I2C interface Heart Rate Sensors©2016
EM7028 Datasheet
Heart Rate Sensor with I2C Interface
Revision V 1.0
2016-05-03 Updated
EM7028 Datasheet
Page 1
I2C interface Heart Rate Sensors©2016
CONTENTS
1. Description .............................................................................................................................6
2. Features .................................................................................................................................6
3. Functional Block Diagram ....................................................................................................... 7
4. PIN Configuration ...................................................................................................................8
5. Functional Description ............................................................................................................8
5.1
HRS in continuous mode .......................................................................................................................... 8
5.2
HRS in pulse mode .................................................................................................................................... 9
5.3
Typical performance chart ........................................................................................................................ 9
6. Parameters ........................................................................................................................... 10
7. Spectral Response Range .................................................................................................... 12
8. Absolute Maximum Ratings .................................................................................................. 12
9. I2C State Machine ................................................................................................................. 13
10.
Timing ............................................................................................................................. 13
11.
Registers Operation......................................................................................................... 14
12.
Registers Definition ......................................................................................................... 14
13.
Sample Application .......................................................................................................... 20
14.
PCB Design ..................................................................................................................... 21
15.
Package Outline Dimensions ........................................................................................... 22
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
16.
Packing ........................................................................................................................... 24
17.
Recommended Reflow Profile ......................................................................................... 25
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
FIGURE LIST
Fig. 1 EM7028 Functional Block Diagram .................................................................................................7
Fig. 2 EM7028 HRS value vs. receiving light lux ....................................................................................9
Fig. 3 EM7028 HRS wave............................................................................................................................9
Fig. 4 Operation current vs. supply voltage in continuous mode w/o current-limiting resistor, and
the current is controlled by VDD_LED and current-limiting resistor. Typical operation current
for heart rate detection is around 1mA. ...........................................................................................10
Fig. 5 Operation current vs. supply voltage in pulse mode w/i current controlled by resisters. .....10
Fig. 6 LED1/LED2 Spectral Response Range (The peak wavelength may change without
notification) ...........................................................................................................................................12
Fig. 7 Slave State Machine ........................................................................................................................13
Fig. 8 Data Structure...................................................................................................................................13
Fig. 9 Write waveform.................................................................................................................................13
Fig. 10 Read waveform ..............................................................................................................................14
Fig. 11 Register random write operation .................................................................................................14
Fig. 12 Register page write operation ......................................................................................................14
Fig. 13 Register random read operation ..................................................................................................14
Fig. 14 Typical Application Circuit in pulse mode of HRS2 ((VDD 2.6~3.6V, VDD_I2C 1.6~3.6V,
VDD_LED 2.6~4.5V) ...........................................................................................................................20
Fig. 15 Typical Application Circuit in continuous mode of HRS1 .........................................................21
Fig. 16 PCB layout design guide (all linear dimensions are in mm) ....................................................22
Fig. 17 Side view of package ...................................................................................................................22
Fig. 18 Package Outline Dimensions .......................................................................................................23
Fig. 19 Tape & Reel Information ..............................................................................................................24
Fig. 20 Recommended Reflow Profile for SMT .....................................................................................25
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
TABLE LIST
Table. 1 Pin Configuration ...........................................................................................................................8
Table. 2 I2C bus timing characteristics ..................................................................................................10
Table. 3 Electrical Characteristics ............................................................................................................ 11
Table. 4 Optical Characteristics ................................................................................................................ 11
Table. 5 Absolute Maximum Ratings .......................................................................................................12
Table. 6 REGISTER DESCRIPTION .......................................................................................................15
Table. 7 REGISTER 0x00 (RESERVED) ................................................................................................15
Table. 8 REGISTER 0x01 (CONFIGURE) - PROX/HRS CONFIGURATION ..................................15
Table. 9 REGISTER 0x02 (INTERRUPT) - PROX/GES/HRS INTERRUPT CONTROL .................16
Table. 10 REGISTER 0x03 (HRS_LT) - INTERRUPT LOW THRESHOLD FOR HRS2/HRS1.....16
Table. 11 REGISTER 0x04 (HRS _LT) - INTERRUPT LOW THRESHOLD FOR HRS2/HRS1 ...16
Table. 12 REGISTER 0x05 (HRS _HT) - INTERRUPT LOW THRESHOLD FOR HRS2/HRS1 ...17
Table. 13 REGISTER 0x06 (HRS _HT) - INTERRUPT LOW THRESHOLD FOR HRS2/HRS1 ...17
Table. 14 REGISTER 0x07 (LED_CURRENT) – HRS2 LED CURRENT FOR HRS2 ....................17
Table. 15 REGISTER 0x08 (HRS2_DATA_OFFSET) – HRS2 DATA OFFSET ..............................17
Table. 16 REGISTER 0x09 (HRS2_CTRL) - HRS2 CONTROL ..........................................................17
Table. 17 REGISTER 0x0A (HRS2_GAIN_CTRL) - PROXIMITY SENSOR GAIN CONTROL ......18
Table. 18 REGISTER 0x0B (Reserved) ..................................................................................................18
Table. 19 REGISTER 0x0C (Reserved) ..................................................................................................18
Table. 20 REGISTER 0x0D (HRS1_CTRL) – HRS1 CONTROL .........................................................18
Table. 21 REGISTER 0x0E (INT_CTRL) –INTERRUPT CONTROL ..................................................19
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
1. Description
EM7028 is a low-power I2C interface module includes Heart Rate Sensor(HRS) and internal LED Current
Drivers with 2 Green LED. It can work in both continuous mode and pulse mode. It is designed for
applications of Heart Beat Rate detection esp. such as smart watch etc.
Heart Rate Sensor in continuous mode is designed to monitor heart rate by optical detection. A 16-bit ADC
detects the result constantly with adjustable gain and resolution.
Heart Rate Sensor in pulse mode is designed to monitor heart rate by optical detection in low-power. It also
acts as a proximity sensor with rejection of ambient light noise. In order to removing component variations
and eliminate offset caused by IR reflection, 2 registers were specially defined for compensation and high
dynamic range of detection.
HRS in continuous mode stores ADC output result into HRS1 registers, while HRS in pulse mode stores
ADC output result into HRS2 registers. All pixels are controlled by analog-MUX in different modes.
2. Features
Heart-Rate Sensors(HRS) with built-in 2 LED of 525nm wavelength integrated in a single Optical
Module
50Hz/60Hz Flicker Noise Rejection
Temperature Compensation
Higher Sensitivity of Proximity Sensing
HRS in continuous mode with higher detection rate
HRS in pulse mode with Ambient Light Rejection
HRS detect rates is up to 1000/s
2048 Steps Programmable LED current driver for flexibility and part-to-part calibration
16bits ADC of Heart Rate Sensor
Offset register adjustment for compensation of DC noise
Programmable Interrupt modes
Low Average Operation Power consumption
Output Type: I2C Bus (HRS2) up to 400K Hz
Operation Voltage 2.5V ~ 3.6V
Logic Interface Voltage VBUS=1.8V or VBUS=VDD
Minimum External Components
Package: (4.0mmX2.4mmX1.35mm)
RoHS package
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
3. Functional Block Diagram
VDD_LED
LEDA
VDD
VDD
Reference
Current/Voltage
Source
Oscillator
Temperature
Compensation
SCL
Registers & I2C
Read/Write
Power-On-Reset
SDA
Clock
HRS2 offset
calibration
HRS2 Gain Ctrl
HRS2 timing
Ctrl
LED2
LED
525nm
LED
525nm
HRS2
Counter
PS
Data
Threshold Compare &
Interrupt Ctrl
INT
HRS 2 Noise
Cancellation
HRS1 timing
ctrl
LED1
LED Array
Programmable
Constant Current
Driver
HRS1
Programmable
ADC
Data
PD
Array
GND
RED/IR Light
Object
Fig. 1 EM7028 Functional Block Diagram
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
4. PIN Configuration
VDD
8
1 SDA
SDA 1
8 VDD
SCL 7
2 INT
INT 2
7 SCL
6
3 LED1
LED1 3
6 GND
LEDA 5
4 LED2
LED2 4
5 LEDA
GND
Top View
Bottom View
Table. 1 Pin Configuration
Pin No.
Pin Name
Type
Description
1
SDA
I/O(Open Drain)
I2C Serial data I/O terminal -serial data I/O for I2C
2
INT
O(Open Drain)
Interrupt.
3
LED1
O(Open Drain)
LED Current Driver for LED1 - up to 200mA
4
LED2
O(Open Drain)
LED Current Driver for LED2 - up to 12mA
5
LEDA
I
LED Anode, connect to VDD_LED on PCB
6
7
8
Power supply ground. All voltages are referenced to
GND
SCL
GND
I(Open Drain)
VDD
I2C serial clock input terminal — clock signal for I2C
serial data.
Power Supply voltage
5. Functional Description
5.1 HRS in continuous mode
In Normal HRS mode, one of the LED turns on, and HRS Sensor detects both ambient light and light
from green LED. The sensitivity of light is 1 lux/count, and totally 65536lux in full range; The typical
resolution of ADC is 16bits and 25ms conversion time.
In low-lux mode, 8 times of ADC gain is chosen for receiving light. The detect range is 0.125lux to
8192lux.
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
200
EM7028
180
160
140
120
LUX
100
80
60
40
20
0
0
500
1000
1500
2000
2500
3000
3500
4000
4500
HRS1 ADC DATA
Fig. 2 EM7028 HRS value vs. receiving light lux
5.2 HRS in pulse mode
The Heart Rate Sensor in pulse mode detects reflected light with LED turned on in pulse.
5.3 Typical performance chart
HRS value typically reflect heart beat status as illustrated in Fig.3
Fig. 3 EM7028 HRS wave
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
operation current vs supply voltage
4
3.5
VDD (V)
3
2.5
2
1.5
1
0.5
0
0
2
4
6
8
10
12
14
current (mA)
Fig. 4 Operation current vs. supply voltage in continuous mode w/o current-limiting resistor, and the current is
controlled by VDD_LED and current-limiting resistor. Typical operation current for heart rate detection is around 1mA.
TBD
Fig. 5 Operation current vs. supply voltage in pulse mode w/i current controlled by resisters.
6. Parameters
Table. 2 I2C bus timing characteristics
Symbol
Parameters
fclk
SCL clock frequency
tSUDAT
data set up time
tHDDAT
trise
tfall
tLOW
tHIGH
tBUF
tHDSTA
Minimum
Maximum Units
Condition
10k
100k
Hz
Normal Mode
10k
400k
Hz
Fast Mode
250
ns
Normal Mode
100
ns
Fast Mode
300
ns
Normal Mode
90
ns
Fast Mode
1000
ns
Normal Mode
300
ns
Fast Mode
300
ns
Normal Mode
300
ns
Fast Mode
4.7
μs
Normal Mode
1.3
μs
Fast Mode
4.0
μs
Normal Mode
0.6
μs
Fast Mode
Bus free time between the start
4.7
μs
Normal Mode
and stop state
1.3
μs
Fast Mode
(repeat) started state holding time 4.0
μs
Normal Mode
data hold time
clock/data rise time
clock/data fall time
I2C clock (SCL) low cycle
I2C clock (SCL) high cycle
EM7028 Datasheet
Typical
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I2C interface Heart Rate Sensors©2016
after this period produce the first
0.6
μs
Fast Mode
4.7
μs
Normal Mode
0.6
μs
Fast Mode
4.0
μs
Normal Mode
0.6
μs
Fast Mode
ms
Normal Mode
ms
Fast Mode
clock
tSUSTA
tSUSTO
tTIMEOUT
Repeat the start state set up time
Stop state set up time
Low detection clock/data timeout
25
35
time
Cload
The capacitive load for each bus
400
pF
-
KΩ
line
RBUS
Pull up resistors SDA and SCL
1
system bus
tVD
Data valid time
0.9
μs
tVDACK
Data valid acknowledge time
0.9
μs
Table. 3 Electrical Characteristics
Symbol
Min
Typ
VDD
2.6
Max
3.6
IDD
Unit
s
V
Introductions
Supply voltage
μA
DC power supply current (with LED
turned off)
VDD_I2C
1.6
3.6
V
I2C power supply voltage
VDD_LED
2.6
4.5
V
LED power supply voltage
nA
Shut Down Current
85
°C
Recommended operating temperature
0.54
V
SCL/SDA Input low voltage
V
SCL/SDA Input high voltage
IDD_SD
TA
-40
VIL
VIH
1.25
Table. 4 Optical Characteristics
Parameters
Full scale HRS1 ADC count
value
HRS detect range
Full scale HRS2 ADC count
value
EM7028 Datasheet
Min
Typ
Max
Units
65536
counts
65536
lux
65536
counts
Descriptions (Ta = +25 ℃)
HRS register maximum count in
continuous mode
HRS detection range
HRS ADC maximum count in pulse
mode
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I2C interface Heart Rate Sensors©2016
HRS2 LED drive
2.5
200
HRS2 LED duty cycle
mA
LED duty cycle, cycle of HRS2 at 100
1/500
ms
VF
TBD
V
LED Forward Voltage, IF =20 mA
V
LED Reverse Voltage, IR =1 μA
mW
LED Radiant Power, IF =20 mA
LED Peak Wavelength, IF =100 mA
VR
Po
HRS2 LED drive current
0.8
λp
525
nm
Δλ
30
nm
Spectrum Width of Half Value, IF =20
mA
TR
ns
LED Optical Rise Time, IF =20 mA
TF
ns
LED Optical Fall Time, IF =20 mA
7. Spectral Response Range
1
0.9
Normalize Response
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
400
450
500
550
wavelength (nm)
600
650
700
Fig. 6 LED1/LED2 Spectral Response Range (The peak wavelength may change without notification)
LED2 has the same spectral response as LED1
8. Absolute Maximum Ratings
Table. 5 Absolute Maximum Ratings
Parameters
Symbol
Min.
Max.
Units
Storage Temperature
TS
-40
85
°C
Operation Temperature
TA
-40
85
°C
Supply Voltage
VDD
2.25
3.6
V
EM7028 Datasheet
Condition
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I2C interface Heart Rate Sensors©2016
ESD
VESD
2K
V
HBM
ESD
VESD
200
V
MM
9. I2C State Machine
IDLE
Address Dec
ACK
TRANS
REV
Fig. 7 Slave State Machine
10.Timing
MSB
6
5
4
3
W
A
2
1
LSB
Fig. 8 Data Structure
SCL
SDA
DATA
S
Slave Address
W
A
DATA
DATA
A/!A
P
A/!A
P
Fig. 9 Write waveform
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
SCL
SDA
DATA
S
R
Slave Address
A
R
DATA
A
!A
DATA
P
!A
P
Fig. 10 Read waveform
11.Registers Operation
S
W
A
REG_ADDR
A REG_WDATA
W
A
REG_ADDR
A
REG_WDATA1
A
Slave Address
A/!A
P
Fig. 11 Register random write operation
S
Slave Address
A
REG_WDATA0
REG_WDATAn A/!A
P
Fig. 12 Register page write operation
S
Slave Address
W
S
A
REG_ADDR
Slave Address
R
A/!A
P
A REG_RDATA
A/!A
P
Fig. 13 Register random read operation
12.Registers Definition
Function Modes:
1. HRS1 (Heart Rate Measurement in Continuous Mode)
2. HRS2 (Heart Rate Measurement in Pulse Mode)
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
Table. 6 REGISTER DESCRIPTION
Address
R/W
0(0x00)
R
Bit7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Default
1(0x01)
R/W
Reserved
HRS1_EN
Reserved
Reserved
Reserved
2(0x02)
R/W HRS2_FLAG
0x00
Reserved
HRS1_FLAG
INT_CTRL
3(0x03)
R/W
HRS_LT[7:0]
0x00
4(0x04)
R/W
HRS _LT[15:8]
0x00
5(0x05)
R/W
HRS _HT[7:0]
0xFF
6(0x06)
R/W
HRS _HT[15:8]
0xFF
7(0x07)
R/W
LED_CAL[7:0]
0x80
8(0x08)
R/W
HRS2_DATA_OFFSET[7:0]
0x00
9(0x09)
R/W
PID
HRS2_EN
Reserved
10(0x0A) R/W HRS2_GAIN
Reserved
Reserved
HRS2_PRST[1:0]
0x36
HRS1_PRST[1:0]
0x00
HRS2_TIME[2]
HRS2_TIME[1]
HRS2_TIME[0]
LED_WIDTH[1]
LED_WIDTH[0]
LED_CNT[1]
LED_CNT[0]
0x40
HRS2_POS[6]
HRS2_POS[5]
HRS2_POS[4]
HRS2_POS[3]
HRS2_POS[2]
HRS2_POS[1]
HRS2_POS[0]
0x01
11(0x0B)
R
SIGN
Reserved
12(0x0C)
R
SIGN
Reserved
13(0x0D) R/W
HRS_GAIN
HRS_RANGE
14(0x0E) R/W
INT_EN
INT_MODE1
HRS_FREQ[2:0], 40960Hz to 2.62144MHz
INT_MODE2
INT_MODE3
0x00
0x00
HRS_RES[1:0], 10b, 12b, 14b, 16b
Reserved
IR_MODE
HRS2_DR[2:0], Programmed LED Current
0x32
0x90
15(0x0F) R/W
SOFT_RESET[7:0]
0x00
32(0x20)
R
HRS2_DATA0[7:0],
0x00
33(0x21)
R
HRS2_DATA0[15:8]
0x00
34(0x22)
R
HRS2_DATA1[7:0]
0x00
35(0x23)
R
HRS2_DATA1[15:8]
0x00
36(0x24)
R
HRS21_DATA2[7:0]
0x00
37(0x25)
R
HRS2_DATA2[15:8]
0x00
38(0x26)
R
HRS2_DATA3[7:0]
0x00
39(0x27)
R
HRS2_DATA3[15:8]
0x00
40(0x28)
R
HRS1_DATA0[7:0]
0x00
41(0x29)
R
HRS1_DATA0[15:8
0x00
42(0x2A)
R
HRS1_DATA1[7:0]
0x00
43(0x2B)
R
HRS1_DATA1[15:8]
0x00
44(0x2C)
R
HRS1_DATA2[7:0]
0x00
45(0x2D)
R
HRS1_DATA2[15:8]
0x00
46(0x2E)
R
HRS1_DATA3[7:0]
0x00
47(0x2F)
R
HRS1_DATA3[15:8]
0x00
48(0x30)
R
HRS1_DATA0[7:0]
0x00
49(0x31)
R
HRS1_DATA0[15:8]
0x00
Table. 7 REGISTER 0x00 (RESERVED)
BIT #
ACCESS
Default
Name
FUNCTION/OPERATION
7:0
RO
0x36
PID
Product ID - readable
Table. 8 REGISTER 0x01 (CONFIGURE) - PROX/HRS CONFIGURATION
BIT#
R/W
7
RW
Default
Value
Name
Name/operation description
When= 0, heart rate sensing in pulse mode is disabled;
0
HRS2_EN
When= 1, heart rate sensing in pulse mode is enabled; The enabled HRS2 pixels
are defined by HRS2_POS, and HRS2 ADC gain is defined by HRS2_GAIN;
6
RW
0
Reserved
Reserved
5
RW
0
Reserved
Reserved
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
4
RW
0
Reserved
Reserved
When= 0, Heart Beat Measurement is disabled;
3
RW
0
HRS1_EN
When= 1, Heart Beat Measurement is enabled with LED1 turned on and only Red
Light Sensor and IR sensor enabled. When LED1 turned on, the result stores to
HRS_DATA0;
2
RW
1
Reserved
Reserved
1
RW
1
Reserved
Reserved
0
RW
1
Reserved
Reserved
Only one of HRS1/HRS2 modes is enabled in a time
Table. 9 REGISTER 0x02 (INTERRUPT) - PROX/GES/HRS INTERRUPT CONTROL
BIT #
ACCESS
Default
BIT Name
Function/Operation
When=0, no proximity interrupt event has occurred since power-
7
FLAG
0
HRS2_FLAG
on or last “clear”
When=1, a proximity interrupt event occurred. Clearable by writing
“0”
When=00, 1 times of HRS2 value transfer threshold value;
6：5
RW
00
HRS2 Persist
When=01, 2 times of HRS2 value transfer threshold value;
When=10, 4 times of HRS2 value transfer threshold value;
When=11, 8 times of HRS2 value transfer threshold value;
4
FLAG
0
Reserved
Reserved
When=0, no HRS1 interrupt event has occurred since power-on
3
FLAG
0
HRS1_FLAG
or last “clear” ;
When=1, an HRS1 interrupt event occurred. Clearable by writing
“0”
When=00, 1 times of HRS1 value transfer threshold value;
2:1
RW
00
HRS1 Persist
When=01, 2 times of HRS1 value transfer threshold value;
When=10, 4 times of HRS1 value transfer threshold value;
When=11, 8 times of HRS1 value transfer threshold value;
0
RW
0
INT_CTRL
When=0, only HRS2 interrupt is enabled, unless INT_EN=0;
When=1, only HRS interrupt is enabled, unless INT_EN=0;
Table. 10 REGISTER 0x03 (HRS_LT) - INTERRUPT LOW THRESHOLD FOR HRS2/HRS1
BIT #
ACCESS
Default
BIT Name
Function/operation
HRS_LT
7:0
RW
0x00
(HRS2/HRS1
Low 8-bit interrupt low threshold for HRS sensing.
Low Threshold)
Table. 11 REGISTER 0x04 (HRS _LT) - INTERRUPT LOW THRESHOLD FOR HRS2/HRS1
BIT #
ACCESS
Default
BIT Name
Function/operation
7:0
RW
0x00
HRS_LT
High 8-bit interrupt low threshold for HRS sensing.
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
(HRS2/HRS1
Low Threshold)
Table. 12 REGISTER 0x05 (HRS _HT) - INTERRUPT LOW THRESHOLD FOR HRS2/HRS1
BIT #
ACCESS
Default
BIT Name
Function/operation
HRS_HT
7:0
RW
0xFF
(HRS2/HRS1
Low 8-bit interrupt high threshold for HRS sensing.
High Threshold)
Table. 13 REGISTER 0x06 (HRS _HT) - INTERRUPT LOW THRESHOLD FOR HRS2/HRS1
BIT #
ACCESS
Default
BIT Name
Function/operation
HRS_HT
7:0
RW
0xFF
(HRS2/HRS1
High 8-bit interrupt high threshold for HRS sensing.
High Threshold)
Table. 14 REGISTER 0x07 (LED_CURRENT) – HRS2 LED CURRENT FOR HRS2
BIT #
ACCESS
Default
BIT Name
Function/operation
When=0x00, LED current is 256/512 of full range;
When=0x01, LED current is 257/512 of full range;
7:0
RW
0x80
LED CAL
When=0x02, LED current is 258/512 of full range;
...
When=0xff, LED current is of full range to maximum;
This function serves for LED calibration;
Table. 15 REGISTER 0x08 (HRS2_DATA_OFFSET) – HRS2 DATA OFFSET
BIT #
ACCESS
Default
BIT Name
Function/operation
7
RW
0X0
Reserved
N/A
When=0x00, no offset;
When=0x01, HRS2 data subtract by 8 counts(6.25n);
6:0
RW
0x00
HRS2_ OFFSET
When=0x02, HRS2 data subtract by 16 counts(12.5n);
...
When=0x8f,
HRS2 data subtract by 1016 counts (793.75n);
Table. 16 REGISTER 0x09 (HRS2_CTRL) - HRS2 CONTROL
BIT #
ACCESS
Default
BIT Name
Function/operation
When=0, HRS2 conversion is continuous;
7
RW
0x0
Reserved
When=1, HRS2 conversion is divided by WAIT time
specified in HRS2_TIME;
When=000, HRS2 WAIT TIME = 0, continuous
6:4
RW
0b100
HRS2_WAIT_TIME
detect;
When=001, HRS2 WAIT TIME = 1.5625ms.;
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
When=010, HRS2 WAIT TIME = 6.25ms;
When=011, HRS2 WAIT TIME = 25ms;
When=100, HRS2 WAIT TIME = 100ms;
When=101, HRS2 WAIT TIME =400ms ;
When=110, HRS2 WAIT TIME = 1.6s;
When=111, HRS2 WAIT TIME = 6.4s;
When=00, LED WIDTH = 8 counts;
3:2
RW
0b10
LED_WIDTH
When=01, LED WIDTH = 32 counts;
When=10, LED WIDTH = 128 counts;
When=11, LED WIDTH = 512 counts;
When=00, LED COUNT = 1;
1:0
RW
0b00
LED_CNT
When=01, LED COUNT =4;
When=10, LED COUNT = 16;
When=11, LED COUNT = 64;
Table. 17 REGISTER 0x0A (HRS2_GAIN_CTRL) - PROXIMITY SENSOR GAIN CONTROL
BIT #
ACCESS
Default
BIT Name
7
RW
0b0
HRS2_GAIN
6:0
RW
0x01
HRS2_POS[6:0]
Function/operation
When=0, HRS2 GAIN = 1;
When=1, HRS2 GAIN = 10;
Each bit mark one pixel;
Table. 18 REGISTER 0x0B (Reserved)
Table. 19 REGISTER 0x0C (Reserved)
Table. 20 REGISTER 0x0D (HRS1_CTRL) – HRS1 CONTROL
BIT #
ACCESS
Default
BIT Name
7
RW
0x1
HRS_GAIN
6
RW
0x1
HRS_RANGE
Function/operation
When = 0, HRS1 GAIN =1;
When =1, HRS1 GAIN =5;:
When = 0, HRS1 RANGE =1;
When =1, HRS1 RANGE =8;
When=000, HRS1 FREQ = 2.62144MHz (1.5625ms);
When=001, HRS1 FREQ = 1.31072MHz(3.125 ms);
When=010, HRS1 FREQ = 655,360Hz(6.25 ms);
5:3
RW
0b110
HRS_FREQ
When=011, HRS1 FREQ = 327,680Hz(12.5ms);
When=100, HRS1 FREQ = 163,840Hz(25ms);
When=101, HRS1 FREQ = 81,920Hz(50ms);
When=110, HRS1 FREQ = 40,960Hz(100ms);
When=111, HRS1 FREQ = 20,480Hz(200ms) ;
When=00, HRS1 RES = 10 bits;
2:1
RW
0b01
HRS_RES
When=01, HRS1 RES = 12 bits;
When=10, HRS1 RES = 14 bits;
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I2C interface Heart Rate Sensors©2016
When=11, HRS1 RES = 16 bits;
0
RW
0b1
IR_MODE
When=0, IR mode;
When=1, HRS1 mode;
Table. 21 REGISTER 0x0E (INT_CTRL) –INTERRUPT CONTROL
BIT #
7
ACCES
S
RW
Default
BIT Name
Function/operation
0b1
INT_EN
When=1, INT mode is enabled
When=0, INT_MODE1 is disabled;
When=1, INT pin is drive “low” and interrupt flag is
6
RW
0b0
INT_MODE1
set to “1” when register value up transfer the high
threshold, and INT pin is pulled “high” and interrupt
flag reset “0” when register value down transfer the
low threshold.
When=0, INT_MODE2 is disabled;
When=1, INT pin is drive “low” and interrupt flag is
5
RW
0b0
INT_MODE2
set to “1” when register value larger than the high
threshold, and INT pin is pulled “high” and interrupt
flag reset “0” when register value is lower than the
low threshold.
When=0, INT_MODE3 is disabled;
When=1, INT pin is drive “low” and interrupt flag is
4
RW
0b1
INT_MODE3
set to “1” when register value is larger than the high
threshold or lower than the low threshold, otherwise
INT pin is pulled “high” and interrupt flag reset “0” .
3
RW
0b0
Reserved
Reserved
Peak current for LED1 of IR light, the average current
for LED1 is 1/500 of programmed current configured,
while the internal duty cycle is 1/500
When=000, LED programmed current = 2.5mA;
When=001, LED programmed current = 5.0mA;
2:0
RW
0b000
HRS2_DR[2:0]
When=010, LED programmed current = 7.5mA;
When=011, LED programmed current = 12.5mA;
When=100, LED programmed current = 25mA;
When=101, LED programmed current = 50mA;
When=110, LED programmed current = 100mA;
When=111, LED programmed current = 200mA;
Table. 22 REGISTER 0x0F (SOFT_RESET) – SOFT RESET BIT
Write any data to the SOFT_RESET register will reset the chip. No need to set a real register.
Table. 23 I2C Device address
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I2C interface Heart Rate Sensors©2016
operation
I2C Device address
7
6
5
4
3
2
1
0
address
Write Register
0
1
0
0
1
0
0
0
0x48H
Read Register
0
1
0
0
1
0
0
1
0x49H
The I2C Interface and 7-bit slave address is 0x24.
13.Sample Application
VDD_I2C
VDD
VDD_LED
R0 10Ω
2kΩ
8
VDD
5
LEDA
4
LED2
3
SCL
EM7028
LED1
SDA
INT
7
SCL
1
SDA
2
MicroProcessor
INT
GND
6
Ambient Light
Detecting Surface
Fig. 14 Typical Application Circuit in pulse mode of HRS2 ((VDD 2.6~3.6V, VDD_I2C 1.6~3.6V, VDD_LED 2.6~4.5V)
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
VDD3.3V
R0 100Ω
8
VDD
5
LEDA
4
LED2
3
SCL
EM7028
LED1
SDA
INT
7
1
I2C BUS SCL
I2C BUS SDA
2
GND
6
GND
Fig. 15 Typical Application Circuit in continuous mode of HRS1
VDD, VDD_I2C, VDD_LED can be connected together as VDD3.3V to 3.3V voltage.
VDD3.3V should connect 0.1uF capacitor to ground.
INT can be disconnected if no need of interrupt mode.
R0 is LED2 adjust resistor, and the typical value of R0 is 100Ω.
14.PCB Design
Suggested PCB pad layout guidelines for the Dual Flat No-Lead surface mount package are shown
below.
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
0.25±0.05
0.72±0.05
0.55±0.05
0.95±0.05
Fig. 16 PCB layout design guide (all linear dimensions are in mm)
15.Package Outline Dimensions
Fig. 17 Side view of package
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
Fig. 18 Package Outline Dimensions
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
16.Packing
Tape and reel dimensions is compliant to JEDEC MSL 3
Ordering Information
Q'TY/REEL
Q'TY/inside box
Q'TY/outside box
EM7028
1000EA
2000EA
20000EA
(7’ reel)
Remark
MBB/Label/Temperature
Card/Silica gel
Fig. 19 Tape & Reel Information
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
17.Recommended Reflow Profile
PARAMETER
REFERENCE
Average temperature gradient in preheating
Soak time
DEVICE
2.5°C/sec
tsoak
2 to 3 minutes
Time above 217°C(T1)
T1
Max 60 sec
Time above 230°C(T2)
T2
Max 50 sec
Time above Tpeak-10°C(T3)
T3
Max 10 sec
Peak temperature in reflow
Tpeak
260°C
Temperature gradient in cooling
Max-5°C/sec
Fig. 20 Recommended Reflow Profile for SMT
The product require to control strictly to prevent moisture absorption into unit. The recommend control
is as following. Rebaking of the reel will be required if the devices is unpack from the MBB bag more
than 24 hours. If rebaking is required, it should be done at 50℃ for 12 hours.
EM7028 Datasheet
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I2C interface Heart Rate Sensors©2016
History
Date
Author
Modification
NOTICE:
1. The information here contained could be changed without notice owing to product and/or technical
improvements. Please make sure before using the product that the information you are referring to is up-to-date.
2. No responsibilities are assumed by us for any consequence resulting from any wrong or improper operation,
etc. of the product.
Epticore Microelectronics Co. Ltd.
For product information and a complete list of distributors, please contact sales@epticore.com or go to our web site:
http://www.epticore.com
Copyright © 2016 by Epticore Microelectronics
The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Epticore
Microelectronics assumes no responsibility arising from the using of the specification described. The applications
mentioned herein are used solely for the purpose of illustration and Epticore Microelectronics makes no warranty or
representation that such application will be suitable without further modification, nor recommends the use of its product
for application that may present a risk to human life due to malfunction or otherwise. Epticore Microelectronics reserves
the right to alter its product without prior notification. For the most up-to-date information, please contact sales
representatives.
EM7028 Datasheet
Page 26
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