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参数资料
| 型号： | MAX1715EEI |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 14/25页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM 28-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 控制器 |
| 输出数： | 2 |
| 频率 - 最大： | 620kHz |
| 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： | 28-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
Ultra-High Efficiency, Dual Step-Down
Controller for Notebook Computers
Table 4. Frequency Selection Guidelines
Table 5. Approximate K-Factor Errors
NOMINAL
FREQUENCY
(kHz)
200
300
420
TYPICAL
APPLICATION
4-cell Li+ notebook
4-cell Li+ notebook
3-cell Li+ notebook
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
TON
SETTING
V CC
OPEN
REF
GND
APPROX
K-FACTOR
ERROR (%)
±10
±10
±12.5
±12.5
MIN V IN
AT V OUT
= 2V (V)
2.6
2.9
3.2
3.6
SIDE 1 K
FACTOR
(μs)
4.24
2.96
2.08
1.63
SIDE 2 K
FACTOR
(μs)
5.81
4.03
2.81
2.18
key.
Good operating point for
For loads above the critical conduction point, the actual
switching frequency is:
540
+5V input
compound buck designs
or desktop circuits.
f =
V OUT + V DROP 1
t ON ( V IN + V DROP 2 )
nominal frequency setting (200kHz, 300kHz, 420kHz, or
540kHz), while the on-times for side 2 are set 15%
lower than nominal. This is done to prevent audio-fre-
quency “beating” between the two sides, which switch
asynchronously for each side:
On-Time = K (V OUT + 0.075V) / V IN
where K is set by the TON pin-strap connection and
0.075V is an approximation to accommodate for the
expected drop across the low-side MOSFET switch.
One-shot timing error increases for the shorter on-time
settings due to fixed propagation delays; it is approxi-
mately ±12.5% at 540kHz and 420kHz nominal settings
and ±10% at the two slower settings. This translates to
reduced switching-frequency accuracy at higher fre-
quencies (Table 5). Switching frequency increases as a
function of load current due to the increasing drop
across the low-side MOSFET, which causes a faster
inductor-current discharge ramp. The on-times guaran-
where V DROP 1 is the sum of the parasitic voltage drops
in the inductor discharge path, including synchronous
rectifier, inductor, and PC board resistances; VDROP2
is the sum of the resistances in the charging path; and
t ON is the on-time calculated by the MAX1715.
Automatic Pulse-Skipping Switchover
In skip mode ( SKIP low), an inherent automatic
switchover to PFM takes place at light loads. This
switchover is effected by a comparator that truncates
the low-side switch on-time at the inductor current’s
zero crossing. This mechanism causes the threshold
between pulse-skipping PFM and nonskipping PWM
operation to coincide with the boundary between con-
tinuous and discontinuous inductor-current operation
(also known as the “critical conduction” point). For a
battery range of 7V to 24V, this threshold is relatively
constant, with only a minor dependence on battery volt-
age.
?
?
? ?
teed in the Electrical Characteristics are influenced by
switching delays in the external high-side power MOS-
FET.
I LOAD(SKIP) ≈
K × V OUT_ ? V IN - V OUT ?
2L V IN
Two external factors that influence switching-frequency
accuracy are resistive drops in the two conduction
loops (including inductor and PC board resistance) and
the dead-time effect. These effects are the largest con-
tributors to the change of frequency with changing load
current. The dead-time effect increases the effective
on-time, reducing the switching frequency as one or
both dead times. It occurs only in PWM mode ( SKIP =
high) when the inductor current reverses at light or neg-
ative load currents. With reversed inductor current, the
inductor’s EMF causes LX to go high earlier than nor-
mal, extending the on-time by a period equal to the
low-to-high dead time.
where K is the on-time scale factor (Table 5). The load-
current level at which PFM/PWM crossover occurs,
I LOAD(SKIP) , is equal to 1/2 the peak-to-peak ripple cur-
rent, which is a function of the inductor value (Figure 4).
For example, in the standard application circuit with
V OUT1 = 2.5V, V IN = 15V, and K = 2.96μs (see Table
5), switchover to pulse-skipping operation occurs at
I LOAD = 0.7A or about 1/6 full load. The crossover point
occurs at an even lower value if a swinging (soft-satura-
tion) inductor is used.
The switching waveforms may appear noisy and asyn-
chronous when light loading causes pulse-skipping
14
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1715EEI+ | 功能描述:DC/DC 开关控制器 Dual Step-Down Controller 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 |
| MAX1715EEI+T | 功能描述:DC/DC 开关控制器 Dual Step-Down Controller 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 |
| MAX1715EEI-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 |
| MAX1715EVKIT | 功能描述:DC/DC 开关控制器 Evaluation Kit for the MAX1715 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 |
| MAX1716EEG | 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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