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| 型号： | MAX1536ETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/19页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK SYNC ADJ 3.6A 28TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 类型： | 降压（降压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 0.7 V ~ 5.5 V |
| 输入电压： | 3 V ~ 5.5 V |
| PWM 型： | 电流模式，混合 |
| 频率 - 开关： | 1.4MHz |
| 电流 - 输出： | 3.6A |
| 同步整流器： | 是 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 包装： | 带卷 (TR) |
| 供应商设备封装： | 28-TQFN-EP（5x5） |
3.6A, 1.4MHz, Low-Voltage, Internal-Switch Step-
Down Regulator with Dynamic Output Voltage Control
= R
R A B ?
- 1 ?
? V OUT
? V FB
?
?
and speeds up the output voltage change during a
negative REFIN voltage change.
Adding a capacitor across REFIN and AGND filters
? R 1 x ( R 2 + R 3 ) ?
τ POS = ? ? C REFIN
τ NEG = R 1 x R 2 C REFIN
V OUT = V FB ? 1 +
?
V FB ( LOW ) = V REF ?
where V FB = V REFIN .
Setting Dynamic Output Voltages with REFIN
The MAX1536 regulates V FB to be equal to V REFIN .
Changing V REFIN allows for a dynamic output voltage
that changes between two set points (see the
Multioutput Voltage Settings section for information on
three or more output-voltage set points). Figure 1 shows
a dynamically adjustable resistive voltage-divider net-
work at REFIN. Keep V REFIN between 0.7V and 2V.
Keep V REFIN below V CC - 1.35V to avoid an undervolt-
age lockout condition. Toggling GATE switches in and
out the resistor connected between OD and AGND
changing V REFIN . A logic high on GATE turns on the
internal N-channel MOSFET, forcing OD to a low-imped-
ance state. A low logic on GATE turns off the internal N-
channel MOSFET, making OD high impedance. The
output voltage is determined by the following equations:
? R A ?
? R B ?
? R 2 ?
?
? R 1 + R 2 ?
noise and controls the rate of change of the REFIN volt-
age during dynamic transitions. With the additional
capacitance, the REFIN voltage slews between the two
set points with a time constant given by the equivalent
parallel resistance seen by the slew capacitor C REFIN .
As shown in Figure 1, the time constant for a positive
REFIN voltage transition is:
? R 1 + R 2 + R 3 ?
and the time constant for a negative REFIN voltage
transition is:
? ?
? ?
? R 1 + R 2 ?
During a negative REFIN voltage transition, the MAX1536
sinks current to discharge the output capacitor and bring
the output voltage down to the new set point. The
MAX1536 does not have a negative current limit, so
τ NEG must be set long enough to keep the sinking cur-
rent within the maximum current capability of the IC:
V FB ( HIGH ) = V REF ?
τ NEG ≥ C OUT OUT and I SINK ≤ I LIMIT
?
?
R 2 + R 3 ?
R 1 + R 2 + R 3 ? ?
x ? V
I SINK
The MAX1536 automatically enters forced-PWM opera-
tion on the rising and falling edges of GATE, and
remains in forced-PWM mode for a minimum time
selected by FBLANK (Table 3). Forced-PWM operation
is required to ensure fast, accurate negative voltage
transitions when REFIN is lowered. Since forced-PWM
operation disables the zero-crossing comparator, the
inductor current can reverse under light loads, quickly
discharging the output capacitors. The MAX1536 also
Programming the No-Load Switching
Frequency and Off-Time
The MAX1536 features a programmable PWM mode
switching frequency, which is set by the input and out-
put voltage and the value of R TOFF . R TOFF sets the
PMOS power switch off-time in PWM mode. Use the fol-
lowing equation to select the off-time according to the
desired no-load switching frequency in PWM mode:
forces PGOOD to a high-impedance state for the peri-
od selected by FBLANK (Table 3).
For a step-voltage change at REFIN, the rate of change
t OFF =
V IN - V OUT
f PWM x V IN
of the output voltage is limited by the inductor current
ramp, the total output capacitance, the current limit,
and the load during the transition. The voltage across
the inductor and the inductance limits the inductor cur-
rent ramp. The total output capacitance determines
how much current is needed to change the output volt-
age. Additional load current slows down the output volt-
age change during a positive REFIN voltage change,
where:
t OFF = the programmed off-time.
V IN = the input voltage.
V OUT = the output voltage.
f PWM = no-load switching frequency, PWM mode.
Select R TOFF according to the formula:
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1536EVKIT | 功能描述:直流/直流开关调节器 Evaluation Kit for the MAX1536 RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5 |
| MAX1537AETX+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX1537ETX | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1537ETX-T | 功能描述:电流和电力监控器、调节器 RoHS:否 制造商:STMicroelectronics 产品:Current Regulators 电源电压-最大:48 V 电源电压-最小:5.5 V 工作温度范围:- 40 C to + 150 C 安装风格:SMD/SMT 封装 / 箱体:HPSO-8 封装:Reel |
| MAX1537EVKIT | 制造商:Maxim Integrated Products 功能描述:MAIN POWER SUPPLY CONTROLLER FOR NOTEBOOK - Bulk |
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