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| 型号： | LT1766IFE-5 |
| 厂商： | Linear Technology |
| 文件页数： | 26/30页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 5V 1.5A 16TSSOP |
| 标准包装： | 95 |
| 类型： | 降压（降压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 5V |
| 输入电压： | 5.5 V ~ 60 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 200kHz |
| 电流 - 输出： | 1.5A |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 125°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-TSSOP（0.173"，4.40mm）裸露焊盘 |
| 包装： | 管件 |
| 供应商设备封装： | 16-TSSOP-EP |
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LT1766/LT1766-5
APPLICATIONS INFORMATION
( V IN P ) 2
) ( I
4 ( V IN + V OUT )( V IN + V OUT + V F )
I P = Maximum rated switch current
V IN = Minimum input voltage
V OUT = Output voltage
V F = Catch diode forward voltage
0.3 = Switch voltage drop at 1.5A
Example: with V IN(MIN) = 5.5V, V OUT = 12V, L = 18μH,
V F = 0.63V, I P = 1.5A: I MAX = 0.280A.
mode formula to calculate minimum inductor needed. If
load current is higher, use the continuous mode formula.
Output current where continuous mode is needed:
2
I CONT >
Minimum inductor discontinuous mode:
OUTPUT DIVIDER
Refer to Applications Information Feedback Pin Functions
L MIN =
2( V OUT )(I OUT )
( f )( I P ) 2
L1*
INPUT ?
18μH
L MIN =
2 ( f )( V IN OUT ) ? I P OUT ? 1 +
+ V
? ?
?
? ?
? ?
to calculate R1 and R2 for the (negative) output voltage
(from Table 1).
D2 ?
1N4148W
C2
0.33μF
BOOST
Minimum inductor continuous mode:
( V IN )( V OUT )
– I
?
( V OUT + V F ) ? ?
V IN
( 40 ) ( 1 . 5 ) 2
4 ( 40 + 12 )( 40 + 12 + 0 . 63 )
5.5V TO
48V
C3
2.2μF
100V
CER
V IN
LT1766
GND
C F
V SW
FB
V C
C C
R C
D1
10MQO60N
R1
44.2k
+
R2
4.99k
C1
100μF
25V
TANT
OUTPUT**
For a 40V to –12V converter using the LT1766 with peak
switch current of 1.5A and a catch diode of 0.63V:
2
I CONT > = 0 . 573 A
–12V, 0.25A
* INCREASE L1 TO 30μH OR 60μH FOR HIGHER CURRENT APPLICATIONS.
1766 F15
For a load current of 0.25A, this says that discontinuous
L MIN = = 13 . 3 μ H
SEE APPLICATIONS INFORMATION
** MAXIMUM LOAD CURRENT DEPENDS ON MINIMUM INPUT VOLTAGE
AND INDUCTOR SIZE. SEE APPLICATIONS INFORMATION
? FOR V IN > 44V AND V OUT = –12V, ADDITIONAL VOLTAGE DROP IN THE
PATH OF D2 IS REQUIRED TO ENSURE BOOST PIN MAXIMUM RATING IS
NOT EXCEEDED. SEE APPLICATIONS INFORMATION (BOOST PIN VOLTAGE)
Figure 15. Positive-to-Negative Converter
Inductor Value
The criteria for choosing the inductor is typically based on
ensuring that peak switch current rating is not exceeded.
This gives the lowest value of inductance that can be
used, but in some cases (lower output load currents) it
may give a value that creates unnecessarily high output
ripple voltage.
The dif?culty in calculating the minimum inductor size
needed is that you must ?rst decide whether the switcher
will be in continuous or discontinuous mode at the critical
point where switch current reaches 1.5A. The ?rst step is
to use the following formula to calculate the load current
above which the switcher must use continuous mode. If
your load current is less than this, use the discontinuous
mode can be used and the minimum inductor needed is
found from:
2 ( 12 )( 0 . 25 )
( 200 ? 10 3 )( 1 . 5 ) 2
In practice, the inductor should be increased by about
30% over the calculated minimum to handle losses and
variations in value. This suggests a minimum inductor of
18μH for this application.
Ripple Current in the Input and Output Capacitors
Positive-to-negative converters have high ripple current
in the input capacitor. For long capacitor lifetime, the RMS
value of this current must be less than the high frequency
ripple current rating of the capacitor. The following formula
will give an approximate value for RMS ripple current. This
formula assumes continuous mode and large inductor
value. Small inductors will give somewhat higher ripple
current, especially in discontinuous mode. The exact
formulas are very complex and appear in Application
1766fc
26
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| LT1766IFE-5#PBF | 功能描述:IC REG BUCK 5V 1.5A 16TSSOP 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 |
| LT1766IFE-5#TR | 功能描述:IC REG BUCK 5V 1.5A 16TSSOP 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 |
| LT1766IFE-5#TRPBF | 功能描述:IC REG BUCK 5V 1.5A 16TSSOP 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 |
| LT1766IFE-5-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:5.5V to 60V 1.5A, 200kHz Step-Down Switching Regulator |
| LT1766IFE-5-TR | 制造商:LINER 制造商全称:Linear Technology 功能描述:5.5V to 60V 1.5A, 200kHz Step-Down Switching Regulator |
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