TPS548A20RVET [TI]
1.5V 至 20V、15A 同步 SWIFT™ 降压转换器 | RVE | 28 | -40 to 125;
| 型号： | TPS548A20RVET |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 1.5V 至 20V、15A 同步 SWIFT™ 降压转换器 | RVE | 28 | -40 to 125 转换器 |
| 文件： | 总38页 (文件大小：2127K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
TPS548A20 具有 PMBus™ 接口的 1.5V 至 20V（4.5V 至 25V 偏置）
输入、15A 同步降压 SWIFT™ 转换器
1 特性
2 应用
1
•
集成的 SWIFT™9.9mΩ 和 4.3mΩ 金属氧化物半导
体场效应晶体管 (MOSFET) 支持 15A 持续 IOUT
•
•
•
•
服务器、云计算、存储
网络互联和电信、负载点 (POL)
•
•
•
•
宽转换输入电压范围：1.5V 至 20V（采用缓冲器）
输出电压范围：0.6V 至 5.5V
IPC、工厂自动化、PLC、测试测量
高性能数字信号处理器 (DSP)、现场可编程门阵列
(FPGA)
支持所有陶瓷输出电容
基准电压：600mV，±0.5% 容限（在 –40°C 至
85°C 的环境温度范围内）
3 说明
TPS548A20 是一款具有自适应导通时间 D-CAP3 控制
模式的小尺寸同步降压转换器。此器件使得空间受限类
电源系统易于使用，并且外部组件数量较少。
•
D-CAP3™控制模式，此模式具有快速负载阶跃响
应
•
•
HICCUP 过流保护
自动跳跃 Eco-mode™，可实现轻负载条件下的高
效率
此器件 特有 高性能集成 MOSFET、精准 0.6V 基准和
一个集成的升压开关。具有竞争力的 特性 包括：极低
外部组件数量、快速负载瞬态响应、自动跳跃模式操
作、内部软启动控制，并且无需补偿。
•
针对严格输出纹波和电压容差要求的强制连续传导
模式 (FCCM)
•
•
预充电启动功能
8 个可通过 PMBus 接口在
200kHz 至 1MHz 之间选择的频率设置
强制持续传导模式有助于满足高性能 DSP 和 FPGA 应
用的严格电压调节精度要求。TPS548A20 采用 28 引
脚 VQFN-CLIP 封装，并且在 -40°C 至 125°C 的环境
温度范围内额定运行。
•
•
4.5mm x 3.5mm 28 引脚超薄四方扁平无引线
(VQFN)-CLIP 封装
WEBENCH™ 设计中心提供支持SWIFT™
器件信息(1)
器件型号
TPS548A20
封装
封装尺寸（标称值）
VQFN-CLIP (28)
4.50mm x 3.50mm
(1) 如需了解所有可用封装，请见数据表末尾的可订购产品附录。
简化应用
PGOOD
VIN
Thermal
Pad
23
22
21
20
18
19
17
16
15
24 VO
PGND 14
PGND 13
PGND 12
PGND 11
PGND 10
25 TRIP
26 NC
TPS548A20
27 GND1
28 GND2
1
2
3
4
5
6
7
8
9
EN
VOUT
VREG
Thermal
Pad
1
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
English Data Sheet: SLUSC78
TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
www.ti.com.cn
目录
7.3 Feature Description................................................. 16
7.4 Device Functional Modes........................................ 22
Application and Implementation ........................ 23
8.1 Application Information............................................ 23
8.2 Typical Application .................................................. 23
Power Supply Recommendations...................... 28
1
2
3
4
5
6
特性.......................................................................... 1
应用.......................................................................... 1
说明.......................................................................... 1
修订历史记录 ........................................................... 2
Pin Configuration and Functions......................... 3
Specifications......................................................... 4
6.1 Absolute Maximum Ratings ...................................... 4
6.2 ESD Ratings.............................................................. 4
6.3 Recommended Operating Conditions....................... 5
6.4 Electrical Characteristics........................................... 5
6.5 Thermal Information.................................................. 7
6.6 Typical Characteristics.............................................. 8
6.7 Thermal Performance ............................................. 14
Detailed Description ............................................ 15
7.1 Overview ................................................................. 15
7.2 Functional Block Diagrams ..................................... 15
8
9
10 Layout................................................................... 28
10.1 Layout Guidelines ................................................. 28
10.2 Layout Example .................................................... 29
11 器件和文档支持 ..................................................... 30
11.1 文档支持................................................................ 30
11.2 商标....................................................................... 30
11.3 静电放电警告......................................................... 30
11.4 Glossary................................................................ 30
12 机械、封装和可订购信息....................................... 30
7
4 修订历史记录
Changes from Original (October 2015) to Revision A
Page
•
已将文档状态从产品预览更新为量产数据 .............................................................................................................................. 1
2
Copyright © 2015, Texas Instruments Incorporated
TPS548A20
www.ti.com.cn
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
5 Pin Configuration and Functions
28-PIN
QFN
(TOP VIEW)
28
27
26
25
24
1
2
3
4
5
6
7
8
9
23
22
21
20
19
18
17
16
15
RF
PGOOD
EN
FB
GND
MODE
VREG
VDD
NC
VBST
NC
SW
SW
VIN
SW
VIN
Thermal Pad
SW
VIN
10
11
12
13
14
Pin Functions
PIN
I/O(1)
DESCRIPTION
NAME
EN
NO.
3
I
I
The enable pin turns on the DC-DC switching converter.
FB
23
VOUT feedback input. Connect this pin to a resistor divider between the VOUT pin and GND.
This pin is the ground of internal analog circuitry and driver circuitry. Connect GND to the PGND
plane with a short trace (For example, connect this pin to the thermal pad with a single trace and
connect the thermal pad to PGND pins and PGND plane).
GND
22
G
GND1
GND2
27
28
Connect this pin to ground. GND1 is the input of unused internal circuitry and must connect to
ground.
G
I
The MODE pin sets the forced continuous-conduction mode (FCCM) or auto-skip mode operation. It
also selects the ramp coefficient of D-CAP3 mode.
MODE
21
5
NC
18
26
10
11
12
13
14
—
G
Not connected. These pins are floating internally.
PGND
These ground pins are connected to the return of the internal low-side MOSFET.
Open-drain power-good status signal which provides startup delay after the FB voltage falls within the
specified limits. After the FB voltage moves outside the specified limits, PGOOD goes low within 2 µs.
PGOOD
RF
2
1
O
I
(1) I = Input, O = Output, P = Supply, G = Ground
Copyright © 2015, Texas Instruments Incorporated
3
TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
www.ti.com.cn
Pin Functions (continued)
PIN
I/O(1)
DESCRIPTION
NAME
NO.
6
7
SW
I/O
SW is the output switching terminal of the power converter. Connect this pin to the output inductor.
8
9
TRIP is the OCL detection threshold setting pin. ITRIP = 10 µA at TA = 25°C, 3000 ppm/°C current is
sourced and sets the OCL trip voltage. See the Current Sense and Overcurrent Protection section for
detailed OCP setting.
TRIP
25
I/O
VBST is the supply rail for the high-side gate driver (boost terminal). Connect the bootstrap capacitor
from this pin to the SW node. Internally connected to VREG via bootstrap PMOS switch.
VBST
VDD
4
P
P
19
15
16
17
20
24
Power-supply input pin for controller. Input of the VREG LDO. The input range is from 4.5 to 25 V.
VIN
P
VIN is the conversion power-supply input pins.
VREG
VO
O
I
VREG is the 5-V LDO output. This voltage supplies the internal circuitry and gate driver.
VOUT voltage input to the controller.
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)
MIN
–0.3
–3
MAX
7.7
25
27
31
6
UNIT
EN
DC
SW
Transient < 10 ns
–5
VBST
VBST(3)
–0.3
–0.3
Input voltage range(2)
V
VBST when transient < 10 ns
33
28
25
6
VDD
–0.3
–0.3
–0.3
–0.3
–0.3
–40
VIN
FB, MODE, VO
PGOOD
TRIP, VREG
7.7
6
Output voltage range
V
Junction temperature, TJ
Storage temperature, Tstg
150
150
°C
°C
–55
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating
Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods my affect device reliability.
(2) All voltages are with respect to network ground terminal.
(3) Voltage values are with respect to the SW terminal.
6.2 ESD Ratings
VALUE
±2500
±1500
UNIT
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)
Charged-device model (CDM), per JEDEC specification JESD22-C101(2)
V(ESD)
Electrostatic discharge
V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
4
Copyright © 2015, Texas Instruments Incorporated
TPS548A20
www.ti.com.cn
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
–0.1
–3
MAX
7
UNIT
EN
SW
20
VBST
VBST(1)
–0.1
–0.1
4.5
25.5
5.5
25
Input voltage range
V
VDD
VIN
1.5
20
FB, MODE, VO
PGOOD
TRIP, VREG
–0.1
–0.1
–0.1
–40
5.5
7
Output voltage range
V
5.5
125
Ambient temperature, TA
°C
(1) Voltage values are with respect to the SW pin.
6.4 Electrical Characteristics
over operating free-air temperature range, VDD = 12V, VREG = 5 V, VEN = 5 V (unless otherwise noted)
PARAMETER
SUPPLY CURRENT
TEST CONDITIONS
MIN
TYP
MAX
UNIT
TA = 25°C, No load
IVDD
VDD bias current
1350
850
1850
µA
Power conversion enabled (no
switching)
TA = 25°C, No load
Power conversion disabled
IVDDSTBY
VDD standby current
VIN leakage current
1150
0.5
µA
µA
IVIN(leak)
TA = 25°C, VEN = 0 V
VREF OUTPUT
VVREF
Reference voltage
FB w/r/t GND, TA = 25°C
597
–0.5
–1.0
600
603
0.5
1.0
mV
%
FB w/r/t GND, -40°C ≤ TJ ≤ 85°C
FB w/r/t GND, –40°C ≤ TJ ≤ 125°C
VVREFTOL
Reference voltage tolerance
OUTPUT VOLTAGE
IFB
FB input current
VFB = 600 mV
50
6
100
nA
uA
VVO = 0.5 V, Power Conversion
Disabled
IVODIS
VO discharge current
SMPS FREQUENCY
VIN = 12 V, VVO = 3.3 V, RRF<0.041
VIN = 12 V, VVO = 3.3 V, RRF=0.096
VIN = 12 V, VVO = 3.3 V, RRF=0.16
VIN = 12 V, VVO = 3.3 V, RRF=0.229
VIN = 12 V, VVO = 3.3 V, RRF=0.297
VIN = 12 V, VVO = 3.3 V, RRF=0.375
VIN = 12 V, VVO = 3.3 V, RRF=0.461
VIN = 12 V, VVO = 3.3 V, RRF>0.557
TA = 25°C(1)
250
300
400
500
600
750
850
1000
60
fSW
VO switching frequency
kHz
tON(min)
Minimum on-time
Minimum off-time
ns
ns
tOFF(min)
TA = 25°C
175
240
310
INTERNAL BOOTSTRAP SW
VF
Forward Voltage
VVREG–VBST, TA = 25°C, IF = 10 mA
0.15
0.01
0.25
1.5
V
TA = 25°C, VVBST = 33 V, VSW = 28
V
IVBST
VBST leakage current
µA
(1) Specified by design. Not production tested.
Copyright © 2015, Texas Instruments Incorporated
5
TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
www.ti.com.cn
Electrical Characteristics (continued)
over operating free-air temperature range, VDD = 12V, VREG = 5 V, VEN = 5 V (unless otherwise noted)
PARAMETER
LOGIC THRESHOLD
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VENH
EN enable threshold voltage
EN disable threshold voltage
EN hysteresis voltage
1.3
1.1
1.4
1.2
0.22
0
1.5
1.3
V
V
VENL
VENHYST
VENLEAK
SOFT-START
tSS
V
EN input leakage current
–1
1
µA
Soft-start time
4
ms
POWERGOOD COMPARATOR
PGOOD in from higher
104
89
108
92
116
84
1.0
2
111
96
%
%
PGOOD in from lower
PGOOD out to higher
PGOOD out to lower
Delay for PGOOD going in
Delay for PGOOD coming out
VPGOOD = 0.5 V
VPGTH
PGOOD threshold
PGOOD delay time
113
80
120
87
%
%
0.8
1.2
ms
µs
mA
µA
tPGDLY
IPG
PGOOD sink current
4
6
IPGLK
PGOOD leakage current
VPGOOD = 5.0 V
–1
0
1
POWER-ON DELAY
tPODLY
Power-on delay time
Delay from enable to switching
1.124
ms
A
CURRENT DETECTION
RTRIP = 49 kΩ
RTRIP = 28 kΩ
RTRIP = 49 kΩ
RTRIP = 28 kΩ
11.5
6.5
15.0
8
17.5
11
IOCL
Current limit threshold, valley
-18.0
-11.5
–14.9
-8.0
0
-10.5
-6.0
Negative current limit threshold,
valley
IOCLN
A
VZC
Zero cross detection offset
mV
PROTECTIONS
Wake-up
3.25
3.00
4.15
3.95
3.34
3.12
4.25
4.05
3.41
3.19
4.35
4.15
VREG undervoltage-lockout (UVLO)
threshold voltage
VVREGUVLO
V
V
Shutdown
Wake-up (default)
Shutdown
VVDDUVLO
VDD UVLO threshold voltage
Overvoltage-protection (OVP)
threshold voltage
VOVP
OVP detect voltage
With 100-mV overdrive
UVP detect voltage
UVP filter delay
116
120
300
68
124
%
ns
%
tOVPDLY
VUVP
OVP propagation delay
Undervoltage-protection (UVP)
threshold voltage
64
71
tUVPDLY
UVP delay
1
ms
THERMAL SHUTDOWN
Shutdown temperature
Hysteresis
140
40
TSDN
Thermal shutdown threshold(1)
°C
LDO VOLTAGE
VREG
LDO output voltage
VIN = 12 V, ILOAD = 10 mA
4.65
170
5
5.45
365
V
VDOVREG
LDO low droop drop-out voltage
VIN = 4.5 V, ILOAD = 30 mA, TA
25°C
=
mV
mA
ILDOMAX
LDO over-current limit
VIN = 12 V, TA = 25°C
200
INTERNAL MOSFETS
RDS(on)H High-side MOSFET on-resistance
RDS(on)L Low-side MOSFET on-resistance
TA = 25°C
TA = 25°C
9.9
4.3
11.4
4.94
mΩ
mΩ
6
Copyright © 2015, Texas Instruments Incorporated
TPS548A20
www.ti.com.cn
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
6.5 Thermal Information
TPS548A20
RVE
UNIT
THERMAL METRIC(1)
(VQFN-CLIP)
28 PINS
θJA
Junction-to-ambient thermal resistance
37.5
34.1
18.1
1.8
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
θJCtop
θJB
Junction-to-case (top) thermal resistance
Junction-to-board thermal resistance
ψJT
Junction-to-top characterization parameter
Junction-to-board characterization parameter
Junction-to-case (bottom) thermal resistance
ψJB
18.1
2.2
θJCbot
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report (SPRA953).
版权 © 2015, Texas Instruments Incorporated
7
TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
www.ti.com.cn
6.6 Typical Characteristics
TA = 25°C (unless otherwise noted)
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
VOUT (V)
0.6
VOUT (V)
0.6
1.2
1.5
1.8
2.5
3.3
5
1.2
1.5
1.8
2.5
3.3
5
0
2
4
6
8
10
12
14
16
0
2
4
6
8
10
12
14
16
Output Current (A)
Output Current (A)
D001
D001
fSW = 500 kHz
VIN = 12 V
fSW = 500 kHz
VIN = 12 V
Auto-skip Mode
FCCM
图 1. Efficiency vs. Output Current
图 2. Efficiency vs. Output Current
100
90
80
70
60
50
40
30
100
90
80
70
60
50
40
30
VOUT (V)
0.6
VOUT (V)
0.6
1.2
1.5
1.8
2.5
3.3
5
1.2
1.5
1.8
2.5
3.3
5
0
2
4
6
8
10
12
14
16
0
2
4
6
8
10
12
14
16
Output Current (A)
Output Current (A)
D001
D001
fSW = 970 kHz
VIN = 12 V
fSW = 970 kHz
VIN = 12 V
Auto-skip Mode
FCCM
图 3. Efficiency vs. Output Current
图 4. Efficiency vs. Output Current
1.3
1.3
VIN = 5
VIN = 5
VIN = 12
VIN = 18
VIN = 12
VIN = 18
1.275
1.25
1.225
1.2
1.275
1.25
1.225
1.2
1.175
1.15
1.125
1.1
1.175
1.15
1.125
1.1
0
3
6
9
12
VOUT = 1.2 V
15
0
3
6
9
12
15
Output Current (A)
Output Current (A)
D001
D001
fSW = 500 kHz
fSW = 970 kHz
VOUT = 1.2 V
图 5. DC Load Regulation
图 6. DC Load Regulation
8
版权 © 2015, Texas Instruments Incorporated
TPS548A20
www.ti.com.cn
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
Typical Characteristics (接下页)
TA = 25°C (unless otherwise noted)
1.3
1.3
1.275
1.25
1.225
1.2
VIN = 5
VIN = 12
VIN = 18
VIN = 5
VIN = 12
VIN = 18
1.275
1.25
1.225
1.2
1.175
1.15
1.125
1.1
1.175
1.15
1.125
1.1
0
3
6
9
12
15
0
3
6
9
12
15
Output Current (A)
Output Current (A)
D001
D001
fSW = 500 kHz
VOUT = 1.2 V
fSW = 970 kHz
VOUT = 1.2 V
图 7. DC Load Regulation
图 8. DC Load Regulation
110
100
90
110
100
90
80
80
70
70
400 LFM
200 LFM
100 LFM
400 LFM
200 LFM
100 LFM
60
60
Natural convection
Natural convection
50
50
0
3
6
9
12
15
0
3
6
9
12
15
Output Current (A)
Output Current (A)
D001
D001
fSW = 500 kHz
VOUT = 5 V
VIN = 12 V
fSW = 500 kHz
VOUT = 1 V
VIN = 12 V
图 9. Safe Operating Area
图 10. Safe Operating Area
1000
900
800
700
600
500
400
300
200
250 kHz, Skip Mode
500 kHz, Skip Mode
970 kHz, Skip Mode
250 kHz, FCCM
500 kHz, FCCM
970 kHz, FCCM
0
3
6
9
12
15
Output Current (A)
D001
VOUT = 1.2 V
VIN = 12 V
图 11. Switching Frequency vs. Output Current
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TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
www.ti.com.cn
Typical Characteristics (接下页)
TA = 25°C (unless otherwise noted)
fSW = 1 MHz
VOUT = 1.2 V
VIN = 12 V
ILOAD = 0 A
fSW = 1 MHz
VOUT = 1.2 V
VIN = 12 V
ILOAD = 0 A
图 12. Skip Mode Steady-State Operation
图 13. FCCM Steady-State Operation
fSW = 1 MHz
VOUT = 1.2 V
VIN = 12 V
ILOAD = 0.1 A
fSW = 1 MHz
VIN = 12 V
ILOAD = 0.1 A
VOUT = 1.2 V
图 14. Skip Mode Steady-State Operation
图 15. Steady-State Operation
10
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TPS548A20
www.ti.com.cn
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
Typical Characteristics (接下页)
TA = 25°C (unless otherwise noted)
fSW = 1 MHz
VOUT = 1.2 V
VIN = 12 V
ILOAD = 8 A
fSW = 1 MHz
VOUT = 1.2 V
VIN = 12 V
ILOAD = 8 A
图 16. Skip Mode Steady-State Operation
图 17. Skip Mode Steady-State Operation
ILOAD from 0 A to 8 A
VIN = 12 V
Div = 2 A/µs
VOUT = 1.2 V
ILOAD from 0 A to 8 A
VIN = 12 V
Div = 2 A/µs
VOUT = 1.2 V
fSW = 1 MHz
fSW = 1 MHz
图 18. Auto-skip Mode Load Transient
图 19. Load Transient
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TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
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Typical Characteristics (接下页)
TA = 25°C (unless otherwise noted)
fSW = 1 MHz
VOUT = 1.2 V
VIN = 12 V
fSW = 1 MHz
VOUT = 1.2 V
VIN = 12 V
图 20. Auto-skip Mode Start-Up
图 21. FCCM Mode Start-Up
ILOAD = 0 A
VIN = 12 V
ILOAD = 0 A
VIN = 12 V
VOUT = 1.2 V
fSW = 1 MHz
VOUT = 1.2 V
fSW = 1 MHz
图 22. Skip Mode Pre-Bias Start-Up
图 23. FCCM Pre-Bias Start-Up
12
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Typical Characteristics (接下页)
TA = 25°C (unless otherwise noted)
ILOAD = 8A
VIN = 12 V
ILOAD = 8 A
VIN = 12 V
VOUT = 1.2 V
fSW = 1 MHz
VOUT = 1.2 V
fSW = 1 MHz
图 24. Auto-skip Mode Shutdown Operation
图 25. Auto-skip Mode Shutdown Operation
ILOAD = 0 A
VIN = 12 V
ILOAD = 8 A
VIN = 12 V
fSW = 1 MHz
VOUT = 1.2 V
fSW = 1 MHz
VOUT = 1.2 V
图 26. FCCM Shutdown Operation
图 27. FCCM Shutdown Operation
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Typical Characteristics (接下页)
TA = 25°C (unless otherwise noted)
图 28. Overcurrent Protection Hiccup
图 29. Overcurrent Protection
6.7 Thermal Performance
fSW = 500 kHz, VIN = 12 V, VOUT = 5 V, IOUT = 12 A, COUT = 10 × 22 µF (1206, 6.3 V, X5R), RBOOT = 0 Ω, SNB = 3 Ω + 470 pF
Inductor: LOUT = 1 µH, PCMC135T-1R0MF, 12.6 mm × 13.8 mm × 5 mm, 2.1 mΩ (typ)
图 30. SP1: 68.2℃ ( TPS548A20 ), SP2: 75℃ (Inductor)
14
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ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
7 Detailed Description
7.1 Overview
The TPS548A20 is a high-efficiency, single-channel, synchronous-buck converter. The device suits low-output
voltage point-of-load applications with 15-A or lower output current in computing and similar digital consumer
applications. The TPS548A20 features proprietary D-CAP3 mode control combined with adaptive on-time
architecture. This combination builds modern low-duty-ratio and ultra-fast load-step-response DC-DC converters
in an ideal fashion. The output voltage ranges from 0.6 V to 5.5 V. The conversion input voltage ranges from
1.5 V to 20 V (with snubber) and the VDD input voltage ranges from 4.5 V to 25 V. D-CAP3 mode operation uses
emulated current information to control the modulation. An advantage of this control scheme is that it does not
require a phase-compensation network outside which makes the device easy-to-use and also allows low-external
component count. Adaptive on-time control tracks the preset switching frequency over a wide range of input and
output voltage while increasing switching frequency as needed during load-step transient.
7.2 Functional Block Diagrams
PGOOD
+
+
0.6 V + 8/16%
0.6 V œ 32%
+
UV
+
Delay
Delay
OV
0.6 V œ 8/16%
0.6 V+20%
VREG
Internal
Ramp
Control Logic
UVP / OVP
Logic
0.6 V
SS
+
+
PWM
OCP
VFB
VBST
VIN
10 µA
GND
+
+
One-
Shot
TRIP
LL
SW
XCON
+
ZC
Control
Logic
PGND
PGND
VO
SW
FCCM / SKIP
RC Time
Constant
ñ
ñ
ñ
ñ
ñ
ñ
On/Off time
Minimum On/Off
Light load
OVP/UVP
FCCM/SKIP
Soft-Start
MODE
Fault
Shut Down
+
NC
VREGOK
3.34 V /
3.12 V
LDO
VREG
VDD
GND1
+
GND2
EN
VDDOK
THOK
4.3 V /
4.03 V
+
+
140°C /
100°C
Enable
1.4 V / 1.2 V
RF
TPS548A20
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7.3 Feature Description
7.3.1 Powergood
The TPS548A20 has powergood output that indicates high when switcher output is within the target. The power-
good function is activated after the soft-start operation is complete. If the output voltage becomes within ±8% of
the target value, internal comparators detect the power-good state and the power-good signal becomes high
after a 1-ms internal delay. If the output voltage goes outside of ±16% of the target value, the power-good signal
becomes low after a 2-μs internal delay. The power-good output is an open-drain output and must be pulled-up
externally.
7.3.2 D-CAP3 Control and Mode Selection
RR
SW
To comparator
CR
VOUT
图 31. Internal RAMP Generation Circuit
The TPS548A20 uses D-CAP3 mode control to achieve fast load transient while maintaining the ease-of-use
feature. An internal RAMP is generated and fed to the VFB pin to reduce jitter and maintain stability. The
amplitude of the ramp is determined by the R-C time-constant as shown in 图 31. At different switching
frequencies, (fSW) the R-C time-constant varies to maintain relatively constant RAMP amplitude.
7.3.3 D-CAP3 Mode
From small-signal loop analysis, a buck converter using the D-CAP3 mode control architecture can be simplified
as shown in 图 32.
VO
SW
CC1
RC1
VIN
CC2
RC2
Sample
and Hold
DRVH
PWM
Comparator
Lx
RFBH
Control
Logic
and
G
+
+
VRAMP
VOUT
FB
DRVL
Driver
RCO
+
VREF
RLOAD
COUT
RFBL
图 32. D-CAP3 Mode
16
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Feature Description (接下页)
The D-CAP3 control architecture includes an internal ripple generation network enabling the use of very low-ESR
output capacitors such as multi-layered ceramic capacitors (MLCC). No external current sensing network or
voltage compensators are required with D-CAP3 control architecture. The role of the internal ripple generation
network is to emulate the ripple component of the inductor current information and then combine it with the
voltage feedback signal to regulate the loop operation. For any control topologies supporting no external
compensation design, there is a minimum and/or maximum range of the output filter it can support. The output
filter used with the TPS548A20 device is a lowpass L-C circuit. This L-C filter has double pole that is described in
公式 1.
1
f =
P
2´ p´ L
´ C
OUT
OUT
(1)
At low frequencies, the overall loop gain is set by the output set-point resistor divider network and the internal
gain of the device. The low frequency L-C double pole has a 180 degree in phase. At the output filter frequency,
the gain rolls off at a –40dB per decade rate and the phase drops rapidly. The internal ripple generation network
introduces a high-frequency zero that reduces the gain roll off from –40dB to –20dB per decade and increases
the phase to 90 degree one decade above the zero frequency.
The inductor and capacitor selected for the output filter must be such that the double pole of 公式 1 is located
close enough to the high-frequency zero so that the phase boost provided by the high-frequency zero provides
adequate phase margin for the stability requirement.
表 1. Locating the Zero
SWITCHING
FREQUENCIES
(fSW) (kHz)
ZERO (fZ) LOCATION (kHz)
250 and 300
400 and 500
600 and 750
850 and 1000
6
7
9
12
After identifying the application requirements, the output inductance should be designed so that the inductor
peak-to-peak ripple current is approximately between 25% and 35% of the ICC(max) (peak current in the
application). Use 表 1 to help locate the internal zero based on the selected switching frequency. In general,
where reasonable (or smaller) output capacitance is desired, 公式 2 can be used to determine the necessary
output capacitance for stable operation.
1
f =
= f
Z
P
2´ p´ L
´ C
OUT
OUT
(2)
If MLCC is used, consider the derating characteristics to determine the final output capacitance for the design.
For example, when using an MLCC with specifications of 10-µF, X5R and 6.3 V, the deratings by DC bias and
AC bias are 80% and 50% respectively. The effective derating is the product of these two factors, which in this
case is 40% and 4-µF. Consult with capacitor manufacturers for specific characteristics of the capacitors to be
used in the system/applications.
表 2 shows the recommended output filter range for an application design with the following specifications:
•
•
•
Input voltage, VIN = 12 V
Switching frequency, fSW = 600 kHz
Output current, IOUT = 8 A
The minimum output capacitance is verified by the small signal measurement conducted on the EVM using the
following two criteria:
•
•
Loop crossover frequency is less than one-half the switching frequency (300 kHz)
Phase margin at the loop crossover is greater than 50 degrees
For the maximum output capacitance recommendation, simplify the procedure to adopt an unrealistically high
output capacitance for this type of converter design, then verify the small signal response on the EVM using the
following one criteria:
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•
Phase margin at the loop crossover is greater than 50 degrees
As indicated by the phase margin, the actual maximum output capacitance (COUT(max)) can continue to go higher.
However, small signal measurement (bode plot) should be done to confirm the design.
Select a MODE pin configuration as shown in 表 3 to double the R-C time constant option for the maximum
output capacitance design and application. Select a MODE pin configuration to use single R-C time constant
option for the normal (or smaller) output capacitance design and application.
The MODE pin also selects Auto-skip-mode or FCCM-mode operation.
表 2. Recommended Component Values
COUT(min) CROSS- PHASE COUT(max) INTERNAL
VOUT RLOWER RUPPER
LOUT
(µH)
INDUCTOR
ΔI/ICC(max)
ICC(max)
(A)
(µF)
OVER
(kHz)
MARGIN
(°)
(µF)
RC SETTING
(µs)
(V)
(kΩ)
(kΩ)
(1)
(1)
3 × 100
9 × 22
4 × 22
3 × 22
2 × 22
247
48
70
62
53
84
57
63
57
59
51
58
40
80
40
80
40
80
40
80
40
80
0.36
0.6
0
33%
33%
34%
33%
28%
PIMB065T-R36MS
30 x 100
30 x 100
30 x 100
30 x 100
30 x 100
207
25
0.68
1.2
2.5
3.3
5.5
10
PIMB065T-R68MS
185
11
1.2
10
31.6
45.3
82.5
8
PIMB065T-1R2MS
185
9
1.5
PIMB065T-1R5MS
185
7
2.2
PIMB065T-2R2MS
(1) All COUT(min) and COUT(max) capacitor specifications are 1206, X5R, 10 V.
For higher output voltage at or above 2.0 V, additional phase boost might be required in order to secure sufficient
phase margin due to phase delay/loss for higher output voltage (large on-time (tON)) setting in a fixed on time
topology based operation.
A feedforward capacitor placing in parallel with RUPPER is found to be very effective to boost the phase margin at
loop crossover.
表 3. Mode Selection and Internal RAMP RC Time Constant
SWITCHING
FREQUENCIES
fSW (kHz)
MODE
SELECTION
RMODE
(kΩ)
R-C TIME
CONSTANT (µs)
ACTION
60
50
275
and
and
and
325
425
625
850
275
425
625
850
275
425
625
850
275
425
625
850
525
750
0
40
30
and 1000
Auto-skip Mode
Pull down to GND
120
100
80
and
and
and
325
525
750
150
20
60
and 1000
60
and
and
and
325
525
750
50
40
30
and 1000
Connect to
PGOOD
FCCM(1)
120
100
80
and
and
and
325
525
750
150
60
and 1000
(1) Device goes into Forced CCM (FCCM) after PGOOD becomes high.
18
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表 3. Mode Selection and Internal RAMP RC Time Constant (接下页)
SWITCHING
FREQUENCIES
fSW (kHz)
MODE
SELECTION
RMODE
(kΩ)
R-C TIME
CONSTANT (µs)
ACTION
120
100
80
275
and
and
and
325
425
625
850
525
750
FCCM
Connect to VREG
0
60
and 1000
7.3.4 Sample and Hold Circuitry
CSP
Sampled_CSP
C1
C2
Buffer 1
Buffer 2
图 33. Sample and Hold Circuitry
The sample and hold circuitry is the difference between D-CAP3 and D-CAP2. The sample and hold circuitry,
which is an advance control scheme to boost output voltage accuracy higher on the TPS548A20 , is one of
features of the TPS548A20 . The sample and hold circuitry generates a new DC voltage of CSN instead of the
voltage which is produced by RC2 and CC2 which allows for tight output-voltage accuracy and makes the
TPS548A20 more competitive.
CSP
CSN
CSP
CSN
CSN_NEW
(sample at valley of CSP)
CSN_NEW
(sample at valley of CSP)
图 34. Continuous Conduction Mode (CCM) With Sample
图 35. Discontinuous Conduction Mode (DCM) With
and Hold Circuitry
Sample and Hold Circuitry
CSP
CSN
CSP
CSN
图 36. Continuous Conduction Mode (CCM) Without
图 37. Discontinuous Conduction Mode (DCM) Without
Sample and Hold Circuitry
Sample and Hold Circuitry
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1.25
1.23
1.21
1.25
1.23
1.21
1.19
1.17
1.15
VIN = 12 V
1.19
VIN = 12 V
VDD = 5 V
VDD = 5 V
VOUT = 1.2 V
fSW = 500 kHz
TA = 25°C
LOUT = 1 ꢀH
VOUT = 1.2 V
fSW = 500 kHz
TA = 25°C
LOUT = 1 ꢀH
Mode = Auto-skip
1.17
D-CAP3
D-CAP2
D-CAP3
D-CAP2
Mode = FCCM
1.15
1
2
3
4
5
6
7
8
9
10 11 12
1
2
3
4
5
6
7
8
9
10 11 12
Output Current (A)
Output Current (A)
C013
C014
图 38. Output Voltage vs Output Current
图 39. Output Voltage vs Output Current
7.3.5 Adaptive Zero-Crossing
The TPS548A20 uses an adaptive zero-crossing circuit to perform optimization of the zero inductor-current
detection during Auto-skip-mode operation. This function allows ideal low-side MOSFET turn-off timing. The
function also compensates the inherent offset voltage of the Z-C comparator and delay time of the Z-C detection
circuit. Adaptive zero-crossing prevents SW-node swing-up caused by too-late detection and minimizes diode
conduction period caused by too-early detection. As a result, the device delivers better light-load efficiency.
7.3.6 Forced Continuous-Conduction Mode
When the MODE pin is tied to the PGOOD pin through a resistor, the controller operates in continuous
conduction mode (CCM) during light-load conditions. During CCM, the switching frequency maintained to an
most constant level over the entire load range which is suitable for applications requiring tight control of the
switching frequency at the cost of lower efficiency.
7.3.7 Current Sense and Overcurrent Protection
The TPS548A20 has cycle-by-cycle overcurrent limiting control. The inductor current is monitored during the OFF
state and the controller maintains the OFF state during the period that the inductor current is larger than the
overcurrent trip level. In order to provide good accuracy and a cost-effective solution, the TPS548A20 supports
temperature compensated MOSFET RDS(on) sensing. Connect the TRIP pin to GND through the trip-voltage
setting resistor, RTRIP(20kΩ<RTRIP<65kΩ ). The TRIP terminal sources ITRIP current, which is 10 μA typically at
room temperature, and the trip level is set to the OCL trip voltage VTRIP as shown in 公式 3.
VTRIP = RTRIP ´ITRIP
where
•
•
•
VTRIP is in mV
RTRIP is in kΩ
ITRIP is in µA
(3)
公式 4 calculates the typical DC OCP level (typical low-side on-resistance [RDS(on)] of 4.3 mΩ should be used);
in order to design for worst case minimum OCP, maximum low-side on-resistance value of 5.7 mΩ should be
used. The inductor current is monitored by the voltage between the GND pin and SW pin so that the SW pin is
properly connected to the drain terminal of the low-side MOSFET. ITRIP has a 3000-ppm/°C temperature slope to
compensate the temperature dependency of RDS(on). The GND pin acts as the positive current-sensing node.
Connect the GND pin to the proper current sensing device, (for example, the source terminal of the low-side
MOSFET.)
Because the comparison occurs during the OFF state, VTRIP sets the valley level of the inductor current. Thus,
the load current at the overcurrent threshold, IOCP, is calculated as shown in 公式 4.
I
V
- V
´ V
(
)
OUT OUT
V
IN
V
V
TRIP
1
IND(ripple)
IN
TRIP
I
=
+
=
+
´
OCP
2
2´L ´ f
8´R
8´R
DS(on)L
SW
(
)
(
)
DS(on)
where
20
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•
•
RDS(on) is the on-resistance of the low-side MOSFET
RTRIP is in kΩ
(4)
In an overcurrent condition, the current to the load exceeds the current to the output capacitor thus the output
voltage tends to decrease. Eventually, the output voltage crosses the undervoltage-protection threshold and
shuts down.
7.3.8 Overvoltage and Undervoltage Protection
The TPS548A20 monitors a resistor-divided feedback voltage to detect overvoltage and undervoltage. When the
feedback voltage becomes lower than 68% of the target voltage, the UVP comparator output goes high and an
internal UVP delay counter begins counting. After 1 ms, the TPS548A20 latches OFF both high-side and low-
side MOSFETs drivers. The UVP function enables after soft-start is complete.
When the feedback voltage becomes higher than 120% of the target voltage, the OVP comparator output goes
high and the circuit latches OFF the high-side MOSFET driver and turns on the low-side MOSFET until reaching
a negative current limit. Upon reaching the negative current limit, the low-side FET is turned off and the high-side
FET is turned on again for a minimum on-time. The TPS548A20 operates in this cycle until the output voltage is
pulled down under the UVP threshold voltage for 1 ms. After the 1-ms UVP delay time, the high-side FET is
latched off and low-side FET is latched on. The fault is cleared with a reset of VDD or by re-toggling EN pin.
7.3.9 Out-of-Bounds Operation (OOB)
The TPS548A20 has an out-of-bounds (OOB) overvoltage protection that protects the output load at a much
lower overvoltage threshold of 8% above the target voltage. OOB protection does not trigger an overvoltage fault,
so the device is not latched off after an OOB event. OOB protection operates as an early no-fault overvoltage-
protection mechanism. During the OOB operation, the controller operates in forced PWM mode only by turning
on the low-side FET. Turning on the low-side FET beyond the zero inductor current quickly discharges the output
capacitor thus causing the output voltage to fall quickly towards the setpoint. During the operation, the cycle-by-
cycle negative current limit is also activated to ensure the safe operation of the internal FETs.
7.3.10 UVLO Protection
The TPS548A20 monitors the voltage on the VDD pin. If the VDD pin voltage is lower than the UVLO off-
threshold voltage, the switch mode power supply shuts off. If the VDD voltage increases beyond the UVLO on-
threshold voltage, the controller turns back on. UVLO is a non-latch protection.
7.3.11 Thermal Shutdown
The TPS548A20 monitors internal temperature. If the temperature exceeds the threshold value (typically 140°C),
TPS548A20 shuts off. When the temperature falls approximately 40°C below the threshold value, the device
turns on. Thermal shutdown is a non-latch protection.
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7.4 Device Functional Modes
7.4.1 Auto-Skip Eco-Mode Light-Load Operation
While the MODE pin is pulled to GND directly or through a 150-kΩ resistor, the TPS548A20 device automatically
reduces the switching frequency at light-load conditions to maintain high efficiency. This section describes the
operation in detail.
As the output current decreases from heavy-load condition, the inductor current also decreases until the rippled
valley of the inductor current touches zero level. Zero level is the boundary between the continuous-conduction
and discontinuous-conduction modes. The synchronous MOSFET turns off when this zero inductor current is
detected. As the load current decreases further, the converter runs into discontinuous-conduction mode (DCM).
The on-time is maintained to a level approximately the same as during continuous-conduction mode operation so
that discharging the output capacitor with a smaller load current to the level of the reference voltage requires
more time. The transition point to the light-load operation IOUT(LL) (for example: the threshold between continuous-
conduction mode and discontinuous-conduction mode) is calculated as shown in 公式 5.
V
- V
´ V
(
)
OUT OUT
V
IN
1
IN
I
=
´
OUT LL
( )
2´L ´ f
SW
where
•
f SW is the PWM switching frequency
(5)
TI recommends only using ceramic capacitors for Auto-skip mode.
7.4.2 Forced Continuous-Conduction Mode
When the MODE pin is tied to the PGOOD pin through a resistor, the controller operates in continuous
conduction mode (CCM) during light-load conditions. During CCM, the switching frequency maintained to an
almost constant level over the entire load range which is suitable for applications requiring tight control of the
switching frequency at the cost of lower efficiency.
22
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ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
The TPS548A20 device is a high-efficiency, single-channel, synchronous-buck converter. The device suits low-
output voltage point-of-load applications with 15-A or lower output current in computing and similar digital
consumer applications.
8.2 Typical Application
R1
PGOOD
6.65 kΩ
R2
C3
C4
2 kΩ
1 µF
1 µF
VIN
Thermal
Pad
R6
150 kΩ
CIN
2.2 nF
CIN
3 × 22 µF
23
22
21
20
19
18
17
16
15
24 VO
PGND 14
PGND 13
PGND 12
PGND 11
PGND 10
25 TRIP
26 NC
NC
R8
64.9 kΩ
TPS548A20
27 GND1
28 GND2
GND1
GND2
1
2
3
4
5
6
7
8
9
PIRB077T-1R0MS-87
VOUT
R4
249 kΩ
R10
100 kΩ
1 µH
R7
0 Ω
C2
0.1 µF
R3
3 Ω
Thermal Pad
COUT
COUT
4 × 10 µF
6 × 22 µF
R5
105 kΩ
VREG
EN
C1
470 pF
Figure 40. Typical Application Circuit Diagram
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Typical Application (continued)
8.2.1 Design Requirements
This design uses the parameters listed in Table 4.
Table 4. Design Example Specifications
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
INPUT CHARACTERISTIC
VIN
Voltage range
5
12
2.5
1
18
V
A
IMAX
Maximum input current
No load input current
VIN = 5 V, IOUT = 8 A
VIN = 12 V, IOUT = 0 A with auto skip mode
mA
OUTPUT CHARACTERISTICS
VOUT
Output voltage
1.2
V
Line regulation,
5 V ≤ VIN ≤ –14 V with FCCM
0.2%
Output voltage regulation
Load regulation,
0.5%
10
VIN = 12 V, 0 A ≤ IOUT ≤ 8 A with FCCM
VRIPPLE
ILOAD
IOVER
tSS
Output voltage ripple
Output load current
Output over current
Soft-start time
VIN = 12 V, IOUT = 8 A with FCCM
mVPP
A
0
12
11
1
ms
SYSTEMS CHARACTERISTICS
fSW
η
Switching frequency
Peak efficiency
1
91.2%
90.3%
25
MHz
ºC
VIN = 12 V, VOUT = 1.2 V, IOUT = 4 A
VIN = 12 V, VOUT = 1.2 V, IOUT = 8 A
η
Full load efficiency
Operating temperature
TA
8.2.2 Detailed Design Procedure
The external components selection is a simple process using D-CAP3 mode. Select the external components
using the following steps.
8.2.2.1 Choose the Switching Frequency
The switching frequency is configured by the resistor divider on the RF pin. Select one of eight switching
frequencies from 250 kHz to 1 MHz. Refer to for the relationship between the switching frequency and resistor-
divider configuration.
8.2.2.2 Choose the Operation Mode
Select the operation mode using 表 3.
8.2.2.3 Choose the Inductor
Determine the inductance value to set the ripple current at approximately ¼ to ½ of the maximum output current.
Larger ripple current increases output ripple voltage, improves signal-to-noise ratio, and helps to stabilize
operation.
V
(
IN
max
(
- V
´ V
V
- V
max
´ V
OUT
OUT
)
)
OUT
(
IN
OUT
)
)
(
)
1
3
L =
´
=
´
I
´ f
V
I
´ f
V
IN(max)
SW
IN
max
(
OUT
SW
IND ripple
(
max
)
(
)
12V -1.2V ´1.2V
)
(
3
=
´
= 1.08mH
6´ 500kHz
12V
(6)
24
Copyright © 2015, Texas Instruments Incorporated
TPS548A20
www.ti.com.cn
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
The inductor requires a low DCR to achieve good efficiency. The inductor also requires enough room above peak
inductor current before saturation. The peak inductor current is estimated using Equation 7.
V
(
IN
max
(
- V
´ V
OUT
OUT
)
)
12V -1.2V ´1.2V
)
)
(
V
10mA ´R
TRIP
1
1
TRIP
I
=
+
´
=
+
´
IND peak
(
)
8´R
L ´ f
V
8´ 4.3mW
1mH´500kHz
12V
SW
IN
max
DS on
( )
(
(7)
8.2.2.4 Choose the Output Capacitor
The output capacitor selection is determined by output ripple and transient requirement. When operating in CCM,
the output ripple has two components as shown in Equation 8. Equation 9 and Equation 10 define these
components.
V
= V
+ V
RIPPLE
RIPPLE(C) RIPPLE(ESR)
(8)
IL ripple
(
)
VRIPPLE C
=
( )
8´ COUT ´ fSW
VRIPPLE ESR = IL ripple ´ESR
(9)
(
)
(
)
(10)
8.2.2.5 Determine the Value of R1 and R2
The output voltage is programmed by the voltage-divider resistors, R1 and R2, shown in Equation 11. Connect
R1 between the VFB pin and the output, and connect R2 between the VFB pin and GND. The recommended R2
value is from 1 kΩ to 20 kΩ. Determine R1 using Equation 11.
V
- 0.6
1.2V - 0.6
OUT
R1=
´R2 =
´10kW = 10kW
0.6
0.6
(11)
8.2.3 Application Curves
TA = 25°C (unless otherwise noted)
1.3
1.275
1.25
1.225
1.2
100
90
80
70
60
50
40
30
VIN = 5
VIN = 12
VIN = 18
1.175
1.15
1.125
1.1
VOUT (V)
1.2
5
0
3
6
9
12
15
0
2
4
6
8
10
12
14
16
Output Current (A)
D001
Output Current (A)
D001
fSW = 500 kHz
VOUT = 1.2 V
fSW = 500 kHz
VIN = 12 V
FCCM
Figure 42. DC Load Regulation
Figure 41. Efficiency vs. Output Current
Copyright © 2015, Texas Instruments Incorporated
25
TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
www.ti.com.cn
TA = 25°C (unless otherwise noted)
1.3
VIN = 5
VIN = 12
VIN = 18
1.275
1.25
1.225
1.2
1.175
1.15
1.125
1.1
0
3
6
9
12
15
Output Current (A)
D001
fSW = 500 kHz
VOUT = 1.2 V
IOUT = 0 A
Figure 43. DC Load Regulation
Figure 44. Auto-skip Mode Steady-State Operation
ILOAD = 0 A
ILOAD = 8 A
Figure 45. FCCM Steady-State Operation
Figure 46. Auto-skip Mode Steady-State Operation
ILOAD = 8 A
ILOAD from 0 A to 8 A
Div = 2 A/µs
Figure 47. Steady-State Operation
Figure 48. Auto-skip Mode Load Transient
26
Copyright © 2015, Texas Instruments Incorporated
TPS548A20
www.ti.com.cn
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
TA = 25°C (unless otherwise noted)
ILOAD from 0 A to 8 A
Div = 2 A/µs
Figure 49. Load Transient
版权 © 2015, Texas Instruments Incorporated
27
TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
www.ti.com.cn
9 Power Supply Recommendations
This device is designed to operate from an input voltage supply between 1.5-V and 18-V (4.5-V and 25-V biased)
Input. use only a well regulated supply. These devices are not designed for split-rail operation. The VIN and VDD
terminals must be the same potential for accurate high-side short circuit protection. Proper bypassing of input
supplies and internal regulators is also critical for noise performance, as is PCB layout and grounding scheme.
See the recommendations in the Layout section.
10 Layout
10.1 Layout Guidelines
Before beginning a design using the TPS548A20 , consider the following:
•
Place the power components (including input and output capacitors, the inductor, and the TPS548A20 ) on
the solder side of the PCB. In order to shield and isolate the small signal traces from noisy power lines, insert
and connect at least one inner plane to ground.
•
All sensitive analog traces and components such as VFB, PGOOD, TRIP, MODE, and ADDR must be placed
away from high-voltage switching nodes such as SW and VBST to avoid coupling. Use internal layers as
ground planes and shield the feedback trace from power traces and components.
•
•
Pin 22 (GND pin) must be connected directly to the thermal pad. Connect the thermal pad to the PGND pins
and then to the GND plane.
Place the VIN decoupling capacitors as close to the VIN and PGND pins as possible to minimize the input
AC-current loop.
•
•
Place the feedback resistor near the IC to minimize the VFB trace distance.
Place the frequency-setting resistor (ADDR), OCP-setting resistor (RTRIP) and mode-setting resistor (RMODE
close to the device. Use the common GND via to connect the resistors to the GND plane if applicable.
)
•
•
•
•
•
•
•
Place the VDD and VREG decoupling capacitors as close to the device as possible. Provide GND vias for
each decoupling capacitor and ensure the loop is as small as possible.
The PCB trace is defined as switch node, which connects the SW pins and high-voltage side of the inductor.
The switch node should be as short and wide as possible.
Use separated vias or trace to connect SW node to the snubber, bootstrap capacitor, and ripple-injection
resistor. Do not combine these connections.
Place one more small capacitor (2.2 nF, 0402 size) between the VIN and PGND pins. This capacitor must be
placed as close to the IC as possible.
TI recommends placing a snubber between the SW shape and GND shape for effective ringing reduction.
The value of snubber design starts at 3 Ω + 470 pF.
Consider R-C-CC network (Ripple injection network) component placement and place the AC coupling
capacitor, CC, close to the device, and R and C close to the power stage.
See 图 50 for the layout recommendation.
28
版权 © 2015, Texas Instruments Incorporated
TPS548A20
www.ti.com.cn
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
10.2 Layout Example
VIN Shape
To inner GND plane
CIN
HF cap.
Cc
2
3
2
1
2
0
1
9
1
8
1
7
1
6
1
5
To VOUT Shape
VO
TRIP
DNC
PGND
PGND
PGND
PGND
PGND
GND Shape
GND1
GND2
COUT
1
2
3
4
5
6
7
8
9
VOUT Shape
SW Shape
LOUT
To VREG Pin
Cap.
Res.
Trace on bottom layer
Trace of top layer
RCC On Bottom layer
Trace of bottom layer
Trace on inner layer
图 50. Layout Recommendation
版权 © 2015, Texas Instruments Incorporated
29
TPS548A20
ZHCSEL7A –NOVEMBER 2015–REVISED DECEMBER 2015
www.ti.com.cn
11 器件和文档支持
11.1 文档支持
相关文档如下：
•
应用报告《采用前馈电容优化内部补偿 DC-DC 转换器的瞬态响应》（文献编号：SLVA289）
11.2 商标
SWIFT, D-CAP3, Eco-mode, WEBENCH are trademarks of Texas Instruments.
All other trademarks are the property of their respective owners.
11.3 静电放电警告
这些装置包含有限的内置 ESD 保护。 存储或装卸时，应将导线一起截短或将装置放置于导电泡棉中，以防止 MOS 门极遭受静电损
伤。
11.4 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 机械、封装和可订购信息
以下页中包括机械、封装和可订购信息。这些信息是针对指定器件可提供的最新数据。这些数据会在无通知且不对
本文档进行修订的情况下发生改变。欲获得该数据表的浏览器版本，请查阅左侧的导航栏。
30
版权 © 2015, Texas Instruments Incorporated
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
Samples
Drawing
Qty
2500
250
(1)
(2)
(3)
(4/5)
(6)
TPS548A20RVER
TPS548A20RVET
ACTIVE
VQFN-CLIP
VQFN-CLIP
RVE
28
28
RoHS-Exempt
& Green
NIPDAU | SN
Level-2-260C-1 YEAR
Level-2-260C-1 YEAR
-40 to 125
-40 to 125
T548A20
T548A20
ACTIVE
RVE
RoHS-Exempt
& Green
NIPDAU | SN
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
Addendum-Page 2
PACKAGE OUTLINE
RVE0028A
VQFN - 1 mm max height
S
C
A
L
E
3
.
3
0
0
PLASTIC QUAD FLATPACK - NO LEAD
3.6
3.4
B
A
PIN 1 INDEX AREA
4.6
4.4
1.0
0.8
C
SEATING PLANE
0.08 C
0.05
0.00
2.1 0.1
2X 1.6
(0.2) TYP
14
EXPOSED
THERMAL PAD
10
24X 0.4
9
15
2X
29
SYMM
3.2
3.1 0.1
23
1
0.25
28X
0.15
28
24
0.1
C A B
PIN 1 ID
(OPTIONAL)
SYMM
28X
0.05
0.5
0.3
4219151/A 07/2022
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance.
www.ti.com
EXAMPLE BOARD LAYOUT
RVE0028A
VQFN - 1 mm max height
PLASTIC QUAD FLATPACK - NO LEAD
(2.1)
SYMM
28
24
28X (0.6)
28X (0.2)
23
1
(1.3) TYP
SYMM
24X (0.4)
29
(4.3)
(3.1)
(R0.05)
TYP
9
15
(
0.2) TYP
VIA
10
14
(3.3)
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE:18X
0.07 MIN
ALL AROUND
0.07 MAX
ALL AROUND
SOLDER MASK
OPENING
METAL
EXPOSED
METAL
EXPOSED
METAL
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
NON SOLDER MASK
DEFINED
SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK DETAILS
4219151/A 07/2022
NOTES: (continued)
4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature
number SLUA271 (www.ti.com/lit/slua271).
5. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown
on this view. It is recommended that vias under paste be filled, plugged or tented.
www.ti.com
EXAMPLE STENCIL DESIGN
RVE0028A
VQFN - 1 mm max height
PLASTIC QUAD FLATPACK - NO LEAD
4X (0.94)
(0.57) TYP
28
24
28X (0.6)
1
23
28X (0.2)
24X (0.4)
(0.775)
TYP
29
SYMM
(4.3)
(R0.05) TYP
4X (1.35)
9
15
METAL
TYP
10
14
SYMM
(3.3)
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
EXPOSED PAD 29
78% PRINTED SOLDER COVERAGE BY AREA UNDER PACKAGE
SCALE:20X
4219151/A 07/2022
NOTES: (continued)
6. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
www.ti.com
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