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參數資料
| 型號： | MAX1875EEG |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Fixed-Point Digital Signal Processor 288-BGA MICROSTAR |
| 中文描述： | DUAL SWITCHING CONTROLLER, 600 kHz SWITCHING FREQ-MAX, PDSO24 |
| 封裝： | 0.150 INCH, QSOP-24 |
| 文件頁數： | 11/21頁 |
| 文件大?。?/td> | 493K |
| 代理商： | MAX1875EEG |
On the rising edge of EN both controllers enter soft-
start. Soft-start gradually ramps up to the reference
voltage seen by the error amplifier in order to control
the outputs
’
rate of rise and reduce input surge cur-
rents during startup. The soft-start period is 1024 clock
cycles (1024/f
SW
), and the internal soft-start DAC
ramps up the voltage in 64 steps. The output reaches
regulation when soft-start is completed. On the falling
edge of EN both controllers simultaneously enter soft-
stop, which reverses the soft-start ramp. The part
enters shutdown after soft-stop is complete.
Reset Output (MAX1876 Only)
RST
is an open-drain output.
RST
pulls low when either
output falls below 90% of its nominal regulation voltage.
Once both outputs exceed 90% of their nominal regulation
voltages and both soft-start cycles are completed,
RST
goes high impedance. To obtain a logic-voltage output,
connect a pullup resistor from
RST
to the logic supply volt-
age. A 100k
resistor works well for most applications. If
unused, leave
RST
grounded or unconnected.
Clock Synchronization (SYNC, CKO)
SYNC serves two functions: SYNC selects the clock
output (CKO) type used to synchronize slave con-
trollers, or it serves as a clock input so the
MAX1875/MAX1876 can be synchronized with an exter-
nal clock signal. This allows the MAX1875/MAX1876 to
funtion as either a master or slave. CKO provides a
clock signal synchronized to the MAX1875/MAX1876s
’
switching frequency, allowing either in-phase (SYNC =
GND) or 90
°
out-of-phase (SYNC = V
L
) synchronization
of additional DC-DC controllers (Figure 5). The
MAX1875/MAX1876 support the following three operat-
ing modes:
SYNC = GND:
The CKO output frequency equals
REG1
’
s switching frequency (f
CKO
= f
DH1
) and the
CKO signal is in phase with REG1
’
s switching fre-
quency. This provides 2-phase operation when syn-
chronized with a second slave controller.
SYNC = VL:
The CKO output frequency equals two
times REG1
’
s switching frequency (f
CKO
= 2f
DH1
)
and the CKO signal is phase shifted by 90
°
with
respect to REG1
’
s switching frequency. This pro-
vides 4-phase operation when synchronized with a
second MAX1875/MAX1876 (slave controller).
SYNC Driven by External Oscillator:
The controller
generates the clock signal by dividing down the
SYNC input signal, so that the switching frequency
equals half the synchronization frequency (f
SW
=
f
SYNC
/2). REG1
’
s conversion cycles initiate on the ris-
ing edge of the internal clock signal. The CKO output
frequency and phase match REG1
’
s switching fre-
quency (f
CKO
= f
DH1
) and the CKO signal is in
phase. Note that the MAX1875/MAX1876 still require
R
OSC
when SYNC is externally clocked and the inter-
nal oscillator frequency should be set to 50% of the
synchronization frequency (f
OSC
= 0.5 f
SYNC
).
Thermal Overload Protection
Thermal overload protection limits total power dissipation
in the MAX1875/MAX1876. When the device
’
s die-junc-
tion temperature exceeds T
J
= +160
°
C, an on-chip ther-
mal sensor shuts down the device, forcing DL_ and DH_
low, allowing the IC to cool. The thermal sensor turns the
part on again after the junction temperature cools by
10
°
C. During thermal shutdown, the regulators shut
down,
RST
goes low, and soft-start is reset. If the V
L
lin-
ear-regulator output is short-circuited, thermal-overload
protection is triggered.
Design Procedure
Effective Input Voltage Range
Although, the MAX1875/MAX1876 controllers can oper-
ate from input supplies ranging from 4.75V to 23V, the
input voltage range can be effectively limited by the
MAX1875/MAX1876s
’
duty-cycle limitations. The maxi-
mum input voltage is limited by the minimum on-time
(t
ON(MIN)
):
V
V
t
IN MAX
(
OUT
ON MIN SW
(
)
)
≤
M
Dual 180° Out-of-Phase PWM Step-
Down Controllers with POR
______________________________________________________________________________________
11
V
L
BST_
DH_
LX_
5
INPUT
(V
IN
)
MAX1875
Figure 3. Reducing the Switching-Node Rise Time
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| MAX1875EEG+ | 功能描述:電壓模式 PWM 控制器 Dual 180 Out PWM Step-Down RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| MAX1875EEG+T | 功能描述:電壓模式 PWM 控制器 Dual 180 Out PWM Step-Down RoHS:否 制造商:Texas Instruments 輸出端數量:1 拓撲結構:Buck 輸出電壓:34 V 輸出電流: 開關頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel |
| MAX1875EEG-T | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MAX1875EVKIT | 功能描述:DC/DC 開關控制器 Evaluation Kit for the MAX1875 MAX1876 MAX1858 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
| MAX1876AEEG | 功能描述:DC/DC 開關控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK |
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