- 您现在的位置：买卖IC网 > PDF目录13623 > ISL85402IRZ-TK (Intersil)IC REG BUCK BOOST SYNC ADJ 20QFN PDF资料下载
参数资料
| 型号： | ISL85402IRZ-TK |
| 厂商： | Intersil |
| 文件页数： | 14/22页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BOOST SYNC ADJ 20QFN |
| 标准包装： | 1,000 |
| 类型： | 降压（降压），升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 可调至 0.8V |
| 输入电压： | 3 V ~ 36 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz ~ 2.2MHz |
| 电流 - 输出： | 2.5A |
| 同步整流器： | 两者兼有 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-VFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 20-QFN（4x4） |
ISL85402
R UP [ M Ω ] = ----------------------
(EQ. 3)
part switching while not exceeding the 44V, as stated in the
Absolute Maximum Ratings.
The lowest IC operating input voltage (VIN pin) depends on VCC
voltage and the Rising and Falling V CC POR Threshold in
Electrical Specifications table on page 7. At IC startup when VCC
is just over rising POR threshold, there is no switching before the
soft-start starts. Therefore, the IC minimum startup voltage on
the VIN pin is 3.05V (MAX of Rising V CC POR). When the soft-start
is initiated, the regulator is switching and the dropout voltage
across the internal LDO increases due to driving current. Thus,
the IC VIN pin shutdown voltage is related to driving current and
VCC POR falling threshold. The internal upper side MOSFET has
typical 10nC gate drive. For a typical example of synchronous
buck with 4nC lower MOSFET gate drive and 500kHz switching
frequency, the driving current is 7mA total causing 70mV drop
across internal LDO under 3V V IN . Then the IC shut down voltage
on the VIN pin is 2.87V (2.8V+0.07V). In practical design, extra
room should be taken into account with concern to voltage
spikes at VIN.
With boost buck configuration, the input voltage range can be
expanded further down to 2.5V or lower depending on the boost
stage voltage drop upon maximum duty cycle. Since the boost
output voltage is connected to the VIN pin as the buck inputs,
after the IC starts up, the IC will keep operating and switching as
long as the boost output voltage can keep the VCC voltage higher
Output Voltage
The ISL85402 output voltage can be programmed down to 0.8V
by a resistor divider from V OUT to FB. The maximum achievable
voltage is (V IN *D MAX - V DROP ), where V DROP is the voltage drop
in the power path including mainly the MOSFET r DS(ON) and
inductor DCR. The maximum duty cycle D MAX is decided by
(1 - Fs * t MIN(OFF) ).
Output Current
With the high-side MOSFET integrated, the maximum output
current, which the ISL85402 can support is decided by the
package and many operating conditions. Thus, including input
voltage, output voltage, duty cycle, switching frequency and
temperature, etc. Note the following points.
? The maximum output current is limited by the maximum OC
threshold that is 4.18A (TYP).
? From the thermal perspective, the die temperature shouldn’t
exceed +125°C with the power loss dissipated inside of the IC.
Figures 10 and 11 show the thermal performance of this part
operating at different conditions.
Figures 10 and 11 show 2A and 2.5A applications under +25°C
still air conditions over V IN range. The temperature rise data in
these figures can be used to estimate the die temperature at
different ambient temperatures under various operating
conditions. Note that more temperature rise is expected at higher
ambient temperature due to more conduction loss caused by
r DS(ON) increase.
Generally, the part can output 2.5A in typical application
conditions (V IN 8~30V, V O 5V, 500kHz, still air and +105°C
14
ambient conditions). For any other operating conditions, refer to
the previous mentioned thermal curves to estimate the
maximum output current. The output current should be derated
under any conditions causing the die temperature to exceed
+125°C.
Basically, the die temperature is equal to the sum of ambient
temperature and the temperature rise resulting from the power
dissipated by the IC package with a certain junction to ambient
thermal impedance θ JA . The power dissipated in the IC is related
to the MOSFET switching loss, conduction loss and the internal
LDO loss. Besides the load, these losses are also related to input
voltage, output voltage, duty cycle, switching frequency and
temperature. With the exposed pad at the bottom, the heat of
the IC mainly goes through the bottom pad and θ JA is greatly
reduced. The θ JA is highly related to layout and air flow
conditions. In layout, multiple vias ( ≥ 9) are strongly
recommended in the IC bottom pad. The bottom pad with its vias
should be placed in the ground copper plane with an area as
large as possible across multiple layers. The θ JA can be reduced
further with air flow. Refer to Figures 8 and 9 for the thermal
performance with 100 CFM air flow.
Boost Converter Operation
to provide input to the following Buck stage. This is for
applications when the input voltage could drop to a very low
voltage in some constants (in some battery powered systems as
for example), causing the output voltage to drop out of
regulation. The boost converter can be enabled to boost the input
voltage up to keep the output voltage in regulation. When system
input voltage recovers back to normal, the boost stage is
disabled while only the buck stage is switching.
The EXT_BOOST pin is used to set boost mode and monitor the
boost input voltage. At IC start-up before soft-start, the controller
will be latched in boost mode when the voltage is at or above
200mV; it will latch in synchronous buck mode if voltage on this
pin is below 200mV. In boost mode the low-side driver output
PWM has the same PWM signal with the buck regulator.
In boost mode, the EXT_BOOST pin is used to monitor boost input
voltage to turn on and turn off the boost PWM. The AUXVCC pin is
used to monitor the boost output voltage to turn on and turn off
the boost PWM.
Referring to Figure 26 on page 15, a resistor divider from boost
input voltage to the EXT_BOOST pin is used to detect the boost
input voltage. When the voltage on EXT_BOOST pin is below 0.8V,
the boost PWM is enabled with a fixed 500μs soft-start and the
boost duty cycle increases linearly from t MIN(ON) *Fs to ~50%. A
3μA sinking current is enabled at the EXT_BOOST pin for
hysteresis purposes. When the voltage on the EXT_BOOST pin
recovers to be above 0.8V, the boost PWM is disabled
immediately. Use Equation 3 to calculate the upper resistor R UP
(R1 in Figure 26) for a desired hysteresis V HYS at boost input
voltage.
VHYS
3 [ μ A ]
FN7640.1
April 25, 2013
相关PDF资料 |
PDF描述 |
|---|---|
| MAX6733AUTYVD2+T | IC SUPERVISOR MPU W/WD SOT23-6 |
| 35ZLK330MT810X16 | CAP ALUM 330UF 35V 20% RADIAL |
| MAX6733AUTYDD1+T | IC SUPERVISOR MPU W/WD SOT23-6 |
| ISL85402IRZ-T | IC REG BUCK BOOST SYNC ADJ 20QFN |
| MAX6733AUTZID5+T | IC SUPERVISOR MPU W/WD SOT23-6 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL8540EVAL1Z | 功能描述:EVALUATION BOARD FOR ISL8540 RoHS:是 类别:编程器，开发系统 >> 评估板 - DC/DC 与 AC/DC（离线）SMPS 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:True Shutdown™ 主要目的:DC/DC，步升 输出及类型:1，非隔离 功率 - 输出:- 输出电压:- 电流 - 输出:1A 输入电压:2.5 V ~ 5.5 V 稳压器拓扑结构:升压 频率 - 开关:3MHz 板类型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL8540IVEZ | 功能描述:IC REG BUCK SYNC ADJ 2A 20HTSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 标准包装:1 系列:EZBuck™ 类型:降压（降压） 输出类型:可调式 输出数:1 输出电压:0.8 V ~ 22.1 V 输入电压:3 V ~ 26 V PWM 型:电流模式 频率 - 开关:1.5MHz 电流 - 输出:1.8A 同步整流器:无 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-WFDFN 裸露焊盘 包装:剪切带 (CT) 供应商设备封装:8-DFN（2x2） 其它名称:785-1276-1 |
| ISL8540IVEZ-T | 功能描述:IC REG BUCK SYNC ADJ 2A 20HTSSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:降压（降压） 输出类型:两者兼有 输出数:1 输出电压:5V，1 V ~ 10 V 输入电压:3.5 V ~ 28 V PWM 型:电流模式 频率 - 开关:220kHz ~ 1MHz 电流 - 输出:600mA 同步整流器:无 工作温度:-40°C ~ 125°C 安装类型:表面贴装 封装/外壳:16-SSOP（0.154"，3.90mm 宽） 包装:带卷 (TR) 供应商设备封装:16-QSOP |
| ISL85410FRZ | 制造商:Intersil Corporation 功能描述:36VIN 1A SYNCHRONOUS SWITCHING REGULATOR- 4X3 12LD DFN PB-FR - Rail/Tube 制造商:Intersil Corporation 功能描述:IC REG BUCK SYNC ADJ 1A 12DFN |
| ISL85410FRZ-T | 制造商:Intersil Corporation 功能描述:36VIN 1A SYNCHRONOUS SWITCHING REGULATOR 4X3 12LD DFN T&R - Tape and Reel 制造商:Intersil Corporation 功能描述:IC REG BUCK SYNC ADJ 1A 12DFN |
发布紧急采购，3分钟左右您将得到回复。