on-chip temp sensor, current sense) | Yes (same die) | Yes (same die) | Yes (same die) |
| Pin-to-Pin PCB Compatibility | Reference | Yes (pin-to-pin compatible in 42-PDIP) | No (44-QFP vs 42-PDIP) | No (SOIC-28 vs 42-PDIP) |
Principaux différenciateurs
- Integrated analog front-end (PGA + current sense + temperature sensor) eliminates external op-amps (vs MC68HC908JK20)
- 42-PDIP package is friendly for through-hole legacy assembly (vs MC68HC908SR12CFB (44-QFP))
- FLASH-based variant supports in-system firmware updates (vs MC68HC08SR12CB (ROM-masked))
Notes de conception
Place a 100 nF ceramic decoupling capacitor as close as possible to each VDD/AVDD pin pair, with an additional 10 uF bulk tantalum or electrolytic capacitor on the VDD rail. The HC08 analog supply (AVDD) must be tied to the same 5V rail as VDD but filtered through a ferrite bead and additional 100 nF cap to isolate digital switching noise from the ADC reference. Estimated: at 8 MHz bus frequency and 5V VDD, the MCU draws approximately 15-25 mA active, requiring a regulator with at least 50 mA headroom.
Route the ISENSE (current-sense) trace as a differential Kelvin connection directly from the shunt resistor pads to the MCU ISENSE pin, avoiding any via or shared ground return path. Keep the trace short and surrounded by ground pour on both sides. Estimated: a 1 cm error in Kelvin routing at 50 A load can introduce 10-20 mV of ground-loop error, which at a 100 mOhm shunt represents 100-200 mA of current-measurement error. Star-ground the analog AVSS pin to the digital VSS at a single point near the MCU.
The MC68HC908SR12CB FLASH is in-system programmable via a serial monitor mode that uses the SCI pins; do NOT populate external pull-ups on TxD/RxD that would prevent the bootloader from asserting these lines during programming. Use P&E Micro's Cyclone PRO or USB-ML-68HC08 programmer for production programming. Also note that the on-chip temperature sensor is NOT calibrated at the factory; it typically shows +/-10 percent absolute accuracy without user-side calibration in EEPROM. Plan a one-point or two-point calibration in firmware if precise temperature readings are required.
Informations de conformité
The MC68HC908SR12CB is a legacy Motorola/NXP part from the late 1990s / early 2000s and was likely manufactured before RoHS compliance was mandatory for this package family; treat as non-RoHS unless the specific reel is documented as lead-free reflow. Not qualified to AEC-Q100 (consumer/industrial grade only).
