|
|
PDF DS2731 Data sheet ( Hoja de datos )
| Número de pieza | DS2731 | |
| Descripción | Cache-Memory Battery-Backup Management IC | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de DS2731 (archivo pdf) en la parte inferior de esta página. Total 20 Páginas | ||
|
No Preview Available !
Rev 1; 1/09
Cache-Memory Battery-Backup Management IC
General Description
The DS2731 is a complete power-management solution
for modular backup applications. It is well-suited for 2.5V
and below memory bus voltages, with an input voltage of
12V. The DS2731 includes an internal MOSFET switching
power stage for charging a one-cell lithium chemistry bat-
tery. It has a fully integrated synchronous buck regulator
capable of supplying up to 450mA of cache backup sup-
ply current, and the necessary logic and power devices
for handling the switchover from system power to battery
power. The battery charging method of the DS2731 is
constant current/constant voltage (CCCV). Output voltage
can be margined from 3.8V to 4.6V using a resistor-
divider. Charge is terminated when the charging current
falls below 5% of full charge current. Switchover to battery
backup is initiated by an internal comparator and occurs
automatically when a sensed-input voltage drops below
2.93V. At light loads, the 2MHz internal synchronous buck
regulator operates in burst mode for maximum efficiency.
All nonessential functions of the DS2731 are disabled
while supplying holdup current to the cache memory, and
the IC goes into very low-current dormant mode when the
battery voltage drops below a user-settable threshold.
The DS2731 keeps track of charge status and signals the
user through open-drain I/O pins that can be used to
drive LEDs.
RAID Controller Card
Applications
Typical Operating Circuit
Features
o Lithium Chemistry CCCV Charger
o Adjustable Regulated Charging Up to 1.5A DC
o Adjustable Charge Voltage from 3.8V to 4.6V
o External and Internal Thermal Protection
o Safety Timer Secondary Termination
o LED Indicator Outputs
o Detects Power Outage and Switches Between
Normal Power and Backup Battery
o Adjustable High-Efficiency Synchronous Buck
Regulator with Skip Mode at Light Loads
o Low-Power Consumption in Discharge Mode
Ordering Information
PART
TEMP RANGE PIN-
PACKAGE
TOP
MARK
DS2731E+
-20°C to +70°C 28 TSSOP-EP* DS2731
(173 mils)
DS2731E+T&R -20°C to +70°C 28 TSSOP-EP*
(173 mils)
+Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
*EP = Exposed pad.
DS2731
Pin Configuration
MAIN
POWER
AUXILIARY
POWER
DS2731
SWITCH MODE
CHARGER
(CCCV)
POWER
MANAGEMENT
SWITCHING
REGULATOR
LITHIUM
BACKUP
CELL
CACHE
MEMORY
TOP VIEW
MARGIN
STMR
CTG
AUX
CBIAS
VREG
CIN
LX
SGND
AGND
REF
LO_BATT
DIV
ENS
1
2
3
4
5
6
7
8
9
10
11
12
13
14
*EXPOSED PAD
DS2731
*EP
TSSOP
28 THM
27 RSET
26 BATT+
25 SNS
24 CGATE
23 VIN
22 CHG1
21 CHG2
20 CGND1
19 CGND2
18 CHARGE
17 FAULT
16 DONE
15 ENC
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Free Datasheet http://www.Datasheet4U.com
1 page  
Cache-Memory Battery-Backup Management IC
THERMAL PROTECTION CHARACTERISTICS
(VIN = +10.8V to +13.2V, TA = -20°C to +70°C, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
THM Pin Internal Pullup Voltage
THM Pin Internal Resistance
Thermistor Overtemperature
HALT Threshold
SYMBOL
VTHM
RTHM
VHOT
CONDITIONS
(Notes 1, 12)
THM to CBIAS (Note 12)
(Notes 12, 13)
MIN
9.8
0.271
TYP
VCBIAS
10.0
0.283
MAX
10.2
0.292
UNITS
V
k
Ratio to
VCBIAS
Thermistor Overtemperature
Resume Threshold
VHYS-HOT
(Notes 12, 13)
0.3055
Ratio to
VCBIAS
Thermistor Undertemperature
HALT Threshold
VCOLD
(Notes 12, 13)
0.727
0.739
0.748
Ratio to
VCBIAS
Thermistor Undertemperature
Resume Threshold
VHYS-COLD
(Notes 12, 13)
0.714
Ratio to
VCBIAS
Thermistor Disable
Threshold
VDISABLE
(Notes 12, 13)
0.02
0.03
0.04 Ratio to
VCBIAS
Internal Overtemperature
Protection Threshold CCCV
TPROTECT_CCCV (Note 12)
160 °C
Internal Overtemperature
Hysteresis CCCV
THYS-PROTECT_CCCV (Note 12)
-20 °C
Internal Overtemperature
Protection Threshold MEM_REG
TPROTECT_MEMREG (Note 14)
165 °C
Internal Overtemperature
Hysteresis MEM_REG
THYS-PROTECT_
MEMREG
(Note 14)
-15 °C
Charging Current Reduction
Threshold
TCHOKE
(Note 12)
100 °C
Charging Current Reduction Rate
TCHOKE_RATE
(Note 12)
133 mA/°C
Note 1: All voltages referenced to AGND pin.
Note 2: VCIN is equivalent to VAUX when VAUX is greater than VTRIP, otherwise VCIN is equivalent to VBATT+.
Note 3: Supply-current specification is only for current drain of the IC and does not include cell-charge current, load-supply cur-
rent, or any external resistor bias currents. The only exception is ISLEEP, which does account for complete current drain of
the lithium cell during low-battery conditions.
Note 4: Below this voltage, the input is guaranteed to be logic-low.
Note 5: Operating from 3.3V ±10%.
Note 6: Above this voltage, the input is guaranteed to be logic-high.
Note 7: Assumes an RSNS value of 0.05Ω.
Note 8: Relative to VCV.
Note 9: With recommended application circuit.
Note 10: Includes complete package resistance.
Note 11: This specification is from the rising or falling edge of ENS to the closure of the switch and includes whatever delay is in the
internal logic and FET drivers.
Note 12: Applies to charger.
Note 13: Multiply these values by CBIAS voltage to get value in volts. Recommended value of resistor in divider network is 10kΩ ±1%.
Tolerance includes tolerances of internal resistance and CBIAS voltage.
Note 14: Applies to memory buck regulator.
_______________________________________________________________________________________ 5
Free Datasheet http://www.Datasheet4U.com
5 Page 
Cache-Memory Battery-Backup Management IC
I
PRECHARGE
MODE
CHARGE
BEGIN
CONSTANT-CURRENT
MODE
ICHARGE
V
CONSTANT-VOLTAGE
MODE
V
CHARGE
END
VPK
I
10% x ICHARGE
VMIN
5% x ICHARGE
t
CHARGE TERMINATION
Figure 4. Li+ Battery Charging Characteristics
Constant-Current (CC) Mode
CC mode is entered either directly from initiate or after
precharge. Current is regulated based on the voltage
drop across an external 50mΩ sense resistor and an
internal feedback circuit. The CC charge rate is set by
the RSET pin. It can be calculated by the following
formula:
ICHARGE = 2500/R
Where R is the value of the resistor connected to RSET.
The charge current can range from 0.5A to 1.5A.
The safety timer begins when CC mode is entered. If it
expires during CC mode, the charger enters a fault
state. If the current-sense feedback or RSET resistor is
shorted, the charger clamps current at IOVERCURRENT.
Li+ Charger CC Operation
Detailed Description
In CC mode, the CCCV charger regulates current by
monitoring the voltage drop across the SNS resistor.
The differential voltage measurement provides feed-
back that controls the switching of the high-side and
low-side FETs. Inside the DS2731 CHG1 and CHG2
pins are a high-side p-channel MOSFET (Q1) and a
low-side n-channel MOSFET (Q2). Q1 and Q2 alternate
on and off, either supplying current to the load and
inductor or providing a current loop for the inductor to
supply the load. The inductor charges during Q1 ON
and discharges during Q2 ON. The Q1 and Q2 switch-
ing is controlled by the voltage across RSNS.
______________________________________________________________________________________ 11
Free Datasheet http://www.Datasheet4U.com
11 Page | ||
| Páginas | Total 20 Páginas | |
| PDF Descargar | [ Datasheet DS2731.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| DS2731 | Cache-Memory Battery-Backup Management IC | Maxim Integrated |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |