PDF《配电开关》

TPS65281, TPS65281-1 www.

ti.com.cn ZHCSA46B CJULY 2012CREVISED DECEMBER

2012 具 具有 有4.5V 至至18V 输 输入 入电 电压 压, ,3A 输 输出 出电 电流 流同 同步 步降 降压 压稳 稳压 压器 器的 的精 精密 密可 可调 调限 限流 流配配电 电开 开关 关查查询 询样 样片 片: TPS65281, TPS65281-1 1特 特性 性集集成 成型 型配 配电 电开 开关 关集集成 成降 降压 压转 转换 换器 器?宽宽输 输入 入电 电压 压范 范围 围: :4.5V 至至18V ? 运 运行 行输 输入 入电 电压 压的 的范 范围 围: :2.5V 到到6.5V ? 最 最大 大持 持续 续3A 输 输出 出电 电流 流?可可调 调电 电流 流限 限值 值: : 75mA-2.7A( (典 典型 型值 值) ) ? 反 反馈 馈基 基准 准电 电压 压: :0.8V±1 % ? 1.7A 电 电流 流时 时+/-6% 电 电流 流限 限制 制精 精度 度( (典 典型 型值 值) ) ? 300kHz 至至1.4MHz 间 间可 可调 调开 开关 关频 频率 率?过过流 流锁 锁存 存保 保护 护(TPS65281) 和 和过 过流 流自 自动 动恢 恢复 复?具具有 有内 内置 置1ms 内 内部 部软 软启 启动 动时 时间 间的 的可 可调 调软 软启 启动 动和 和跟 跟(TPS65281-1) 踪踪?反反向 向输 输入 入-输 输出 出电 电压 压保 保护 护?逐逐周 周期 期电 电流 流限 限制 制?内内置 置软 软启 启动 动?输输出 出过 过压 压保 保护 护?接接通 通阻 阻抗 抗为 为100m? 的 的集 集成 成型 型背 背靠 靠背 背功 功率 率金 金属 属氧 氧化 化?16 导 导线 线四 四方 方扁 扁平 平无 无引 引线 线(QFN) (RGV) 4mm x 物 物场 场效 效应 应晶 晶体 体管 管(MOSFET) 4mm 封 封装 装?过过热 热保 保护 护应应用 用范 范围 围xxx xxx ? USB 端 端口 口和 和集 集线 线器 器xxx ? 数 数字 字电 电视 视xxx ? 机 机顶 顶盒 盒xxx ? 网 网络 络语 语音 音(VOIP) 电 电话 话xxx ? 平 平板 板电 电脑 脑xxx xxx xxx 说 说明 明/订 订购 购信 信息 息TPS65281/TPS65281-1 组装有一个 N 通道背靠背功率 MOSFET 开关和一个单片降压转换器. 此器件用于为数字 电视、机顶盒、平板电脑和 VOIP 电话等应用提供一个总体的配电解决方案,在这些应用中需要精密电流限制或者 有可能出现高电容负载或者短路. 一个 100m? 独立配电开关通过使用一个外部电阻器将输出电流限制在典型值为 75mA 至2.7A 的可编程电流限值 阀值之间. 在更高电流限制设置中,可实现 ±6% 的严格电流限制精度. 在过流或者反向电压情况下,通过锁存电 源开关,TPS65281 提供电路断路器功能. 当输出负载超过电流限制阀值时,通过使用一个恒定电流模 式,TPS65281-1 将输出电流限制在一个安全水平上. 当输出电压被驱动至高于输入时,一个内部反向电压比较器 将电源开关禁用来保护正常运行时的开关输入端上的器件. 在过流和反向电压期间,nFAULT 输出被置为低电平有 效. 背靠背功率 MOSFET 结构在电源开关关闭期间防止输出端口上有源负载的反向电流注入. 为了优化电源效率并且减少外部组件数量,降压直流/直流转换器集成了功率 MOSFET. 到降压转换器的宽 4.5V 至18V 输入电源范围包括大多数运行自 5V,9V,12V 或者 15V 电源总线的的中间总线电压. 恒定频率峰值电流 模式简化了补偿并提供快速瞬态响应. 降压可被精准排序并斜升以与带有软启动引脚的系统内其它电源轨保持一 致. 当SS 引脚悬空时,内置的 1ms 软启动时间可防止涌入电流. 逐周期过流保护和断续模式运行在短路或者负 载故障条件下限制 MOSFET 功率耗散. 借助于一个 ROSC 引脚上的外部电阻器,转换器的开关频率可在 300kHz 至1.4MHz 之间进行设定. 在ROSC 引脚连接到 V7V 引脚、悬空、或者接地时,可选择一个缺省固定开关频率来 减少一个外部电阻器.

1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Copyright ? 2012, Texas Instruments Incorporated Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not English Data Sheet: SLVSBH7 necessarily include testing of all parameters. TPS65281, TPS65281-1 ZHCSA46B CJULY 2012CREVISED DECEMBER

2012 www.ti.com.cn TPS65281/TPS65281-1 采用

16 导线耐热增强型 QFN (RGV) 4mm x 4mm 薄型封装. ORDERING INFORMATION(1) TA PACKAGE(2) ORDERABLE PART NUMBER TOP-SIDE MARKING TPS65281RGVR TPS65281 TPS65281RGVT C40°C to 85°C 16-Pin QFN (RGV) TPS65281-1RGVR TPS65281-1 TPS65281-1RGVT (1) For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI web site at www.ti.com. (2) Package drawings, thermal data, and symbolization are available at www.ti.com/packaging.

2 Copyright ? 2012, Texas Instruments Incorporated TPS65281, TPS65281-1 www.ti.com.cn ZHCSA46B CJULY 2012CREVISED DECEMBER

2012 This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. TYPICAL APPLICATION Figure 1. 12-V Power Bus Figure 2. 5-V Power Bus Copyright ? 2012, Texas Instruments Incorporated

3 TPS65281, TPS65281-1 ZHCSA46B CJULY 2012CREVISED DECEMBER

2012 www.ti.com.cn FUNCTION BLOCK DIAGRAM

4 Copyright ? 2012, Texas Instruments Incorporated TPS65281, TPS65281-1 www.ti.com.cn ZHCSA46B CJULY 2012CREVISED DECEMBER

2012 PIN OUT Exposed thermal pad must be soldered to PCB for optimal thermal performance. Copyright ? 2012, Texas Instruments Incorporated

5 TPS65281, TPS65281-1 ZHCSA46B CJULY 2012CREVISED DECEMBER

2012 www.ti.com.cn TERMINAL FUNCTIONS NAME NO. DESCRIPTION SS

1 Soft-start and tracking input for buck converter. An internal 5-?A current source is connected to this pin. An external soft-start can be programmed by connecting a capacitor between this pin and ground. Leave the pin floating to have a default 1-ms of soft-start time. This pin allows the start-up of buck output to track an external voltage using an external resistor divider at this pin. COMP

2 Error amplifier output and Loop compensation pin for buck. Connect a series RC to compensate the control loop of buck converter. ROSC

3 Oscillator clock frequency control pin. Connect the pin to ground for a fixed 300-kHz switching frequency. Connect the pin to V7V or float the pin for a fixed 600-kHz switching frequency. Other switch frequencies between

300 kHz to 1.4 MHz can be programmed using a resistor connected from this pin to ground. A internal 10-?A pull-up current develops a voltage to be used in oscillator. Directly applying the voltage to the ROSC pin can linearly adjust the switching frequency. RLIM

4 Power switch current limit control pin. An external resistor used to set current limit threshold of power switch. Recommended

15 k? ≤ RLIM ≤

232 k?. EN_SW

5 Enable pin of power switch. Logic high turns on power switch. Forcing the pin below 0.4 V shuts down power switch. Not recommend floating this pin, though there is a 2.5-M? pull-up resistor connecting this pin. nFAULT

6 Active low open drain output, asserted in conditions when over-current happens for more than

10 ms or reverse-voltage of power switch for more than

4 ms. AGND

7 Analog ground common to buck controller and power switch controller. It must be routed separately from high current power grounds to the (-) terminal of bypass capacitor of internal V7V LDO output. SW_OUT

8 Power switch output pin SW_IN

9 Power switch input pin FB

10 Feedback sensing pin for buck output voltage. Connect this pin to the resistor divider of buck output. The feedback reference voltage is 0.8 V±1%. LX

11 Switching node connection to the internal power FETs, inductor and bootstrap capacitor for buck converter. The voltage swing at this pin is from a diode voltage below the ground up to VIN voltage. BST

12 Bootstrapped supply to the high side floating gate driver in buck converter. Connect a capacitor (recommend

47 nF) from BST pin to LX pin. PGND

13 Power ground connection. Connect PGND pin as close as practical to the (-) terminal of input ceramic capacitor. VIN

14 Input power supply for buck. Connect VIN pin as close as practical to the (+) terminal of a input ceramic capacitor (suggest

10 ?F). V7V

15 Internal LDO output. The internal gate driver for low side power MOSFET and control cirduits are powered from this voltage. Decouple this pin to power ground with a minimum 1-?F ceramic capacitor. The output voltage level of LDO is regulated to typical 6.3 V for optimal conduction on-resistances of internal power MOSFETs. EN

16 Enable for buck converter and the device. Logic high enables buck converter and bias supply to power switches. Forcing the pin below 0.4 V shuts down the entire device, reducing the quiescent current to approximate typical

7 ?A. Not recommend floating this pin. The device can be automatically started up with connecting EN pin to VIN though a

10 kΩ resistor. Power PAD Exposed pad beneath the IC. Connect to the ground. Always solder power pad to the board, and have as many thermal vias as possible on the PCB to enhance power dissipation. There is no ground or any other electric signal downbonded to the pad inside the IC package.

6 Copyright ? 2012, Texas Instruments Incorporated TPS65281, TPS65281-1 www.ti.com.cn ZHCSA46B CJULY 2012CREVISED DECEMBER

2012 ABSOLUTE MAXIMUM RATINGS (1) over operating free-air temperature range (unless otherwise noted) VIN C0.3 to

18 V LX (Maximum withstand voltage transient <

20ns) C1.0 to

18 V BST referenced to LX pin C0.3 to

7 V SW_IN, SW_OUT C0.3 to

7 V EN, EN_SW, nFAULT, V7V, ROSC, RLIM C0.3 to

7 V SS, COMP, FB C0.3 to 3.6 V AGND, PGND C0.3 to 0.3 V TJ Operating virtual junction temperature range C40 to

125 °C TSTG Storage temperature range C55 to

150 °C (1) Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absoluteCmaximumCrated conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS over operating free-air temperature range (unless otherwise noted) MIN NOM MAX UNIT VIN Input operating voltage 4.5

18 V TA Ambient temperature C40

85 °C ELECTROSTATIC DISCHARGE (ESD) PROTECTION(1) MIN MAX UNIT Human body model (HBM)

4000 V Charge device model (CDM)

500 V Machine model (MM)

200 V (1) SW_OUT pin human body model (HBM) ESD protection rating

4 kV, and machine model (MM) rating 200V. THERMAL INFORMATION TPS65281/TPS65281-1 THERMAL METRIC(1) RGV UNITS

16 PINS θJA Junction-to-ambient thermal resistance(2) 36.5 θJCtop Junction-to-case (top) thermal resistance(3) 42.7 θJB Junction-to-board thermal resistance(4) 14.7 °C/W ψJT Junction-to-top characterization parameter(........