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| 型号： | LTC1558CS-3.3 |
| 厂商： | Linear Technology |
| 文件页数： | 10/20页 |
| 文件大小： | 0K |
| 描述： | IC BACKUP BATT CNTRLR3.3V 16SOIC |
| 标准包装： | 50 |
| 功能： | 备份管理 |
| 电池化学： | 镍镉 |
| 电源电压： | 2.9 V ~ 3.46 V |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SOIC |
| 包装： | 管件 |
LTC1558-3.3/LTC1558-5
APPLICATIO N S I N FOR M ATIO N
proportional to the difference between V BAK (3V to 10V)
and the battery cell voltage, V BAT (1.2V).
Assuming ESR = 0.2 ? , I IND(PEAK) = 330mA, V BAK = 6V,
V RIPPLE(P-P) = (I IND(PEAK) )(R ESR(CAP) )
= (330mA)(0.2 ? )
= 66mV
Since V BAK must be scaled down to V FB , the external
resistor ratio
= 6V/1.272V
= 4.717
Therefore the noise amplitude seen by the FB compara-
tors is:
= 66mV/4.717
= 14mV
The discharge time period,
t DISCH = (L ? I IND(PEAK) )/(V BAK – V BAT )
= (22 μ H ? 330mA)/(6V – 1.2V)
= 1.5 μ s
For lowest V BAK = 3V and maximum I IND(PEAK) = 445mA,
V RIPPLE(P-P) = 89mV
RB resistor ratio = 2.358
Noise amplitude = 37.7mV
t DISCH = 5 μ s
The internal V FB comparators are designed to have a slow
response time to filter away this ripple. The (V REF – 6%)
FB comparator has a 6 μ s rising edge delay and 2 μ s falling
edge delay. The (V REF – 7.5%) FB comparator has a
similar 6 μ s rising time delay but a much longer falling
time delay of 20 μ s. This enables the comparator to
control the booster properly, and avoids turning off the
boost converter prematurely due to false triggering by
the ESR ripple.
Exit from Backup
When a new battery is inserted into the system, the higher
main battery voltage turns on the external P-channel
MOSFET’s body diode and raises V BAK (and V FB ) to a
higher voltage. The LTC1558 detects the return of the main
10
battery by watching for V FB to exceed (V REF – 6%). The
LTC1558 then stops its internal boost converter and
begins to recharge the NiCd cell. BACKUP is deasserted to
signal to the system controller to restore system loading
and resume normal operations. At the same time, the
external P-channel MOSFET is driven by the BACKUP
signal. The P-channel MOSFET turns on and allows the
main battery to bypass its body diode and drive the system
regulator directly.
Since the user can replace the main battery anytime during
the LTC1558’s backup operations, the BACKUP signal
may be deasserted while the boost converter is switching.
To prevent the potential problem of residual energy in the
inductor, the LTC1558 will only stop the boost converter
after it has completed the current boost cycle.
UVLO Lockout Under Excessive Backup Load
Very heavy loads (above the LTC1558’s maximum power
output) will pull the boost converter’s output below the
boost threshold. Under these conditions, the LTC1558’s
boost converter will continue to supply 330mA current
pulses to the system regulator while charge on the V BAK
capacitor (C IN ) drains away. The system regulator will not
maintain its output regulation and the system V CC will
drop. When V CC drops below – 9% of the rated voltage for
more than 9 μ s, the LTC1558’s V CC supervisory circuit
activates UVLO mode, shutting off the boost converter and
asserting the RESET pins. The 9 μ s delay prevents the
LTC1558 from being fooled by brief transients or noise
spikes on its V CC pin. Upon receipt of the reset signals, the
host system should shut down in a orderly manner. The
LTC1558’s V CC supervisory circuit will remain alive until
V CC is less than 1V to ensure valid reset pin signals.
Backup Cell Voltage Monitoring
As the boost converter removes charge from the backup
NiCd cell, the cell’s terminal voltage falls. Permanent
damage to the NiCd cell can occur if it is discharged to
below 0.9V. To prevent this, the LTC1558 monitors the
cell’s terminal voltage through the CTL pin during backup.
If the CTL pin drops below 0.9V for more than 20 μ s, the
UVLO circuit shuts down the boost converter and asserts
the RESET pins. Since the CTL pin can also be connected
to an external pushbutton reset, the LTC1558 includes
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相关代理商/技术参数 |
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| LTC1558CS-5 | 功能描述:IC BACKUP BATT CNTRLR 5V 16-SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:2,000 系列:Impedance Track™ 功能:燃料，电量检测计/监控器 电池化学:锂离子（Li-Ion） 电源电压:2.4 V ~ 2.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:20-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:20-TSSOP 包装:带卷 (TR) 产品目录页面:1020 (CN2011-ZH PDF) 配用:BQ27350EVM-ND - BQ27350EVM 其它名称:296-21665-2 |
| LTC1558CS-5#PBF | 功能描述:IC BACKUP BATT CNTRLR 5V 16-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:1 系列:- 功能:充电管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:3.75 V ~ 6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:剪切带 (CT) 产品目录页面:669 (CN2011-ZH PDF) 其它名称:MCP73831T-2ACI/OTCT |
| LTC1558CS-5#TRPBF | 功能描述:IC BACKUP BATT CNTRLR 5V 16-SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:1 系列:- 功能:充电管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:3.75 V ~ 6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:剪切带 (CT) 产品目录页面:669 (CN2011-ZH PDF) 其它名称:MCP73831T-2ACI/OTCT |
| LTC1558CS8-3.3 | 功能描述:IC BACKUP BATT CNTRLR 3.3V 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:2,000 系列:Impedance Track™ 功能:燃料，电量检测计/监控器 电池化学:锂离子（Li-Ion） 电源电压:2.4 V ~ 2.6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:20-TSSOP（0.173"，4.40mm 宽） 供应商设备封装:20-TSSOP 包装:带卷 (TR) 产品目录页面:1020 (CN2011-ZH PDF) 配用:BQ27350EVM-ND - BQ27350EVM 其它名称:296-21665-2 |
| LTC1558CS8-3.3#PBF | 功能描述:IC BACKUP BATT CNTRLR 3.3V 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:1 系列:- 功能:充电管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:3.75 V ~ 6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:剪切带 (CT) 产品目录页面:669 (CN2011-ZH PDF) 其它名称:MCP73831T-2ACI/OTCT |
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