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参数资料
| 型号： | MAX767EAP+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 12/19页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 20-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,000 |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 340kHz |
| 占空比： | 95% |
| 电源电压： | 4.5 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： | 0°C ~ 70°C |
| 封装/外壳： | 20-SSOP（0.209"，5.30mm 宽） |
| 包装： | 带卷 (TR) |
5V-to-3.3V, Synchronous, Step-Down
Power-Supply Controller
Place R1 as close as possible to the MAX767, prefer-
ably less than 10mm. Run the traces at minimum spac-
In idle-mode, the ripple has a capacitive and a resistive
component:
V OUT(RPL) (C) = _____________ x 0.89 Volts
ing from one another. If they are longer than 20mm,
bypass CS to FB with a 1nF capacitor placed as close
as possible to these pins. The wiring layout for these
traces is critical for stable, low-ripple outputs (see
Layout and Grounding section).
Input Filter Capacitor, C1
.
0.0004 x L
R1 2 x C2
0.02 x ESR C2
Use at least 6μF per watt of output power for C1. If the
5V input is some distance away or comes through a PC
bus, greater capacitance may be desirable to improve
the load-transient response. Use a low-ESR capacitor
located no further than 10mm from the MOSFET switch
V OUT(RPL) (R) = _____________
R1
The total ripple, V OUT(RPL) , can be approximated as
follows:
(N1) to prevent ringing. The ripple current rating must
be at least I RMS = 0.5 x I OUT . For high-current applica-
tions, two or more capacitors in parallel may be needed
if
V OUT(RPL) (R) < 0.5 V OUT(RPL) (C)
3 ?
I STEP 2 x L
( ESR C2 + — 2 x —— π x f x C2 — )
to meet these requirements.
The ESR of C1 is effectively in series with the input. The
resistive dissipation of C1, I RMS 2 x ESR C1 , can signifi-
cantly impact the circuit’s efficiency.
Output Filter Capacitor, C2
The output filter capacitor determines the loop stability,
output voltage ripple, and output load-transient
response.
Stability
To ensure stability, stay above the minimum capaci-
tance value and below the maximum ESR value. These
values are:
C2 > —— μF
R1
and
ESR C2 < R1
Be sure to satisfy both these requirements. To achieve
the low ESR required, it may be appropriate to parallel
two or more capacitors and/or use a total capacitance
2 or 3 times larger than the calculated minimum.
Output Ripple
The output ripple in continuous-conduction mode is:
V OUT(RPL) = I OUT (max) x LIR x
1
———
where f is the switching frequency (200kHz or 300kHz).
then
V OUT(RPL) = V OUT(RPL) (C)
otherwise
V OUT(RPL) = 0.5 V OUT(RPL) (C) +
V OUT(RPL) (R)
Load-Transient Performance
In response to a large step increase in load current, the
output voltage will sag for several microseconds unless
C2 is increased beyond the values that satisfy the
above requirements. Note that an increase in capaci-
tance is all that ’s required to improve the transient
response, and that the ESR requirements don’t change.
Therefore, the added capacitance can be supplied by
an additional low-cost bulk capacitor in parallel with the
normal low-ESR switching-regulator capacitor. The
equation for voltage sag under a step load change is:
V SAG = ________________________________
2 x C2 x (V IN (min) x DMAX - 3.3V)
where DMAX is the maximum duty cycle. Higher duty
cycles are possible when the oscillator frequency is
reduced to 200kHz, since fixed propagation delays
through the PWM comparator become a lesser part of
the whole period. The tested worst-case limit for DMAX
is 92% at 200kHz or 89% at 300kHz. Lower inductance
values can reduce the filter capacitance requirement,
but only at the expense of increased output ripple (due
to higher peak currents).
12
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX767EVKIT-SO | 功能描述:DC/DC 开关控制器 Evaluation Kit for the MAX767 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX767RCAP | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX767RCAP-T | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX767REAP | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX767REAP+ | 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
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