参数资料
型号: LTC1436ACGN-PLL#TRPBF
厂商: Linear Technology
文件页数: 12/28页
文件大小: 0K
描述: IC REG CTRLR BUCK PWM CM 24-SSOP
标准包装: 2,500
PWM 型: 电流模式
输出数: 1
频率 - 最大: 138kHz
占空比: 99%
电源电压: 3.5 V ~ 30 V
降压:
升压:
回扫:
反相:
倍增器:
除法器:
Cuk:
隔离:
工作温度: 0°C ~ 70°C
封装/外壳: 24-SSOP(0.154",3.90mm 宽)
包装: 带卷 (TR)
LTC1436A
LTC1436-PLL-A/LTC1437A
APPLICATIO N S I N FOR M ATIO N
( )
? ?
?
? – 11
C OSC pF =
( )
? Frequency kHz ?
( )( )
1 . 37 ( 10 4 )
? ?
A graph for selecting C OSC vs frequency is given in Figure
2. As the operating frequency is increased the gate
charge losses will be higher, reducing efficiency (see
Efficiency Considerations). The maximum recommended
switching frequency is 400kHz. When using Figure 2 for
synchronizable applications, choose C OSC correspond-
ing to a frequency approximately 30% below your center
frequency. (See Phase-Locked Loop and Frequency Syn-
chronization.)
300
V PLLLPF = 0V
250
200
150
1 ? V ?
? I L = V OUT ? 1 ? OUT ?
f L ? V IN ?
Accepting larger values of ? I L allows the use of low
inductances, but results in higher output voltage ripple
and greater core losses. A reasonable starting point for
setting ripple current is ? I L = 0.4 (I MAX ). Remember, the
maximum ? I L occurs at the maximum input voltage.
The inductor value also has an effect on low current
operation. The transition to low current operation begins
when the inductor current reaches zero while the bottom
MOSFET is on. Lower inductor values (higher ? I L ) will
cause this to occur at higher load currents, which can
cause a dip in efficiency in the upper range of low current
operation. In Burst Mode operation (TGS pin open),
lower inductance values will cause the burst frequency to
decrease.
The Figure 3 graph gives a range of recommended induc-
tor values vs operating frequency and V OUT .
100
60
50
50
V OUT = 5V
V OUT = 3.3V
V OUT ≤ 2.5V
0
0
100 200 300 400
OPERATING FREQUENCY (kHz)
500
40
1436 F02
Figure 2. Timing Capacitor Value
Inductor Value Calculation
30
20
10
The operating frequency and inductor selection are inter-
related in that higher operating frequencies allow the use
0
0
50 100 150 200 250
OPERATING FREQUENCY (kHz)
300
t ON ( MIN ) =
( V IN ( MAX ) )( ) f
of smaller inductor and capacitor values. So why would
anyone ever choose to operate at lower frequencies with
larger components? The answer is efficiency. A higher
frequency generally results in lower efficiency because of
MOSFET gate charge losses. In addition to this basic
trade-off, the effect of inductor value on ripple current and
low current operation must also be considered.
The inductor value has a direct effect on ripple current. The
inductor ripple current ? I L decreases with higher induc-
tance or frequency and increases with higher V IN or V OUT :
1436 F03
Figure 3. Recommended Inductor Values
For low duty cycle, high frequency applications where the
required minimum on-time,
V OUT
is less than 350ns, there may be further restrictions on the
inductance to ensure proper operation. See Minimum On-
Time Considerations section for more details.
14367afb
12
相关PDF资料
PDF描述
VE-B5V-EV-F4 CONVERTER MOD DC/DC 5.8V 150W
LTC1628IG#TRPBF IC REG CTRLR BUCK PWM CM 28-SSOP
VE-B5V-EV-F2 CONVERTER MOD DC/DC 5.8V 150W
URZ1C332MHD CAP ALUM 3300UF 16V 20% RADIAL
VE-B5W-EV-F4 CONVERTER MOD DC/DC 5.5V 150W
相关代理商/技术参数
参数描述
LTC1436AEGN#PBF 功能描述:IC REG CTRLR BUCK PWM CM 24-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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR)
LTC1436AEGN#TRPBF 功能描述:IC REG CTRLR BUCK PWM CM 24-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:4,000 系列:- PWM 型:电压模式 输出数:1 频率 - 最大:1.5MHz 占空比:66.7% 电源电压:4.75 V ~ 5.25 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 ~ 85°C 封装/外壳:40-VFQFN 裸露焊盘 包装:带卷 (TR)
LTC1436AIGN 功能描述:IC REG CTRLR BUCK PWM CM 24-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
LTC1436AIGN#PBF 功能描述:IC REG CTRLR BUCK PWM CM 24-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
LTC1436AIGN#TR 功能描述:IC REG CTRLR BUCK PWM CM 24-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