Microchip MCP9805 Memory module digital temperature sensor Datasheet

MCP9805
Memory Module Digital Temperature Sensor
Features
Description
• Meets JEDEC Standard JC42.4 for Mobile
Platform Memory Module Thermal Sensor
• Temperature-to-Digital Converter
• Accuracy with 0.25 °C/LSb Resolution:
- ±1°C (max.) from +75°C to +95°C
- ±2°C (max.) from +40°C to +125°C
- ±3°C (max.) from -20°C to +125°C
• Programmable Temperature Monitor Boundary
• Critical Temperature Output
• Operating Voltage Range: 3.0V to 3.6V
• 2-wire Interface: SMBus/Standard mode I2C™
Compatible
• Operating Current: 200 µA (typ.)
• Shutdown Current: 0.1 µA (typ.)
• Available Packages: 2x3 DFN-8, TSSOP-8
Microchip Technology Inc.’s MCP9805 digital temperature sensor converts temperatures between -40°C and
+125°C to a digital word. This sensor is designed to
meet the JEDEC standard JC42.4 for Mobile Platform
Memory Module Thermal Sensor. This device provides
an accuracy of ±1°C (max.) from a temperature range
of +75°C to +95°C (active range) and ±2°C (max.) from
+40°C to +125°C (monitor range) as defined in the
JEDEC standard.
Typical Applications
•
•
•
•
Dual In-line Memory Module (DIMM)
Personal Computers (PCs) and Servers
Hard Disk Drives and Other PC Peripherals
General Purpose Temperature Sensor
The MCP9805 comes with user-programmable
registers
that
provide
flexibility
for
DIMM
temperature-sensing applications. The registers allow
user-selectable settings such as Shutdown or
Low-Power modes and the specification of temperature event and critical output boundaries. When the
temperature changes beyond the specified boundary
limits, the MCP9805 outputs an Event signal. The user
has the option of setting the Event output signal polarity
as either an active-low or active-high comparator
output for thermostat operation, or as a temperature
event interrupt output for microprocessor-based
systems. The Event output can also be configured as a
critical temperature output.
This sensor has a 2-wire industry-standard SMBus
and Standard mode I2C compatible (100 kHz bus
clock) serial interface protocol, allowing up to eight sensors to be controlled in a single serial bus. These features make the MCP9805 ideal for sophisticated
multi-zone temperature-monitoring applications.
Typical Application
Memory Module
Memory
SPD*
Temperature
Sensor
EEPROM
MCP9805
Package Types
MCP9805
8-Pin DFN (2x3)
A1 2
8 VDD
7 Event
A2 3
6 SCLK
A0 1
R
GND 4
5 SDA
8-Pin TSSOP
R
3.3 VDD_SPD
SDA SCLK
Event
A0 1
8 VDD
A1 2
7 Event
A2 3
6 SCLK
GND 4
5 SDA
* Serial Presence Detect
© 2005 Microchip Technology Inc.
DS21977B-page 1
MCP9805
1.0
ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings †
VDD ....................................................................... 6.0V
†Notice: Stresses above those listed under “Maximum
ratings” may cause permanent damage to the device. This is
a stress rating only and functional operation of the device at
those or any other conditions above those indicated in the
operational listings of this specification is not implied.
Exposure to maximum rating conditions for extended periods
may affect device reliability.
Voltage at all Input/Output pins .... GND – 0.3V to 5.5V
Storage temperature ..........................-65°C to +150°C
Ambient temp. with power applied .....-40°C to +125°C
Junction Temperature (TJ)................................ +150°C
ESD protection on all pins (HBM:MM)....... (4 kV:200V)
Latch-Up Current at each pin ........................ ±200 mA
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, VDD = 3.0V to 3.6V, GND = Ground and TA = -20°C to +125°C.
Parameters
Sym
Min
Typ
Max
Unit
Conditions
VDD
3.0
—
3.6
V
Operating Current
IDD
—
200
500
µA
Continuous Operation
Shutdown Current
ISHDN
—
0.1
2
µA
Shutdown Mode
VDD Falling Edge
Power Supply
Operating Voltage Range
Power-On Reset Threshold (POR)
VPOR
—
2.2
—
V
PSRDC
—
±0.3
—
°C
PSRAC
—
±0.5
—
°C
VDD = 3.3V + 150 mVpp
(0 to 1 MHz), TA = +25°C
+75°C to +95°C
TACY
-1.0
±0.5
+1.0
°C
Active Temp. Range
+40°C to +125°C
TACY
-2.0
±1.0
+2.0
°C
Monitor Temp. Range
-20°C to +125°C
TACY
-3.0
±2.0
+3.0
°C
TA = -40°C
TACY
—
±2
—
°C
tCONV
—
65
125
ms
17 samples/sec. (typ.)
High-Level Current (leakage)
IOH
—
—
1
µA
VOH = 3.6V
Low-Level Voltage
VOL
—
—
0.4
V
IOL= 3 mA
tRES
—
0.7
—
s
tRES
—
1.5
—
s
Time to 63% of +22°C (Air)
to +125°C (Oil Bath)
Power Supply Rejection
Temperature Sensor Accuracy
Accuracy with 0.25 °C/LSb Resolution:
Internal ΔΣ ADC
Conversion Time (10-bits + Sign):
0.25 °C/LSb
Event Output (Open-Drain)
Thermal Response
Response Time (Note):
DFN
TSSOP
Note:
Thermal response with 1x1 inch dual-sided copper clad.
DS21977B-page 2
© 2005 Microchip Technology Inc.
MCP9805
DIGITAL INPUT/OUTPUT PIN CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, VDD = 3.0V to 3.6V, GND = Ground and TA = -20°C to +125°C.
Parameters
Sym
Min
Typ
Max
Units
VIH
2.1
Low-Level Voltage
VIL
—
Input Current
IIN
Low-Level Voltage
Conditions
—
—
V
—
0.8
V
—
—
±5
µA
VOL
—
—
0.4
V
IOL= 3 mA
High-Level Current (leakage)
IOH
—
—
1
µA
VOH = 3.6V
Low-Level Current
IOL
6
—
—
mA
VOL = 0.6V
CIN
—
5
—
pF
VHYST
—
0.5
—
V
Serial Input/Output (SCLK, SDA, A0, A1, A2)
Input
High-Level Voltage
Output (SDA)
Capacitance
SDA and SCLK Inputs
Hysteresis
Graphical Symbol Description
SDA OUTPUT
SDA & SCLK INPUTS
Voltage
Voltage
VDD
VDD
VIH
VIL
VOL
time
time
Current
Current
IOL
IOH
IIN
time
time
© 2005 Microchip Technology Inc.
DS21977B-page 3
MCP9805
SERIAL INTERFACE TIMING CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, VDD = 3.0V to 3.6V, GND = Ground, TA = -20°C to +125°C,
CL = 80 pF and all limits measured to 50% point.
Parameters
Sym
2-Wire SMBus/Standard Mode
Min
Typ
Max
Units
Conditions
I2
C™ Compatible Interface (Note)
fSC
10
—
100
kHz
Low Clock
tLOW
4.7
—
—
µs
High Clock
tHIGH
4.0
—
—
µs
Rise Time
tR
—
—
1000
ns
(VIL MAX - 0.15V) to (VIH MIN + 0.15V)
Fall Time
tF
—
—
300
ns
(VIH MIN + 0.15V) to (VIL MAX - 0.15V)
tSU-DATA
250
—
—
ns
Data Hold After SCLK Low
tHD-DATA
300
—
—
ns
Start Condition Setup Time
tSU-START
4.7
—
—
µs
Start Condition Hold Time
tHD-START
4.0
—
—
µs
Stop Condition Setup Time
tSU-STOP
4.0
—
—
µs
Bus Free
tB-FREE
4.7
—
—
µs
Time Out
tOUT
25
40
50
ms
Serial Port Clock Frequency
Data Setup Before SCLK High
Note:
The serial interface specification min./max. limits are specified by characterization (not production tested).
Timing Diagram
tH-START
tSU-START
tHIGH
tB-FREE
tSU-STOP
tLOW
SCLK
SDA
tOUT
tR, tF
tH-DATA
tSU-DATA
START Condition
Data Transmission
STOP Condition
TEMPERATURE CHARACTERISTICS
Electrical Specifications: Unless otherwise indicated, VDD = 3.0V to 3.6V, GND = Ground.
Parameters
Sym
Min
Typ
Max
Units
Conditions
Temperature Ranges
Specified Temperature Range
TA
-20
—
+125
°C
Operating Temperature Range
TA
-40
—
+125
°C
Storage Temperature Range
TA
-65
—
+150
°C
Thermal Resistance, 8L-DFN
θJA
—
41
—
°C/W
Thermal Resistance, 8L-TSSOP
θJA
—
123.7
—
°C/W
Note 1
Thermal Package Resistances
Note 1:
Operation in this range must not cause TJ to exceed Maximum Junction Temperature (+150°C).
DS21977B-page 4
© 2005 Microchip Technology Inc.
MCP9805
2.0
TYPICAL PERFORMANCE CURVES
Note:
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
Note: Unless otherwise noted: VDD = 3.0V to 3.6V, GND = Ground, Cde_cap = 0.1 µF
500
VDD= 3.3V to 3.6V
400
1.0
Spec. Limits
0.0
-1.0
350
300
250
200
-2.0
150
-3.0
100
-40
-20
0
20
FIGURE 2-1:
Accuracy.
40
60
TA (°C)
80
100
120
Average Temperature
-40
50%
0
20
40
60
TA (°C)
80
100
120
Supply Current vs. Ambient
2.00
VDD = 3.3V to 3.6V
TA = +95°C
VDD = 3.3V
120 samples
1.50
ISHDN (µA)
60%
-20
FIGURE 2-4:
Temperature.
70%
Occurrences
VDD = 3.3V to 3.6V
450
2.0
IDD (µA)
Temperature Accuracy (°C)
3.0
40%
30%
20%
1.00
0.50
10%
0.00
1.00
0.75
0.50
0.25
0.00
-0.25
-0.50
-0.75
-1.00
0%
-40
-20
0
20
Temperature Accuracy (°C)
70%
30%
2
1.5
20%
1
10%
0.5
Temperature Accuracy (°C)
FIGURE 2-3:
Temperature Accuracy
Histogram, TA = +75°C.
© 2005 Microchip Technology Inc.
1.00
0.75
0.50
0.25
0.00
-0.25
-0.50
0%
-0.75
120
2.5
40%
-1.00
100
3
TA = +75°C
VDD = 3.3V
120 samples
VPOR (V)
Occurrences
50%
80
FIGURE 2-5:
Shutdown Current vs.
Ambient Temperature.
FIGURE 2-2:
Temperature Accuracy
Histogram, TA = +95°C.
60%
40
60
TA (°C )
0
-40
-20
0
20
40
60
TA (°C)
80
100
120
FIGURE 2-6:
Power-on Reset Threshold
Voltage vs. Ambient Temperature.
DS21977B-page 5
MCP9805
Note: Unless otherwise noted: VDD = 3.0V to 3.6V, GND = Ground, Cde_cap = 0.1 µF.
48
VOL = 0.6V
IOL = 3mA
42
0.3
SDA I OL (mA)
Event & SDA V OL (V)
0.4
SDA, VDD = 3.0V
VDD = 3.3V
VDD = 3.6V
0.2
0.1
Event, VDD = 3.0V to 3.6V
30
VDD = 3.6V
24
18
6
-40
-20
0
20
40
60
TA (°C)
80
100
120
FIGURE 2-7:
Event and SDA VOL vs.
Ambient Temperature.
-40
-20
0
FIGURE 2-10:
Temperature.
20
40
60
TA (°C)
80
100
120
SDA IOL vs. Ambient
3.0
Temperature Accuracy (°C)
125
VDD = 3.0V to 3.6V
110
tCONV (ms)
VDD = 3.3V
VDD = 3.0V
12
0
95
80
65
50
35
-40
-20
0
20
40
60
TA (°C)
80
100
2.0
VDD = 3.0V
VDD = 3.6V
1.0
PSRDC = 0.3°C/V
0.0
-1.0
-2.0
-3.0
-40
120
-20
0
FIGURE 2-11:
VDD.
FIGURE 2-8:
Conversion Rate vs.
Ambient Temperature.
20
40
60
TA (°C)
80
100
120
Temperature Accuracy vs.
120%
1.0
PSRAC, VDD = 3.3V + 150mVPP (AC)
TA = 25°C
+25°C
0.5
0.0
-0.5
No decoupling capacitor
-1.0 100
100
1,000
1k
1k
10,000
10k
10k
100,000
100k
100k
1,000,000
1M
1M
Thermal Response (%)
Normalized Temp. Error (°C)
36
100%
80%
60%
TSSOP-8
DFN-8
40%
20%
22°C (Air) to +125°C (Oil bath)
0%
-2
0
Frequency (Hz)
FIGURE 2-9:
Frequency.
DS21977B-page 6
Power Supply Rejection vs.
FIGURE 2-12:
Response.
2
4
6
8
Time (s)
10
12
14
16
Package Thermal
© 2005 Microchip Technology Inc.
MCP9805
3.0
PIN DESCRIPTION
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLES
DFN/TSSOP
Symbol
1
A0
Slave Address
2
A1
Slave Address
3
A2
Slave Address
4
GND
3.1
Pin Function
Ground
5
SDA
Serial Data Line
6
SCLK
Serial Clock Line
7
Event
8
VDD
Temperature Event Output
Power
Slave Address Pins (A0, A1, A2 )
3.4
A0, A1 and A2 are device slave address input pins.
The address pins correspond to the Least Significant
bits (LSbs) of the address byte (see Section 5.1.4
“Address Byte”). The Most Significant bits A6, A5, A4,
A3 are factory set. This is shown in Table 3-2.
TABLE 3-2:
Device
MCP9805
Note:
3.2
MCP9805 ADDRESS BYTE
Address Code
Slave Address
A6 A5 A4 A3
A2
A1
A0
X
X
X
0
0
1
1
User-selectable address is shown by X.
The SCLK is a clock input pin. All communication and
timing is relative to the signal on this pin. The clock is
generated by the host or master controller on the bus.
(See Section 5.0 “Serial Communication”).
3.5
Open-Drain Temperature Event
Output pin (Event)
The MCP9805 Event pin is an open-drain output. The
device outputs a signal when the ambient temperature
goes beyond the user-programmed temperature limit.
(see Section 4.2.3 “Event Output Configuration”).
Ground Pin (GND)
The GND pin is the system ground pin.
3.3
Open-Drain Serial Clock Line
(SCLK)
Open-Drain Serial Data Line (SDA)
SDA is a bidirectional input/output pin, used to serially
transmit data to/from the host controller. This pin
requires a pull-up resistor. (See Section 5.0 “Serial
Communication”).
© 2005 Microchip Technology Inc.
3.6
Power Pin (VDD)
VDD is the power pin. The operating voltage range, as
specified in the DC electrical specification table, is
applied on this pin.
DS21977B-page 7
MCP9805
4.0
SMBus/Standard mode I2C compatible serial interface
protocol. Figure 4-1 shows a block diagram of the
register structure.
FUNCTIONAL DESCRIPTION
The MCP9805 temperature sensors consist of a band
gap
temperature
sensor,
a
Delta-Sigma
Analog-to-Digital
Converter
(ΔΣ
ADC)
and
user-programmable
registers
using
a
2-wire
Event Output Hysteresis
Continuous Conversion or Shutdown
Critical Boundary Trip Lock
Event Boundary Window Lock bit
Clear Event Output Interrupt
Event Output Status
Enable/Disable Event Output
Critical Event Output only
Event Output Polarity, Active-High/Low
Band Gap
Temperature
Sensor
Event Output Comparator/Interrupt
Configuration Register
ΔΣ ADC
Temperature Register (TA)
Temperature Upper-Boundary (TUPPER)
Temperature Lower-Boundary (TLOWER)
Critical Temperature Limit (TCRIT)
Manufacturer Identification Register
Device Identification and Revision Register
Device Capability Register
Measurement Resolution
Measurement Range
Measurement Accuracy
Temperature Event Output
SMBus/Standard I2C™
Interface
Register Pointer
A0
FIGURE 4-1:
DS21977B-page 8
A1
A2
Event
VDD
GND
SDA
SCLK
Register Structure Block Diagram.
© 2005 Microchip Technology Inc.
MCP9805
4.1
Registers
The MCP9805 has several registers that are
user-accessible. These registers include the Capability
register, Configuration register, Event Temperature
Upper-Boundary and Lower-Boundary Trip registers,
Critical Temperature Trip register, Temperature register, Manufacturer Identification register and Device
Identification register.
The Temperature register is read-only, used to access
the ambient temperature data. The data is loaded in
parallel to this register after tCONV. The Event
Temperature Upper-Boundary and Lower-Boundary
Trip registers are read/writes. If the ambient temperature drifts beyond the user-specified limits, the
MCP9805 outputs a signal using the Event pin (refer to
Section 4.2.3 “Event Output Configuration”). In
addition, the Critical Temperature Trip register is used
to provide an additional critical temperature limit.
REGISTER 4-1:
The Capability register is used to provide bits
describing the MCP9805’s capability in measurement
resolution, measurement range and device accuracy.
The device Configuration register provides access to
configure the MCP9805’s various features. These
registers are described in further detail in the following
sections.
The registers are accessed by sending a Register
Pointer to the MCP9805 using the serial interface. This
is an 8-bit write-only pointer. However, the three Least
Significant bits (3-LSbs) are used as pointers and all
unused bits (bits 7-3) need to be cleared or set to ‘0’.
Register 4-1 describes the pointer or the address of
each register.
REGISTER ADDRESS POINTER (WRITE-ONLY)
W-0
W-0
W-0
W-0
W-0
W-0
W-0
W-0
0
0
0
0
0
P2
P1
P0
bit 7
bit 7-3
bit 0
Writable Bits: Write ‘0’
Bits 7-3 must always be cleared or written to ‘0’. This device has additional registers that are
reserved for test and calibration. If these registers are accessed, the device may not perform
according to the specification.
bit 2-0
Pointer Bits:
000 = Capability register
001 = Configuration register (CONFIG)
010 = Event Temperature Upper-Boundary Trip register (TUPPER)
011 = Event Temperature Lower-Boundary Trip register (TLOWER)
100 = Critical Temperature Trip register (TCRIT)
101 = Temperature register (TA)
110 = Manufacturer ID register
111 = Device ID/Revision register
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
- n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
© 2005 Microchip Technology Inc.
x = Bit is unknown
DS21977B-page 9
MCP9805
4.1.1
CAPABILITY REGISTER
This is a read-only register used to identify the temperature sensor capability. In this case, the MCP9805 is
capable of providing temperature at 0.25°C resolution,
measuring temperature below and above 0°C,
providing ±1°C and ±2°C accuracy over the active and
monitor temperature ranges (respectively) and providing user-programmable temperature event boundary
trip limits. Register 4-2 describes the Capability
register. These functions are described in further detail
in the following sections.
REGISTER 4-2:
Upper-Half:
U-0
—
bit 15
CAPABILITY REGISTER (READ-ONLY)
U-0
—
U-0
—
Lower-Half:
U-0
U-0
—
U-0
—
U-0
—
U-0
→ ADDRESS ‘0000 0000’b
U-0
—
U-0
—
R-0
R-1
Resolution
U-0
—
bit 8
R-1
Meas.
Range
R-1
Accuracy
bit 7
bit 15-5
bit 4-3
bit 2
bit 1
bit 0
R-1
Temp.
Event
bit 0
Unimplemented: Read as ‘0’
RESOLUTION bits:
00 = 0.5 °C/LSb
01 = 0.25 °C/LSb (default resolution)
10 = 0.125 °C/LSb
11 = 0.0625 °C/LSb
TEMPERATURE MEASUREMENT RANGE (Meas. Range) bit:
0 = TA = 0x0000 (Hexadecimal) for temperature below 0°C
1 = The part can measure temperature below 0°C
ACCURACY bit:
0 = Accuracy → ±2°C from +75°C to +95°C (Active Range) and ±3°C from +40°C to +125°C
(Monitor Range)
1 = Accuracy → ±1°C from +75°C to +95°C (Active Range) and ±2°C from +40°C to +125°C
(Monitor Range)
BASIC CAPABILITY (Temp. Event) bit:
0 = No defined function (This bit will never be cleared or set to ‘0’).
1 = The part has temperature boundary trip limits (TUPPER/TLOWER/TCRIT registers) and a temperautre
event output (JC 42.4 required feature).
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
- n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
DS21977B-page 10
x = Bit is unknown
© 2005 Microchip Technology Inc.
MCP9805
4.1.2
SENSOR CONFIGURATION
REGISTER (CONFIG)
The temperature hysteresis bits 10 and 9 can be used
to prevent output chatter when the ambient temperature gradually changes beyond the user-specified
temperature boundary (see Section 4.2.2 “Temperature Hysteresis (THYST)”. The Continuous Conversion
or Shutdown mode is selected using bit 8. In Shutdown
mode, the band gap temperature sensor circuit stops
converting temperature and the Ambient Temperature
register (TA) holds the previous successfully converted
temperature data (see Section 4.2.1 “Shutdown
Mode”). Bits 7 and 6 are used to lock the
user-specified boundaries TUPPER, TLOWER and TCRIT
to prevent an accidental rewrite. Bits 5 thru 0 are used
to configure the temperature Event output pin. All
functions are described in Register 4-3 (see
Section 4.2.3 “Event Output Configuration”).
The MCP9805 has a 16-bit Configuration register
(CONFIG) that allows the user to set various functions
for a robust temperature monitoring system. Bits 10
thru 0 are used to select Event output boundary hysteresis, device Shutdown or Low-Power mode, temperature boundary and critical temperature lock,
temperature Event output enable/disable. In addition,
the user can select the Event output condition (output
set for TUPPER and TLOWER temperature boundary or
TCRIT only), read Event output status and set Event
output polarity and mode (Comparator Output or Interrupt Output mode).
CONFIGURATION REGISTER (CONFIG) → ADDRESS ‘0000 0001’b
REGISTER 4-3:
Upper-Half:
U-0
—
bit 15
U-0
—
U-0
—
U-0
—
Lower-Half:
R/W-0
R/W-0
Crit. Lock Win. Lock
R/W-0
Int. Clear
U-0
—
R/W-0
R/W-0
THYST
R-0
R/W-0
Event Stat. Event Cnt.
R/W-0
SHDN
bit 8
R/W-0
Event
Sel.
R/W-0
Event
Pol.
bit 7
R/W-0
Event
Mod.
bit 0
bit 15-11 Unimplemented: Read as ‘0’
bit 10-9 Limit Hysteresis (THYST) bits:
00 = 0°C (power-up default)
01 = 1.5°C
10 = 3.0°C
11 = 6.0°C
(Refer to Section 4.2.3 “Event Output Configuration”)
bit 8
Shutdown Mode (SHDN) bit:
0 = Continuous Conversion (power-up default)
1 = Shutdown (Low-Power mode)
In shutdown, all power-consuming activities are disabled, though all registers can be written to or read.
This bit cannot be set ‘1’ when either of the lock bits is set (bit 6 and bit 7). However, it can be cleared ‘0’
for Continuous Conversion while locked. (Refer to Section 4.2.1 “Shutdown Mode”)
bit 7
TCRIT Lock Bit (Crit. Lock) bit:
0 = Unlocked. TCRIT register can be written. (power-up default)
1 = Locked. TCRIT register cannot be written to.
When enabled, this bit remains set ‘1’ or locked until cleared by internal reset (Section 4.3 “Summary of
Power-up Default”). This bit does not require a double-write.
.
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
- n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
© 2005 Microchip Technology Inc.
x = Bit is unknown
DS21977B-page 11
MCP9805
CONFIGURATION REGISTER (CONFIG) → ADDRESS ‘0000 0001’b
(CONTINUED)
REGISTER 4-3:
Upper-Half:
U-0
—
bit 15
U-0
—
U-0
—
U-0
—
Lower-Half:
R/W-0
R/W-0
Crit. Lock Win. Lock
R/W-0
Int. Clear
U-0
—
R/W-0
R/W-0
THYST
R-0
R/W-0
Event Stat. Event Cnt.
R/W-0
SHDN
bit 8
R/W-0
Event
Sel.
R/W-0
Event
Pol.
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
R/W-0
Event
Mod.
bit 0
TUPPER and TLOWER Boundary Window Lock (Win. Lock) bit:
0 = Unlocked. TUPPER and TLOWER registers can be written. (power-up default)
1 = Locked. TUPPER and TLOWER registers cannot be written.
When enabled, this bit remains set ‘1’ or locked until cleared by internal reset (Section 4.3 “Summary of
Power-up Default”). This bit does not require a double-write.
Interrupt Clear (Int. Clear) bit:
0 = No effect. (power-up default)
1 = Clear interrupt output. When read this bit returns ‘0’.
Event Output Status (Event Stat.) bit:
0 = Event output is not asserted by the device. (power-up default)
1 = Event output is asserted as a comparator/interrupt or critical temperature output.
Event Output Control (Event Cnt.) bit:
0 = Disabled. (power-up default)
1 = Enabled.
This bit can not be altered when either of the lock bits is set (bit 6 and bit 7).
Event Output Select (Event Sel.) bit:
0 = Event output for TUPPER, TLOWER and TCRIT. (power-up default)
1 = TA ≥ TCRIT only. (TUPPER and TLOWER temperature boundaries are disabled.)
When the Alarm Window Lock bit is set ‘1’ (bit 6), this bit cannot be altered until unlocked.
Event Output Polarity (Event Pol.) bit:
0 = Active-low. (power-up default)
1 = Active-high.
This bit cannot be altered when either of the lock bits is set (bit 6 and bit 7).
Event Output Mode (Event Mod.) bit:
0 = Comparator output. (power-up default)
1 = Interrupt output.
This bit cannot be altered when either of the lock bits is set (bit 6 and bit 7).
.
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
- n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
DS21977B-page 12
x = Bit is unknown
© 2005 Microchip Technology Inc.
MCP9805
4.1.3
TEMPERATURE EVENT
UPPER/LOWER/CRITICAL
BOUNDARY TRIP REGISTERS
(TUPPER/TLOWER/TCRIT)
The MCP9805 has a 16-bit read/write Event output
Temperature Upper-Boundary Trip register (TUPPER), a
16-bit Lower-Boundary Trip register (TLOWER) and a
16-bit Critical Boundary Trip register (TCRIT) that
contains 11-bit data in two’s compliment format
(0.25 °C/LSb). This data represents the maximum and
minimum temperature boundary or temperature
window that can be used to monitor ambient temperature. If this feature is enabled (Section 4.1.2 “Sensor
Configuration Register (CONFIG)”) and the ambient
temperature exceeds the specified boundary or
window, the MCP9805 asserts an Event output. (Refer
to Section 4.2.3 “Event Output Configuration”).
REGISTER 4-4:
Upper-Half:
U-0
—
bit 15
UPPER/LOWER/CRITICAL TEMPERATURE BOUNDARY TRIP REGISTERS
(TUPPER/TLOWER/TCRIT) → ADDRESS ‘0000 0010’b/‘0000 0011’b/‘0000 0100’b
U-0
—
U-0
—
R/W-0
SIGN
bit 11-2
bit 1-0
R/W-0
R/W-0
R/W-0
26 °C/LSb
25 °C/LSb
24 °C/LSb
bit 8
Lower-Half:
R/W-0
R/W-0
23 °C/LSb 22 °C/LSb
bit 7
bit 15-13
bit 12
R/W-0
27 °C/LSb
R/W-0
21 °C/LSb
R/W-0
20 °C/LSb
R/W-0
R/W-0
2-1 °C/LSb 2-2 °C/LSb
U-0
—
U-0
—
bit 0
Unimplemented: Read as ‘0’
SIGN bit:
0 = TA ≥ 0°C
1 = TA < 0°C
TUPPER/TLOWER/TCRIT bits:
Temperature boundary trip data in two’s compliment format.
Unimplemented: Read as ‘0’
Note: This table reflects the three 16-bit registers TUPPER, TLOWER and TCRIT located at address ‘0000 0010’b,
‘0000 0011’b and ‘0000 0100’b, respectively (see Register 4-1).
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = bit is set
‘0’ = bit is cleared
© 2005 Microchip Technology Inc.
x = bit is unknown
DS21977B-page 13
MCP9805
4.1.4
AMBIENT TEMPERATURE
REGISTER (TA)
EQUATION 4-1:
The MCP9805 uses a band gap temperature sensor
circuit to output analog voltage proportional to absolute
temperature. An internal ΔΣ ADC is used to convert the
analog voltage to a digital word. The converter resolution is set to 0.25 °C/LSb + sign (11-bit data). The digital
word is loaded to a 16-bit read-only Ambient Temperature register (TA) that contains 11-bit temperature data
in two’s complement format.
DECIMAL CODE TO
TEMPERATURE
CONVERSION
T A = Code × 2
–2
Where:
TA = Ambient Temperature (°C)
Code = MCP9805 output magnitude in
decimal
The TA register bits (bits 12 thru 0) are double-buffered.
Therefore, the user can access the register while, in the
background, the MCP9805 performs an analog-to-digital conversion of the band gap temperature sensor.
The temperature data from the ΔΣ ADC is loaded in
parallel to TA at tCONV refresh rate.
In addition, the TA register uses three bits (bits 15, 14
and 13) to reflect the Event pin state. This allows the
user to identify the cause of the Event output trigger
(see Section 4.2.3 “Event Output Configuration”);
bit 15 is set to ‘1’ if TA is greater than or equal to TCRIT,
bit 14 is set to ‘1’ if TA is greater than TUPPER and bit 13
is set to ‘1’ if TA is less than TLOWER.
The TA magnitude in decimal to ambient temperature
conversion is shown in Equation 4-1:
The TA register bit assignment and boundary
conditions are described in Register 4-5.
AMBIENT TEMPERATURE REGISTER (TA) → ADDRESS ‘0000 0101’b
REGISTER 4-5:
Upper-Half:
R-0
TA Vs. TCRIT
bit 15
R-0
R-0
TA Vs. TUPPER TA Vs. TLOWER
R-0
SIGN
R-0
R-0
R-0
R-0
27 °C/LSb
26 °C/LSb
25 °C/LSb
24 °C/LSb
bit 8
Lower-Half:
R-0
R-0
23 °C/LSb 22 °C/LSb
bit 7
R-0
21 °C/LSb
R-0
20 °C/LSb
R-0
R-0
2-1 °C/LSb 2-2 °C/LSb
U-0
—(2)
U-0
—
bit 0
TA vs. TCRIT(1) bit:
0 = TA < TCRIT
1 = TA ≥ TCRIT
bit 14
TA vs. TUPPER(1) bit:
0 = TA ≤ TUPPER
1 = TA > TUPPER
bit 13
TA vs. TLOWER(1) bit:
0 = TA ≥ TLOWER
1 = TA < TLOWER
bit 12
SIGN bit:
0 = TA ≥ 0°C
1 = TA < 0°C
Note 1: Not affected by the status of the Event output configuration (bits 5 to 0 of CONFIG) and THYST = 0°C,
Register 4-3.
bit 15
2: Bit 1 may remain set ‘1’ for some devices indicating 2-3 °C/LSb or 0.125°C temperature resolution,
depending on the state of the device calibration code.
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = bit is set
‘0’ = bit is cleared
DS21977B-page 14
x = bit is unknown
© 2005 Microchip Technology Inc.
MCP9805
AMBIENT TEMPERATURE REGISTER (TA) → ADDRESS ‘0000 0101’b
(CONTINUED)
REGISTER 4-5:
Upper-Half:
R-0
TA Vs. TCRIT
bit 15
R-0
R-0
TA Vs. TUPPER TA Vs. TLOWER
Lower-Half:
R-0
R-0
3
2
2 °C/LSb 2 °C/LSb
bit 7
R-0
2 °C/LSb
1
R-0
SIGN
R-0
R-0
R-0
R-0
27 °C/LSb 26 °C/LSb 25 °C/LSb 24 °C/LSb
bit 8
R-0
2 °C/LSb
0
R-0
R-0
-2
2 °C/LSb 2 °C/LSb
-1
U-0
—(2)
U-0
—
bit 0
bit 11-2
Ambient Temperature (TA) bits:
10-bit Ambient Temperature data in two’s compliment format.
bit 1, 0
Unimplemented: Read as ‘0’ (Note 2)
Note 1: Not affected by the status of the Event output configuration (bits 5 to 0 of CONFIG) and THYST = 0°C,
Register 4-3.
2: Bit 1 may remain set ‘1’ for some devices indicating 2-3 °C/LSb or 0.125°C temperature resolution,
depending on the state of the device calibration code.
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = bit is set
‘0’ = bit is cleared
© 2005 Microchip Technology Inc.
x = bit is unknown
DS21977B-page 15
MCP9805
4.1.5
MANUFACTURER ID REGISTER
This register is used to identify the device manufacturer
in order to perform manufacturer-specific operations.
The manufacturer ID for the MCP9805 is 0x0054
(hexadecimal).
MANUFACTURER ID REGISTER (READ-ONLY) → ADDRESS ‘0000 0110’b
REGISTER 4-1:
Upper-Half:
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
Manufacturer ID
bit 15
bit 8
Lower-Half:
R-0
R-1
R-0
R-1
R-0
R-1
R-0
R-0
Manufacturer ID
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
- n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
4.1.6
DEVICE ID AND REVISION
REGISTER
x = Bit is unknown
The revision begins with 0x00 (hex) for the first release,
with the number being incremented as revised versions
are released.
The upper byte of this register is used to specify the
device identification and the lower byte is used to
specify device revision. The device ID for the MCP9805
is 0x00 (hex).
DEVICE ID AND DEVICE REVISION (READ-ONLY) → ADDRESS ‘0000 0111’b
REGISTER 4-2:
Upper-Half:
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
Device ID
bit 15
bit 8
Lower-Half:
R-0
R-0
R-0
R-0
R-0
R-0
R-0
R-0
Device Revision
bit 7
bit 0
Legend:
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
- n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
DS21977B-page 16
x = Bit is unknown
© 2005 Microchip Technology Inc.
MCP9805
4.2
4.2.1
Sensor Feature Description
SHUTDOWN MODE
Shutdown mode disables all power-consuming
activities (including temperature sampling operations)
while leaving the serial interface active. This mode is
selected by setting bit 8 of CONFIG to ‘1’. In this mode,
the device consumes ISHDN. It remains in this mode
until bit 8 is cleared ‘0’ to enable Continuous
Conversion mode, or until power is recycled.
The Shutdown bit (bit 8) cannot be set to ‘1’ while bits
6 and 7 of CONFIG (Lock bits) are set to ‘1’. However,
it can be cleared ‘0’ or returned to Continuous
Conversion while locked.
In Shutdown mode, all registers can be read or written.
However, the serial bus activity increases the shutdown
current. In addition, if the device is shutdown while the
Event pin is asserted as active-low or deasserted
active-low (see Section 4.2.3.1 “Comparator Mode”
and Section 4.2.3.2 “Interrupt Mode”), the device will
retain the active-low state. This increases the
shutdown current due to the additional Event output
pull-down current.
4.2.2
TEMPERATURE HYSTERESIS
(THYST)
A hysteresis of 0°C, 1.5°C, 3°C or 6°C can be selected
for the TUPPER, TLOWER and TCRIT temperate boundaries using bits 10 and 9 of CONFIG. The hysteresis
applies for decreasing temperature only (hot to cold), or
as temperature drifts below the specified limit.
The TUPPER, TLOWER and TCRIT boundary conditions
are described graphically in Figure 4-2.
4.2.3
EVENT OUTPUT CONFIGURATION
The Event output can be enabled using bit 3 of
CONFIG (Event output control bit) and can be
configured as either a comparator output or as Interrupt
Output mode using bit 0 of CONFIG (Event mode). The
polarity can also be specified as an active-high or
active-low using bit 1 of CONFIG (Event polarity).
The Event output can also be used as a critical temperature output using bit 2 of CONFIG (critical output
only). When this feature is selected, the Event output
becomes a comparator output. In this mode, the
interrupt output configuration (bit 0 of CONFIG) is
ignored.
4.2.3.1
Comparator Mode
Comparator mode is selected using bit 0 of CONFIG. In
this mode, the Event output is asserted as active-high
or active-low using bit 1 of CONFIG. Figure 4-2 shows
the conditions that toggle the Event output.
If the device enters Shutdown mode with asserted
Event output, the output remains asserted during
Shutdown. The device must be operating in Continuous Conversion mode for tCONV; the TA vs. TUPPER,
TLOWER and TCRIT boundary conditions need to be
satisfied in order for the Event output to deassert.
Comparator mode is useful for thermostat-type applications, such as turning on a cooling fan or triggering a
system shutdown when the temperature exceeds a
safe operating range.
4.2.3.2
Interrupt Mode
Interrupt mode is selected using bit 0 of CONFIG. In
this mode, the Event output is asserted as active-high
or active-low using bit 1 of CONFIG. The output is
deasserted by setting ‘1’ to bit 5 of CONFIG (interrupt
clear). Shutting down the device will not reset or deassert the Event output. However, clearing the interrupt
using bit 5 of CONFIG while in Shutdown mode will
deassert the Event output.
This mode is ignored when the Event output is used as
critical temperature output only (bit 2 of CONFIG).
Interrupt mode applies to interrupt-driven, microcontroller-based systems. The microcontroller receiving
the interrupt will have to acknowledge the interrupt by
setting ‘1’ to bit 5 of CONFIG.
When the ambient temperature increases above the
critical temperature limit, the Event output is forced to a
comparator output (regardless of bit 0 of CONFIG).
When the temperature drifts below the critical temperature limit, the Event output automatically returns to the
state specified by bit 0 of CONFIG.
The status of the Event output can be read using bit 4
of CONFIG (Event status).
Bit 7 and 6 of the CONFIG register can be used to lock
the TUPPER, TLOWER and TCRIT registers. The bits
prevent false triggers at the Event output due to an
accidental rewrite to these registers.
© 2005 Microchip Technology Inc.
DS21977B-page 17
MCP9805
TCRIT - THYST
TCRIT
TUPPER - THYST
TUPPER - THYST
TUPPER
TA
TLOWER -THYST
TLOWER
TLOWER -THYST
(Active-Low)
Event Output
Comparator
Interrupt
S/W Int. Clear
Critical
Note: 1
Event Output Boundary
Conditions
Note
1
2
3
4
5
6
*
1 3
2
4
3 5
*
6 4
TA bits
Event Output
Comparator
Interrupt
2
Critical
15
14
13
H
L
H
0
0
0
TA ≥ TLOWER
L
L
H
0
0
1
TA < TLOWER - THYST
TA > TUPPER
L
L
H
0
1
0
H
L
H
0
0
0
TA ≤ TUPPER - THYST
TA ≥ TCRIT
L
L
L
1
0
0
TA < TCRIT - THYST
L
H
H
0
1
0
When TA ≥ TCRIT and TA < TCRIT - THYST, the Event output is in Comparator mode and bit 0 of
CONFIG (Interrupt mode) is ignored.
FIGURE 4-2:
DS21977B-page 18
Event Output Boundary Conditions.
© 2005 Microchip Technology Inc.
MCP9805
4.3
Summary of Power-up Default
The MCP9805 has an internal Power-on Reset (POR)
circuit. If the power supply voltage VDD drifts below the
VPOR threshold, the device resets the registers to the
power-up default settings.
Table 4-6 shows the power-up default summary.
TABLE 4-6:
POWER-UP DEFAULTS
Registers
Address (Hex)
Register Label
Default Register
Data (Hex)
0x00
Capability
0x000F
0x01
CONFIG
0x0000
0x02
0x03
0x04
0x05
0x06
0x07
TUPPER
TLOWER
TCRIT
TA
Manufacturer ID
Device ID/Device Revision
0x0000
0x0000
0x0000
0x0000
0x0054
0x0000
© 2005 Microchip Technology Inc.
Power-up Default
Register Description
0.25 °C/LSb
Measures Temperature Below 0°C
±1°C Accuracy Over Active Range
Basic Capability (Event output)
Comparator Mode
Active-Low Output
Event and Critical output
Output Enabled
Event Not Asserted
Interrupt Cleared
Event Limits Unlocked
Critical Limit Unlocked
Continuous Conversion
0°C Hysteresis
0°C
0°C
0°C
0°C
0x0054 (hex)
0x0000 (hex)
DS21977B-page 19
MCP9805
5.0
SERIAL COMMUNICATION
5.1.1
5.1
2-Wire SMBus/Standard Mode
I2C™ Protocol-Compatible
Interface
Data transfers are initiated by a Start condition
(START), followed by a 7-bit device address and a
read/write bit. An Acknowledge (ACK) from the slave
confirms the reception of each byte. Each access must
be terminated by a Stop condition (STOP).
The MCP9805 serial clock input (SCLK) and the
bidirectional serial data line (SDA) form a 2-Wire
bidirectional SMBus/Standard mode I2C compatible
communication port (refer to the Digital Input/Output
Pin Characteristics Table and Serial Interface Timing
Characteristics Table).
The following bus protocol has been defined:
TABLE 5-1:
MCP9805 SERIAL BUS
PROTOCOL DESCRIPTIONS
Term
Master
Slave
Description
The device that controls the serial bus,
typically a microcontroller.
The device addressed by the master,
such as the MCP9805.
Transmitter Device sending data to the bus.
Receiver
Device receiving data from the bus.
START
A unique signal from master to initiate
serial interface with a slave.
STOP
A unique signal from the master to
terminate serial interface from a slave.
Read/Write A read or write to the MCP9805
registers.
ACK
A receiver Acknowledges (ACK) the
reception of each byte by polling the
bus.
NAK
A receiver Not-Acknowledges (NAK) or
releases the bus to show End-of-Data
(EOD).
Busy
Communication is not possible
because the bus is in use.
Not Busy
The bus is in the idle state, both SDA
and SCLK remain high.
Data Valid
SDA must remain stable before SCLK
becomes high in order for a data bit to
be considered valid. During normal
data transfers, SDA only changes state
while SCLK is low.
DS21977B-page 20
DATA TRANSFER
Repeated communication is initiated after tB-FREE.
This device does not support sequential register
read/write. Each register needs to be addressed using
the Register Pointer.
This device supports the receive protocol. The register
can be specified using the pointer for the initial read
(see Figure 5-4). Each repeated read or receive can
then be followed with a Start condition, followed by an
address byte. The MCP9805 retains the previously
selected register. Therefore, it expects a read from the
previously-specified
register
(repeated
pointer
specification is not necessary).
5.1.2
MASTER/SLAVE
The bus is controlled by a master device (typically a
microcontroller) that controls the bus access and generates the Start and Stop conditions. The MCP9805 is a
slave device and does not control other devices in the
bus. Both master and slave devices can operate as
either transmitter or receiver. However, the master
device determines which mode is activated.
5.1.3
START/STOP CONDITION
A high-to-low transition of the SDA line (while SCLK is
high) is the Start condition. All data transfers must be
preceded by a Start condition from the master. If a Start
condition is generated during data transfer, the
MCP9805 resets and accepts the new Start condition.
A low-to-high transition of the SDA line (while SCLK is
high) signifies a Stop condition. If a Stop condition is
introduced during data transmission, the MCP9805
releases the bus. All data transfers are ended by a Stop
condition from the master. However, for continuous data
reception from the previously-specified pointer
(Register 4-1), a Start condition can be introduced at the
end of data reception. The MCP9805 retains the previously-set pointer. Therefore, there is no need to repeat
the pointer specification (see Register 5-4).
5.1.4
ADDRESS BYTE
Following the Start condition, the host must transmit an
8-bit address byte to the MCP9805. The address for the
MCP9805 is ‘0011,A2,A1,A0’ in binary, where the A2,
A1 and A0 bits are set externally by connecting the
corresponding pins to VDD ‘1’ or GND ‘0’. The 7-bit
address transmitted in the serial bit stream must match
the selected address for the MCP9805 to respond with
an ACK. Bit 8 in the address byte is a read/write bit.
Setting this bit to ‘1’ commands a read operation, while
‘0’ commands a write operation (see Figure 5-1).
© 2005 Microchip Technology Inc.
MCP9805
5.1.6
ACKNOWLEDGE (ACK)
Address Byte
SCLK
1
2
3
4
5
6
7
SDA
0
0
1
1 A2 A1 A0
8
9
A
C
K
Start
Address
Code
Slave
Address
R/W
MCP9805 Response
FIGURE 5-1:
5.1.5
Device Addressing.
DATA VALID
After the Start condition, each bit of data in transmission needs to be settled for a time specified by tSU-DATA
before SCLK toggles from low-to-high (see Serial
Interface Timing Characteristics).
© 2005 Microchip Technology Inc.
Each receiving device, when addressed, is obliged to
generate an ACK bit after the reception of each byte.
The master device must generate an extra clock pulse
for ACK to be recognized.
The acknowledging device pulls down the SDA line for
tSU-DATA before the low-to-high transition of SCLK from
the master. SDA also needs to remain pulled down for
tH-DATA after a high-to-low transition of SCLK.
During read, the master must signal an End-of-Data
(EOD) to the slave by not generating an ACK bit (NAK)
once the last bit has been clocked out of the slave. In
this case, the slave will leave the data line released to
enable the master to generate the Stop condition.
5.1.7
TIME OUT
If the SCLK stays high or low for a time specified by
tOUT, the MCP9805 releases the bus and resets the
serial interface. The master will have to restart the
communication cycle with a Start condition. This
dictates the minimum clock speed.
DS21977B-page 21
MCP9805
5.2
Timing Diagram
Read 1-byte Data
1
2
3
4
5
6
7
8
0
0
1
1
A
2
A
1
A
0
W C
K
1
2
3
4
5
6
7
8
0
0
0
0
0
P
2
P
1
P
0
SCLK
SDA
S
A
Address Byte
A
C
K
Pointer
MCP9805
MCP9805
1
2
3
4
5
6
7
8
0
0
1
1
A
2
A
1
A
0
R C
1
2
3
4
5
6
7
8
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
SCLK
SDA
S
A
K
Address Byte
N
A
K
P
Data
Master
MCP9805
Read 2-byte Data
1
2
3
4
5
6
7
8
0
0
1
1
A
2
A
1
A
0
W C
K
1
2
3
4
5
6
7
8
0
0
0
0
0
P
2
P
1
P
0
SCLK
SDA
S
A
Address Byte
A
C
K
Pointer
MCP9805
MCP9805
1
2
3
4
5
6
7
0
0
1
1
A
2
A
1
A
0
8
1
2
3
4
5
6
7
8
D D D D D D
K 15 14 13 12 11 10 9
D
8
1
2
3
4
5
6
7
8
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
SCLK
SDA
S
A
R C D
A
C
K
MSb Data
Address Byte
MCP9805
N
A
K
P
LSb Data
Master
Master
S = START Condition
P = STOP Condition
FIGURE 5-2:
DS21977B-page 22
Read 1-byte and 2-byte data from a Register.
© 2005 Microchip Technology Inc.
MCP9805
Write 1-byte Data
1
2
3
4
5
6
7
8
0
0
1
1
A
2
A
1
A
0
W C
1
2
3
4
5
6
7
8
0
0
0
0
0
P
2
P
1
P
0
1
2
3
4
5
6
7
8
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
SCLK
SDA
S
A
K
Address Byte
A
C
K
Pointer
A
C
K
P
Data
MCP9805
MCP9805
MCP9805
Write 2-byte Data
1
2
3
4
5
6
7
8
0
0
1
1
A
2
A
1
A
0
W C
1
2
3
4
5
6
7
8
0
0
0
0
0
P
2
P
1
P
0
SCLK
SDA
S
A
K
Address Byte
Pointer
MCP9805
MCP9805
1
A
C
K
2
3
4
5
6
7
8
D D D D D D D
15 14 13 12 11 10 9
D
8
1
A
C
K
2
3
4
5
6
7
8
D D
7 6
D
5
D
4
D
3
D
2
D
1
D
0
MSb Data
A
C
K
P
LSb Data
MCP9805
MCP9805
S = START Condition
P = STOP Condition
FIGURE 5-3:
Write 1-byte and 2-byte data from a Register.
© 2005 Microchip Technology Inc.
DS21977B-page 23
MCP9805
Register Pointer Setting for Continuous Reception(Note)
1
2
3
4
5
6
7
8
0
0
1
1
A
2
A
1
A
0
W C
K
1
2
3
4
5
6
7
8
0
0
0
0
0
P
2
P
1
P
0
SCLK
SDA
S
A
Address Byte
A
C
K
Pointer
MCP9805
MCP9805
Receive 1-byte Data
1
2
3
4
5
6
7
8
0
0
1
1
A
2
A
1
A
0
R C
1
2
3
4
5
6
7
8
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
SCLK
SDA
S
A
K
Address Byte
N
A
K
Data
Master
MCP9805
Receive Another 1-byte Data
1
2
3
4
5
6
7
8
0
0
1
1
A
2
A
1
A
0
R C
1
2
3
4
5
6
7
8
D
7
D
6
D
5
D
4
D
3
D
2
D
1
D
0
SCLK
SDA
S
A
K
Address Byte
Data
MCP9805
Note:
N
A
K
Master
User can continue to receive 1-byte or 2-byte data (depending on the specific register)
indefinitely from a previously-set Register Pointer.
This device does not support sequential read/write.
S = START Condition
P = STOP Condition
FIGURE 5-4:
DS21977B-page 24
Receive 1-byte Data from Previously Set Pointer.
© 2005 Microchip Technology Inc.
MCP9805
6.0
APPLICATIONS INFORMATION
6.1
Connecting to the Serial Bus
The SDA and SCLK serial interface pins are
open-drain pins that require pull-up resistors. This
configuration is shown in Figure 6-1.
Microcontroller
VDD
MCP9805
R
R
R
SDA
SCLK
Event
Master
FIGURE 6-1:
Interface.
Slave
Pull-up Resistors On Serial
The number of devices connected to the bus is limited
only by the maximum rise and fall times of the SDA and
SCLK lines. Unlike I2C specifications, SMBus does not
specify a maximum bus capacitance value. Rather, the
SMBus specification requires that the maximum
current through the pull-up resistor be 350 µA and
minimum 100 µA. Because of this, the value of the
pull-up resistors will vary depending on the system’s
bias voltage (VDD). The pull-up resistor values for a
3.3 V system ranges 9 kΩ to 33 kΩ. Minimizing bus
capacitance is still very important as it directly affects
the rise and fall times of the SDA and SCLK lines.
Although SMBus specifications only require the SDA
and SCLK lines to pull-down 350 µA, with a maximum
voltage drop of 0.4 V, the MCP9805 is designed to
meet a maximum voltage drop of 0.4 V, with 3 mA of
current. This allows lower pull-up resistor values to be
used, allowing the MCP9805 to handle higher bus
capacitance. In such applications, all devices on the
bus must meet the same pull-down current
requirements.
A possible configuration using multiple devices on the
SMBus is shown in Figure 6-2.
6.2
Layout Considerations
The MCP9805 does not require any additional components besides the master controller in order to measure
temperature. However, it is recommended that a
decoupling capacitor of 0.1 µF to 1 µF be used
between the VDD and GND pins. A high-frequency
ceramic capacitor is recommended. It is necessary for
the capacitor to be located as close as possible to the
power and ground pins of the device in order to provide
effective noise protection.
6.3
Thermal Considerations
A potential for self-heating errors can exist if the
MCP9805 SDA, SCLK and Event lines are heavily
loaded with pull-ups (high current). Typically, the
self-heating error is negligible because of the relatively
small current consumption of the MCP9805. A
temperature accuracy error of approximately 0.5°C
could result from self-heating if the communication pins
sink/source the maximum current specified.
For example, if the Event output is loaded to maximum
IOL, Equation 6-1 can be used to determine the effect
of self-heating.
EQUATION 6-1:
T
Δ
EFFECT OF
SELF-HEATING
= θ JA ( V DD • I DD + V OL_Event • I OL_Event
+ VOL_SDA • IOL_SDA )
Where:
TΔ = TJ - TA
TJ = Junction Temperature
TA = Ambient Temperature
θJA = Package Thermal Resistance
VOL_Event, SDA = Event and SDA Output VOL
(0.4 Vmax)
IOL_Event, SDA = Event and SDA Output IOL
(3 mAmax)
At room temperature (TA = +25°C) with maximum
IDD = 500 µA and VDD = 3.6V, the self-heating due to
power dissipation TΔ is 0.2°C for the DFN-8 package
and 0.5°C for the TSSOP-8 package.
SDA SCLK
MCP9805
24LCS52
Temperature
Sensor
FIGURE 6-2:
SMBus.
EEPROM
Multiple Devices on DIMM
© 2005 Microchip Technology Inc.
DS21977B-page 25
MCP9805
7.0
PACKAGING INFORMATION
7.1
Package Marking Information
8-Lead DFN (MC)
XXX
YWW
NN
ABA
536
56
8-Lead TSSOP (ST)
XXXX
805B
0536
NNN
256
e3
*
DS21977B-page 26
Example:
YYWW
Legend: XX...X
Y
YY
WW
NNN
Note:
Example:
Customer-specific information
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
Pb-free JEDEC designator for Matte Tin (Sn)
This package is Pb-free. The Pb-free JEDEC designator ( e3 )
can be found on the outer packaging for this package.
In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line, thus limiting the number of available
characters for customer-specific information.
© 2005 Microchip Technology Inc.
MCP9805
8-Lead Plastic Dual Flat No-Lead Package (MC) 2x3x0.9 mm Body (DFN) – Saw Singulated
b
D
p
n
L
K
E2
E
EXPOSED
METAL
PAD
(NOTE 2)
PIN 1
ID INDEX
AREA
(NOTE 1)
2
DETAIL
ALTERNATE
CONTACT
CONFIGURATION
TOP VIEW
A1
Units
n
MILLIMETERS*
INCHES
MIN
Number of Pins
BOTTOM VIEW
EXPOSED
TIE BAR
(NOTE 3)
A
A3
Dimension Limits
1
D2
NOM
MAX
MIN
MAX
NOM
8
8
Pitch
e
Overall Height
A
.031
.035
.039
0.80
0.90
1.00
Standoff
A1
.000
.001
.002
0.00
0.02
0.05
Contact Thickness
A3
.008 REF.
0.20 REF.
Overall Length
D
.079 BSC
2.00 BSC
Overall Width
E
.118 BSC
0.50 BSC
.020 BSC
3.00 BSC
Exposed Pad Length
D2
.051
–
.069
1.30**
–
1.75
Exposed Pad Width
E2
.059
–
.075
1.50**
–
1.90
L
.012
K
.008
b
.008
Contact Length §
Contact-to-Exposed Pad
Contact Width
§
.016
.020
–
.010
–
.012
* Controlling Parameter
** Not within JEDEC parameters
§ Significant Characteristic
Notes:
1. Pin 1 visual index feature may vary, but must be located within the hatched area.
2. Exposed pad may vary according to die attach paddle size.
3. Package may have one or more exposed tie bars at ends.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
See ASME Y14.5M
REF: Reference Dimension, usually without tolerance, for information purposes only.
See ASME Y14.5M
JEDEC Equivalent MO-229 VCED-2
DWG No. C04-123
© 2005 Microchip Technology Inc.
0.30
0.20
0.20
0.40
0.50
–
–
0.25
0.30
Revised 09-12-05
DS21977B-page 27
MCP9805
8-Lead Plastic Thin Shrink Small Outline (ST) – 4.4 mm Body (TSSOP)
E
E1
p
D
2
1
n
B
α
A
c
β
φ
L
Units
Dimension Limits
A2
A1
MILLIMETERS*
INCHES
MIN
NOM
MAX
MIN
NOM
MAX
Pitch
n
p
Overall Height
A
.039
.041
.043
1.00
1.05
1.10
Molded Package Thickness
A2
.033
.035
.037
0.85
0.90
0.95
Number of Pins
8
8
.026
0.65
Standoff
A1
.002
.004
.006
0.05
0.10
0.15
Overall Width
E
.246
.251
.256
6.25
6.38
6.50
Molded Package Width
E1
.169
.173
.177
4.30
4.40
4.50
Molded Package Length
D
.114
.118
.122
2.90
3.00
3.10
Foot Length
L
φ
.020
.024
.028
0.50
0.60
0.70
Foot Angle
Lead Thickness
c
.004
.006
.008
0.09
0.15
0.20
Lead Width
B
α
.007
.010
.012
0.19
0.25
0.30
Mold Draft Angle Top
Mold Draft Angle Bottom
β
0°
4°
8°
0°
4°
8°
0°
5°
10°
0°
5°
10°
0°
5°
10°
0°
5°
10°
* Controlling Parameter
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed .005" (0.127mm) per side.
JEDEC Equivalent: MO-153
Drawing No. C04-086
DS21977B-page 28
Revised 07-21-05
© 2005 Microchip Technology Inc.
MCP9805
APPENDIX A:
REVISION HISTORY
Revision B (September 2005)
• Added the text “for Mobile Platform Memory
Module Thermal Sensor” to first bullet under
Features section.
Revision A (September 2005)
• Original Release of this Document.
© 2005 Microchip Technology Inc.
DS21977B-page 29
MCP9805
NOTES:
DS21977B-page 30
© 2005 Microchip Technology Inc.
MCP9805
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
–X
X
/XX
Device
Grade
Temperature
Range
Package
Examples:
a)
b)
Device:
MCP9805: Digital Temperature Sensor
MCP9805T: Digital Temperature Sensor
(Tape and Reel)
Grade:
B
B
B
= ±1°C (max.) from +75°C to +95°C,
±2°C (max.) from +40°C to +125°C, and
±3°C (max.) from -20°C to +125°C
Temperature Range:
E
= -40°C to +125°C
Package:
MC = Dual Flat No Lead (2x3 mm Body), 8-lead
ST = Plastic Thin Shrink Small Outline (4x4 mm Body),
8-lead
© 2005 Microchip Technology Inc.
c)
MCP9805T-BE/MC: Tape and Reel,
Extended Temp.,
8LD DFN pkg.
MCP9805-BE/ST:
Extended Temp.,
8LD TSSOP pkg.
MCP9805T-BE/ST: Tape and Reel,
Extended Temp.,
8LD TSSOP pkg.
DS21977B-page 31
MCP9805
NOTES:
DS21977B-page 32
© 2005 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is provided only for your convenience
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED,
WRITTEN OR ORAL, STATUTORY OR OTHERWISE,
RELATED TO THE INFORMATION, INCLUDING BUT NOT
LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE,
MERCHANTABILITY OR FITNESS FOR PURPOSE.
Microchip disclaims all liability arising from this information and
its use. Use of Microchip’s products as critical components in
life support systems is not authorized except with express
written approval by Microchip. No licenses are conveyed,
implicitly or otherwise, under any Microchip intellectual property
rights.
Trademarks
The Microchip name and logo, the Microchip logo, Accuron,
dsPIC, KEELOQ, microID, MPLAB, PIC, PICmicro,
PICSTART, PRO MATE, PowerSmart, rfPIC, and
SmartShunt are registered trademarks of Microchip
Technology Incorporated in the U.S.A. and other countries.
AmpLab, FilterLab, Migratable Memory, MXDEV, MXLAB,
PICMASTER, SEEVAL, SmartSensor and The Embedded
Control Solutions Company are registered trademarks of
Microchip Technology Incorporated in the U.S.A.
Analog-for-the-Digital Age, Application Maestro, dsPICDEM,
dsPICDEM.net, dsPICworks, ECAN, ECONOMONITOR,
FanSense, FlexROM, fuzzyLAB, In-Circuit Serial
Programming, ICSP, ICEPIC, Linear Active Thermistor,
MPASM, MPLIB, MPLINK, MPSIM, PICkit, PICDEM,
PICDEM.net, PICLAB, PICtail, PowerCal, PowerInfo,
PowerMate, PowerTool, rfLAB, rfPICDEM, Select Mode,
Smart Serial, SmartTel, Total Endurance and WiperLock are
trademarks of Microchip Technology Incorporated in the
U.S.A. and other countries.
SQTP is a service mark of Microchip Technology Incorporated
in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2005, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received ISO/TS-16949:2002 quality system certification for
its worldwide headquarters, design and wafer fabrication facilities in
Chandler and Tempe, Arizona and Mountain View, California in
October 2003. The Company’s quality system processes and
procedures are for its PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals, nonvolatile memory and
analog products. In addition, Microchip’s quality system for the design
and manufacture of development systems is ISO 9001:2000 certified.
© 2005 Microchip Technology Inc.
DS21977B-page 33
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**DS21977B**
08/24/05
DS21977B-page 34
© 2005 Microchip Technology Inc.