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参数资料
| 型号： | MAX1980 |
| 厂商： | Maxim Integrated Products, Inc. |
| 元件分类： | DC/DC变换器 |
| 英文描述： | Quick-PWM Slave Controller with Driver Disable for Multiphase DC-DC Converter |
| 中文描述： | Quick-PWM从控制器，带有驱动禁止功能，用于多相DC-DC转换器 |
| 文件页数： | 15/33页 |
| 文件大小： | 1153K |
| 代理商： | MAX1980 |
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M
Quick-PWM Slave Controller with
Driver Disable for Multiphase DC-DC Converter
______________________________________________________________________________________
15
(V
IN
<
η
V
OUT
), the input currents of the overlapping
phases may sum together, increasing the total input
and output ripple voltage and RMS ripple current.
During in-phase operation, the input capacitors must
support large, instantaneous input currents when the
high-side MOSFETs turn on simultaneously, resulting in
increased ripple voltage and current when compared
to out-of-phase operation. The higher RMS ripple cur-
rent degrades efficiency due to power loss associated
with the input capacitor
’
s effective series resistance
(ESR). This typically requires a large number of low-
ESR input capacitors in parallel to meet input ripple
current ratings or minimize ESR-related losses.
The polarity select input (POL) determines whether ris-
ing edges (POL = V
CC
) or falling edges (POL = GND)
trigger a new cycle. For low duty-cycle applications
(duty factor < 50%), triggering on the rising edge of the
master
’
s low-side gate driver prevents both high-side
MOSFETs from turning on at the same time. Staggering
the phases in this way lowers the input ripple current,
thereby reducing the input capacitor requirements. For
applications operating with approximately a 50% duty
factor, out-of-phase operation (POL = V
CC
) causes the
slave controller to complete an on-pulse coincident to
the master controller determining when to initiate its
next on time. The noise generated when the slave con-
troller turns off its high-side MOSFET could compro-
mise the master controller
’
s feedback voltage and
current-sense inputs, causing inaccurate decisions that
lead to more jitter in the switching waveforms. Under
these conditions, triggering off of the falling edge (POL
= GND) of the master
’
s low-side gate driver forces the
controllers to operate in-phase, improving the system
’
s
noise immunity.
5V Bias Supply (V
CC
and V
DD
)
The MAX1980 requires an external 5V bias supply in
addition to the battery. Typically this 5V bias supply is
the notebook
’
s 95% efficient 5V system supply.
Keeping the bias supply external to the IC improves
efficiency, eliminates power dissipation limitations, and
removes the cost associated with the internal, 5V linear
regulator that would otherwise be needed to supply the
PWM circuit and gate drivers. If standalone capability is
needed, the 5V supply can be generated with an exter-
nal linear regulator.
The MAX1980 has a separate analog PWM supply volt-
age input (V
CC
) and gate-driver supply input (V
DD
).
The battery input (V+) and 5V bias inputs (V
CC
and
V
DD
) can be tied together if the input source is a fixed
4.5V to 5.5V supply.
The maximum current required from the 5V bias supply
to power V
CC
(PWM controller) and V
DD
(gate-drive
power) is:
I
BIAS
= I
CC
+ f
SW
(Q
G1
+ Q
G2
) = 10mA to 45mA (typ)
where I
CC
is 525μA typical, f
SW
is the switching
frequency, and Q
G1
and Q
G2
are the MOSFET data
sheets
’
total gate-charge specification limits at
V
GS
= 5V.
Driver Disable
When
DD
is driven low, the MAX1980 disables the dri-
vers by forcing DL and DH low, effectively disabling the
slave controller. Disabling the MAX1980 for single-
phase operation allows the master controller to enter
low-power pulse-skipping operation under light load
conditions.
When
DD
is driven high, the MAX1980 enables the dri-
vers, allowing normal PWM operation (see the
On-time
Control and Active Current Balancing
section). Since
the slave controller cannot skip pulses, the master con-
troller should be configured for forced-PWM operation
while the MAX1980
’
s drivers are enabled. This PWM
control scheme forces the low-side gate drive wave-
form to be the complement of the high-side gate drive
waveform, allowing the inductor current to reverse.
During negative load and downward output-voltage
transitions, forced-PWM operation allows the converter
to sink current, rapidly pulling down the output voltage.
Another benefit of forced-PWM operation, the switching
frequency remains relatively constant over the full load
and input voltage ranges.
Standby Mode
The MAX1980 slave controller enters a low-power
standby mode when the ILIM voltage (V
ILIM
) drops
below 250mV (Table 4). Standby forces DL and DH
low, and disables the PWM controller to inhibit switch-
ing; however, the bias and fault-protection circuitry
remain active so the MAX1980 can continuously moni-
tor the ILIM input. When V
ILIM
is driven above 250mV,
the PWM controller is enabled.
Table 3. Approximate K-Factor Errors
TON
CONNECTION
FREQUENCY
SETTING
(kHz)
K-FACTOR
(μs)
MAX
K-FACTOR
ERROR
(%)
V
CC
Float
GND
200
300
550
5
10
10
10
3.3
1.8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1980EGP | 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 |
| MAX1980EGP-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 |
| MAX1980ETP | 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 |
| MAX1980ETP+ | 功能描述:DC/DC 开关控制器 PWM Slave Controller w/Driver Disable 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 |
| MAX1980ETP+T | 功能描述:DC/DC 开关控制器 PWM Slave Controller w/Driver Disable 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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