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PDF DS2720AU Data sheet ( Hoja de datos )

Número de pieza DS2720AU
Descripción Efficient/ Addressable Single-Cell Rechargeable Lithium Protection IC
Fabricantes Dallas Semiconducotr 
Logotipo Dallas Semiconducotr Logotipo



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No Preview Available ! DS2720AU Hoja de datos, Descripción, Manual

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FEATURES
§ Rechargeable Lithium-Ion (Li+) Safety
Circuit
- Overvoltage Protection
- Overcurrent/Short-Circuit Protection
- Undervoltage Protection
- Overtemperature Protection
§ Controls High-Side N-Channel Power
MOSFETs Driven from 9V Charge Pump
§ System Power Management and Control
Feature Support
§ Eight Bytes of Lockable EEPROM
§ Dallas 1-Wire® Interface with Unique 64-Bit
Device Address
§ 8-Pin mSOP Package
§ Low Power Consumption:
- Active Current: 12.5mA typ
- Sleep Current: 1.5mA typ
DS2720
Efficient, Addressable Single-Cell
Rechargeable Lithium Protection IC
PIN CONFIGURATION
PLS
PS
DQ
VSS
1
2
3
4
8 CP
7 DC
6 CC
5 VDD
DS2720U
mSOP
PIN DESCRIPTION
PLS - Battery-Pack Positive Terminal Input
PS - Power-Switch Sense Input
DQ - Data Input/Output
VSS - Device Ground
VDD - Power-Supply Input
CP - Reservoir Capacitor
CC - Charge Control Output
DC - Discharge Control Output
DESCRIPTION
The DS2720 single-cell rechargeable Li+ protection IC provides electronic safety functions required for
rechargeable Li+ applications including protecting the battery during charge, protection of the circuit
from damage during periods of excess current flow and maximization of battery life by limiting the level
of cell depletion. Protection is facilitated by electronically disconnecting the charge and discharge
conduction path with switching devices such as low-cost N-channel power MOSFETs.
Since the DS2720 provides high-side drive to external N-channel protection MOSFETs from a 9V charge
pump, superior on-resistance performance results compared to common low-side protector circuits using
the same FETs. The FET on-resistance actually decreases as the battery discharges.
Adding to the uniqueness of the DS2720 is the ability of the system to control the FETs from either the
data interface or a dedicated input thereby eliminating the power-switch control redundancy of
rechargeable Li+ battery systems.
Through its 1-Wire interface, the DS2720 gives the host system read/write access to status and control
registers, instrumentation registers, and general-purpose data storage. Each device has a factory-
programmed 64-bit net address that allows it to be individually addressed by the host system.
1-Wire is a registered trademark of Dallas Semiconductor.
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DS2720AU pdf
DS2720
POWER MODES
The DS2720 has two power modes: active and sleep. While in active mode, the DS2720 continuously
performs safety monitoring. In sleep mode, the DS2720 ceases monitoring activities and drives both the
charge and discharge protection FETs to an “off state”. Upon returning to the active mode from the sleep
mode, DS2720 resumes safety monitoring and conditionally turns on the protection FETs.
Table 2. POWER MODE TRANSITION CONDITIONS
Active ® Sleep
Sleep ® Active(1)
VDD < VUV
PS pulled to VSS or
VPLS > VDD + VCH
(1) DS2720 does not transition to Active Mode if VDD < VSC.
RECHARGEABLE Li+ PROTECTION CIRCUITRY
During active mode, the DS2720 constantly monitors cell voltage and voltage drop across the FETs to
protect the battery from overcharge (overvoltage), overdischarge (undervoltage), and excessive discharge
currents (overcurrent, short circuit). Conditions and DS2720 responses are described in the sections
below and summarized in Table 3 and Figure 3.
Table 3. PROTECTION CONDITIONS AND DS2720 RESPONSES
CONDITION
NAME
Overvoltage
ACTIVATION
THRESHOLD DELAY RESPONSE
VDD > VOV
tOVD(1)
CC = VOLCC
RELEASE
THRESHOLD
VDD < VCE or
VDD - VPLS > VOC
Undervoltage
VSC < VDD < VUV
tUVD
CC = VOLCC
DC = VOLDC
VPLS > VDD + VCH and
VDD > VUV
(charger connected)
Recovery Charge
VDD < VSC or
(while in active
mode) VDD < VCE
RTST enabled(2)
VDD ³ VCE
Overcurrent
VDD - VPLS > VOC
tOCD
CC = VOLCC
DC = VOLCC
VPLS > VDD - VOC(3)
Short Circuit
VDD < VSC
tSCD
CC = VOLCC
DC = VOLDC
VPLS > VDD - VOC(3)
Overtemperature
Tdevice > TMAX
CC = VOLCC
DC = VOLDC
Tdevice < TMAX
All voltages are with respect to VSS.
(1) During transition from sleep to active, tOVD = 0.
(2) Recovery charge current is limited by RTST and forward voltage of blocking diode, which prevents discharging through
RTST when recovery charge enabled.
(3) With test current ITST flowing from VDD to PLS (pullup on PLS).
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DS2720AU arduino
DS2720
SPECIAL FEATURE REGISTER
The format of the special feature register is shown in Figure 7. The function of each bit is described in
detail in the following paragraphs.
Figure 7. SPECIAL FEATURE REGISTER FORMAT
Bit 7
PSF
Bit 6
X
Bit 5
X
Address 08
Bit 4 Bit 3
XX
Bit 2
X
Bit 1
X
Bit 0
OT
PSF— PS Flag. This bit is reset to 0 when the DS2720 detects the PS pin is pulled to VSS. This bit does
not set itself to a 1 after the PS pin returns to a high logic level, and thus must be set by the host system
to detect future events. This bit is initialized to a 1 upon POR.
OT—Overtemperature Flag. When set to 1, this bit indicates the battery pack has experienced an
overtemperature condition. This bit does not clear itself after the overtemperature state is corrected, and
thus must be reset by the host system after the temperature decreases below TMAX to re-enable the charge
and discharge FETs. Writing a 1 to this bit disables the FETs, but this is not recommended. The OT bit is
a volatile R/W bit, initialized to 0 upon POR.
X—Reserved Bits.
PS INPUT PIN
The PS pin is internally pulled to VDD through a high-value resistance. PS is continuously monitored for
a low-impedance connection to VSS. Connecting PS to VSS wakes up the DS2720 if it was in sleep mode.
If the DS2720 was in active mode, PS has no effect.
1-WIRE BUS SYSTEM
The 1-Wire bus is a system that has a single bus master and one or more slaves. A multidrop bus is a 1-
Wire bus with multiple slaves. A single-drop bus has only one slave device. In all instances, the DS2720
is a slave device. The bus master is typically a microprocessor in the host system. The discussion of this
bus system consists of four topics: 64-bit net address, hardware configuration, transaction sequence, and
1-Wire signaling.
64-BIT NET ADDRESS
Each DS2720 has a unique, factory-programmed 1-Wire net address that is 64 bits in length. The first
eight bits are the 1-Wire family code (31h for DS2720). The next 48 bits are a unique serial number. The
last eight bits are a CRC of the first 56 bits (see Figure 8). The 64-bit net address and the 1-Wire I/O
circuitry built into the device enable the DS2720 to communicate through the 1-Wire protocol detailed in
the 1-Wire Bus System section of this data sheet.
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