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参数资料
| 型号： | LT1374IR-SYNC#TR |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 稳压器 |
| 英文描述： | 8.5 A SWITCHING REGULATOR, 560 kHz SWITCHING FREQ-MAX, PSSO7 |
| 封装： | PLASTIC, D2PAK-7 |
| 文件页数： | 18/32页 |
| 文件大小： | 698K |
| 代理商： | LT1374IR-SYNC#TR |
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LT1374
1374fd
APPLICATIONS INFORMATION
WU
U
likely to be changed in production is the output capacitor,
because that is the component most likely to have manu-
facturer variations (in ESR) large enough to cause prob-
lems. It would be a wise move to lock down the sources of
the output capacitor in production.
A possible exception to the “clean response” rule is at very
light loads, as evidenced in Figure 14 with ILOAD = 50mA.
Switching regulators tend to have dramatic shifts in loop
response at very light loads, mostly because the inductor
current becomes discontinuous. One common result is very
slow but stable characteristics. A second possibility is low
phase margin, as evidenced by ringing at the output with
transients. The good news is that the low phase margin at
light loads is not particularly sensitive to component varia-
tion, so if it looks reasonable under a transient test, it will
probably not be a problem in production. Note that
fre-
quency of the light load ringing may vary with component
tolerance but phase margin generally hangs in there.
POSITIVE-TO-NEGATIVE CONVERTER
The circuit in Figure 15 is a classic positive-to-negative
topology using a grounded inductor. It differs from the
standard approach in the way the IC chip derives its
feedback signal, however, because the LT1374 accepts
only positive feedback signals, the ground pin must be tied
to the regulated negative output. A resistor divider to
ground or, in this case, the sense pin, then provides the
proper feedback voltage for the chip.
Inverting regulators differ from buck regulators in the
basic switching network. Current is delivered to the output
as
square waves with a peak-to-peak amplitude much
greater than load current. This means that maximum load
current will be significantly less than the LT1374’s 4.5A
maximum switch current, even with large inductor values.
The buck converter in comparison, delivers current to the
output as a triangular wave superimposed on a DC level
equal to load current, and load current can approach 4.5A
with large inductors. Output ripple voltage for the positive-
to-negative converter will be much higher than a buck
converter. Ripple current in the output capacitor will also
be much higher. The following equations can be used to
calculate operating conditions for the positive-to-negative
converter.
Maximum load current:
IP = Maximum rated switch current
VIN = Minimum input voltage
VOUT = Output voltage
VF = Catch diode forward voltage
0.35 = Switch voltage drop at 4.5A
Example: with VIN(MIN) = 5.5V, VOUT = 5V, L = 10H,
VF = 0.5V, IP = 4.5A: IMAX = 2A. Note that this equation does
not take into account that maximum rated switch current
(IP) on the LT1374 is reduced slightly for duty cycles
above 50%. If duty cycle is expected to exceed 50% (input
voltage less than output voltage), use the actual IP value
from the Electrical Characteristics table.
Operating duty cycle:
(This formula uses an average value for switch loss, so it
may be several percent in error.)
OUTPUT**
–5V, 1.8A
INPUT
5.5V TO
20V
1374 F15
C2
0.27F
CC
RC
D2
MBRS330T3
C1
100F
10V TANT
× 2
C3
10F TO
50F
D1
CMDSH-3
L1*
5H
BOOST
LT1374-5
VIN
VSW
SENSE
GND
VC
* INCREASE L1 TO 10H OR 20H FOR HIGHER CURRENT APPLICATIONS.
SEE APPLICATIONS INFORMATION
** MAXIMUM LOAD CURRENT DEPENDS ON MINIMUM INPUT VOLTAGE
AND INDUCTOR SIZE. SEE APPLICATIONS INFORMATION
+
D3
Figure 15. Positive-to-Negative Converter
相关PDF资料 |
PDF描述 |
|---|---|
| LT1374IS8-5SYNC#TR | 8.5 A SWITCHING REGULATOR, 560 kHz SWITCHING FREQ-MAX, PDSO8 |
| LT1374IS8-5SYNC#TRPBF | 8.5 A SWITCHING REGULATOR, 560 kHz SWITCHING FREQ-MAX, PDSO8 |
| LT1374IS8-SYNC#TRPBF | 8.5 A SWITCHING REGULATOR, 560 kHz SWITCHING FREQ-MAX, PDSO8 |
| LT1374IR#TR | 8.5 A SWITCHING REGULATOR, 560 kHz SWITCHING FREQ-MAX, PSSO7 |
| LT1374IR-5SYNC#TRPBF | 8.5 A SWITCHING REGULATOR, 560 kHz SWITCHING FREQ-MAX, PSSO7 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1374IS8 | 功能描述:IC REG BUCK ADJ 4.5A 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT1374IS8#PBF | 功能描述:IC REG BUCK ADJ 4.5A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT1374IS8#PBF | 制造商:Linear Technology 功能描述:ICSMPS CONTROLLERCURRENT-MOD 制造商:Linear Technology 功能描述:IC,SMPS CONTROLLER,CURRENT-MODE,BIPOLAR, |
| LT1374IS8#TR | 功能描述:IC REG BUCK ADJ 4.5A 8SOIC RoHS:否 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
| LT1374IS8#TRPBF | 功能描述:IC REG BUCK ADJ 4.5A 8SOIC RoHS:是 类别:集成电路 (IC) >> PMIC - 稳压器 - DC DC 开关稳压器 系列:- 设计资源:Design Support Tool 标准包装:1 系列:- 类型:升压（升压） 输出类型:固定 输出数:1 输出电压:3V 输入电压:0.75 V ~ 2 V PWM 型:- 频率 - 开关:- 电流 - 输出:100mA 同步整流器:是 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-5 细型，TSOT-23-5 包装:剪切带 (CT) 供应商设备封装:TSOT-23-5 其它名称:AS1323-BTTT-30CT |
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