Datasheet

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General Description

The MAX6652 system supervisor monitors multiple

power-supply voltages, including its own, and also fea-

tures an on-board temperature sensor. Voltages and

temperature are converted to an 8-bit code using an

analog-to-digital converter (ADC). A multiplexer automat-

ically sequences through the voltage and temperature

measurements. The digitized signals are then stored in

registers and compared to the over/under threshold lim-

its programmed over the 2-wire serial interface.

When a temperature measurement exceeds the pro-

grammed threshold, or when an input voltage falls out-

side the programmed voltage limits, the MAX6652

generates a latched interrupt output ALERT. Three inter-

rupt modes are available for temperature excursions:

default mode, one-time interrupt mode, and comparator

mode. The ALERT output is cleared, except for tempera-

ture interrupts generated in comparator mode, by read-

ing the interrupt status register (Table 5). The ALERT

output can also be masked by writing to the appropriate

bits in the interrupt mask register (Table 6) or by setting

bit 1 of the configuration register (Table 4) to 0. The

MAX6652 I

™

-compatible/SMBus interface also

responds to the SMB alert response address.

The 2-wire serial interface accepts both I

C and standard

system management bus (SMBus) write byte, read byte,

send byte, and receive byte commands to program the

alarm thresholds and to read voltage and temperature

data. Voltage data is scaled so that when the nominal

voltage is present at a pin (e.g., 3.3V for the 3.3V

pin),

the conversion result is equal to 3/4 of the ADC full-scale

range or a decimal count of 192 (Table 3). The tempera-

ture data format is 7 bits plus sign, with each data bit

representing 1°C, in two's complement format (Table 2).

The MAX6652 has only one address pin, ADD. One of

four different address codes can be selected by con-

necting the ADD pin to GND, V

, SDA, or SCL.

Whenever an I

C-compatible/SMBus transaction is initiat-

ed, the two LSBs of the slave address register are deter-

mined by connection, setting the chip address to one of

four possible values. In addition, an address code can

also be directly written to the serial address register. This

code will overwrite the code set by connection of the

ADD pin, until the MAX6652 is taken through a power-on

reset cycle.

The MAX6652 features 60Hz or 50Hz line-frequency

rejection for optimal performance. The device operates

from +2.7V to +5.5V and is specified for operation from

-40°C to +125°C. It is available in a tiny 10-pin µMAX

package.

Features

♦ Monitors Four Voltages (2.5V, 3.3V, 12V, V

)

♦ Monitors Local Temperature

♦ Temperature Measurement Accuracy,

±2°C (T

= +25°C)

♦ User-Programmable Voltage and Temperature

Thresholds

♦ Alert Function with Ability to Respond to SMB

Alert Response Address

♦ +2.7V to +5.5V Supply Range

♦ -40°C to +125°C Temperature Range

♦ 60Hz or 50Hz Line-Frequency Rejection

♦ Tiny 10-Pin µMAX Package

Applications

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

________________________________________________________________ Maxim Integrated Products 1

SCL

SDA

ADDN.C.

3.3V

2.5V

12V

MAX6652

µMAX

TOP VIEW

GND ALERT

Pin Configuration

19-1959; Rev 1; 8/01

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

PART TEMP. RANGE PIN-PACKAGE

MAX6652AUB -40°C to +125°C 10 µMAX

C is a trademark of Philips Corp.

Workstations

Servers

Networking

Telecommunications

Typical Application Circuit and Functional Diagram appear

at end of data sheet.

Summary of content (12 pages)

PAGE 1
9-1959; Rev 1; 8/01 Temperature Sensor and System Monitor in a 10-Pin µMAX When a temperature measurement exceeds the programmed threshold, or when an input voltage falls outside the programmed voltage limits, the MAX6652 generates a latched interrupt output ALERT. Three interrupt modes are available for temperature excursions: default mode, one-time interrupt mode, and comparator mode.
PAGE 2
MAX6652 Temperature Sensor and System Monitor in a 10-Pin µMAX ABSOLUTE MAXIMUM RATINGS All Voltages Are Referenced to GND VCC ........................................................................-0.3V to +6.0V Voltage on 12VIN ...................................................-0.3V to +16V All Other Pins ........................................................-0.3V to +6.0V Output Current (SDA, ALERT) ............................-1mA to +50mA Junction Temperature ......................................
PAGE 3
Temperature Sensor and System Monitor in a 10-Pin µMAX (TA = -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +5V, TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS START Condition Hold Time tHD:STA 0.6 µs STOP Condition Hold Time tSU:STO 0.6 µs tLOW 1.3 µs µs Clock Low Period Clock High Period tHIGH 0.6 Data Setup Time tSP:DAT 100 Data Hold Time tHD:DAT (Note 2) Receive SCL/SDA Minimum Rise Time tR (Note 3) 20 + 0.
PAGE 4
Typical Operating Characteristics (continued) (VCC = +5V, ADD = GND, ALERT = 10kΩ to VCC, TA = +25°C, unless otherwise noted.) TEMPERATURE ERROR vs. SUPPLY NOISE FREQUENCY -1 -2 -3 -4 -5 -6 -7 -8 VCC = +5V BYPASS CAP REMOVED MAX6652 toc05 1.00 0.75 TEMPERATURE ERROR (°C) 200mVp-p TEMPERATURE ERROR vs. TEMPERATURE MAX6652 toc04 2 1 0 TEMPERATURE ERROR (°C) MAX6652 Temperature Sensor and System Monitor in a 10-Pin µMAX 0.50 0.25 0 -0.25 -0.50 -0.75 -9 -10 -1.
PAGE 5
Temperature Sensor and System Monitor in a 10-Pin µMAX The MAX6652 is a voltage and temperature monitor designed to communicate through an I2C-compatible/ SMBus interface with an external microcontroller (µC). A µC with no built-in I2C-compatible or SMBus capabilities can generate SMBus serial commands by “bitbanging” general-purpose input-output (GPIO) pins. The MAX6652 can monitor external supply voltages of typically 2.5V, 3.3V, and 12V, as well as its own supply voltage and temperature.
PAGE 6
MAX6652 Temperature Sensor and System Monitor in a 10-Pin µMAX corresponding interrupt status bit (bits 0 through 4) to 1 (Table 5). The interrupt will be cleared by reading the interrupt status register, except for temperature interrupts generated in comparator mode. Reading the interrupt status register also clears the register itself, except for temperature interrupt bits set in comparator mode.
PAGE 7
Temperature Sensor and System Monitor in a 10-Pin µMAX MAX6652 Table 4. Configuration Register (Address 41h, Power-Up Default = 00h) BIT NAME READ/WRITE DESCRIPTION 0 Start/Stop R/W This bit controls the monitoring loop. Setting the bit to 0 stops the monitoring loop and puts the device into shutdown mode. The I2C/SMBus interface is still active during the shutdown mode. Setting the bit to 1 starts the monitoring cycle. All high/low limits should be set before setting this bit to 1.
PAGE 8
MAX6652 Temperature Sensor and System Monitor in a 10-Pin µMAX Table 6. Interrupt Mask Register (Address 43h, Power-Up Default = 00h) BIT NAME READ/WRITE DESCRIPTION 0 2.5V R/W Setting the bit to 1 disables the interrupt status register bit (bit 0) and the ALERT output for the 2.5VIN input. 1 12V R/W Setting the bit to 1 disables the interrupt status register bit (bit 1) and the ALERT output for the 12VIN input. 2 3.
PAGE 9
Temperature Sensor and System Monitor in a 10-Pin µMAX One-Time Interrupt Mode An interrupt is initiated when temperature exceeds THOT (address 39Ah). The interrupt is cleared only by reading the interrupt status register. The next interrupt is then initiated when temperature falls below the THYST (address 3Ah). Comparator Mode An interrupt is initiated when temperature exceeds THOT (address 39Ah). The ALERT output will remain asserted low until the temperature goes below THOT.
PAGE 10
MAX6652 Temperature Sensor and System Monitor in a 10-Pin µMAX Table 7. Temperature Configuration Register BIT NAME R/W DESCRIPTION 0-1 Hot Temperature Interrupt Mode Select R/W Bit 1, Bit 0 00: Default Mode Bit 1, Bit 0 01: One-Time Interrupt Mode Bit 1, Bit 0 10: Comparator Mode Bit 1, Bit 0 11: Default Mode 2-7 Reserved R/W — TEMPERATURE MONITORING CYCLE INTERRUPT STATUS READ THOT THYST ALERT DEFAULT MODE ALERT ALERT ONE-TIME INTERRUPT MODE COMPARATOR MODE Figure 1.
PAGE 11
Temperature Sensor and System Monitor in a 10-Pin µMAX MAX6652 Write Byte Format S ADDRESS WR ACK COMMAND 7 bits ACK DATA 8 bits Slave Address: equivalent to chip-select line of a 3-wire interface ACK P 8 bits Command Byte: selects which register you are writing to Data Byte: data goes into the register set by the co mma nd byte ( to se t thresholds, configuration masks, and sampling rate) Read Byte Format S WR ADDRESS ACK COMMAND 7 bits ACK S 8 bits Slave Address: equivalent to chi
PAGE 12
MAX6652 Temperature Sensor and System Monitor in a 10-Pin µMAX A tLOW B C tHIGH D E F G H I J K L M SMBCLK SMBDATA tSU:STA tHD:STA tSU:DAT A = START CONDITION B = MSB OF ADDRESS CLOCKED INTO SLAVE C = LSB OF ADDRESS CLOCKED INTO SLAVE D = R/W BIT CLOCKED INTO SLAVE E = SLAVE PULLS SMBDATA LINE LOW tHD:DAT tSU:STO tBUF J = ACKNOWLEDGE CLOCKED INTO SLAVE K = ACKNOWLEDGE CLOCK PULSE L = STOP CONDITION M = NEW START CONDITION F = ACKNOWLEDGE BIT CLOCKED INTO MASTER G = MSB OF DATA CLOCK