參數(shù)資料
型號: LTC3770
廠商: Linear Technology Corporation
英文描述: Synchronous Controller with Margining, Tracking and PLL
中文描述: 同步控制器裕,跟蹤和PLL
文件頁數(shù): 17/24頁
文件大?。?/td> 302K
代理商: LTC3770
17
LTC3770
3770f
Figure 7. Two Different Modes of Output Voltage Tracking
TIME
(7a) Coincident Tracking
V
OUT1
V
OUT2
O
TIME
3770 F07
(7b) Ratiometric Tracking
V
OUT1
V
OUT2
O
Figure 8. Setup for Coincident and Ratiometric Tracking
R3
R1
R4
R2
R3
V
OUT2
R4
(8a) Coincident Tracking Setup
TO
V
FB1
PIN
TO
TRACK/SS2
PIN
TO
V
PIN
V
OUT1
R1
R2
R3
V
OUT2
R4
3770 F08
(8b) Ratiometric Tracking Setup
TO
V
FB1
PIN
TO
TRACK/SS2
PIN
TO
V
PIN
V
OUT1
+
I
I
D1
TRACK/SS2
0.6V
V
FB2
D2
D3
3770 F09
EA2
Figure 9. Equivalent Input Circuit of Error Amplifier
mode, V
OUT1
must be set higher than V
OUT2
. To implement
the ratiometric tracking, the ratio of the divider should be
exactly the same as the master IC’s feedback divider. Note
that the pin Z1 of the slave IC should be tied to INTV
CC
so
that the internal soft-start current is disabled in both
tracking modes or it will introduce a small error on the
tracking voltage depending on the absolute values of the
tracking resistive divider.
By selecting different resistors, the LTC3770 can achieve
different modes of tracking including the two in Figure 7.
So which mode should be programmed While either
mode in Figure 7 satisfies most practical applications,
there do exist some tradeoffs. The ratiometric mode saves
a pair of resistors, but the coincident mode offers better
output regulation. This can be better understood with the
help of Figure 9. At the input stage of the slave IC’s error
amplifier, two common anode diodes are used to clamp
the equivalent reference voltage and an additional diode is
used to match the shifted common mode voltage. The top
two current sources are of the same amplitude. In the
coincident mode, the TRACK/SS voltage is substantially
higher than 0.6V at steady state and effectively turns off
D1. D2 and D3 will therefore conduct the same current and
offer tight matching between V
FB2
and the internal preci-
sion 0.6V reference. In the ratiometric mode, however,
TRACK/SS equals 0.6V at steady state. D1 will divert part
of the bias current to make V
FB2
slightly lower than 0.6V.
Although this error is minimized by the exponential I-V
characteristic of the diode, it does impose a finite amount
of output voltage deviation. Furthermore, when the master
IC’s output experiences dynamic excursion (under load
transient, for example), the slave IC output will be affected
as well. For better output regulation, use the coincident
tracking mode instead of ratiometric.
APPLICATIU
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U
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參數(shù)描述
LTC3770EG 制造商:Linear Technology 功能描述:LDO Cntrlr SYNC BUCK REG 0.6V to 32V 28-Pin SSOP
LTC3770EG#PBF 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR)
LTC3770EG#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 28-SSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR)
LTC3770EUH#PBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR)
LTC3770EUH#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 32-QFN RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:- PWM 型:電流模式 輸出數(shù):1 頻率 - 最大:500kHz 占空比:96% 電源電壓:4 V ~ 36 V 降壓:無 升壓:是 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 125°C 封裝/外殼:24-WQFN 裸露焊盤 包裝:帶卷 (TR)