System Overview
C8051F91x-C8051F90x devices are fully integrated mixed-signal System-on-a-Chip MCUs. Highlighted features are listed below. Refer to Table 2.1 for specific product feature selection and part ordering numbers.

• Single/Dual Battery operation with on-chip dc-dc boost converter.
• High-speed pipelined 8051-compatible microcontroller core (up to 25 MIPS)
• In-system, full-speed, non-intrusive debug interface (on-chip)
• 10-bit 300 ksps or 12-bit 75 ksps single-ended ADC with analog multiplexer
• 6-Bit Programmable Current Reference. Resolution can be increased with PWM.
• Precision programmable 24.5 MHz internal oscillator with spread spectrum technology.
• 16 kB or 8 kB of on-chip Flash memory
• 768 bytes of on-chip RAM
• SMBus/I2C, Enhanced UART, and two Enhanced SPI serial interfaces implemented in hardware
• Four general-purpose 16-bit timers
• Programmable Counter/Timer Array (PCA) with six capture/compare modules and Watchdog Timer function
• On-chip Power-On Reset, VDD Monitor, and Temperature Sensor
• Two On-chip Voltage Comparators with 15 Capacitive Touch Sense inputs.
• 16 Port I/O (5 V tolerant)

With on-chip Power-On Reset, VDD monitor, Watchdog Timer, and clock oscillator, the C8051F91x C8051F90x devices are truly stand-alone System-on-a-Chip solutions. The Flash memory can be reprogrammed even in-circuit, providing non-volatile data storage, and also allowing field upgrades of the 8051 firmware. User software has complete control of all peripherals, and may individually shut down any or all peripherals for power savings.

Ultra-Low Power
   - 160 uA/MHz in active mode (24.5 MHz clock)
   - 2 us wake-up time (two-cell mode)
   - 10 nA sleep mode with memory retention;
   - 50 nA sleep mode with brownout detector
   - 300 nA sleep mode with LFO (‘F912/02 only)
   - 600 nA sleep mode with external crystal
Supply Voltage 0.9 to 3.6 V
   - One-cell mode supports 0.9 to 1.8 V operation (‘F911/01). ‘F912 and ‘F902 devices can operate from 0.9 to 3.6 V continuously
   - Two-cell mode supports 1.8 to 3.6 V operation
   - Built-in dc-dc converter with 1.8 to 3.3 V output for use in one-cell mode
   - Built-in LDO regulator allows a high analog supply voltage and low digital core voltage
   - 2 built in supply monitors (brownout detectors) 12-Bit or 10-Bit Analog to Digital Converter
   - ±1 LSB INL (10-bit mode); ±1.5 LSB INL (12-bit mode, ‘F912/02 only) no missing codes
   - Programmable throughput up to 300 ksps (10-Bit Mode) or 75 ksps (12-bit mode, ‘F912/02 only)
   - Up to 15 external inputs
   - On-chip voltage reference
   - On-Chip PGA allows measuring voltages up to twice the reference voltage
   - 16-bit auto-averaging accumulator with burst mode provides increased ADC resolution
   - Data dependent windowed interrupt generator
   - Built-in temperature sensor
Two Comparators
   - Programmable hysteresis and response time
   - Configurable as wake-up or reset source
   - Up to 15 Capacitive Touch Sense Inputs 6-Bit Programmable Current Reference
   - Up to ±500 µA. Can be used as a bias or for generating a custom reference voltage
   - PWM enhanced mode on ‘F912/02 devices
High-Speed 8051 µC Core
   - Pipelined instruction architecture; executes 70% of instructions in 1 or 2 system clocks
   - Up to 25 MIPS throughput with 25 MHz clock
   - Expanded interrupt handler Memory
   - 768 bytes RAM
   - 16 kB (‘F912/1), or 8 kB (‘F902/1) Flash; In-system programmable
Digital Peripherals
   - 16 port I/O; All 5 V tolerant with high sink current and programmable drive strength
   - Hardware SMBus™ (I2C™ Compatible), 2 x SPI™, and UART serial ports available concurrently
   - Four general purpose 16-bit counter/timers
   - Programmable 16-bit counter/timer array with six capture/compare modules and watchdog timer
Clock Sources
   - Internal oscillators: 24.5 MHz, 2% accuracy supports UART operation; 20 MHz low power oscillator requires very little bias current.
   - External oscillator: Crystal, RC, C, or CMOS clock
   - SmaRTClock oscillator: 32 kHz crystal or internal low frequency oscillator (‘F912/02) or self-oscillate mode
   - Can switch between clock sources on-the-fly; useful in implementing various power saving modes
On-Chip Debug
   - On-chip debug circuitry facilitates full-speed, nonintrusive in-system debug (no emulator required)
   - Provides 4 breakpoints, single stepping
   - Inspect/modify memory and registers
   - Complete development kit
Packages
   - 24-pin QFN (4 x 4 mm)
   - 24-pin QSOP (easy to hand-solder)
   - Tested die available
Temperature Range: –40 to +85 °C