Silicon Laboratories C8051F921 Technical data

C8051F921

Single/Dual Battery, 0.9-3.6 V, 32 kB, smaRTClock, 10-Bit ADC MCU

Supply Voltage: 0.9 to 3.6 V

- One-cell mode supports 0.9–1.8 V operation

- Two-cell mode supports 1.8–3.6 V operation

- Built-in dc-dc converter with 1.8 –3.3 V output (65 mW max) for

use in one-cell mode; can supply external devices

- Typical sleep mode current < 0.1 µA; retains state and RAM-

contents over full supply range; fast wakeup

- 2 built-in brown-out detectors cover sleep and active modes

10-Bit Analog to Digital Converter

- Up to 300 ksps

- Up to 15 external inputs

- External pin or internal VREF (no external capacitor required)

- Built-in temperature sensor

- External conversion start input option

- Autonomous Burst Mode with 16-bit automatic averaging

accumulator

Two Comparators

- Programmable hysteresis and response time

- Configurable as interrupt or reset source

- Low current (< 0.5 µA)

- Up to 15 Capacitive Touch Sense inputs

Memory

- 4352 bytes internal data RAM (256 + 4K)

- 32 kB bytes Flash; In-system programmable in 1024-byte sec-

tors; Full read/write/erase functionality over the entire
supply range

On-Chip Debug

- On-chip debug circuitry facilitates full speed, non-intrusive in-

system debug (no emulator required)

High-Speed 8051 µC Core

- Pipe-lined instruction architecture; executes 70% of instructions

in 1 or 2 system clocks

- 25 MIPS peak throughput with 25 MHz clock

- Expanded interrupt handler

Digital Peripherals

- 16 port I/O; All 5 V tolerant with programmable drive strength

- Hardware enhanced UART, SPI and SMBus™ serial ports

available concurrently

- Low power 32-bit smaRTClock (0.5 uA) operates down to 0.9V

- Four general purpose 16-bit counter/timers

- 16-bit programmable counter array (PCA) with six capture/com-

pare modules and watchdog timer:

• 8, 9, 10, 11, or 16-bit PWM

• Rising/falling edge capture

• Frequency output

• Software timer

Clock Sources

- Precision internal oscillators: 24.5 MHz with ±2% accuracy sup-

ports UART operation; spread-spectrum mode for reduced EMI

- Low power internal oscillator: 20 MHz

- External oscillator: Crystal, RC, C, CMOS clock

- smaRTClock oscillator: 32.768 kHz crystal or self-oscillate

- Can switch between clock sources on-the-fly; useful in power

saving modes

Ultra-Small Package

- 24-pin QFN (4x4 mm)

Temperature Range: –40 to +85 °C

Port I/O Configuration

Digital Peripherals

UART

Timers 0,

1, 2, 3

PCA/
WDT

SMBus

SPI 0,1

Crossbar Control

Analog Peripherals

6-bit
IREF

External

Internal

VREF

VREF

10-bit
300ksps
ADC

CP1, CP1A

CP0, CP0A

A
M
U
X

+

-

Comparators

Priority

Crossbar

Decoder

IREF0

VDD

VREF

Temp

Sensor

GND

+

-

Port 0

Drivers

Port 1

Drivers

Port 2

Drivers

P0.0/VREF
P0.1/AGND
P0.2/XTAL1
P0.3/XTAL2
P0.4/TX
P0.5/RX
P0.6/CNVSTR
P0.7/IREF0

P1.0/AD0
P1.1/AD1
P1.2/AD2
P1.3/AD3
P1.4/AD4
P1.5/AD5
P1.6/AD6

P2.7/C2D

C2CK/RST

VDD/DC+

GND/DC-

VBAT

GND

XTAL3

XTAL4

Power On

Reset/PMU

Debug /

Programming

Hardware

C2D

Power Net

Analog

Power

DC/DC

Converter

XTAL1

XTAL2

Wake

Reset

VREG

CIP-51 8051

Controller Core

32k Byte ISP Flash

Program Memory

256 Byte SRAM

4096 Byte XRAM

Digital
Power

Precision

24.5 MHz
Oscillator

Low Power

20 MHz

Oscillator

External

Oscillator

Circuit

smaRTClock

Oscillator

System Clock
Configuration

Engine

SYSCLK

CRC

SFR

Bus

Low-Voltage/Low-Power Copyright © 2008 by Silicon Laboratories 1.14.2008

C8051F921

Single/Dual Battery, 0.9-3.6 V, 32 kB, smaRTClock, 10-Bit ADC MCU

Selected Electrical Specifications

(At 25 C°)

Parameter Conditions Min Typ Max Units

Supply Input Voltage

two-cell mode
one-cell mode

DC-DC Boost Converter Output
Power (V

= 1.8–3.3 V)

OUT

Supply Current with CPU Active

Supply Current (shutdown)

= 1.8 V)

(V

BAT

Clock Frequency Range DC — 25 MHz

Wakeup Time

Frequency

Resolution 10 bits
Throughput Rate — — 300 ksps

DC-DC converter disabled 1.8 — 3.6 V

DC-DC converter enabled 0.9 — 1.8 V

Includes on and off-chip current — — 65 mW

VDD = 1.8–3.6 V

Clock = 24.5 MHz

—4.1—mA

(±2% internal precision oscillator)

Sleep mode; smaRTClock off — 50 — nA

Sleep mode; smaRTClock running — 0.6 — µA

two-cell mode — 2 — µs
one-cell mode — 10 — µs

Internal Oscillator

Precision oscillator 24 24.5 25 MHz

Low power oscillator 18 20 22 MHz

A/D Converter

Package Information: 24-Pin QFN

MM

Min Typ Max

A

0.70 0.75 0.80

A1

0.00 0.02 0.05

b

0.18 0.25 0.30

D

4.00 BSC

D2

2.50 2.60 2.70

e

0.50 BSC

E

4.00 BSC

E2

2.50 2.60 2.70

L

0.35 0.40 0.45

L1

— — 0.15

aaa

— — 0.10

bbb

— — 0.10

ccc

— — 0.05

ddd

— — 0.10

C8051F9xx Product Family

Device Part # Package Flash Size RAM Size

C8051F930-GQ 32-pin LQFP 64 kB 4 kB
C8051F930-GM 32-pin QFN 64 kB 4 kB
C8051F931-GM 24-pin QFN 64 kB 4 kB
C8051F920-GQ 32-pin LQFP 32 kB 4 kB
C8051F920-GM 32-pin QFN 32 kB 4 kB
C8051F921-GM 24-pin QFN 32 kB 4 kB

Low-Voltage/Low-Power Copyright © 2008 by Silicon Laboratories 1.14.2008

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