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| 型号： | MAX1858EEG+T |
| 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： | 2,500 |
| 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： | 带卷 (TR) |
Dual 180° Out-of-Phase PWM Step-Down
Controller with Power Sequencing and POR
V L
INPUT
(V IN )
ply voltage. A 100k ? resistor works well for most appli-
cations. If unused, leave RST grounded or unconnected.
Clock Synchronization (SYNC, CKO)
SYNC serves two functions: SYNC selects the clock out-
MAX1858
BST_
DH_
LX_
5 ?
put (CKO) type used to synchronize slave controllers, or
it serves as a clock input so the MAX1858 can be syn-
chronized with an external clock signal. This allows the
MAX1858 to function as either a master or slave. CKO
provides a clock signal synchronized to the MAX1858 ’ s
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
MAX1858 supports the following three operating 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-
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.
Output-Voltage Sequencing
After the startup circuitry enables the controller, the
MAX1858 begins the startup sequence. Regulator 1
(OUT1) powers up with soft-start enabled. Once the first
converter ’ s soft-start sequence ends, Regulator 2 (OUT2)
powers up with soft-start enabled. Finally, when both con-
verters complete soft-start and both output voltages
exceed 90% of their nominal values, the reset output
( RST ) goes high (see the Reset Output section). Soft-stop
is initiated by pulling EN low. Soft-stop occurs in reverse
order of soft-start, allowing last-on/first-off operation.
Reset Output
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 regula-
tion voltages and both soft-start cycles are completed,
RST goes high impedance. To obtain a logic-voltage out-
put, connect a pullup resistor from RST to the logic sup-
chronized with a second slave controller.
? SYNC = V L : 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 MAX1858 (slave controller).
? SYNC Driven by External Oscillator: The controller
generates the clock signal by dividing down the
SYNC input signal, so the switching frequency equals
half the synchronization frequency (f SW = f SYNC /2).
REG1 ’ s conversion cycles initiate on the rising edge
of the internal clock signal. The CKO output frequen-
cy and phase match REG1 ’ s switching frequency
(f CKO = f DH1 ) and the CKO signal is in phase. Note
that the MAX1858 still requires R OSC when SYNC is
externally clocked and the internal oscillator frequen-
cy should be set to 50% of the synchronization fre-
quency (f OSC = 0.5f SYNC ).
Thermal Overload Protection
Thermal overload protection limits total power dissipation
in the MAX1858. When the device ’ s die-junction tempera-
ture exceeds T J = +160 ° C, an on-chip thermal sensor
shuts down the device, forcing DL_ and DH_ low, allow-
ing 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 linear-regulator
output is short-circuited, thermal-overload protection is
triggered.
______________________________________________________________________________________________________
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| MAX1858EVKIT | 功能描述:DC/DC 开关控制器 Evaluation Kit for the MAX1858 MAX1875 MAX1876 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 |
| MAX185ACNG | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX185ACNG+ | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX185ACWG | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX185ACWG+ | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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