IC STEP-DOWN SWIFT CONV 10-MSOP

TPS54040DGQ

Manufacturer Part NumberTPS54040DGQ
DescriptionIC STEP-DOWN SWIFT CONV 10-MSOP
ManufacturerTexas Instruments
SeriesSWIFT™, Eco-Mode™
TypeStep-Down (Buck)
TPS54040DGQ datasheet
 


Specifications of TPS54040DGQ

Internal Switch(s)YesSynchronous RectifierNo
Number Of Outputs1Voltage - Output0.8 ~ 39 V
Current - Output500mAFrequency - Switching100kHz ~ 2.5MHz
Voltage - Input3.5 ~ 42 VOperating Temperature-40°C ~ 150°C
Mounting TypeSurface MountPackage / Case10-MSOP Exposed Pad, 10-HMSOP, 10-eMSOP
Mounting StyleSMD/SMTDuty Cycle (max)98 %
Input / Supply Voltage (max)42 VInput / Supply Voltage (min)3.5 V
Maximum Operating Temperature+ 150 CMinimum Operating Temperature- 40 C
Output Current0.5 AOutput Voltage0.8 V to 39 V
Supply Current116 uASwitching Frequency2500 KHz
Dc To Dc Converter TypeStep DownPin Count10
Input Voltage42VSwitching Freq2500KHz
Package TypeHTSSOP EPOutput TypeAdjustable
Switching RegulatorYesMountingSurface Mount
Input Voltage (min)3.5VOperating Temperature ClassificationAutomotive
Lead Free Status / RoHS StatusLead free / RoHS CompliantPower - Output-
Other names296-24228-5  
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Page 21
22
Page 22
23
Page 23
24
Page 24
25
Page 25
26
Page 26
27
Page 27
28
Page 28
29
Page 29
30
Page 30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
Page 26/47

Download datasheet (3Mb)Embed
PrevNext
TPS54040
SLVS918 – MARCH
2009...................................................................................................................................................................................................
Simple Small Signal Model for Peak Current Mode Control
Figure 47
describes a simple small signal model that can be used to understand how to design the frequency
compensation. The TPS54040 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 14
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
transconductance. The gm
for the TPS54040 is 1.9A/V. The low-frequency gain of the power stage frequency
PS
response is the product of the transconductance and the load resistance as shown in
As the load current increases and decreases, the low-frequency gain decreases and increases, respectively. This
variation with the load may seem problematic at first glance, but fortunately the dominant pole moves with the
load current (see
Equation
16). The combined effect is highlighted by the dashed line in the right half of
Figure
47. 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. The type of output capacitor chosen determines whether the ESR zero has a profound effect on
the frequency compensation design. Using high ESR aluminum electrolytic capacitors may reduce the number
frequency compensation components needed to stabilize the overall loop because the phase margin increases
from the ESR zero at the lower frequencies (see
VC
æ
ö
s
+
ç
÷
1
p ´
2
f
V
è
ø
Z
OUT
=
´
Adc
æ
ö
V
s
C
+
ç
÷
1
p ´
2
f
è
ø
P
Adc = gm
R
´
ps
L
1
f
=
P
C
R
2
´
´ p
OUT
L
1
f
=
Z
C
R
2
´
´ p
OUT
ESR
Small Signal Model for Frequency Compensation
The TPS54040 uses a transconductance amplifier for the error amplifier and readily supports three of the
commonly-used frequency compensation circuits. Compensation circuits Type 2A, Type 2B, and Type 1 are
shown in
Figure
48. Type 2 circuits most likely implemented in high bandwidth power-supply designs using low
ESR output capacitors. The Type 1 circuit is used with power-supply designs with high-ESR aluminum
electrolytic or tantalum capacitors..
the amplifier to the small signal model in
and C
shown in
Figure
48. See the application section for a design example using a Type 2A network with a
O
low ESR output capacitor.
26
Submit Documentation Feedback
DETAILED DESCRIPTION (continued)
Equation
17).
V
O
Adc
R
ESR
fp
R
L
gm
ps
C
OUT
Figure 47. Simple Small Signal Model and Frequency
Response for Peak Current Mode Control
Equation 18
and
Equation 19
show how to relate the frequency response of
Figure
48. The open-loop gain and bandwidth are modeled using the R
Product Folder Link(s):
TPS54040
www.ti.com
Figure
46) is the power stage
Equation
15.
fz
(14)
(15)
(16)
(17)
Copyright © 2009, Texas Instruments Incorporated
O