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| 型号： | MAX1992ETG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 16/36页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 24-TQFN |
| 标准包装： | 75 |
| 系列： | Quick-PWM™ |
| PWM 型： | 电流模式 |
| 输出数： | 1 |
| 频率 - 最大： | 600kHz |
| 占空比： | 100% |
| 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： | -40°C ~ 85°C |
| 封装/外壳： | 24-WFQFN 裸露焊盘 |
| 包装： | 管件 |
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Quick-PWM Step-Down Controllers with Inductor
Saturation Protection and Dynamic Output Voltages
Detailed Description
The MAX1992/MAX1993 buck controllers are ideal for
low-voltage power supplies for notebook computers.
Maxim’s proprietary Quick-PWM pulse-width modulator
in the MAX1992/MAX1993 is designed for handling fast
load steps while maintaining a relatively constant oper-
ating frequency and inductor operating point over a
wide range of input voltages. The Quick-PWM architec-
ture circumvents the poor load-transient timing prob-
lems of fixed-frequency current-mode PWMs while
avoiding the problems caused by widely varying
switching frequencies in conventional constant-on-time
and constant-off-time PWM schemes.
See Table 1 for component selections and Table 2 for a
list of component suppliers.
+5V Bias Supply (V CC and V DD )
The MAX1992/MAX1993 require an external 5V bias
supply in addition to the battery. Typically, this 5V bias
supply is the notebook’s 95%-efficient 5V system sup-
ply. Keeping the bias supply external to the IC improves
efficiency and eliminates the cost associated with the 5V
linear regulator that would otherwise be needed to sup-
ply the PWM circuit and gate drivers. If stand-alone
capability is needed, the 5V supply can be generated
with an external linear regulator such as the MAX1615.
The 5V bias supply must provide V CC (PWM controller)
and V DD (gate-drive power), so the maximum current
drawn is:
I BIAS = I CC + f SW (Q G(LOW) + Q G(HIGH) )
= 2mA to 20mA (typ)
where I CC is 550μA (typ), f SW is the switching frequency,
and Q G(LOW) and Q G(HIGH) are the MOSFET data
Table 3. Approximate K-Factor Errors
sheet’s total gate-charge specification limits at V GS = 5V.
The V+ battery input and 5V bias inputs (V CC and V DD )
can be connected together if the input source is a fixed
4.5V to 5.5V supply. If the 5V bias supply is powered
up prior to the battery supply, the enable signal ( SHDN
going from low to high) must be delayed until the bat-
tery voltage is present in order to ensure startup.
Free-Running Constant-On-Time PWM
Controller with Input Feed Forward
The Quick-PWM control architecture is a pseudofixed-
frequency, constant on-time, current-mode regulator
with voltage feed forward (Figure 2). This architecture
relies on the output filter capacitor’s ESR to act as a
current-sense resistor, so the output ripple voltage pro-
vides the PWM ramp signal. The control algorithm is
simple: the high-side switch on-time is determined sole-
ly by a one-shot whose pulse width is inversely propor-
tional to input voltage and directly proportional to
output voltage. Another one-shot sets a minimum off-
time (400ns typ). The on-time one-shot is triggered if
the error comparator is low, the low-side switch current
is below the valley current-limit threshold, and the mini-
mum off-time one-shot has timed out.
On-Time One-Shot (TON)
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 battery and output voltage. The high-side
switch on-time is inversely proportional to the battery
voltage as measured by the V+ input and is proportional
to the output voltage:
On-time = K (V OUT + 0.075V) / V IN
TON SETTING
(kHz)
200
(TON = V CC )
300
(TON = open)
450
(TON = REF)
600
(TON = GND)
TYPICAL
K-FACTOR (μs)
5.0
3.3
2.2
1.7
K-FACTOR
ERROR (%)
±10
±10
±12.5
±12.5
MINIMUM V IN
AT V OUT = 2.5V
(h = 1.5) (V)
3.14
3.47
4.13
5.61
TYPICAL
APPLICATION
4-cell Li+ notebook
4-cell Li+ notebook
3-cell Li+ notebook
+5V input
COMMENTS
Use for absolute best efficiency
Considered mainstream by
current standards
Useful in 3-cell systems for
lighter loads than the CPU core
or where size is key
Good operating point for
compound buck designs or
desktop circuits
16
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1992ETG+ | 功能描述:电压模式 PWM 控制器 Step-Down w/Inductor RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX1992ETG+T | 功能描述:电压模式 PWM 控制器 Step-Down w/Inductor RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX1992ETG-T | 功能描述:电压模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX1993ETG | 功能描述:电压模式 PWM 控制器 RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
| MAX1993ETG+ | 功能描述:电压模式 PWM 控制器 Step-Down w/Inductor RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel |
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