X
X
R
R
P
P
7
7
7
7
1
1
4
4
Q
Q
u
u
a
a
d
d
C
C
h
h
a
a
n
n
n
n
e
e
l
l
D
D
i
i
g
g
i
i
t
t
a
a
l
l
P
P
W
W
M
M
S
S
t
t
e
e
p
p
D
D
o
o
w
w
n
n
C
C
o
o
n
n
t
t
r
r
o
o
l
l
l
l
e
e
r
r
?2011 Exar Corporation
13/29
Rev. 1.1.6
For those using active 3.3V or 5V logic on the Enable pin an RC delay from VCCA to the Enable pin
may be used. When using an RC delay from VCCA, attention must be paid to the amount of
bypass capacitance loading AVDD since it will delay the time it takes for AVDD to power up and
regulate. The AVDD and DVDD pins do not require more than 2.2uF for proper bypassing. See
Figure 21 for the recommended components for sequencing the Enable pin through an RC delay
from VCCA. If more capacitance is added to AVDD and DVDD, the time constant must be
increased. Once Enable is asserted, an internal CHIP_READY flag goes high and enables the I
2
C to
acknowledge the Hosts serial commands. Channels that are configured as always-on channels are
enabled. Channels that are configured to be enabled by GPIOs are also enabled if the respective
GPIO is asserted.
Enable Pin
VCCA
10K
.1uF
Fig. 21: RC Delay for Enable taken from VCCA
In almost all cases, a simple check will ensure proper sequencing has been achieved. VCCA
regulates at approximately 4.6V when the Enable pin is logic level low and at 5.1V when Enable is
asserted. VCCA will typically power up and regulate before AVDD and because the internal logic is
not yet powered up there is no internal shutdown signal, it will regulate at 5.1V. Once AVDD has
reached sufficient voltage (and Enable is low) it will assert the internal shutdown signal and VCCA
will reduce its regulated voltage to 4.6V. When the Enable is asserted, the chip will power up and
VCCA will regulate at 5.1V. If our device is sequenced properly, VCCA will achieve 5.1V then drop
down to 4.6V and toggle back to 5.1V. See Figure 22 for an example.
Fig. 22: VCCA (green) Startup Waveform
发布紧急采购，3分钟左右您将得到回复。
相关PDF资料
XRP7740ILB-0X18-F
IC REG 5OUT BCK/LINEAR 40TQFN
XRP7740ILBTR-F
IC REG 5OUT BCK/LINEAR 40TQFN
ZDS1009TA
IC CURRENT MIRROR SOT223-8
ZXCT1008FTA
IC CURRENT MONITOR 1% SOT23-3
ZXCT1009T8TA
IC CURRENT MONITOR 1% SM8
ZXCT1010E5TA
IC CURRENT MONITOR 1% SOT-23-5
ZXCT1011E5TA
IC CURRENT MONITOR 1% SOT23-5
ZXCT1012DAATA
IC CURRENT MONITOR 2.5% 5TDFN
相关代理商/技术参数
XRP7714ILB-0X18-F
功能描述:电压模式 PWM 控制器 4CH DIGITAL PWM CTRL I2C INTERFACE
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
XRP7714ILB-0X1C-F
功能描述:电压模式 PWM 控制器 4CH DIGITAL PWM CTRL I2C INTERFACE
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
XRP7714ILB-F
功能描述:软开关 PWM 控制器 4Ch Digital Pwr Cntr w/LDO prog. thru PC
RoHS:否 制造商:Fairchild Semiconductor 输出端数量: 输出电流: 开关频率: 工作电源电压:30 V 电源电流: 最大工作温度:+ 105 C 最小工作温度:- 40 C 安装风格:SMD/SMT 封装 / 箱体:SOIC-8 封装:Reel
XRP7714ILBTR-0X10-F
制造商:EXAR 制造商全称:EXAR 功能描述:Quad Channel Digital PWM Step Down Controller
XRP7714ILBTR-0X14-F
制造商:EXAR 制造商全称:EXAR 功能描述:Quad Channel Digital PWM Step Down Controller
XRP7714ILBTR-0X18-F
制造商:EXAR 制造商全称:EXAR 功能描述:Quad Channel Digital PWM Step Down Controller
XRP7714ILBTR-0X1C-F
制造商:EXAR 制造商全称:EXAR 功能描述:Quad Channel Digital PWM Step Down Controller
XRP7714ILBTR-F
功能描述:直流/直流开关调节器 4Ch Dgtl Pwr Cntrllr w/LDO prog thru PC
RoHS:否 制造商:International Rectifier 最大输入电压:21 V 开关频率:1.5 MHz 输出电压:0.5 V to 0.86 V 输出电流:4 A 输出端数量: 最大工作温度: 安装风格:SMD/SMT 封装 / 箱体:PQFN 4 x 5