Rainbow Electronics MAX6660 - Manual (Page 12)

MAX6660
Remote-Junction Temperature-Controlled
Fan-Speed Regulator with SMBus Interface
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(rather than the 8-bit READ BYTE), the LSB contains the
data and the MSB contains 00h in both cases.
Slave Addresses
The MAX6660 can be programmed to have one of nine
different addresses by pin strapping ADD0 and ADD1
so that up to nine MAX6660s can reside on the same
bus without address conflicts. See Table 7 for address
information.
The address pin state is checked at POR only, and the
address data stays latched to reduce quiescent supply
current due to the bias current needed for high-Z state
detection.
The MAX6660 also responds to the SMBus Alert
Response slave address (see the Alert Response
Address section).
POR and UVLO
The MAX6660 has a volatile memory. To prevent unreli-
able power-supply conditions from corrupting the data
in memory and causing erratic behavior, a POR voltage
detector monitors V
CC and clears the memory if V CC
falls below 1.91V (typ, see Electrical Characteristics).
When power is first applied and V
CC rises above 2.0V
(typ), the logic blocks begin operating, although reads
and writes at V
CC levels below 3.0V are not recom-
mended. A second V CC comparator, the ADC under-
voltage lockout (UVLO) comparator prevents the ADC
from converting until there is sufficient headroom (V
CC
= 2.8V typ).
The SPOR software POR command can force a power-on
reset of the MAX6660 registers through the serial interface.
Use the SEND BYTE protocol with COMMAND = FCh.
REGISTERS COMMAND POR STATE FUNCTION
RRL 00h 00000000 Read Remote Temperature Low Byte (3MSBs)
RRH 01h 00000000 Read Remote Temperature High Byte (Sign Bit and First 7 Bits)
RSL 02h 00000000 Read Status Byte
RCL/WCL 03h/09h 00000000 Read/Write Configuration Byte
RFCR/WFCR 04h/0Ah 00000010 Read/Write Fan-Conversion Rate Byte
RTMAX/WTMAX 10h/12h 01100100 at +100 °C Read/Write Remote T MAX
RTHYST/WTHYST 11h/13h 01011111 at +95 °C Read/Write Remote T
HYST
RTHIGH/WTHIGH 07h/0Dh 01111111 at +127 °C Read/Write Remote T HIGH
RTLOW/WTLOW 08h/0Eh 11001001 at -55 °C Read/Write Remote T LOW
SPOR FCh N/A Write Software POR
OSHT 0Fh N/A Write One-Shot Temperature Conversion
RTFAN/WTFAN 14h/19h 00111100 at +60 °C Read/Write Fan-Control Threshold Temperature T FAN
RFSC/WFSC 15h/1Ah 00000000 Read/Write Fan-Speed Control
RFG/WFG 16h/1Bh 10000000 Read/Write Fan Gain
RFTC 17h 00000000 Read Fan Tachometer Count
RFTCL/WFTCL 18h/1Ch 11111111 Read/Write Fan Tachometer Count Limit (Fan Failure Limit)
RFCD/WFCD 1Dh/1Eh 00000001 Read/Write Fan Count Divisor
RFS/WFS 1Fh/20h 11111111 Read/Write Full-Scale Register
RM/WM FAh/FBh 00000000 Read/Write Mode Register
ID Code FEh 01001101 Read Manufacturer ID Code
ID Code 9Dh 00001001 Read Device ID Code
Table 4. Command-Byte Bit Assignments