参数资料
型号: LTC1709EG-7
厂商: Linear Technology
文件页数: 24/28页
文件大小: 0K
描述: IC REG CTRLR BUCK PWM CM 36-SSOP
标准包装: 37
PWM 型: 电流模式
输出数: 1
频率 - 最大: 360kHz
占空比: 99.5%
电源电压: 4 V ~ 36 V
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: -40°C ~ 85°C
封装/外壳: 36-SSOP(0.209",5.30mm 宽)
包装: 管件
产品目录页面: 1339 (CN2011-ZH PDF)
LTC1709-7
APPLICATIO S I FOR ATIO
t ON ( ) =
=
= 1 . 1 μ s
( )(
)
V IN f
( ) ( 1 . 48 ) ( 0 . 013 ? )
5 . 5 V ? 1 . 8 V
P SYNC =
A 1.5μH inductor will produce 27% ripple current. The
peak inductor current will be the maximum DC value plus
one half the ripple current, or 11.5A. The minimum on-
time occurs at maximum V IN :
V OUT 1 . 8 V
MIN
5 . 5 V 300 kHz
The R SENSE resistors value can be calculated by using the
maximum current sense voltage specification with some
accomodation for tolerances:
The worst-case power disipated by the synchronous
MOSFET under short-circuit conditions at elevated ambi-
ent temperature and estimated 50 ° C junction temperature
rise is:
2
7 A
5 . 5 V
= 630 mW
which is less than normal, full-load conditions. Inciden-
tally, since the load no longer dissipates power in the
shorted condition, total system power dissipation is de-
R SENSE =
50mV
11 . 5 A
≈ 0 . 004 ?
creased by over 99%.
The duty factor for this application is:
DF =
= = 0 . 36
The power dissipation on the topside MOSFET can be
easily estimated. Using a Siliconix Si4420DY for example;
R DS(ON) = 0.013 ? , C RSS = 300pF. At maximum input
voltage with T J (estimated) = 110 ° C at an elevated ambient
temperature:
V O 1 . 8 V
V IN 5 V
Using Figure 4, the RMS ripple current will be:
I INRMS = (20A)(0.23) = 4.6A RMS
( ) [ 1 + ( ) ( ) C ° ]
0 . 005 110 ° C ? 25
0 . 013 ? + 1 . 7 ( ) ( )( )
P MAIN =
1. 8 V 2
10
5 . 5 V
5 . 5 V 10 A 300 pF
( 300 kHz ) = 0 . 65 W
2
An input capacitor(s) with a 4.6A RMS ripple current rating
is required.
The output capacitor ripple current is calculated by using
the inductor ripple already calculated for each inductor
and multiplying by the factor obtained from Figure 3
along with the calculated duty factor. The output ripple in
( ) ( ) ( ) ?
5 . 5 V ? 1 . 8 V
P SYNC =
( )
1 ? 200 ns 5 . 5 V
? ?
? = 7 A
I SC =
+
?
?
( )
? I COUT =
V OUT
? I COUTMAX =
( ) ( )
The  worst-case  power  disipated  by  the  synchronous
MOSFET under normal operating conditions at elevated
ambient temperature and estimated 50 ° C junction tem-
perature rise is:
2
10 A 1 . 48 0 . 013
5 . 5 V
= 1 . 29 W
A short-circuit to ground will result in a folded back current
of about:
25 mV
0 . 004 ? 2 ? 1 . 5 μ H ?
24
continuous mode will be highest at the maximum input
voltage since the duty factor is < 50%. The maximum
output current ripple is:
0 . 3 at 33 % D F
fL
1 . 8 V
0 . 3
300 kHz 1 . 5 μ H
= 1 . 2 A RMS
V OUTRIPPLE = 20 m ? ( 1 . 2 A RMS ) = 24 mV RMS
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LTC1709EG-7#PBF 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:2,000 系列:- PWM 型:电流模式 输出数:1 频率 - 最大:1MHz 占空比:50% 电源电压:9 V ~ 10 V 降压:无 升压:是 回扫:是 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:8-TSSOP(0.173",4.40mm 宽) 包装:带卷 (TR)
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LTC1709EG-7#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX
LTC1709EG-8 功能描述:IC REG CTRLR BUCK PWM CM 36-SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 切换控制器 系列:- 标准包装:4,500 系列:PowerWise® PWM 型:控制器 输出数:1 频率 - 最大:1MHz 占空比:95% 电源电压:2.8 V ~ 5.5 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 ~ 125°C 封装/外壳:6-WDFN 裸露焊盘 包装:带卷 (TR) 配用:LM1771EVAL-ND - BOARD EVALUATION LM1771 其它名称:LM1771SSDX
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