参数资料
| 型号： | ISL8121IRZ |
| 厂商： | Intersil |
| 文件页数： | 16/26页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 24-QFN |
| 标准包装： | 75 |
| PWM 型： | 电压模式 |
| 输出数： | 1 |
| 频率 - 最大： | 2MHz |
| 占空比： | 66% |
| 电源电压： | 4.9 V ~ 5.5 V |
| 降压： | 是 |
| 升压： | 无 |
| 回扫： | 无 |
| 反相： | 无 |
| 倍增器： | 无 |
| 除法器： | 无 |
| Cuk： | 无 |
| 隔离： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 封装/外壳： | 24-VFQFN 裸露焊盘 |
| 包装： | 管件 |
ISL8121
ISL8121
EXTERNAL CIRCUIT
+5V
ISL8121
EXTERNAL CIRCUIT
PVCC
POR
CIRCUIT
VCC
V IN
POR
CIRCUIT
VCC
R BIAS
V IN
V REF
(0.61V)
R S
E/A
-
+
EN
COMP
-
EN
R P
Q1
OFF
ON
+
VREF
VREG
I H
(20 μ A)
VCC
FIGURE 16. START-UP COORDINATION USING THE EN
PIN
A secondary disablement feature is available via the
threshold-sensitive enable input, the EN. This optional
feature prevents the ISL8121 from operating until a
certain chosen voltage rail is available and above some
selectable threshold. One example would be the input
voltage: it may be desirable the ISL8121-based
converter does not start up until the input voltage is
sufficiently high. The schematic in Figure 16
demonstrates coordination of the ISL8121 start-up with
such a rail. The internal current source, I H , provides the
means to a user-adjustable hysteresis. The resistor value
selection process follows the same equations as those
Additionally, an open-drain or open-collector device (Q1)
can be used to wire-AND a second (or multiple) control
signal. To defeat the threshold-sensitive enable, connect
EN to VCC directly or via a pull-up resistor.
In summary, for the ISL8121 to operate, VCC and PVCC
must be greater than their respective POR thresholds
and the voltage at EN must be greater than the
comparator’s reference (see typical threshold in
“Electrical Specifications” on page 5). Once these
conditions are met, the controller immediately initiates a
soft-start sequence.
General Application Design
Guide
This design guide is intended to provide a high-level
explanation of the steps necessary to create a multi-
phase power converter. It is assumed that the reader is
familiar with many of the basic skills and techniques in
the following sections. In addition to this guide, Intersil
provides complete reference designs that include
schematics, bills of materials, and example board
layouts for typical applications.
16
SHUNT REG
FIGURE 17. INTERNAL SHUNT REGULATOR USE WITH
EXTERNAL RESISTOR (PASSIVE
CONFIGURATION)
BIAS SUPPLY CONSIDERATIONS
The ISL8121 features an on-board shunt regulator
capable of sinking up to 100mA (minimally). This
integrated regulator can be used to produce the
necessary bias voltage for the controller and the
MOSFETs. The integrated regulator can be utilized
directly, via a properly sized resistor, as shown in
Figure 17, or via an external NPN transistor and
additional resistors when either the current needed or
the power being dissipated becomes too large to be
handled inside the ISL8121 in the given operating
environment.
A first step in determining the feasibility and selecting the
proper bias regulator configuration consists in
determining the maximum bias current required by the
circuit. While the bias current required by the ISL8121 is
listed in “Electrical Specifications” table on page 5, the
bias current required by the controlled MOSFETs needs
be calculated. The following equation helps determine
this bias current function of the sum of the gate charge
of all the controlled MOSFETs at 5V V GS , Q GTOTAL , and
the switching frequency, F SW :
I B ? Q GTOTAL ? F SW
(EQ. 10)
I BIAS = I VCC + I B
Total required bias current, I BIAS , sums up the ISL8121’s
bias current, I VCC , to that required by the MOSFETs, I B .
FN6352.2
October 27, 2009
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL8121IRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 24-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL8121IRZ-TR5453 | 制造商:Intersil Corporation 功能描述:STD. ISL8121IRZ-T WITH GOLD BOND WIRE ONLY - Tape and Reel |
| ISL8126 | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Dual/n-Phase Buck PWM Controller with Integrated Drivers |
| ISL8126CRZ | 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
| ISL8126CRZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 32-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:275kHz 占空比:50% 电源电压:18 V ~ 110 V 降压:无 升压:无 回扫:无 反相:无 倍增器:无 除法器:无 Cuk:无 隔离:是 工作温度:-40°C ~ 85°C 封装/外壳:8-SOIC（0.154"，3.90mm 宽） 包装:带卷 (TR) |
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