EMC1201-AFZQ-TR SMSC, EMC1201-AFZQ-TR Datasheet - Page 7

• Manufacturer Part Number: EMC1201-AFZQ-TR
• Description: Board Mount Temperature Sensors Temp Snsr
• Manufacturer: SMSC

Specifications of EMC1201-AFZQ-TR

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Single/Dual Single-Wire Temp Sensor in SOT23-5 Using SMSC BudgetBus
Datasheet
SMSC EMC1201/EMC1202
3.1.1
3.2
Remote Diode
SMSC BudgetBus™ Sensor Interface
Internal or
Figure 3.2
EMC1201 and EMC1202 incorporates switched capacitor technology that samples the temperature
diode voltage at two bias currents and holds the difference voltage. The sample frequency is 100kHz
and the current levels Ihigh and Ilow are 170uA and 10uA respectively.
The output of the switched capacitor sample and hold circuit interfaces to a single bit delta sigma
analog to digital converter. This ADC runs at 100kHz sample frequency and its output is digitally filtered
and averaged over 2048 samples effectively generating 11 bit accuracy.
The advantages of this architecture over Nyquist rate FLASH or SAR converters are superb linearity
and inherent noise immunity. The linearity can be directly attributed to the delta sigma ADC single bit
comparator while the noise immunity is achieved by the digital averaging filter. The overall effective
bandwidth of the system is fs/2048 which translates to a 50Hz bandwidth at 100kHz sample rate.
Conversion time equals about 20ms per temperature monitor.
EMC1202 Temperature Monitoring
The EMC1202, incorporates one internal diode and can monitor an additional temperature zone via
one external diode. An internal analog multiplexer switches between the internal and external diode.
Total conversion time for one internal and one external temperature reading is about 40ms. The
external diode can be either a CPU substrate diode or a discrete diode connected transistor like the
2N3904 or 2N3906. External diode connected transistors examples are shown in
The EMC1201 and EMC1202 communicate with a host controller, such as the KBC1100, through the
proprietary single wire SMSC BudgetBus™ Sensor Interface known as BBUS. The BBUS is a single
wire serial communication protocol between the computer host and its peripheral devices. Please refer
to the BBUS Specification for detailed information about the modes of operation.
V
Figure 3.2 Detailed Block Diagram of Temperature Monitor Architecture
DD
i.e. CPU substrate PNP
I
high
substrate transistor
shows a detailed block diagram of the temperature measurement circuit. As shown, the
Typical remote
Local Ground
I
Figure 3.3 EMC1202 External Diode Examples
low
Diode
Bias
I
bias
DN
DP
to
to
Delta Vbe
Sample
discrete PNP transistor
Hold
DATASHEET
fs
&
Typical remote
i.e. 2N3906
7
TM
Sensor Interface
Modulator
Sigma
Delta
1-bit
fs
DP
DN
to
to
discrete NPN transistor
Typical remote
i.e. 2N3904
Averaging
Digital
Filter
fs
DP
DN
to
to
Revision 1.0 (06-10-08)
Conversion
Figure
Accurate
fs/2048
11-bit
3.3: