X
X
R
R
P
P
7
7
7
7
0
0
8
8
a
a
n
n
d
d
X
X
R
R
P
P
7
7
7
7
4
4
0
0
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
s
s
?2012 Exar Corporation
24/28
Rev. 1.2.2
The XRP7740ILB-0X18-F has an I
2
C address of 0x18. The internal registers are written by sending
a data value of 0x30 and read by sending a data value of 0x31. This reflects the address being
shifted one bit to the left and the least significant bit being set to reflect a read or write operation
in order to stuff the byte correctly.
The second byte sent to the device is the location of a specific register.
Using GPIO3 to select I
2
C Address
GPIO3 may be used to change the LSB of the 7-bit address. This option can be enabled within the
PowerArchitect
TM
software by checking the Use GPIO3 to control LSB of I2C address box at the
top right of the Digital Design tab. More about the use of this option and other methods of
changing the default I2C address of the part are available in ANP-31 Power
XR
Configuration and
Programming.
EXTERNAL COMPONENT SELECTION
Inductor Selection
Select the Inductor for inductance L and saturation current Isat. Select an inductor with Isat higher
than the programmed over current limit. Calculate inductance from:
5 =
(
55V5[ 5I5\5b5a
)
?5I5\5b5a
55V5[
?/DIV>
1
55`
?/DIV>
1
55_5V5]
Where:
Vin is the converter input voltage
Vout is the converter output voltage
fs is the switching frequency
Irip is the inductor peak-to-peak current ripple (nominally set to 30% of Iout)
Keep in mind that a higher Irip results in a smaller inductance value which has the advantages of
smaller size, lower DC equivalent resistance (DCR), and allows the use of a lower output
capacitance to meet a given step load transient. A higher Irip, however, increases the output
voltage ripple, requires higher saturation current limit, and increases critical conduction. Notice
that this critical conduction current is half of Irip.
Capacitor Selection
"    Output Capacitor Selection
Select the output capacitor for voltage rating, capacitance and Equivalent Series Resistance (ESR).
Nominally the voltage rating is selected to be at least twice as large as the output voltage. Select
the capacitance to satisfy the specification for output voltage overshoot/undershoot caused by the
current step load. A sudden decrease in the load current forces the energy surplus in the inductor
to be absorbed by Cout. This causes an overshoot in output voltage that is corrected by power
switch reduced duty cycle. Use the following equation to calculate Cout:
5 = 5? ?/DIV>
(5<
2
5<
1
)
2
5
55F
2
5I
55H5G
2
Where:
L is the output inductance
I2 is the step load high current
相關代理商/技術參數(shù) |
參數(shù)描述 |
XRP77XXEVB-XCM |
功能描述:EVAL BOARD W/USB-I2C FOR XRP7704 RoHS:是 類別:編程器,開發(fā)系統(tǒng) >> 評估板 - DC/DC 與 AC/DC(離線)SMPS 系列:- 產品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:True Shutdown™ 主要目的:DC/DC,步升 輸出及類型:1,非隔離 功率 - 輸出:- 輸出電壓:- 電流 - 輸出:1A 輸入電壓:2.5 V ~ 5.5 V 穩(wěn)壓器拓撲結構:升壓 頻率 - 開關:3MHz 板類型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
XRP77XXEVB-XPM |
功能描述:電源管理IC開發(fā)工具 XRP77XXEVB-XPM RoHS:否 制造商:Maxim Integrated 產品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
XRP9710EVB |
制造商:Exar Corporation 功能描述:Evaluation Board for the XRP9710 Series Dual 6 A Programmable Power Module 制造商:Exar Corporation 功能描述:XRP9710 eval |
XRP9710EVB-DEMO-1 |
功能描述:XRP9710 - DC/DC, Step Down 2, Non-Isolated Outputs Evaluation Board 制造商:exar corporation 系列:- 零件狀態(tài):有效 主要用途:DC/DC,步降 輸出和類型:2,非隔離 功率 - 輸出:- 電壓 - 輸出:1.8V,2.5V 電流 - 輸出:6A,6A 電壓 - 輸入:5.5 V ~ 22 V 穩(wěn)壓器拓撲:降壓 頻率 - 開關:- 板類型:完全填充 所含物品:板 使用的 IC/零件:XRP9710 標準包裝:1 |
XRP9710EY-F |
制造商:Exar Corporation 功能描述:Dual 6Amp Programmable Power Module |