参数资料
型号: TPS54478RTET
厂商: Texas Instruments
文件页数: 18/38页
文件大小: 0K
描述: IC REG BUCK SYNC ADJ 4A 16WQFN
标准包装: 1
系列: SWIFT™
类型: 降压(降压)
输出类型: 可调式
输出数: 1
输出电压: 0.6 V ~ 4.5 V
输入电压: 2.95 V ~ 6 V
PWM 型: 电流模式
频率 - 开关: 500kHz
电流 - 输出: 4A
同步整流器:
工作温度: -40°C ~ 150°C
安装类型: 表面贴装
封装/外壳: 16-WFQFN 裸露焊盘
包装: 标准包装
供应商设备封装: 16-WQFN 裸露焊盘(3x3)
其它名称: 296-29064-6
SLVSAS2 – JUNE 2011
SIMPLE SMALL SIGNAL MODEL FOR PEAK CURRENT MODE CONTROL
Figure 31 is a simple small signal model that can be used to understand how to design the frequency
compensation without slope compensation effect. The TPS54478 power stage can be approximated to a voltage
controlled current source (duty cycle modulator) supplying current to the output capacitor and load resistor. The
control to output transfer function is shown in Equation 9 and consists of a dc gain, one dominant pole and one
ESR zero. The quotient of the change in switch current and the change in COMP pin voltage (node c in
Figure 31 ) is the power stage transconductance. The gm for the TPS54478 is 14 A/V. The low frequency gain of
the power stage frequency response is the product of the transconductance and the load resistance as shown in
Equation 10 . As the load current increases and decreases, the low frequency gain decreases and increases,
respectively. This variation with load may seem problematic at first glance, but the dominant pole moves with
load current [see Equation 11 ]. The combined effect is highlighted by the dashed line in the right half of
Figure 32 . As the load current decreases, the gain increases and the pole frequency lowers, keeping the 0-dB
crossover frequency the same for the varying load conditions which makes it easier to design the frequency
compensation.
vertical spacer
vertical spacer
VO
VC
gm ps
R ESR
RL
Adc
fp
C OUT
fz
Figure 32. Simple Small Signal Model and Frequency Response for Peak Current Mode Control without
Slope Comp Effect
× | z ?
× | p ?
vo
vc
= Adc ′
?
? 1+
è
?
? 1+
è
2 p
2 p
s ?
÷
s ?
÷
(9)
Adc = gm ps ′ R L
(10)
| p =
C OUT
1
′ R L ′ 2 p
(11)
vertical spacer
| z =
1
C OUT ′ R ESR ′ 2 p
(12)
SMALL SIGNAL MODEL FOR FREQUENCY COMPENSATION
The TPS54478 uses a transconductance amplifier for the error amplifier and readily supports two of the
commonly used frequency compensation circuits. The compensation circuits are shown in Figure 33 . The Type 2
circuits are most likely implemented in high bandwidth power supply designs using low ESR output capacitors. In
Type 2A, one additional high frequency pole is added to attenuate high frequency noise.
18
Copyright ? 2011, Texas Instruments Incorporated
相关PDF资料
PDF描述
VI-B6K-EV-F4 CONVERTER MOD DC/DC 40V 150W
MAX6462UR24+T IC VOLT DETECTOR LP SOT23-3
MAX6462UR19+T IC VOLT DETECTOR LP SOT23-3
MAX6462UR21+T IC VOLT DETECTOR LP SOT23-3
VI-B6J-EV-F4 CONVERTER MOD DC/DC 36V 150W
相关代理商/技术参数
参数描述
TPS54494 制造商:TI 制造商全称:Texas Instruments 功能描述:4A/2A Dual Channel Synchronous Step-Down Switcher with Integrated FET
TPS54494EVM-057 制造商:Texas Instruments 功能描述:Evaluation Module Access To The Features Of The TPS54494 制造商:Texas Instruments 功能描述:TPS54494EVM-057 - Boxed Product (Development Kits) 制造商:Texas Instruments 功能描述:EVAL MODULE FOR TPS54494-057 制造商:Texas Instruments 功能描述:TPS54494 Eval Mod
TPS54494PWP 功能描述:直流/直流开关转换器 4A Dual Channel Sync SD Switcher RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT
TPS54494PWPR 功能描述:直流/直流开关转换器 4A Dual Channel Sync SD Switcher RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT
TPS54494RSAR 制造商:Texas Instruments 功能描述:IC REG BUCK SYNC ADJ 4A/2A 16QFN 制造商:Texas Instruments 功能描述:4A/2A Dual Channel Sync Converter