ISL9440BEVAL1Z【PDF 17/24 页】EVAL BOARD 1 FOR ISL9440B

您好，
买卖IC网欢迎您。
请登录
免费注册

13页 14页 15页 16页 [17页]18页 19页 20页 21页

ISL9440B, ISL9440C

Functional Description

General Description

The ISL9440B and ISL9440C integrate control circuits for

three synchronous buck converters and one linear controller.

The three synchronous bucks operate out-of-phase to

substantially reduce the input ripple and thus reduce the

input filter requirements. Each part has 3 control lines

(EN/SS1, EN/SS2 and EN/SS3), which provide independent

control and programmable soft-start for each of the

synchronous buck outputs.

The buck PWM controllers employ free-running frequency of

300kHz (ISL9440B) and 600kHz (ISL9440C). The current

mode control scheme with an input voltage feed-forward

ramp input to the PWM modulator provides an excellent

rejection of input voltage variations and simplifies loop

compensation design.

The linear controller can drive either a PNP bipolar junction

transistor or P-Channel MOSFET to provide ultra low-dropout

regulation with programmable voltages.

Internal 5V Linear Regulator (VCC_5V)

All ISL9440B and ISL9440C functions are internally powered

from an on-chip, low dropout 5V regulator. The maximum

regulator input voltage is 24V. Bypass the regulator ’s output

soft-start capacitors connected from the EN/SSx pin to the

GND. The PWM output remains inactive until the voltage on

the corresponding EN/SSx pin reaches 1.3V. After that, the

reference voltage is clamped to the voltage on the EN/SSx

pin minus 1.3V. Then the output voltage ramps up with the

voltage on EN/SSx until the voltage reaches 2.1V. The

charging continues until the voltage on the EN/SSx reaches

3.5V.

Each PWM output can be disabled by pulling the

corresponding EN/SSx to the ground.

PGOOD will not toggle to high until soft-start is complete and

all the four outputs are up and in regulations.

Output Voltage Programming

The ISL9440B and ISL9440C use a precision internal

reference voltage to set the output voltage. Based on this

internal reference, the output voltage can thus be set from

0.8V up to a level determined by the input voltage, the

maximum duty cycle, and the conversion efficiency of the

circuit.

A resistive divider from the output to ground sets the output

voltage of either PWM channel. The center point of the

divider shall be connected to the FBx pin. The output voltage

value is determined by Equation 2.

V OUTx = 0.8V ? ---------------------- ?

(VCC_5V) with a 4.7μF capacitor to ground. The dropout

voltage for this LDO is typically 600mV, so when V IN is

? R2 ?

R1 + R2

(EQ. 2)

greater than 5.6V, VCC_5V is typically 5V. The ISL9440B

and ISL9440C also employ an undervoltage lockout circuit

that disables both regulators when VCC_5V falls below 3.7V.

The internal LDO can source over 60mA to supply the IC,

power the low-side gate drivers and charge the external boot

capacitor. When driving large FETs especially at 300kHz

frequency, little or no regulator current may be available for

external loads.

For example, a single large FET with 15nC total gate charge

requires 15nC x 300kHz = 4.5mA (15nC x 600kHz = 9mA).

Also, at higher input voltages with larger FETs, the power

dissipation across the internal 5V will increase. Excessive

dissipation across this regulator must be avoided to prevent

junction temperature rise. Larger FETs can be used with 5V

±10% input applications. The thermal overload protection

circuit will be triggered, if the VCC_5V output is short-circuit.

Connect VCC_5V to V IN for 5V ±10% input applications.

Enable Signals and Soft-Start Operation

The typical applications for the ISL9440B and ISL9440C are

using programmable analog soft-start. The soft-start time

can be set by the value of the soft-start capacitors connected

from the EN/SSx pins to the ground. The start-up in-rush

current can be alleviated by adjusting the soft starting time.

After the VCC_5V pin reaches the UVLO threshold, the

ISL9440B and ISL9440C soft-start circuitry becomes active.

The internal 1.55μA charge current begins charging up the

17

Where R1 is the top resistor of the feedback divider network

and R2 is the resistor connected from FBx to ground.

Out-of-Phase Operation

To reduce input ripple current, Channel 1 and Channel 2

operate 180° out-of-phase, Channel 3 keeps 0° phase with

Channel 1. Channel 1 and Channel 2 typically output higher

load compared to Channel 3 because of their stronger drivers.

This reduces the input capacitor ripple current requirements,

reduces power supply-induced noise, and improves EMI. This

effectively helps to lower component cost, save board space

and reduce EMI.

Triple PWMs typically operate in-phase and turn on both upper

FETs at the same time. The input capacitor must then support

the instantaneous current requirements of the three switching

regulators simultaneously, resulting in increased ripple voltage

and current. The higher RMS ripple current lowers the

efficiency due to the power loss associated with the ESR of the

input capacitor. This typically requires more low-ESR capacitors

in parallel to minimize the input voltage ripple and ESR-related

losses, or to meet the required ripple current rating.

With synchronized out-of-phase operation, the high-side

MOSFETs turn on 180° out-of-phase. The instantaneous input

current peaks of both regulators no longer overlap, resulting in

reduced RMS ripple current and input voltage ripple. This

reduces the required input capacitor ripple current rating,

allowing fewer or less expensive capacitors, and reducing the

FN6799.3

June 24, 2010

发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

*型号	*数量	厂商	批号	封装

添加更多采购

我的联系方式

*

*

*

相关PDF资料

ISL97631IHTZ-T7 IC LED DRIVR WHITE BCKLGT TSOT-6

ISL97634IRT26Z-TK IC LED DRIVR WHITE BCKLGT 8-TDFN

ISL97635AIRZ IC LED DRVR WHT/RGB BCKLGT 24QFN

ISL97635IRZ IC LED DRVR WHT/RGB BCKLGT 24QFN

ISL97636AIRZ IC LED DRIVR WHITE BCKLGT 24-QFN

ISL97636IRZ-TK IC LED DRIVR WHITE BCKLGT 24-QFN

ISL97671AIRZ IC LED DVR PWM CTRL 6CH 20QFN

ISL97672AIRZ IC LED DRVR LOW DIMMING 20QFN

相关代理商/技术参数

ISL9440BIRZ 功能描述:IC REG QD BCK/LINEAR SYNC 32-QFN RoHS:是类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1）功能:任何功能输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器电压/电流 - 输出 2:控制器电压/电流 - 输出 3:控制器带 LED 驱动器:无带监控器:无带序列发生器:是电源电压:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽）供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR

ISL9440BIRZ-T 功能描述:IC REG QD BCK/LINEAR SYNC 32-QFN RoHS:是类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1）功能:任何功能输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器电压/电流 - 输出 2:控制器电压/电流 - 输出 3:控制器带 LED 驱动器:无带监控器:无带序列发生器:是电源电压:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽）供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR

ISL9440CEVAL1Z 功能描述:EVAL BOARD 1 FOR ISL9440C 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

ISL9440CIRZ 功能描述:IC REG QD BCK/LINEAR SYNC 32-QFN RoHS:是类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1）功能:任何功能输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器电压/电流 - 输出 2:控制器电压/电流 - 输出 3:控制器带 LED 驱动器:无带监控器:无带序列发生器:是电源电压:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽）供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR

ISL9440CIRZ-T 功能描述:IC REG QD BCK/LINEAR SYNC 32-QFN RoHS:是类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1）功能:任何功能输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器电压/电流 - 输出 2:控制器电压/电流 - 输出 3:控制器带 LED 驱动器:无带监控器:无带序列发生器:是电源电压:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽）供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR

ISL9440EVAL2Z 功能描述:EVAL BOARD FOR ISL9940 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

ISL9440IRZ 功能描述:IC REG QD BCK/LINEAR SYNC 32-QFN RoHS:是类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2）功能:任何功能输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器电压/电流 - 输出 2:控制器电压/电流 - 输出 3:控制器带 LED 驱动器:无带监控器:无带序列发生器:是电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:*

ISL9440IRZ-T 功能描述:IC REG QD BCK/LINEAR SYNC 32-QFN RoHS:是类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（2），线性（LDO）（1）功能:任何功能输出数:3 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器电压/电流 - 输出 2:控制器电压/电流 - 输出 3:控制器带 LED 驱动器:无带监控器:无带序列发生器:是电源电压:4.5 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:28-TSSOP（0.173"，4.40mm 宽）供应商设备封装:* 包装:带卷 (TR) 其它名称:ISL6402IVZ-TTR