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参数资料
| 型号： | MAX1992ETG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 19/36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
DC output accuracy specifications refer to the thresh-
old of the error comparator. When the inductor is in
continuous conduction, the MAX1992/MAX1993 regu-
late the valley of the output ripple, so the actual DC out-
put voltage is higher than the trip level by 50% of the
Δ I
Δ t
=
V IN - V OUT
L
I PEAK
output ripple voltage. In discontinuous conduction
( SKIP = GND and I OUT < I LOAD(SKIP) ), the output volt-
age has a DC regulation level higher than the error-
comparator threshold by approximately 1.5% because
of slope compensation.
Forced-PWM Mode ( SKIP = V CC )
The low-noise forced-PWM mode ( SKIP = V CC ) dis-
ables the zero-crossing comparator, which controls the
I LOAD = I PEAK /2
low-side switch on-time. This forces the low-side gate-
0
ON-TIME
TIME
drive waveform to constantly be the complement of the
high-side gate-drive waveform, so the inductor current
reverses at light loads while DH maintains a duty factor
of V OUT /V IN . Forced-PWM mode keeps the switching
frequency fairly constant. However, forced-PWM opera-
tion comes at a cost: the no-load 5V bias current
Figure 3. Pulse-Skipping/Discontinuous Crossover Point
remains between 2mA and 20mA, depending on the
external MOSFETs and switching frequency.
Forced-PWM mode is most useful for reducing audio-
MAX1992
MAX1993
REF
C REF
frequency noise, improving load-transient response,
and providing sink-current capability for dynamic out-
put voltage adjustment. The MAX1993 uses forced-
PWM operation during all dynamic output voltage
transitions (GATE transition detected) in order to ensure
TO VALLEY
CURRENT-LIMIT
COMPARATOR
(FIGURE 2)
ILIM
6 μ A
R A
R B
C ILIM
( LIR2 )
fast, accurate transitions. Because forced-PWM opera-
tion disables the zero-crossing comparator, the induc-
tor current reverses under light loads, quickly
discharging the output capacitors. FBLANK determines
how long the MAX1993 maintains forced-PWM opera-
tion—140μs (FBLANK = V CC ), 90μs (FBLANK = open
or AGND), or 40μs (FBLANK = REF).
Current-Limit Protection (ILIM)
Valley Current Limit
The current-limit circuit employs a unique “valley” cur-
rent-sensing algorithm that uses a current-sense resis-
tor between CSP and CSN as the current-sensing
element (Figure 10). If the magnitude of the current-
sense signal is above the valley current-limit threshold,
the PWM controller is not allowed to initiate a new cycle
(Figure 5). The actual peak current is greater than the
valley current-limit threshold by an amount equal to the
inductor ripple current. Therefore, the exact current-
limit characteristic and maximum load capability are a
function of the current-sense resistance, inductor value,
FROM LSAT
COMPARATOR
AND LOGIC
(FIGURE 2)
Figure 4. Adjustable Current-Limit Threshold
I LIM(VAL) = I LOAD(MAX) 1-
I PEAK
I LOAD
I LIMIT
and battery voltage. When combined with the under-
voltage protection circuit, this current-limit method is
0
TIME
effective in almost every circumstance.
Figure 5. “Valley” Current-Limit Threshold Point
______________________________________________________________________________________
19
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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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