ADM1030ARQZ Datasheet ADM1030ARQZ-REEL, ADM1030ARQZ, ADM1030ARQ | P7-P9

ADM1030

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General Description

The ADM1030 is a temperature monitor and PWM fan

controller for microprocessor-based systems. The device

communicates with the system via a serial System

Management Bus. The serial bus controller has a hardwired

address pin for device selection (Pin 13), a serial data line for

reading and writing addresses and data (Pin 15), and an

input line for the serial clock (Pin 16). All control and

programming functions of the ADM1030 are performed

over the serial bus. The device also supports the SMBus

Alert Response Address (ARA) function.

Internal Registers of the ADM1030

A brief description of the ADM1030’s principal internal

registers is given below. More detailed information on the

function of each register is given in Table 16 to Table 30.

Configuration Register

Provides control and configuration of various functions

on the device.

Address Pointer Register

This register contains the address that selects one of the

other internal registers. When writing to the ADM1030, the

first byte of data is always a register address, which is written

to the Address Pointer Register.

Status Registers

These registers provide status of each limit comparison.

Value and Limit Registers

The results of temperature and fan speed measurements

are stored in these registers, along with their limit values.

Fan Speed Config Register

This register is used to program the PWM duty cycle for

the fan.

Offset Registers

Allows the temperature channel readings to be offset by

a 5-bit two’s complement value written to these registers.

These values will automatically be added to the temperature

values (or subtracted from if negative). This allows the

systems designer to optimize the system if required, by

adding or subtracting up to 15C from a temperature

reading.

Fan Characteristics Register

This register is used to select the spin-up time, PWM

frequency, and speed range for the fan used.

THERM Limit Registers

These registers contain the temperature values at which

THERM

will be asserted.

MIN

RANGE

Registers

These registers are read/write registers that hold the

minimum temperature value below which the fan will not

run when the device is in Automatic Fan Speed Control

Mode. These registers also hold the values defining the

range over that auto fan control will be provided, and hence

determines the temperature at which the fan will run at full

speed.

Serial Bus Interface

Control of the ADM1030 is carried out via the SMBus.

The ADM1030 is connected to this bus as a slave device,

under the control of a master device, e.g., the 810 chipset.

The ADM1030 has a 7-bit serial bus address. When the

device is powered up, it will do so with a default serial bus

address. The five MSBs of the address are set to 01011, the

two LSBs are determined by the logical state of Pin 13

(ADD). This is a three-state input that can be grounded,

connected to V

, or left open-circuit to give three different

addresses. The state of the ADD pin is only sampled at

power-up, so changing ADD with power on will have no

effect until the device is powered off, then on again.

Table 5. ADD PIN TRUTH TABLE

ADD Pin A1 A0

GND 0 0

No Connect 1 0

0 1

If ADD is left open-circuit, the default address will be

0101110.

The facility to make hardwired changes at the ADD pin

allows the user to avoid conflicts with other devices sharing

the same serial bus, for example, if more than one ADM1030

is used in a system.

The serial bus protocol operates as follows:

1. The master initiates data transfer by establishing a

START condition, defined as a high-to-low

transition on the serial data line SDA while the

serial clock line SCL remains high. This indicates

that an address/data stream will follow. All slave

peripherals connected to the serial bus respond to

the START condition, and shift in the next 8 bits,

consisting of a 7-bit address (MSB first) plus an

R/W

bit that determines the direction of the data

transfer, i.e., whether data will be written to or

read from the slave device.

The peripheral whose address corresponds to the

transmitted address responds by pulling the data

line low during the low period before the ninth

clock pulse, known as the Acknowledge Bit. All

other devices on the bus now remain idle while the

selected device waits for data to be read from or

written to it. If the R/W

bit is a 0, the master will

write to the slave device. If the R/W

bit is a 1, the

master will read from the slave device.

2. Data is sent over the serial bus in sequences of

nine clock pulses, eight bits of data followed by an

Acknowledge Bit from the slave device.

Transitions on the data line must occur during the

low period of the clock signal and remain stable

ADM1030

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during the high period, as a low-to-high transition

when the clock is high may be interpreted as a

STOP signal. The number of data bytes that can be

transmitted over the serial bus in a single READ or

WRITE operation is limited only by what the

master and slave devices can handle.

3. When all data bytes have been read or written,

stop conditions are established. In WRITE mode,

the master will pull the data line high during the

tenth clock pulse to assert a STOP condition. In

READ mode, the master device will override the

acknowledge bit by pulling the data line high

during the low period before the ninth clock pulse.

This is known as No Acknowledge. The master

will then take the data line low during the low

period before the tenth clock pulse, then high

during the tenth clock pulse to assert a STOP

condition.

Any number of bytes of data may be transferred over the

serial bus in one operation, but it is not possible to mix read

and write in one operation, because the type of operation is

determined at the beginning and cannot subsequently be

changed without starting a new operation.

In the case of the ADM1030, write operations contain

either one or two bytes, and read operations contain one

byte, and perform the following functions.

To write data to one of the device data registers or read

data from it, the Address Pointer Register must be set so that

the correct data register is addressed; data can then be

written into that register or read from it. The first byte of a

write operation always contains an address that is stored in

the Address Pointer Register. If data is to be written to the

device, then the write operation contains a second data byte

that is written to the register selected by the address pointer

This is illustrated in Figure 15. The device address is sent

over the bus followed by R/W

set to 0. This is followed by

two data bytes. The first data byte is the address of the

internal data register to be written to, which is stored in the

Address Pointer Register. The second data byte is the data to

be written to the internal data register.

When reading data from a register there are two

possibilities:

1. If the ADM1030’s Address Pointer Register value

is unknown or not the desired value, it is first

necessary to set it to the correct value before data

can be read from the desired data register. This is

done by performing a write to the ADM1030 as

before, but only the data byte containing the

to the register. This is shown in Figure 16.

A read operation is then performed consisting of

the serial bus address, R/W

bit set to 1, followed

by the data byte read from the data register. This is

shown in Figure 17.

2. If the Address Pointer Register is known to be

already at the desired address, data can be read

from the corresponding data register without first

writing to the Address Pointer Register, so

Figure 16 can be omitted.

NOTES:

1. Although it is possible to read a data byte from a data

if the Address Pointer Register is already at the correct

value, it is not possible to write data to a register without

writing to the Address Pointer Register, because the first

data byte of a write is always written to the Address Pointer

2. In Figures 15 to 17, the serial bus address is shown as the

default value 01011(A1)(A0), where A1 and A0 are set by

the three-state ADD pin.

3. The ADM1030 also supports the Read Byte protocol, as

described in the System Management Bus specification.

Figure 15. Writing a Register Address to the Address Pointer Register,

then Writing Data to the Selected Register

R/W

SCL

SDA

ACK. BY

ADM1030

START BY

MASTER

191

ACK. BY

ADM1030

ACK. BY

ADM1030

STOP BY

MASTER

SCL (CONTINUED)

SDA (CONTINUED)

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 2

ADDRESS POINTER REGISTER BYTE

FRAME 3

DATA BYTE

ADM1030

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Figure 16. Writing to the Address Pointer Register Only

SCL

SDA

ACK. BY

ADM1030

START BY

MASTER

ACK. BY

ADM1030

STOP BY

MASTER

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 2

ADDRESS POINTER REGISTER BYTE

R/W

Figure 17. Reading Data from a Previously Selected Register

SCL

SDA

NO ACK.

BY MASTER

START BY

MASTER

ACK. BY

ADM1030

STOP BY

MASTER

A1 A0

FRAME 1

SERIAL BUS ADDRESS BYTE

FRAME 2

DATA BYTE FROM ADM1030

R/W

Alert Response Address

Alert Response Address (ARA) is a feature of SMBus

devices that allows an interrupting device to identify itself

to the host when multiple devices exist on the same bus.

The INT

output can be used as an interrupt output or can

be used as an SMBALERT

. One or more INT outputs can be

connected to a common SMBALERT

line connected to the

master. If a device’s INT

line goes low, the following

procedure occurs:

1. SMBALERT

pulled low.

2. Master initiates a read operation and sends the

Alert Response Address (ARA = 0001 100). This

is a general call address that must not be used as a

specific device address.

3. The device whose INT

output is low responds to

the Alert Response Address, and the master reads

its device address. The address of the device is

now known and can be interrogated in the usual

way.

4. If more than one device’s INT

output is low, the

one with the lowest device address will have

priority, in accordance with normal SMBus

arbitration.

5. Once the ADM1030 has responded to the Alert

Response Address, it will reset its INT

output;

however, if the error condition that caused the

interrupt persists, INT

will be reasserted on the

next monitoring cycle.

Temperature Measurement System

Internal Temperature Measurement

The ADM1030 contains an on-chip bandgap temperature

sensor. The on-chip ADC performs conversions on the

output of this sensor and outputs the temperature data in

10-bit two’s complement format. The resolution of the local

temperature sensor is 0.25C. The format of the temperature

data is shown in Table 6.

External Temperature Measurement

The ADM1030 can measure the temperature of an

external diode sensor or diode-connected transistor,

connected to Pins 9 and 10.

These pins are a dedicated temperature input channel. The

function of Pin 7 is as a THERM

input/output and is used to

flag overtemperature conditions.

The forward voltage of a diode or diode-connected

transistor, operated at a constant current, exhibits a negative

temperature coefficient of about –2 mV/C. Unfortunately,

the absolute value of V

, varies from device to device, and

individual calibration is required to null this out, so the

technique is unsuitable for mass production.

The technique used in the ADM1030 is to measure the

change in V

when the device is operated at two different

currents.

This is given by:

(eq. 1)

+ KTńq ln(N)

where:

K is Boltzmann’s constant

q is charge on the carrier

T is absolute temperature in Kelvins

N is ratio of the two currents

Figure 18 shows the input signal conditioning used to

measure the output of an external temperature sensor. This

figure shows the external sensor as a substrate transistor,

provided for temperature monitoring on some

microprocessors, but it could equally well be a discrete

transistor.

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Motor / Motion / Ignition Controllers & Drivers TDM & PWM FAN CNTRLRS IC

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