MMA8491QR2 - NXP SEMICONDUCTORS

MMA8491Q

3-Axis Multifunction Digital Accelerometer

Rev. 2.1 — 26 April 2016 Data sheet: Technical data

COMPANY PUBLIC

1 General description

The MMA8491Q is a low voltage, 3-axis low-g accelerometer housed in a 3 mm x 3 mm

QFN package. The device can accommodate two accelerometer configurations, acting

as either a 45° tilt sensor or a digital output accelerometer with I2C bus.

•As a 45° tilt sensor, the MMA8491Q device offers extreme ease of implementation by

using a single line output per axis.

•As a digital output accelerometer, the 14-bit ±8 g accelerometer data can be read from

the device with a 1 mg/LSB sensitivity.

The extreme low power capabilities of the MMA8491Q will reduce the low data rate

current consumption to less than 400 nA per Hz.

2 Features and benefits

•Extreme low power, 400 nA per Hz

•Ultra-fast data output time, ~700 μs

•VDD supply range of 1.95 V to 3.6 V

•3 mm x 3 mm, 0.65 mm pitch with visual solder joint inspection

•±8 g full-scale range

•14-bit digital output, 1 mg/LSB sensitivity

•Output Data Rate (ODR), implementation based from < 1 Hz to 800 Hz1

•I2C digital interface

•3-axis, 45° tilt outputs

3 Typical applications

•Smart grid: tamper detect

•Anti-theft

•White goods tilt

•Remote controls

1The ODR for this device is user defined by the period of the Enable pulsed signal. The maximum

recommended frequency of the Enable signal or the ODR that can be achieved for this device is 800 Hz.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 2 / 28

4 Ordering information

Table 1. Ordering information

Part Number Temperature Range Package Shipping

MMA8491QT –40 to +85 °C QFN 12 Tray

MMA8491QR1 –40 to +85 °C QFN 12 1000 pc / Tape & Reel

MMA8491QR2 –40 to +85 °C QFN 12 5000 pc / Tape & Reel

5 Related documentation

The MMA8491Q device features and operations are described in a variety of reference

manuals, user guides, and application notes. To find the most current versions of these

documents:

1. Go to the NXP homepage at: http://www.nxp.com/

2. In the Keyword search box at the top of the page, enter the device number

MMA8491Q. In the Refine Your Result pane on the left, click on the Documentation

link.

6 Block diagram

Figure 1. Block Diagram

7 Pinout

MMA8491Q is hosted in a 12-pin 3 mm x 3 mm QFN package. Ten pins are used for

functions; two pins are unconnected. Refer to Table 2 for complete pin descriptions and

functions.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 3 / 28

MMA8491Q

Transparent top view

12 NC

SCL

Gnd

SDA

VDD

Byp Xout

Yout

Zout

Gnd

Figure 2. Pin connection diagram

Table 2. Pin descriptions

Pin Symbol Function Description Pin status

1 Byp Internal regulator

output capacitor

connection

The internal regulator voltage of 1.8 V is present on this

pin. Connect to external 0.1 μF bypass capacitor.

Output

2 VDD Power Supply Device power is supplied through the VDD line. Power

supply decoupling capacitors should be placed as near as

possible to pin 1 of the device.

Input

3 SDA I2C Data I2C Slave Data Line, open drain

•7-bit I2C device address is 0x55

•The SDA and SCL I2C connections are open drain, and

therefore usually require a pull-up resistor

Input/Output

4 EN Enable pin The Enable pin fully turns on the accelerometer system

when it is pulled up to logic high. The accelerometer

system is turned off when the Enable pin is logic low.

Input

5 SCL I2C Clock I2C Slave Clock Line, open drain Input

6 Gnd Ground Ground Ground

7 Gnd Ground Ground Ground

8 Zout Push-pull Z-Axis

Tilt Detection

Output

9 Yout Push-pull Y-Axis

Tilt Detection

Output

10 Xout Push-pull X-Axis

Tilt Detection

Output

•Output is high when acceleration is > 0.688 g (axis is |

φ| > 45°).

•Output is low when acceleration is ≤ 0.688 g (axis is |φ|

≤ 45°).

•These pins are push-pull output pins.

Output

11 NC No internal

connection

No internal connection

12 NC No internal

connection

No internal connection

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 4 / 28

8 Recommended application diagram

Figure 3. VDD connects to power supply and EN is pulsed

To ensure the accelerometer is fully functional, connect the MMA8491Q as suggested in

Figure 3.

•A capacitor must be connected to the Bypass pin (pin 1) to assist the internal voltage

regulator. It is recommended to use a 0.1 μF capacitor. The capacitor should be placed

as near as possible to the Bypass pin.

•The device power is supplied through the VDD line. The power supply decoupling

capacitor should be placed as close as possible to the VDD pin.

–Use a 1.0 or 4.7 μF capacitor when the VDD and EN are not tied together.

–When VDD and EN are tied together, use a 0.1 μF capacitor. The 0.1 μF capacitor

value has been chosen to minimize the average current consumption while still

maintaining an acceptable level of power supply high frequency filtering.

•Both ground pins (pins 6 and 7) must be connected to ground.

•When the I2C communication line is used, use a pull-up resistor to connect to line SDA

and SCL. The SCL line can be driven by a push-pull driver, in which case, no pull-up

resistor is necessary. If SDA and SCL pins are not used, then they should be tied to

ground.

9 Sensing direction and output response

The MMA8491Q has three tilt detection outputs: Xout, Yout, and Zout. The following

figure shows the output results at the six different orientation positions.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 5 / 28

Top view Side view

Landscape Right

Gravity

Landscape Left

Portrait Up

Portrait Down

Back

Front

(Top view)

Reference frame for acceleration measurement

Xout @ 0

Yout @ –1

Zout @ 0

Xout @ 1

Yout @ 0

Zout @ 0

Xout @ 0

Yout @ 1

Zout @ 0

Xout @ –1

Yout @ 0

Zout @ 0 g

Xout @ 0

Yout @ 0

Zout @ –1

Xout @ 0

Yout @ 0

Zout @ 1

Figure 4. Sensitive axes orientation and output response to ±1 g (gravity) stimulus

10 Mechanical and electrical specifications

10.1 Absolute maximum ratings

Absolute maximum ratings are the limits the device can be exposed to without damage.

Functional operation at absolute maximum rating is not guaranteed.

Although this device contains circuitry to protect against damage due to high static

voltage or electrostatic fields, it is advised that normal precautions be taken to avoid

application of any voltage higher than the maximum-rated voltage.

Table 3. Absolute maximum ratings

Symbol Rating Min Max Unit

gmax Maximum acceleration (all axes, 100 μs) — 10 000 V

VDD Analog supply voltage –0.3 3.6 V

Ddrop Drop test — 1.8 m

TAGOC Operating temperature –40 +85 °C

TSTG Storage temperature –40 +125 °C

Table 4. ESD and latch-up protection characteristics

Symbol Rating Value Unit

VHBM Human body model (HBM) ±2000 V

VMM Machine model (MM) ±200 V

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 6 / 28

Symbol Rating Value Unit

VCDM Charge device model (CDM) ±500 V

ILU Latch-up current at TA = 85 °C ±100 mA

10.2 Mechanical characteristics

Table 5. Accelerometer mechanical characteristics

VDD = 2.8 V, T = 25 °C, unless otherwise noted.

Typical number is the target number, unless otherwise specified.

All numbers are based on VDD cap = 4.7 μF.

Parameter Symbol Conditions Min Typ Max Unit

Full-scale measurement range FS[1] — — ±8 — g

Sensitivity So[2] — 973 1024 1075 counts/g

Calibrated sensitivity error CSE[2] All axes, all ranges –5 — 5 %

Cross-axis sensitivity CXSEN

[1] Die rotation included –4.2 — 4.2 %

Sensitivity temperature variation TCS[1] –40 °C to +85 °C –0.014 — 0.014 %/°C

Zero-g level temperature variation TCO[1] –40 °C to +85 °C –0.98 — 0.98 mg/°C

Zero-g level offset accuracy TyOff[2][3] — –100 — 100 mg

Zero-g level after board mount TyOffPBM[1][4] — –120 — 120 mg

Noise RMS[1] — — 11.5 18 mg-rms

Nonlinearity NL[1] — — — 1 %FS

TDL[6] 25 °C 0.583 0.688 0.780Threshold / g-value[5]

TDL[1][4][6] –40 °C to +85 °C 0.577 0.688 0.784

TAGOC

[1] 25 °C 35.6 43.5 51.3Threshold / Tilt angle[7]

–40 °C to +85 °C 35.2 43.5 51.7

degrees

Temperature range — –40 25 85 °C

[1] Verified by characterization; not tested in production.

[2] Parameters tested 100% at final test at room temperature.

[3] Before board mount.

[4] Post-board mount offset specifications are based on a 4-layer PCB, relative to 25 °C.

[5] Internal threshold of output level change (from 0 g reference), g values are calculated from trip angles.

[6] All angles are based on the trip angle from static 0 g to 1 g; the g-values are calculated from the trip angle.

[7] Internal threshold of output level change (from 0 g reference).

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 7 / 28

10.3 Electrical characteristics

Table 6. Electrical characteristics

VDD = 2.8 V, T = 25 °C, unless otherwise noted.

Typical values represent mean or mean ±1 σ values, depending on the specific parameter.

Typical number is the target number unless otherwise specified.

All numbers are based on VDD cap = 4.7 μF.

Symbol Parameter Conditions Min Typ Max Unit

VDD Supply voltage[1] — 1.71 1.8 3.6 V

IDD Supply current in one-shot mode VDD = 2.8 V, EN is

pulsed to VDD for 1 ms

— 400[2][3][4] 980[1][5][6] nA/Hz

ISD Supply current in shutdown

mode

VDD = 2.8 V, EN = 0 — 1.8[2][3] 68[1][6] nA

CBYP

[2] Bypass capacitor at Byp pin — 70 100 470 nF

VOH

[1] High level output voltage Xout,

Yout, Zout

IO = 500 μA 0.85

* VDD

— — V

VOL

[1] Low level output voltage Xout,

Yout, Zout

IO = 500 μA — — 0.15 * VDD V

VIH

[1] High level input voltage EN VDD = 2.8 V 0.85

* VDD

— — V

VIL

[1] Low level input voltage EN VDD = 2.8 V — — 0.15 * VDD V

VOLS

[7] Low level output voltage SDA IO = 3 mA — — 0.4 V

VIH

[7] High level input voltage SDA,

SCL

VDD = 2.8 V 0.7 * VDD — — V

VIL

[7] Low level input voltage SDA,

SCL

VDD = 2.8 V — — 0.3 * VDD V

ISOURCE

[1] Output source current Xout,

Yout, Zout

Voltage high level

Vout = 0.85 x

VDD, VDD = 2.8 V

— — 7.3 mA

ISINK

[1] Output sink current Xout, Yout,

Zout

Voltage low level

Vout = 0.15 x

VDD, VDD = 2.8 V

— — 8.9 mA

TON /

TACTIVE

[8] Turn-on time

Measured from the time EN =

1.95 V to valid outputs

— — 720[2][3][4] 900[1][5][6] μs

TRST

[7] Reset Time

The time between falling edge of

EN and next rising edge of EN

VDD = 2.8 V 1000 — — μs

[1] Verified by characterization; not tested in production.

[2] Evaluation data: not tested in production.

[3] Typical number is mean data.

[4] Data is based on typical bypass cap = 100 nF.

[5] Data is based on max bypass cap = 470 nF.

[6] Over temperature -40 °C to 85 °C.

[7] Guaranteed by design.

[8] For application connection, see Figure 3

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 8 / 28

11 I2C Interface

Acceleration data may be accessed through an I2C interface, thus making the device

particularly suitable for direct interfacing with a microcontroller. The MMA8491Q features

three interrupt signals that indicate the tilt-sensing results on X, Y, Z axis respectively.

The raw accelerometer data are readable via I2C at the same time when an interrupt

signal is available.

The registers embedded inside the MMA8491Q are accessible through the I2C serial

interface, Table 7. To enable the I2C interface, the EN pin must be HIGH. If either EN or

VDD are absent, the MMA8491Q I2C interface reads invalid data. The I2C interface may

be used for communications along with other I2C devices. Removing power from the VDD

pin of the MMA8491Q does not affect the I2C bus.

Table 7. Serial interface pins

Pin Description

SCL I2C Serial Clock

SDA I2C Serial Data

There are two signals associated with the I2C bus; the Serial Clock Line (SCL) and the

Serial Data Line (SDA). The SDA is a bidirectional line used for sending and receiving

the data to/from the interface. External pull-up resistors connected to VDD are expected

for SDA and SCL. When the bus is free both the lines are HIGH. The I2C interface is

compliant with Fast mode (400 kHz, Table 8).

Table 8. I2C slave timing values

I2C Fast Mode[1]

Parameter Symbol

Min Max

Unit

SCL clock frequency fSCL 0 400 kHz

Bus-free time between STOP and START condition tBUF 1.3 — μs

(Repeated) START hold time tHD;STA 0.6 — μs

Repeated START setup time tSU;STA 0.6 — μs

STOP condition setup time tSU;STO 0.6 — μs

SDA data hold time tHD;DAT 0.05 0.9[2] μs

SDA setup time tSU;DAT 100 — μs

SCL clock low time tLOW 1.3 — μs

SCL clock high time tHIGH 0.6 — μs

SDA and SCL rise time tr20 + 0.1 Cb

[3] 300 μs

SDA and SCL fall time tf20 + 0.1 Cb

[3] 300 μs

SDA valid time[4] tVD;DAT — 0.9[2] μs

SDA valid acknowledge time[5] tVD;ACK — 0.9[2] μs

Pulse width of spikes on SDA and SCL that must be suppressed by

internal input filter

tSP 0 50 μs

Capacitive load for each bus line Cb— 400 pF

[1] All values referred to VIH(min) (0.3VDD) and VIL(max) (0.7VDD) levels.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 9 / 28

[2] This device does not stretch the LOW period (tLOW) of the SCL signal.

[3] Cb = total capacitance of one bus line in pF.

[4] tVD;DAT = time for data signal from SCL LOW to SDA output (HIGH or LOW, depending on which one is worse).

[5] tVD;ACK = time for Acknowledgement signal from SCL LOW to SDA output (HIGH or LOW, depending on which one is worse).

Figure 5. I2C slave timing diagram

11.1 I2C read operations

The transaction on the bus is started through a start condition (START) signal. A START

condition is defined as a HIGH-to-LOW transition on the data line while the SCL line is

held HIGH.

After START has been transmitted by the Master, the bus is considered busy. The next

byte of data transmitted after START contains the slave address in the first seven bits,

and the eighth bit tells whether the Master is receiving data from the slave or transmitting

data to the slave. When an address is sent, each device in the system compares the first

seven bits after a start condition with its address. If they match, then the device considers

itself addressed by the Master.

The ninth clock pulse, following the slave address byte, and each subsequent byte, is the

acknowledge (ACK). The transmitter must release the SDA line during the ACK period.

The receiver must then pull the data line LOW so that it remains stable low during the

high period of the acknowledge clock period.

A LOW-to-HIGH transition on SDA while SCL is HIGH is defined as a stop condition

(STOP). A data transfer is always terminated by a STOP.

A Master may also issue a repeated START during a data transfer. The MMA8491Q

expects repeated STARTs to be used to randomly read from specific registers.

The MMA8491Q accelerometer standard 7-bit slave address is 01010101(0x55).

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 10 / 28

Table 9. I2C device address sequence

Command [7:1] Device

Address

[7:1] Device

Address

[0] R/W [7:0] 8-bit

Final Value

Read 01010101 0x55 1 0xAB

Write 01010101 0x55 0 0xAA

11.1.1 Single-byte read

The transmission of an 8-bit command begins on the falling edge of SCL. After the 8

clock cycles are used to send the command, note that the data returned is sent with

the MSB first after the data is received. Figure 6 shows the timing diagram for the

accelerometer 8-bit I2C read operation.

1. The Master (or MCU) transmits a start condition (ST) to the MMA8491Q, slave

address (0x55), with the R/W bit set to “0” for a write, and the MMA8491Q sends an

acknowledgement.

2. Then the Master (or MCU) transmits the address of the register to read and the

MMA8491Q sends an acknowledgement.

3. The Master (or MCU) transmits a repeated start condition (SR) and then addresses

the MMA8491Q (0x1D) with the R/ W bit set to 1 for a read from the previously

selected register.

4. The Slave then acknowledges and transmits the data from the requested register.

5. The Master does not acknowledge (NAK) the transmitted data, but transmits a stop

condition to end the data transfer.

11.1.2 Multiple-byte read

When performing a multiple-byte read or burst read, the MMA8491Q automatically

increments the received register address commands after a read command is received.

Therefore, after following the steps of a single-byte read, multiple bytes of data can be

read from sequential registers after each MMA8491Q acknowledgment (AK) is received,

until a no acknowledge (NAK) occurs from the Master, followed by a stop condition (SP)

signaling an end of transmission.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 11 / 28

11.1.3 I2C data sequence diagrams

c o n tinued . . .

Master ST Device

Address[7:1] WRegister

Address[7:0] SR Device

Address[7:1] RAK

Slave AK AK AK Data[7:0]

Master AK AK NAK SP

Slave Data[7:0] Data[7:0] Data[7:0]

Multiple-byte read

Legend

ST: Start Condition SP: Stop Condition NAK: No Acknowledge W: Write = 0

SR: Repeated Start Condition AK: Acknowledge R: Read = 1

Master ST Device

Address[7:1] WRegister

Address[7:0] SR Device

Address[7:1] RNAK SP

Slave AK AK AK Data[7:0]

Single-byte read

Figure 6. I2C data sequence diagrams

12 Modes of operation

EN = Low

= Off

ACTIVE STANDBY

OFF*

Mode

SHUTDOWN

Mode Mode Mode

EN =

Don’t Care

= On

EN = Low

One sample

EN = High V

= On

EN = High

= On EN = High is acquired

= On

*OFF mode can be entered from any state by removing the power.

Figure 7. MMA8491Q operating modes

Table 10. MMA8491Q operating modes

Mode Conditions Function description Digital output state

OFF VDD = OFF

EN = Don’t Care

Device is powered off. Hi-Z

SHUTDOWN VDD = ON

EN = Low

All blocks are shut down. Hi-Z

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 12 / 28

Mode Conditions Function description Digital output state

ACTIVE VDD = ON

EN = High

All blocks are enabled.

Device enters Standby mode automatically

after data conversion.

Deasserted, Xout = 0, Yout= 0, Zout = 0

STANDBY VDD = ON

EN = High

Only digital output subsystem is enabled.

Data is valid and available only in this

stage.

Active, I2C outputs become valid

12.1 ACTIVE mode

The accelerometer subsystem is turned on at the rising edge of the EN pin, and acquires

one sample for each of the three axes. Note that EN should not be asserted before VDD

reaches 1.95 V. Samples are acquired, converted, and compensated for zero-g offset

and gain errors, and then compared to an internal threshold value of 0.688 g and stored.

•If any of the X, Y, Z axes sample’s absolute value > this threshold, then the

corresponding outputs on these axes drive logic highs.

•If any of the X, Y, Z axes sample’s absolute value ≤ this threshold, then the

corresponding outputs on these axes drive logic lows.

Read register 00h in this stage to determine whether the sample data is ready to be read.

12.2 STANDBY mode

The device enters STANDBY mode automatically after the previously described function

(powers into SHUTDOWN mode, ACTIVE mode) is accomplished. The digital output

system outputs valid data, which can also be read via the I2C communication bus. This

is the appropriate phase to read the measured data, either from the three push-pull logic

outputs or through the I2C transaction. All other subsystems are turned off.

These outputs are held until the MMA8491Q operation mode changes. For lower power

consumption, deassert the EN pin as soon as data is read (to enter SHUTDOWN mode).

12.3 Next sample acquisition

The MMA8491Q needs to be brought back to the ACTIVE mode again by pulling EN pin

up to a Logic 1. Another option is to power down the device and start from OFF mode as

illustrated in Figure 7.

For applications where sampling intervals are greater than 30 seconds, the host can shut

off the tilt sensor power after acquisition of tilt sensor output data to conserve energy and

prolong battery life.

12.4 Power-up timing sequences

The power-up timing sequence for MMA84591Q is shown in the following figure, where

VDD is powered and the EN pin is activated to acquire a single sample. Additional

samples can be acquired by repeating the EN pulse.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 13 / 28

OFF ACTIVE STANDBY SHUTDOWN

SHUTDOWN

Data

Available

Hi-Z

Figure 8. MMA8491Q timing sequence

tON is the time between EN to the end of ACTIVE stage, after which the newly acquired

sample data is available.

12.5 45° tilt detection

The output value changes according to the absolute value of the acceleration of the

MMA8491Q compared to the threshold:

•When the acceleration’s absolute value > the threshold 0.688 g, the output = 1.

•When the acceleration’s absolute value ≤ the threshold, the output = 0.

For example,

•When the MMA8491Q is set on a table, it senses 1 g acceleration on Z-axis and

senses 0 g on X- and Y-axes.

•When the MMA8491Q is flipped upside down on the table, it senses –1 g acceleration

on Z-axis and senses 0 g on X- and Y-axes.

In both cases Xout = 0, Yout = 0, and Zout = 1.

12.6 Tilt angle

Tilt angles can be calculated from the g-value threshold using the equation below. The

tilt threshold is 0.688 g, which corresponds to 43.5°. Figure 9 illustrates the tilt angle

threshold.

( )

Tilt Angle

g-value

-------------------

asin=

•When 0 g acceleration is present on an axis, the tilt angle = 0°; when 1 g acceleration

is present on an axis, the tilt angle = 90°.

•When the tilt angle > the tilt threshold, the output for the axis is HIGH; when the tilt

angle ≤ the tilt threshold, the output for the axis is LOW.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 14 / 28

Horizontal

Reference

Threshold = 0.688g

Threshold (g-value) = 0.688g

Projected g-value =

Tilt Angle

= 55°

Horizontal

Reference

0.688g

Horizontal

Reference

0.688g

Output = 1

Tilt Angle

= 30°

Output = 0

Tilt Angle

= 70°

Output = 1

Ø Ø

Figure 9. MMA8491Q output is based on tilt angle and sensor g-value

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 15 / 28

13 Register descriptions

Table 11. Register address map

Name Type Register

Address

Auto-

increment

Address[1]

Reset Comment

STATUS R 0x00 0x01 0x00 Read time status

OUT_X_MSB R 0x01 0x02 Output [7:0] are the 8 MSBs of the 14-bit sample

OUT_X_LSB R 0x02 0x03 Output [7:2] are the 6 LSBs of the 14-bit sample

OUT_Y_MSB R 0x03 0x04 Output [7:0] are the 8 MSBs of the 14-bit sample

OUT_Y_LSB R 0x04 0x05 Output [7:2] are the 6 LSBs of the 14-bit sample

OUT_Z_MSB R 0x05 0x06 Output [7:0] are the 8 MSBs of the 14-bit sample

OUT_Z_LSB R 0x06 0x00 Output [7:2] are the 6 LSBs of the 14-bit sample

[1] Auto-increment is the I2C feature that the I2C read address is automatically updated after each read. Auto-increment addresses that are not a simple

increment are highlighted in bold. The auto-increment addressing is only enabled when device registers are read using I2C burst read mode. Therefore

the internal storage of the auto-increment address is cleared whenever a stop-bit is detected.

Notes:

•Register contents are preserved when EN pin is set high after sampling.

•Register contents are reset when EN pin is set low.

13.1 STATUS - Status register (address 00h)

The data read bits (ZYXDR, ZDR, YDR, XDR) are set when samples are taken and ready

to be read.

Table 12. STATUS - Status register (address 00h) bit allocation

Bit 7 6 5 4 3 2 1 0

Symbol — ZYXDR ZDR YDR XDR

Reset 0 0 0 0 0 0 0 0

Access R R R R R R R R

Table 13. STATUS - Status register (address 00h) field descriptions

Field Description

ZYXDR

X-, Y-, Z-axis new Data Ready (and available)

•ZYXDR signals that a new sample for all channels is available.

•ZYXDR is cleared when the high-bytes of the acceleration data (OUT_X_MSB, OUT_Y_MSB,

OUT_Z_MSB) of all channels are read..

0: No new set of data ready (default value)

1: A new set of XYZ acceleration and temperature data is available

ZDR

Z-axis new Data Ready (and available)

•ZDR is set whenever a new acceleration sample related to the Z-axis is generated.

•ZDR is cleared anytime OUT_Z_MSB register is read.

0: No new Z-axis data is ready (default value)

1: A new Z-axis data is ready

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 16 / 28

Field Description

YDR

Y-axis new Data Ready (and available)

•YDR is set whenever a new acceleration sample related to the Y-axis is generated.

•YDR is cleared anytime OUT_Y_MSB register is read.

0: No new Y-axis data ready (default value)

1: A new Y-axis data is ready

XDR

X-axis new Data Ready (and available)

•XDR is set whenever a new acceleration sample related to the X-axis is generated.

•XDR is cleared anytime OUT_X_MSB register is read.

0: No new X-axis data ready (default value)

1: A new X-axis data is ready

13.2 Output data registers (addresses 01h to 06h)

These registers contain the X-axis, Y-axis, and Z-axis14-bit output sample data

(expressed as 2's complement numbers).

•OUT_X_MSB, OUT_X_LSB, OUT_Y_MSB, OUT_Y_LSB, OUT_Z_MSB, and

OUT_Z_LSB are stored in the autoincrementing address range of 0x01 – 0x06.

•The LSB registers can only be read immediately following the read access of the

corresponding MSB register. A random read access to the LSB registers is not

possible.

•Reading the MSB register and then the LSB register in sequence ensures that both

bytes (LSB and MSB) belong to the same data sample, even if a new data sample

arrives between reading the MSB and the LSB byte.

•The accelerometer data registers should be read only after the status register has

confirmed that new data on all axes is available.

Table 14. OUT_X_MSB - Output data register (address 01h) bit allocation

Bit76543210

Symbol XD[13:6]

Reset00000000

Access R R R R R R R R

Table 15. OUT_X_LSB - Output data register (address 02h) bit allocation

Bit 7 6 5 4 3 2 1 0

Symbol XD[5:0] — —

Reset 0 0 0 0 0 0 0 0

Access R R R R R R R R

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 17 / 28

Table 16. OUT_Y_MSB - Output data register (address 03h) bit allocation

Bit 7 6 5 4 3 2 1 0

Symbol YD[13:6]

Reset 0 0 0 0 0 0 0 0

Access R R R R R R R R

Table 17. OUT_Y_LSB - Output data register (address 04h) bit allocation

Bit 7 6 5 4 3 2 1 0

Symbol YD[13:6] — —

Reset 0 0 0 0 0 0 0 0

Access R R R R R R R R

Table 18. OUT_Z_MSB - Output data register (address 05h) bit allocation

Bit 7 6 5 4 3 2 1 0

Symbol OUT_Z[7:0]

Reset 0 0 0 0 0 0 0 0

Access R R R R R R R R

Table 19. OUT_Z_LSB - Output data register (address 06h) bit allocation

Bit 7 6 5 4 3 2 1 0

Symbol ZD[5:0] — —

Reset 0 0 0 0 0 0 0 0

Access R R R R R R R R

13.3 Accelerometer output conversion

Table 20. Accelerometer output data

14-bit Data Range ±8 g (1 mg/count)

01 1111 1111 1111 +8.000 g

01 1111 1111 1110 +7.998 g

... ...

00 0000 0000 0000 0.000 g

11 1111 1111 1111 –0.001 g

... ...

10 0000 0000 0001 –7.998 g

10 0000 0000 0000 –8.000 g

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 18 / 28

14 Mounting guidelines

Surface-mount printed circuit board (PCB) layout is a critical portion of the total design.

The footprint for the surface mount package must be the correct size to ensure proper

solder connection interface between the PCB and the package. With the correct

footprint, the package will self-align when subjected to a solder reflow process. The

purpose is to minimize the stress on the package after board mounting. The MMA8491Q

accelerometers use the QFN package. This section describes suggested methods of

soldering and mounting these devices to the PCB for consumer applications.

14.1 Overview of soldering considerations

The information provided here is based on experiments executed on QFN devices. They

do not represent exact conditions present at a customer site. Therefore, information

herein should be used as guidance only, and process and design optimizations are

recommended to develop an application specific solution. It should be noted that with

the proper PCB footprint and solder stencil designs, the package will self-align during the

solder reflow process.

14.2 Halogen content

This package is designed to be Halogen Free, exceeding most industry and customer

standards. Halogen Free means that no homogeneous material within the assembly

package shall contain chlorine (Cl) in excess of 700 ppm or 0.07% weight/weight or

bromine (Br) in excess of 900 ppm or 0.09% weight/weight.

14.3 PCB mounting recommendations

•Do not solder down the six exposed pads under the package, thus minimizing board-

mounting stress impact to product performance.

•PCB landing pad is 0.675 mm x 0.325 mm as shown in Figure 10.

•Solder mask opening = PCB land pad edge + 0.2 mm larger all around.

•Stencil opening size is 0.625 mm x 0.3 mm.

•Stencil thickness is 100 μm or 125 μm.

•The solder mask should not cover any of the PCB landing pads, as shown in Figure 10.

•No additional via nor metal pattern underneath package on the top of the PCB layer.

•Do not place any components or vias within 2 mm of the package land area. This may

cause additional package stress if it is too close to the package land area.

•Signal traces connected to pads should be as symmetric as possible. Put dummy

traces on NC pads, to have the same length of exposed trace for all pads.

•Use a standard pick-and-place process and equipment. Do not use a hand soldering

process.

•Customers are advised to be cautious about the proximity of screw-down holes to the

sensor, and the location of any press fit to the assembled PCB when in an enclosure.

It is important that the assembled PCB remain flat after assembly to keep electronic

operation of the device optimal.

•The PCB should be rated for the multiple lead-free reflow condition with a maximum

260 °C temperature.

•NXP sensors are compliant with Restrictions on Hazardous Substances (RoHS),

having halide-free molding compound (green) and lead-free terminations. These

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 19 / 28

terminations are compatible with tin-lead (Sn-Pb) as well as tin-silver-copper (Sn-Ag-

Cu) solder paste soldering processes. Reflow profiles applicable to those processes

can be used successfully for soldering the devices.

Figure 10. PCB footprint guidelines

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 20 / 28

15 Package Information

The MMA8491Q uses a 12-lead QFN package, case number 98ASA00290D.

15.1 Tape and reel information

Figure 11. Tape dimensions

Barcode label

side of reel

Pin 1

Direction

to unreel

Figure 12. Tape and reel orientation

15.2 Package description

This drawing is available for download at http://www.nxp.com/files/shared/doc/

package_info/98ASA00290D.pdf. Please consult the most recently issued drawing before

initiating or completing a design.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 21 / 28

Figure 13. Case 2169-02, Issue X1, 12-Lead QFN—page 1

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 22 / 28

Figure 14. Case 2169-02, Issue X1, 12-Lead QFN—page 2

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 23 / 28

Figure 15. Case 2169-02, Issue X1, 12-Lead QFN—page 3

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 24 / 28

16 Revision history

Revision

number

Revision

date Description

1.0 10/2012 •Initial release

2.0 11/2012 •Characterization data verified to be complete and final

2.1 4/2016 •Added MMA8491QR2 to Ordering information table

•Added paragraphs describing absolute maximum ratings

•Revised package dimensions drawings to the NXP format, no technical changes

•The format of this data sheet has been redesigned to comply with the new identity guidelines

of NXP Semiconductors

•Legal texts have been adapted to the new company name where appropriate

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 25 / 28

17 Legal information

Data sheet status

Document status[1] Product status[2] Definition

Data sheet: Product preview Development This document contains information on a product

under development. NXP reserves the right to change

or discontinue this product without notice.

Data sheet: Advance information Qualification This document contains information on a pre-

production product. Specifications and pre-production

information herein are subject to change without

notice.

Data sheet: Technical data Production NXP reserves the right to change the production

detail specifications as may be required to permit

improvements in the design of its products.

[1] Please consult the most recently issued document before initiating or completing a design.

[2] The product status of device(s) described in this document may have changed since this document was published and

may differ in case of multiple devices. The latest product status information is available on the Internet at URL nxp.com.

Definitions

Draft — The document is a draft version only. The

content is still under internal review and subject to formal

approval, which may result in modifications or additions.

NXP Semiconductors does not give any representations

or warranties as to the accuracy or completeness of

information included herein and shall have no liability for the

consequences of use of such information.

Disclaimers

Information in this document is provided solely to enable

system and software implementers to use NXP products.

There are no express or implied copyright licenses granted

hereunder to design or fabricate any integrated circuits based

on the information in this document. NXP reserves the right to

make changes without further notice to any products herein.

NXP makes no warranty, representation, or guarantee

regarding the suitability of its products for any particular

purpose, nor does NXP assume any liability arising out

of the application or use of any product or circuit, and

specifically disclaims any and all liability, including without

limitation consequential or incidental damages. “Typical”

parameters that may be provided in NXP data sheets and/

or specifications can and do vary in different applications,

and actual performance may vary over time. All operating

parameters, including “typicals,” must be validated for each

customer application by customer's technical experts. NXP

does not convey any license under its patent rights nor the

rights of others. NXP sells products pursuant to standard

terms and conditions of sale, which can be found at the

following address: nxp.com/salestermsandconditions.

Trademarks

NXP, the NXP logo, Freescale, the Freescale logo and

SMARTMOS are trademarks of NXP B.V. All other product or

service names are the property of their respective owners.

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 26 / 28

Tables

Tab. 1. Ordering information ..........................................2

Tab. 2. Pin descriptions .................................................3

Tab. 3. Absolute maximum ratings ................................5

Tab. 4. ESD and latch-up protection characteristics ......5

Tab. 5. Accelerometer mechanical characteristics ........ 6

Tab. 6. Electrical characteristics ....................................7

Tab. 7. Serial interface pins .......................................... 8

Tab. 8. I2C slave timing values .....................................8

Tab. 9. I2C device address sequence .........................10

Tab. 10. MMA8491Q operating modes ......................... 11

Tab. 11. Register address map ..................................... 15

Tab. 12. STATUS - Status register (address 00h) bit

allocation ......................................................... 15

Tab. 13. STATUS - Status register (address 00h) field

descriptions ..................................................... 15

Tab. 14. OUT_X_MSB - Output data register

(address 01h) bit allocation ............................. 16

Tab. 15. OUT_X_LSB - Output data register (address

02h) bit allocation ............................................16

Tab. 16. OUT_Y_MSB - Output data register

(address 03h) bit allocation ............................. 17

Tab. 17. OUT_Y_LSB - Output data register (address

04h) bit allocation ............................................17

Tab. 18. OUT_Z_MSB - Output data register

(address 05h) bit allocation ............................. 17

Tab. 19. OUT_Z_LSB - Output data register (address

06h) bit allocation ............................................17

Tab. 20. Accelerometer output data .............................. 17

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Data sheet: Technical data Rev. 2.1 — 26 April 2016

COMPANY PUBLIC 27 / 28

Figures

Fig. 1. Block Diagram ...................................................2

Fig. 2. Pin connection diagram .....................................3

Fig. 3. VDD connects to power supply and EN is

pulsed ................................................................4

Fig. 4. Sensitive axes orientation and output

response to ±1 g (gravity) stimulus ................... 5

Fig. 5. I2C slave timing diagram .................................. 9

Fig. 6. I2C data sequence diagrams .......................... 11

Fig. 7. MMA8491Q operating modes ......................... 11

Fig. 8. MMA8491Q timing sequence .......................... 13

Fig. 9. MMA8491Q output is based on tilt angle and

sensor g-value .................................................14

Fig. 10. PCB footprint guidelines ..................................19

Fig. 11. Tape dimensions ............................................. 20

Fig. 12. Tape and reel orientation ................................ 20

Fig. 13. Case 2169-02, Issue X1, 12-Lead QFN—

page 1 ............................................................. 21

Fig. 14. Case 2169-02, Issue X1, 12-Lead QFN—

page 2 ............................................................. 22

Fig. 15. Case 2169-02, Issue X1, 12-Lead QFN—

page 3 ............................................................. 23

NXP Semiconductors MMA8491Q

3-Axis Multifunction Digital Accelerometer

Contents

1 General description ............................................ 1

2 Features and benefits .........................................1

3 Typical applications ............................................1

4 Ordering information .......................................... 2

5 Related documentation ...................................... 2

6 Block diagram ..................................................... 2

7 Pinout ................................................................... 2

8 Recommended application diagram ..................4

9 Sensing direction and output response ............4

10 Mechanical and electrical specifications .......... 5

10.1 Absolute maximum ratings ................................ 5

10.2 Mechanical characteristics .................................6

10.3 Electrical characteristics .................................... 7

11 I2C Interface ........................................................ 8

11.1 I2C read operations ...........................................9

11.1.1 Single-byte read .............................................. 10

11.1.2 Multiple-byte read ............................................ 10

11.1.3 I2C data sequence diagrams ...........................11

12 Modes of operation ...........................................11

12.1 ACTIVE mode ..................................................12

12.2 STANDBY mode ..............................................12

12.3 Next sample acquisition ...................................12

12.4 Power-up timing sequences ............................ 12

12.5 45° tilt detection ...............................................13

12.6 Tilt angle .......................................................... 13

13 Register descriptions ....................................... 15

13.1 STATUS - Status register (address 00h) ......... 15

13.2 Output data registers (addresses 01h to 06h) .. 16

13.3 Accelerometer output conversion .................... 17

14 Mounting guidelines ......................................... 18

14.1 Overview of soldering considerations .............. 18

14.2 Halogen content .............................................. 18

14.3 PCB mounting recommendations .................... 18

15 Package Information .........................................20

15.1 Tape and reel information ............................... 20

15.2 Package description ........................................ 20

16 Revision history ................................................ 24

17 Legal information .............................................. 25

For more information, please visit: http://www.nxp.com

For sales office addresses, please send an email to: salesaddresses@nxp.com

Released on 26 April 2016