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参数资料
| 型号： | MAX1653EEE |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 18/28页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM CM 16-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 100 |
| PWM 型： | 电流模式，混合 |
| 输出数： | 1 |
| 频率 - 最大： | 350kHz |
| 占空比： | 98% |
| 电源电压： | 4.5 V ~ 30 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： | 16-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
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High-Efficiency, PWM, Step-Down
DC-DC Controllers in 16-Pin QSOP
With high input voltages, the required duty factor is
approximately (V OUT + V Q2 )/ V IN , where V Q2 is the volt-
age drop across the synchronous rectifier. The
MAX1652 ’s minimum duty factor is determined by
delays through the feedback network, error comparator,
internal logic gate drivers, and the external MOSFETs,
which typically total 400ns. This delay is about 12% of
the switching period at 300kHz and 6% at 150kHz, limit-
ing the typical minimum duty factor to these values.
Even if the circuit can not attain the required duty factor
dictated by the input and output voltages, the output
voltage will remain in regulation. However, there may be
intermittent or continuous half-frequency operation. This
can cause a factor-of-two increase in output voltage rip-
ple and current ripple, which will increase noise and
reduce efficiency. Choose 150kHz operation for high-
input-voltage/low-output-voltage circuits.
Secondary Feedback-Regulation Loop
(SECFB Pin)
A flyback winding control loop regulates a secondary
winding output (MAX1652/MAX1654 only), improving
cross-regulation when the primary is lightly loaded
or when there is a low input-output differential voltage.
If SECFB crosses its regulation threshold, a 1μs one-
shot is triggered that extends the low-side switch ’s
on-time beyond the point where the inductor current
crosses zero (in discontinuous mode). This causes the
inductor (primary) current to reverse, which in turn pulls
current out of the output filter capacitor and causes the
flyback transformer to operate in the forward mode. The
low impedance presented by the transformer secondary
in the forward mode dumps current into the secondary
output, charging up the secondary capacitor and bring-
ing SECFB back into regulation. The SECFB feedback
loop does not improve secondary output accuracy in
normal flyback mode, where the main (primary) output is
heavily loaded. In this mode, secondary output accura-
cy is determined (as usual) by the secondary rectifier
drop, turns ratio, and accuracy of the main output volt-
age. Hence, a linear post-regulator may still be needed
in order to meet tight output accuracy specifications.
The secondary output voltage-regulation point is deter-
mined by an external resistor-divider at SECFB. For neg-
ative output voltages, the SECFB comparator is
referenced to GND (MAX1654); for positive output volt-
ages, SECFB regulates at the 2.50V reference
(MAX1652). As a result, output resistor-divider connec-
tions and design equations for the two device types dif-
fer slightly (Figure 7). Ordinarily, the secondary
regulation point is set 5% to 10% below the voltage nor-
mally produced by the flyback effect. For example, if the
0.33 μ F
1-SHOT
SECFB
R3
1-SHOT
REF
SECFB
R3
TRIG
R2
TRIG
R2
2.5V REF
V+
POSITIVE
SECONDARY
OUTPUT
V+
NEGATIVE
SECONDARY
OUTPUT
DH
DH
MAX1652
DL
MAIN
OUTPUT
MAX1654
DL
MAIN
OUTPUT
(
)
( )
R2
+V TRIP = V REF 1 + –––
R3
WHERE V REF (NOMINAL) = 2.5V
R2
-V TRIP = -V REF –––
R3
R3 = 100k ? (RECOMMENDED)
Figure 7. Secondary-Output Feedback Dividers
18
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1653EEE+ | 功能描述:DC/DC 开关控制器 PWM Step-Down 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 |
| MAX1653EEE+T | 功能描述:DC/DC 开关控制器 PWM Step-Down 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 |
| MAX1653EEE+-T | 制造商:Maxim Integrated Products 功能描述:DC DC CNTRLR SGL-OUT W/PWM/STEP DOWN 4.5V TO 30V 16QSOP - Tape and Reel |
| MAX1653EEE-T | 功能描述:DC/DC 开关控制器 PWM Step-Down 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 |
| MAX1653EEE-TG068 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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