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参数资料
| 型号： | LT3507AIUHF#PBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | SWITCHING REGULATOR, PQCC38 |
| 封装： | 5 X 7 MM, LEAD FREE, PLASTIC, QFN-38 |
| 文件页数： | 10/28页 |
| 文件大小： | 372K |
| 代理商： | LT3507AIUHF#PBF |
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LT3507A
18
3507af
APPLICATIONS INFORMATION
Figure 8. Two Different Modes of Output Voltage Tracking
Figure 9. Setup for Coincident and Ratiometric Tracking
Figure 10. Equivalent Input Circuit of Error Amplifier
outputs at start-up, they also disable the slaved channels
if the master channel falls out of regulation (due to a short
circuit or a collapsing input voltage).
Finally, be aware that the circuit in Figure 7e does not
work, because the power good comparators are disabled
in shutdown.
OUTPUT VOLTAGE TRACKING
The LT3507A allows the user to program how the output
ramps up by means of the TRK/SS pins. Through these
pins, any channel output can be set up to either coinci-
dently or ratiometrically track any other channel output.
This example will show the channel 2 output tracking the
channel 1 output, as shown in Figure 8. The TRK/SS2 pin
acts as a clamp on channel 2’s reference voltage. VOUT2
is referenced to the TRK/SS2 voltage when the TRK/SS2
< 0.8V and to the internal precision reference when TRK/
SS2 > 0.8V.
To implement the coincident tracking in Figure 8a, con-
nect an extra resistive divider to the output of channel 1
and connect its midpoint to the TRK/SS2 pin (Figure 9).
The ratio of this divider should be selected the same as
that of channel 2’s feedback divider (R5 = R3 and R6 =
R4). In this tracking mode, VOUT1 must be set higher than
VOUT2. To implement the ratiometric tracking in Figure 8b,
change the extra divider ratio to R5 = R1 and R6 = R2 +
ΔR. The extra resistance on R6 should be set so that the
TRK/SS2 voltage is ≥1V when VOUT1 is at its final value.
The need for this extra resistance is best understood with
the help of the equivalent input circuit shown in Figure 10.
Attheinputstageoftheerroramplifier,twocommonanode
diodes are used to clamp the equivalent reference voltage
and an additional diode is used to match the shifted com-
mon mode voltage. The top two current sources are of
the same amplitude. In the coincident mode, the TRK/SS2
R1
R2
=
VOUT1
0.8
– 1,
R3
R4
=
VOUT2
0.8
– 1
R5
R1
R6
R2
VOUT2
R4
R3
Tracking Setup
TO
VFB1
PIN
TO
TRK/SS2
PIN
TO
VFB2
PIN
VOUT1
COINCIDENT
R3
R4
R5 =
R6 =
RATIOMETRIC
R1
VOUT1/1V – 1
SELECTING VALUES FOR R5 AND R6
TIME
(8a) Coincident Tracking
VOUT1
VOUT2
OUTPUT
VOL
TAGE
TIME
3507A F08
(8b) Ratiometric Tracking
VOUT1
VOUT2
OUTPUT
VOL
TAGE
1.25A
–
+
I
D1
TRK/SS
0.8V
FB
D2
D3
3507A F10
EA2
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LT3507EUHF#2ESPBF | 制造商:Linear Technology 功能描述:TRIPLE MONOLITHIC STEP-DOWN REGULATOR WITH LDO |
| LT3507EUHF#PBF | 功能描述:IC REG QD BUCK/LINEAR 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| LT3507EUHF#TRPBF | 功能描述:IC REG QD BUCK/LINEAR 38-QFN RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - 线性 + 切换式 系列:- 标准包装:2,500 系列:- 拓扑:降压（降压）同步（3），线性（LDO）（2） 功能:任何功能 输出数:5 频率 - 开关:300kHz 电压/电流 - 输出 1:控制器 电压/电流 - 输出 2:控制器 电压/电流 - 输出 3:控制器 带 LED 驱动器:无 带监控器:无 带序列发生器:是 电源电压:5.6 V ~ 24 V 工作温度:-40°C ~ 85°C 安装类型:* 封装/外壳:* 供应商设备封装:* 包装:* |
| LT3507EUHFPBF | 制造商:Linear Technology 功能描述:Step Down Regulator with LDO |
| LT3507EUHF-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Triple Monolithic Step-Down Regulator with LDO |
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