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参数资料
| 型号： | UCC3957MTR-2 |
| 厂商： | Texas Instruments |
| 文件页数： | 8/15页 |
| 文件大小： | 0K |
| 描述： | IC LI-ION PROTECT CIRCUIT 16QSOP |
| 标准包装： | 2,500 |
| 功能： | 过压/欠压保护 |
| 电池化学： | 锂离子（Li-Ion） |
| 电源电压： | 5 V ~ 20 V |
| 工作温度： | -20°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SSOP/QSOP |
| 包装： | 带卷 (TR) |
Not Recommended for New Designs
UCC3957 1, UCC3957 2, UCC3957 3, UCC3957 4
SLUS236B – JANUARY 1999 – REVISED SEPTEMBER 2002
APPLICATION INFORMATION
protection against a runaway charger
The use of a small N-channel level shifter (Q3 in the application diagrams) allows the IC to interface with the
high-side charge FET (Q1), even in the presence of a runaway charger. Only the drain-source voltage rating
of the charge FET limits the charge voltage that the protection circuit can withstand. The wakeup (WU) pin is
designed to handle input voltages greater than VDD, as long as the current is limited. In the examples shown,
the charge FET ’ s gate-source resistor (R1) provides this current limiting. Note that in Figure 2, a resistor and
zener (R2 and VR1) have been added to protect Q1 against any possibility of a voltage transient exceeding its
maximum gate-source rating.
overcurrent protection
The UCC3957 protects the battery pack from an overload or a hard short circuit using a two-tier overcurrent
protection scheme. The overcurrent protection is designed to go into a hiccup mode when the voltage drop
across an external-sense resistor (connected to the AN4 and BATLO pins) exceeds a certain threshold. In this
mode, the discharge FET is periodically turned off and on until the fault is removed. Once the fault is removed,
normal operation is automatically resumed.
To facilitate charging large capacitive loads, there are two overcurrent threshold voltages, each with its own
user-programmable time delay. This two-tier approach provides fast response to short circuits, while enabling
the battery pack to provide short-duration surge currents. It also facilitates the charging of large filter caps
without causing nuisance overcurrent trips.
The first-tier threshold is 150 mV nominal, corresponding to 6 A using a .025- ? sense resistor as shown in the
examples of Figure 1 and Figure 2. If the pack-discharge current exceeds this amount for a period of time,
determined by the capacitor on the CDLY1 pin, it then enters the hiccup mode. The first-tier hiccup duty cycle
is fixed at approximately 6%, minimizing power dissipation in the event of a sustained overload. The absolute
on and off times of the discharge FET (Q2) are controlled by the CDLY1 capacitor. A curve relating the delay
(on time) to this capacitor value is shown in Figure 4. The off time is approximately 17 times longer than the on
time.
The second-tier overcurrent threshold is nominally 375 mV, corresponding to 15 A using a .025- ? sense resistor.
If the pack current exceeds this value for a period of time, determined by the capacitor on the CDLY2 pin, it then
enters the hiccup-mode with a much lower duty cycle, typically less than 1%. The relationship of this time delay
(on time) to the CDLY2 capacitor value is shown in the curve of Figure 5. The off time during this hiccup mode
is still determined by the CDLY1 capacitor, as previously described. This technique greatly reduces the stress
and power dissipation in the FETs during short-circuit conditions.
In the examples shown in Figure 1 and Figure 2 (with CDLY1 = .022 μ F), the first-tier overcurrent on time is
approximately 10 msec, while the off time is approximately 170 msec, resulting in a 5.9% duty cycle for currents
over 6 A (but less than 15 A). If no CDLY2 capacitor is used, the second-tier on time is less than 200 μ sec
(assuming no stray capacitance), resulting in a duty cycle of about 0.1% for currents over 15 A. If CDLY2 = 22pF,
the typical on time for currents exceeding 15 A is approximately 800 μ sec, resulting in a duty cycle of 0.5%.
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相关代理商/技术参数 |
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|---|---|
| UCC3957MTR-2G4 | 功能描述:电池管理 3-4-Cell Lithium-Ion Protection IC RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| UCC3957MTR-3 | 功能描述:电池管理 3-4-Cell Lithium-Ion Protection IC RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| UCC3957MTR-3G4 | 功能描述:电池管理 3-4-Cell Lithium-Ion Protection IC RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| UCC3957MTR-4 | 功能描述:电池管理 3-4-Cell Lithium-Ion Protection IC RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| UCC3957MTR-4G4 | 功能描述:电池管理 3-4-Cell Lithium-Ion Protection IC RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
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