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PDF DS1858 Data sheet ( Hoja de datos )
| Número de pieza | DS1858 | |
| Descripción | Dual Temperature-Controlled Resistors | |
| Fabricantes | Maxim Integrated Products | |
| Logotipo |  |
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Rev 0; 1/03
Dualwww.DataSheet4U.com Temperature-Controlled Resistors with
Three Monitors
General Description
The DS1858 dual temperature-controlled nonvolatile
(NV) variable resistors with three monitors consists of
two 50kΩ 256-position linear variable resistors, three
analog monitor inputs (MON1, MON2, MON3), and a
direct-to-digital temperature sensor. The device pro-
vides an ideal method for setting and temperature-com-
pensating bias voltages and currents in control
applications using minimal circuitry. The variable resis-
tor settings are stored in EEPROM memory and can be
accessed over the 2-wire serial bus.
Applications
Optical Transceivers
Optical Transponders
Instrumentation and Industrial Controls
RF Power Amps
Diagnostic Monitoring
Features
♦ Five Total Monitored Channels (Temperature,
VCC, MON1, MON2, MON3)
♦ Three External Analog Inputs (MON1, MON2,
MON3)
♦ Internal Direct-to-Digital Temperature Sensor
♦ Two 50kΩ, Linear, 256-Position, Nonvolatile
Temperature-Controlled Variable Resistors
♦ Resistor Settings Changeable Every 2°C
♦ Access to Monitoring and ID Information
Configurable with Separate Device Addresses
♦ 2-Wire Serial Interface
♦ Two Buffers with TTL/CMOS-Compatible Inputs
and Open-Drain Outputs
♦ Operates from a 3.3V or 5V Supply
♦ SFF-8472 Compatible
Typical Operating Circuit
VCC
4.7kΩ
2-WIRE
INTERFACE
Tx-FAULT
LOS
GROUND TO
DISABLE WRITE
PROTECT
VCC = 3.3V
4.7kΩ
1
SDA
2
SCL
3
OUT1
4
IN1
5
OUT2
6
IN2
7
WPEN
8
GND
DS1858
16
VCC
H1 15
14
L1
13
H0
L0 12
0.1µF
DECOUPLING
CAP
TO LASER BIAS
CONTROL
TO LASER
MODULATION
CONTROL
11 Tx POWER*
MON3
10 Rx POWER*
MON2
MON1 9 Tx BIAS*
DIAGNOSTIC
INPUTS
0 TO 2.5V FS
*Rx POWER, Tx BIAS, AND Tx POWER CAN BE
ARBITRARILY ASSIGNED TO THE MON INPUTS
Ordering Information
PART
DS1858E-050
TEMP RANGE PIN-PACKAGE
-40°C to +95°C 16 TSSOP
DS1858E-050/T&R -40°C to +95°C 16 TSSOP
(Tape-and-Reel)
DS1858B-050
-40°C to +95°C 16-Ball CSBGA
Pin Configurations
TOP VIEW
A IN1 SCL
VCC
H1
B OUT2 SDA
H0
L1
C WPEN IN2 OUT1 MON3
D GND L0 MON1 MON2
1234
16-BALL CSBGA (4mm x 4mm)
1.0mm PITCH
1 SDA
2 SCL
3 OUT1
4 IN1
5 OUT2
6 IN2
7 WPEN
8 GND
VCC 16
H1 15
L1 14
DS1858
H0 13
L0 12
MON3 11
MON2 10
MON1 9
16 TSSOP
______________________________________________ Maxim Integrated Products 1
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.
1 page  
Dualwww.DataSheet4U.com Temperature-Controlled Resistors with
Three Monitors
AC ELECTRICAL CHARACTERISTICS (continued)
(VCC = 3.0V to 5.5V, TA = -40°C to +95°C, unless otherwise noted.)
Note 10: After this period, the first clock pulse is generated.
Note 11: The maximum tHD:DAT only has to be met if the device does not stretch the LOW period (tLOW) of the SCL signal.
Note 12: A device must internally provide a hold time of at least 300ns for the SDA signal (see the VIH MIN of the SCL signal) in order
to bridge the undefined region of the falling edge of SCL.
Note 13: CB—total capacitance of one bus line, timing referenced to 0.9 x VCC and 0.1 x VCC.
Note 14: EEPROM write begins after a STOP condition occurs.
(VCC = 5.0V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
700
660
620
580
540
500
-40 -20
0 20 40 60
TEMPERATURE (°C)
80 100
RESISTANCE vs. SETTING
60
50
40
30
20
10
0
0 50 100 150 200 250 300
SETTING
Typical Operating Characteristics
SUPPLY CURRENT vs. VOLTAGE
700
650
600
550
500
450
400
3.0 3.5 4.0 4.5 5.0 5.5
VOLTAGE (V)
ACTIVE SUPPLY CURRENT
vs. SCL FREQUENCY
700
SDA = 5V
660
620
580
540
500
0
100 200 300
SCL FREQUENCY (kHz)
400
_____________________________________________________________________ 5
5 Page 
Dualwww.DataSheet4U.com Temperature-Controlled Resistors with
Three Monitors
Variable Resistors
The value of each variable resistor is determined by
a temperature-addressed look-up table, which can
assign a unique value (00h to FFh) to each resistor for
every 2°C increment over the -40°C to +102°C range
(see Table 3). See the Temperature Conversion section
for more information.
The variable resistors can also be used in manual
mode. If the TEN bit equals 0, then the resistors are in
manual mode and the temperature indexing is dis-
abled. The user sets the resistors in manual mode by
writing to addresses 82h and 83h in Table 01 to control
resistors 0 and 1, respectively.
Memory Description
Main and auxiliary memories can be accessed by two
separate device addresses. The Main Device address
is A2h (or value in Table 01 byte 8Ch, when ADFIX = 1)
and the Auxiliary Device address is A0h. A user option
is provided to respond to one or two device addresses.
This feature can be used to save component count in
SFF applications (Main Device address can be used)
or other applications where both GBIC (Auxiliary
Device address can be used) and monitoring functions
are implemented and two device addresses are need-
ed. The memory blocks are enabled with the corre-
sponding device address. Memory space from 80h and
up is accessible only through the Main Device address.
This memory is organized as three tables; the desired
table can be selected by the contents of memory loca-
tion 7Fh, Main Device. The Auxiliary Device address
has no access to the tables, but the Auxiliary Device
address can be mapped into the Main Device’s memo-
ry space as a fourth table. Device addresses are pro-
grammable with two control bits in EEPROM.
ADEN configures memory access to respond to differ-
ent device addresses (see Tables 4 and 5).
The default device address for EEPROM-generated
addresses is A2h.
If the ADEN bit is 1, additional 128 bytes of EEPROM
are accessible through the Main Device, selected as
Table 00 (see Figure 3). In this configuration, the
Auxiliary Device is not accessible. APEN controls the
protection of Table 00 regardless of the setting of
ADEN.
ADFIX (address fixed) determines whether the Main
Device address is determined by an EEPROM byte
(Table 01, byte 8Ch, when ADFIX =1). There can be up
to 128 devices sharing a common 2-wire bus, with
each device having its own unique device address.
Memory Protection
Memory access from either device address can be
either read/write or read only. Write protection
is accomplished by a combination of control bits in
EEPROM (APEN and MPEN in configuration register
89h) and a write-protect enable (WPEN) pin. Since the
WPEN pin is often not accessible from outside the mod-
ule, this scheme effectively allows the module to be
locked by the manufacturer to prevent accidental writes
by the end user.
Separate write protection is provided for the Auxiliary
and Main Device address through distinct bits APEN
and MPEN. APEN and MPEN are bits from configura-
tion register 89h, Table 01. Due to the location, the
APEN and MPEN bits can only be written through the
Main Device address. The control of write privileges
through the Auxiliary Device address is dependent on
the value of APEN. Care should be taken with the set-
ting of MPEN, once set to a 1, assuming WPEN is high,
access through the Main Device is thereafter denied
unless WPEN is taken to a low level. By this means
inadvertent end-user write access can be denied.
Main Device address space 60h to 7Fh is SRAM and is
not write protected by APEN, MPEN, or WPEN. For
example, the user may reset flags set by the device.
Bytes designated as “Reserved” may be used as
scratchpad, but they will not be stored in a power cycle
because of their volatility. These bytes are reserved for
added functionality in future versions of this device.
Note that in single device mode (ADEN bit = 1), APEN
determines the protection level of Table 00, indepen-
dent of WPEN.
The write-protect operation, for both Main and Auxiliary
Devices, is summarized in Tables 6 and 7.
Table 6. Main Device
WPEN
0
X
1
MPEN
X
0
1
PROTECT MAIN
No
No
Yes
Table 7. Auxiliary Device
APEN
0
1
WPEN
X
X
PROTECT AUXILIARY
No
Yes
____________________________________________________________________ 11
11 Page | ||
| Páginas | Total 22 Páginas | |
| PDF Descargar | [ Datasheet DS1858.PDF ] | |
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