参数资料
| 型号： | ISL8121IRZ |
| 厂商： | Intersil |
| 文件页数： | 18/26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
Should the simple series bias resistor configuration fall
short of providing the necessary bias current, the internal
shunt regulator can be used in conjunction with an
ISL8121
EXTERNAL CIRCUIT
PVCC
external BJT transistor to increase the shunt regulator
current. Figure 21 details such an implementation
utilizing a PNP transistor. Selection of R1 can be based on
the graphs provided for the passive regulator
POR
CIRCUIT
VCC
Q1
R1
(OPTIONAL)
V IN
configuration. Maximum power dissipation inside Q1 will
take place when maximum voltage is applied to the
circuit and the ISL8121 is disabled; determine I VREGMAX
by reverse-use of the graph in Figure 18 and use the
obtained number to calculate Q1 power dissipation.
E/A
-
+
ISL8121
EXTERNAL CIRCUIT
VREF
VREG
R2
PVCC
POR
V IN
SHUNT REGULATOR
CIRCUIT
VCC
Q1
R1
FIGURE 22. INTERNAL SHUNT REGULATOR USE WITH
EXTERNAL NPN TRANSISTOR (ACTIVE
CONFIGURATION)
E/A
-
+
R2
(OPTIONAL)
FREQUENCY COMPENSATION
The ISL8121 multi-phase converter behaves in a similar
manner to a voltage-mode controller. This section
VREF
VREG
highlights the design consideration for a voltage-mode
controller requiring external compensation. To address a
broad range of applications, a type-3 feedback network is
SHUNT REGULATOR
FIGURE 21. INTERNAL SHUNT REGULATOR USE WITH
recommended (see Figure 23).
C2
EXTERNAL PNP TRANSISTOR (ACTIVE
CONFIGURATION)
An NPN transistor can also be used to increase the
maximum available bias current, as shown in Figure 22.
Used as a series pass element, Q1 will dissipate the most
power when the circuit is enabled and operational, and
R1
R2
C1
C3
COMP
FB
ISL8121
the input voltage, V IN , is at its highest level.
With the series pass element configuration shown in
Figure 22, the difference between the input and the
regulation level at the VCC pin has to be higher than the
lowest acceptable V CE of Q1 (may choose to run Q1 into
saturation, but must consider the reduced gain). Thus,
R2 has to be chosen such that it will provide appropriate
base current at lowest V CE of Q1. Next, ensure the
ISL8121’s I VREGMAX is not exceeded when the input
voltage swings to its highest extreme (assume base
current goes to 0 when the IC is disabled). R1 is an
optional circuit element: it can be added to offset some
of the power dissipation in Q1, but it also reduces the
available V CE for Q1. If utilizing such a series resistor,
check that it does not impede on the proper operation at
the lowest input voltage and choose a power rating
corresponding to the highest bias current that the
ISL8121 may require to drive the switching MOSFETs.
18
R3
V DIFF (V OUT )
FIGURE 23. COMPENSATION CONFIGURATION FOR
ISL8121 CIRCUIT
Figure 24 highlights the voltage-mode control loop for a
synchronous-rectified buck converter, applicable, with a
small number of adjustments, to the multi-phase
ISL8121 circuit. The output voltage (V OUT ) is regulated
to the reference voltage, VREF, level. The error amplifier
output (COMP pin voltage) is compared with the
oscillator (OSC) modified saw-tooth wave to provide a
pulse-width modulated wave with an amplitude of V IN at
the PHASE node. The PWM wave is smoothed by the
output filter (L and C). The output filter capacitor bank’s
equivalent series resistance is represented by the series
resistor E.
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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