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| 型号： | MAX1875EEG+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 11/21页 |
| 文件大小： | 0K |
| 描述： | IC REG CTRLR BUCK PWM VM 24-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| PWM 型： | 电压模式 |
| 输出数： | 2 |
| 频率 - 最大： | 660kHz |
| 占空比： | 90% |
| 电源电压： | 4.75 V ~ 23 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-SSOP（0.154"，3.90mm 宽） |
| 包装： | 管件 |
Dual 180° Out-of-Phase PWM Step-
Down Controllers with POR
MAX1875/MAX1876 support the following three operat-
V L
INPUT
(V IN )
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-
MAX1875
BST_
DH_
LX_
5 ?
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 =
Figure 3. Reducing the Switching-Node Rise Time
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-
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) ):
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
V IN ( MAX ) ≤
V OUT
t ON ( MIN ) f SW
______________________________________________________________________________________
11
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相关代理商/技术参数 |
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| MAX1875EEG+ | 功能描述:电压模式 PWM 控制器 Dual 180 Out PWM Step-Down 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 |
| MAX1875EEG+T | 功能描述:电压模式 PWM 控制器 Dual 180 Out PWM Step-Down 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 |
| MAX1875EEG-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 |
| MAX1875EVKIT | 功能描述:DC/DC 开关控制器 Evaluation Kit for the MAX1875 MAX1876 MAX1858 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 |
| MAX1876AEEG | 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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