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参数资料
| 型号： | MAX8792EVKIT+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/28页 |
| 文件大小： | 0K |
| 描述： | KIT EVAL FOR MAX8792 |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 1 |
| 主要目的： | DC/DC，步降 |
| 输出及类型： | 1，非隔离 |
| 输出电压： | 1.5V |
| 电流 - 输出： | 10A |
| 输入电压： | 7 ~ 20 V |
| 稳压器拓扑结构： | 降压 |
| 频率 - 开关： | 300kHz |
| 板类型： | 完全填充 |
| 已供物品： | 板 |
| 已用 IC / 零件： | MAX8792 |
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Single Quick-PWM Step-Down
Controller with Dynamic REFIN
input voltage and directly proportional to output volt-
age. Another one-shot sets a minimum off-time (200ns
typ). The on-time one-shot is triggered if the error com-
parator is low, the low-side switch current is below the
valley current-limit threshold, and the minimum off-time
one-shot has timed out.
On-Time One-Shot
The heart of the PWM core is the one-shot that sets the
high-side switch on-time. This fast, low-jitter, adjustable
one-shot includes circuitry that varies the on-time in
response to input and output voltage. The high-side
switch on-time is inversely proportional to the input volt-
age as sensed by the TON input, and proportional to
the feedback voltage as sensed by the FB input:
On-Time (t ON ) = T SW (V FB /V IN )
where T SW (switching period) is set by the resistance
(R TON ) between TON and V IN . This algorithm results in
Power-Up Sequence (POR, UVLO)
The MAX8792 is enabled when EN is driven high and
the 5V bias supply (V DD ) is present. The reference
powers up first. Once the reference exceeds its UVLO
threshold, the internal analog blocks are turned on and
masked by a 50μs one-shot delay in order to allow the
bias circuitry and analog blocks enough time to settle
to their proper states. With the control circuitry reliably
powered up, the PWM controller may begin switching.
Power-on reset (POR) occurs when V CC rises above
approximately 3V, resetting the fault latch and prepar-
ing the controller for operation. The V CC UVLO circuitry
inhibits switching until V CC rises above 4.25V. The con-
troller powers up the reference once the system
enables the controller, V CC exceeds 4.25V, and EN is
driven high. With the reference in regulation, the con-
troller ramps the output voltage to the target REFIN volt-
age with a 1mV/μs slew rate:
a nearly constant switching frequency despite the lack
of a fixed-frequency clock generator. Connect a resis-
tor (R TON ) between TON and V IN to set the switching
t START =
V FB
1 mV μ s
=
V FB
1 V ms
T SW = C TON ( R TON + 6 . 5 k Ω ) ?
( V OUT + V DIS )
f SW =
period T SW = 1/f SW :
? V FB ?
? V OUT ? ?
where C TON = 16.26pF. When used with unity-gain feed-
back (V OUT = V FB ), a 96.75k Ω to 303.25k Ω corresponds
to switching periods of 167ns (600kHz) to 500ns
(200kHz), respectively. High-frequency (600kHz) opera-
tion optimizes the application for the smallest compo-
nent size, trading off efficiency due to higher switching
losses. This may be acceptable in ultra-portable devices
where the load currents are lower and the controller is
powered from a lower voltage supply. Low-frequency
(200kHz) operation offers the best overall efficiency at
the expense of component size and board space.
For continuous conduction operation, the actual switching
frequency can be estimated by:
t ON ( V IN + V DIS ? V CHG )
where V DIS is the sum of the parasitic voltage drops in
the inductor discharge path, including synchronous recti-
fier, inductor, and PCB resistances; V CHG is the sum of
the parasitic voltage drops in the charging path, includ-
ing the high-side switch, inductor, and PCB resistances;
The soft-start circuitry does not use a variable current
limit, so full output current is available immediately.
PGOOD becomes high impedance approximately
200μs after the target REFIN voltage has been reached.
The MAX8792 automatically uses pulse-skipping mode
during soft-start and uses forced-PWM mode during
soft-shutdown, regardless of the SKIP configuration.
For automatic startup, the battery voltage should be
present before V CC . If the controller attempts to bring
the output into regulation without the battery voltage
present, the fault latch trips. The controller remains shut
down until the fault latch is cleared by toggling EN or
cycling the V CC power supply below 0.5V.
If the V CC voltage drops below 4.25V, the controller
assumes that there is not enough supply voltage to
make valid decisions. To protect the output from over-
voltage faults, the controller shuts down immediately
and forces a high-impedance output (DL and DH
pulled low).
Shutdown
When the system pulls EN low, the MAX8792 enters
low-power shutdown mode. PGOOD is pulled low
immediately, and the output voltage ramps down with a
1mV/μs slew rate:
=
and t ON is the on-time calculated by the MAX8792.
t SHDN =
V FB V FB
1 mV μ s 1 V ms
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8792EVKIT+ | 功能描述:电源管理IC开发工具 MAX8792 Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX8794ETB/V+T | 功能描述:低压差稳压器 - LDO Low-Voltage DDR Linear Regulator RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| MAX8794ETB+ | 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:LOW-VOLTAGE DDR LINEAR REGULATOR - Rail/Tube |
| MAX8794ETB+T | 功能描述:低压差稳压器 - LDO Low-Voltage DDR Linear Regulator RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| MAX8795AETJ+ | 功能描述:直流/直流开关转换器 TFT-LCD DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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