TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
3.3-V/5-V 输入，D-CAP+™模式同步降压型集成场效应晶体管(FET)转换器
此转换器含2位VID
查询样品: TPS51462
特性
说明
1
•
2
•
•
•
•
•
集成FET转换器w/德州仪器自有知识产权的
D-CAP+™ 模式架构
最小外部部件数量
支持所有 MLCC 输出电容器与 SP/POSCAP
“ 自动跳过” 模式
700kHz和1MHz可选频率
小型4mm x 4mm，24引脚，方形扁平无引
脚(QFN)封装
TPS51462是一款采用D-CAP+™技术的完全集成同步
降压稳压器。 在系统尺寸最优的地方此器件用于最
高5V压降，性能和优化的物料清单(BOM)是必要条
件。
此器件完全支持具有集成2位VID功能的英特尔(Intel)系
统代理应用。
TPS51462还特有2个开关频率设置（700 kHz 和
1 MHz），跳跃模式，预偏置启动，可编程外部电容器
软启动时间/电压转换时间，输出放电，内部VBST开
关，2V基准(±1%)，电源正常和使能。
应用范围
•
•
5 V 或 3.3 V 电轨的低电压应用步降
笔记本/台式机
TPS51462采用4 mm × 4 mm，24引脚，QFN封
装（绿色RoHs兼容且无铅），额定温度范围-40°C 至
85°C。
+5V
17
16
15
14
13
V5FILT
PGOOD
VID1
VID0
EN
19 PGND
18
V5DRV
ENABLE
VID0
VID1
PGOOD
20 PGND
BST 12
SW 11
21 PGND
SW 10
TPS51462
SW
7
24 VIN
MODE
8
VOUT
SW
SLEW
23 VIN
COMP
9
VREF
SW
GND
VIN
VCCSA
22 VIN
1
2
3
4
5
6
VCCSASNS
UDG-11143
1
2
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas
Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
D-CAP+ is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2011, Texas Instruments Incorporated
English Data Sheet: SLUSAQ1
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
ORDERING INFORMATION (1)
TA
PACKAGE (2)
ORDERING NUMBER
PINS
OUTPUT SUPPLY
MINIMUM
QUANTITY
-40°C to 85°C
Plastic QFN
(RGE)
TPS51462RGER
24
Tape and reel
3000
TPS51462RGET
24
Mini reel
250
(1)
(2)
ECO PLAN
Green (RoHS and
no Pb/Br)
For the most current package and ordering information, see the Package Option Addendum at the end of this document, or visit the TI
website at www.ti.com.
Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at
www.ti.com/sc/package.
THERMAL INFORMATION
THERMAL METRIC (1)
TPS51462
θJA
Junction-to-ambient thermal resistance
38.3
θJCtop
Junction-to-case (top) thermal resistance
44.7
θJB
Junction-to-board thermal resistance
16
ψJT
Junction-to-top characterization parameter
0.8
ψJB
Junction-to-board characterization parameter
16.1
θJCbot
Junction-to-case (bottom) thermal resistance
5.4
(1)
UNITS
RGE (24) PIN
°C/W
有关传统和新的热度量的更多信息，请参阅 IC 封装热度量 应用报告 SPRA953。
ABSOLUTE MAXIMUM RATINGS (1)
over operating free-air temperature range (unless otherwise noted)
VALUE
Input voltage range
Output voltage range
Electrostatic Discharge
UNIT
MIN
MAX
VIN, EN, MODE
–0.3
7.0
V5DRV, V5FILT, VBST (with respect to SW)
–0.3
7.0
VBST
–0.3
12.5
VID0, VID1
–0.3
3.6
VOUT
–1.0
3.6
SW
–2.0
7.0
SW (transient 20 ns and E=5 µJ)
–3.5
COMP, SLEW, VREF
–0.3
3.6
PGND
–0.3
0.3
PGOOD
–0.3
Human Body Model (HBM)
V
7.0
2000
Charged Device Model (CDM)
V
500
V
Storage temperature
Tstg
–55
150
˚C
Junction temperature
TJ
–40
150
˚C
300
˚C
Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds
(1)
2
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 may affect device reliability.
Copyright © 2011, Texas Instruments Incorporated
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
RECOMMENDED OPERATING CONDITIONS
VALUE
MIN
Input voltage range
Output voltage range
TYP
VIN, EN, MODE
–0.1
6.5
V5DRV, V5FILT, VBST(with respect to SW)
–0.1
5.5
VBST
–0.1
11.75
VID0, VID1
–0.1
3.5
VOUT
–0.8
2.0
SW
–0.8
6.5
COMP, SLEW, VREF
–0.1
3.5
PGOOD
–0.1
6.5
PGND
–0.1
0.1
-40
85
Ambient temperature range, TA
UNIT
MAX
V
V
°C
ELECTRICAL CHARACTERISTICS
over recommended free-air temperature range, VVIN = 5.0 V, VV5DRV = VV5FILT = 5 V, MODE = OPEN, PGND = GND (unless
otherwise noted)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNIT
SUPPLY: VOLTAGE, CURRENTS AND 5 V UVLO
IVINSD
VIN shutdown current
EN = 'LO'
V5VIN
5VIN supply voltage
V5DRV and V5FILT voltage range
I5VIN
5VIN supply current
EN =’HI’, V5DRV + V5FILT supply current
I5VINSD
5VIN shutdown current
EN = ‘LO’, V5DRV + V5FILT shutdown current
VV5UVLO
V5FILT UVLO
Ramp up; EN = 'HI'
VV5UVHYS
V5FILT UVLO hysteresis
Falling hysteresis
VVREFUVLO
REF UVLO (1)
Rising edge of VREF, EN = 'HI'
VVREFUVHYS
REF UVLO hysteresis (1)
VPOR5VFILT
Reset
OVP latch is reset by V5FILT falling below the reset threshold
4.5
4.2
µA
0.02
5
5.0
5.5
V
1.6
3.0
mA
10
50
µA
4.3
4.5
440
V
mV
1.8
V
100
mV
1.5
2.3
3.1
–1.5%
0%
1.5%
V
VOLTAGE FEEDBACK LOOP: VREF, VOUT, AND VOLTAGE GM AMPLIFIER
VOUTTOL
VOUT accuracy
VVOUT = 0.8V, No droop
VVREF
VREF
IVREF = 0 µA, TA = 25°C
GM
Transconductance
VDM
Differential mode input voltage
ICOMPSRC
COMP pin maximum sourcing current
VCOMP = 2 V
VOFFSET
Input offset voltage
TA = 25°C
RDSCH
Output voltage discharge resistance
f–3dbVL
–3dB Frequency (1)
2
V
1
mS
0
80
mV
5
mV
–80
–5
0
µA
42
Ω
6
MHz
CURRENT SENSE: CURRENT SENSE AMPLIFIER, OVER CURRENT AND ZERO CROSSING
Gain from the current of the low-side FET to PWM comparator
when PWM = "OFF"
ACSINT
Internal current sense gain
43
50
57
mV/A
IOCL
Positive overcurrent limit (valley)
6.6
IOCL(neg)
Negative overcurrent limit (valley)
–6
A
VZXOFF
Zero crossing comp internal offset
0
mV
A
DRIVERS: BOOT STRAP SWITCH
RDSONBST
Internal BST switch on-resistance
IVBST = 10 mA, TA = 25°C
IBSTLK
Internal BST switch leakage current
VVBST = 14 V, VSW = 7 V, TA = 25°C
(1)
5
10
Ω
1
µA
Ensured by design, not production tested.
Copyright © 2011, Texas Instruments Incorporated
3
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
ELECTRICAL CHARACTERISTICS (continued)
over recommended free-air temperature range, VVIN = 5.0 V, VV5DRV = VV5FILT = 5 V, MODE = OPEN, PGND = GND (unless
otherwise noted)
PARAMETER
CONDITIONS
MIN
TYP
MAX
Measured at the VOUT pin w/r/t VSLEW
82%
84%
86%
UNIT
PROTECTION: OVP, UVP, PGOOD, and THERMAL SHUTDOWN
VPGDLL
PGOOD deassert to lower
(PGOOD → Low)
VPGHYSHL
PGOOD high hysteresis
VPGDLH
PGOOD de-assert to higher
(PGOOD → Low)
VPGHYSHH
PGOOD high hysteresis
VINMINPG
Minimum VIN voltage for valid
PGOOD
Measured at the VIN pin with a 2-mA sink current on PGOOD
pin
VOVP
OVP threshold
Measured at the VOUT pin w/r/t VSLEW
UVP threshold
Measured at the VOUT pin w/r/t VSLEW, device latches OFF,
begins soft-stop
VUVP
8%
Measured at the VOUT pin w/r/t VSLEW
114%
116%
118%
-8%
(2)
THSD
Thermal shutdown
THSD(hys)
Thermal Shutdown hysteresis (2)
0.9
1.3
1.5
118%
120%
122%
66%
68%
70%
V
125
°C
10
°C
VVIN = 5 V, VVOUT = 0.8 V, fSW = 667 kHz, fixed VID mode
240
ns
VVIN = 5 V, VVOUT = 0.8 V, fSW = 1 MHz, fixed VID mode
160
ns
VVIN = 5 V, VVOUT = 0.8 V, fSW = 1 MHz, DRVL on,
SW = PGND, VVOUT < VSLEW
357
ns
3
ms
Latch off controller, attempt soft-stop.
Controller re-starts after temperature has dropped
TIMERS: ON-TIME, MINIMUM OFF TIME, SS, AND I/O TIMINGS
tONESHOTC
PWM one-shot (2)
tMIN(off)
Minimum OFF time (2)
tPGDDLY
PGOOD startup delay time
SLEW ramp up time)
tPGDPDLYH
PGOOD high propagation delay
time (2)
(2)
(excl.
Delay starts from VOUT = VID code 00 and excludes SLEW
ramp up time
50 mV over drive, rising edge
(2)
0.8
10
µs
0.2
µs
3
ms
OVP delay time (2)
tUVDLYEN
Undervoltage fault enable delay (excl. Time from (VOUT = VID code 00) going high to undervoltage
SLEW ramp up time) (2)
fault is ready
UVP delay time
ISLEW
Soft-start and voltage transition
ms
Time from the VOUT pin out of +20% of VSLEW to OVP fault
PGOOD low propagation delay time
tOVPDLY
tUVPDLY
1.2
50 mV over drive, falling edge
tPGDPDLYL
(2)
1
Time from the VOUT pin out of –30% of VSLEW to UVP fault
CSS = 10 nF assuming voltage slew rate of 1 mV/µs
µs
8.5
9
10
0
11
µA
LOGIC PINS: I/O VOLTAGE AND CURRENT
VPGDPD
PGOOD pull down voltage
PGOOD low impedance, ISINK = 4 mA, VVIN = VV5FILT = 4.5 V
IPGDLKG
PGOOD leakage current
PGOOD high impedance, forced to 5.5 V
–1
VENH
EN logic high
EN, VCCP logic
0.8
VENL
EN logic low
EN, VCCP logic
IEN
EN input current
VVIDH
VID logic high
VID0, VID1
VVIDL
VID logic low
VID0, VID1
VMODETH
MODE threshold voltage (3)
0.3
V
1
µA
V
0.3
V
1
µA
0.8
V
0.3
MODE 3
0.37
0.42
0.47
MODE 4
0.55
0.60
0.65
MODE 7
1.75
1.80
1.85
V
V
IMODE
MODE current
15
µA
RPD
VID pull-down resistance
10
kΩ
(2)
(3)
4
Ensured by design, not production tested.
See Table 3 for descriptions of MODE parameters.
Copyright © 2011, Texas Instruments Incorporated
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
VIN
VIN
VIN
PGND
PGND
PGND
RGE PACKAGE
24
23
22
21
20
19
GND
1
18 V5DRV
VREF
2
17 V5FILT
COMP
3
16 PGOOD
TPS51462
6
13 EN
SW
7
8
9
10
11
12
BST
MODE
14 VID0
Thermal Pad
SW
5
SW
VOUT
15 VID1
SW
4
SW
SLEW
PIN FUNCTIONS
PIN
NO.
NAME
I/O
DESCRIPTION
19
20
PGND
I
Power ground. Source terminal of the rectifying low-side power FET.
VIN
I
Power supply input pin. Drain terminal of the switching high-side power FET.
21
22
23
24
1
GND
–
Signal ground.
2
VREF
O
2.0-V reference output. Connect a 0.22-µF ceramic capacitor to GND.
3
COMP
O
Connect series R-C to the VREF pin for loop compensation.
4
SLEW
I/O
Program the startup and voltage transition time using an external capacitor via 10-µA current source.
5
VOUT
I
Output voltage monitor input pin.
6
MODE
I
Allows selection of switching frequencies and output voltage. (See Table 3)
SW
I/O
BST
I
Power supply for internal high-side gate driver. Connect a 0.1-µF bootstrap capacitor between this pin and
the SW pin.
13
EN
I
Enable of the SMPS.
14
VID0
15
VID1
I
2-bit VID input.
16
PGOOD
O
Power good output. Connect pull-up resistor.
17
V5FILT
I
5-V power supply for analog circuits.
18
V5DRV
I
5-V power supply for the gate driver.
–
Connect directly to system GND plane with multiple vias.
7
8
9
Switching node output. Connect to the external inductor.
10
11
12
Thermal Pad
Copyright © 2011, Texas Instruments Incorporated
5
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
BLOCK DIAGRAM
10 mA
00
01
10
14 VID0
11
15 VID1
+
VREFIN +8/16 %
EN 13
+
+
OV
VREFIN –8/16 %
VREFIN +20%
COMP
16 PGOOD
+
+
UV
VREFIN –32%
3
UVP
15 mA
Control Logic
On-Time
and LL
Selection
OVP
VS
+
SLEW
4
VREF
2
VOUT
5
MODE
12 BST
+
VCS
PWM
22 VIN
23 VIN
Bandgap
24 VIN
8R
+
PGND
+
CS
OC
tON
OneShot
R
7
SW
8
SW
9
SW
XCON
10 SW
11 SW
SW
18 V5DRV
Sense
ZC
+
GND
6
17 V5FILT
Discharge
1
TPS51462
19
PGND
20
PGND
21
PGND
UDG-11209
Table 1. Intel SA VID
(1)
6
VID 0
VID 1
0
0
VCCSA
0
1
0.80 V
(1)
0
1
0.85 V
(1)
1
0
0.725 V
1
1
0.675 V
0.9 V
MODE = Open
MODE = 33 kΩ
0.8 V for 2012/2013 SV processors and 0.85 V for 2012 LV/ULV
processors.
Copyright © 2011, Texas Instruments Incorporated
VIN
10 mF
10 mF 0.1 mF
VIN
VIN
17
3.3 nF
0.22 mF
2
3
14
13
5 kW
4
10 nF
5
6
8
7
SW
SW
DNP
9
SW
SW 10
SW 11
BST 12
15
16
TPS51462
Thermal Pad
1
24 VIN
23
22
21 PGND
20 PGND
19 PGND
18
GND
1 kW
V5FILT
1 kW
V5DRV
VREF
100 kW
PGOOD
ENABLE
VID0
VID1
PGOOD
COMP
0W
VID1
SLEW
2.2 mF
VID0
VOUT
1 mF
EN
Copyright © 2011, Texas Instruments Incorporated
MODE
+5V
0.1 mF
DNP
DNP
L
0.42 mH
22 mF
22 mF
22 mF
22 mF
100 W
UDG-11144
VCCSASNS
VCCSA
TPS51462
www.ti.com.cn
ZHCS623 – DECEMBER 2011
TPS51462 APPLICATION DIAGRAM
Figure 1. Application Schematic Using Non-Droop Configuration
7
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
Application Circuit List of Materials
Recommended part numbers for key external components for the circuit in Figure 1 are listed in Table 2.
Table 2. Key External Component Recommendations
(Figure 1)
FUNCTION
MANUFACTURER
PART NUMBER
Output Inductor
Nec-Tokin
MPCG0740LR42C
Panasonic
ECJ2FB0J226M
Murata
GRM21BR60J226ME39L
Ceramic Output Capacitors
8
Copyright © 2011, Texas Instruments Incorporated
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
APPLICATION INFORMATION
Functional Overview
The TPS51462 is a D-CAP+™ mode adaptive on-time converter. The output voltage is set using a 2-bit DAC that
outputs a reference voltage in accordance with the code defined in Table 1. VID-on-the-fly transitions are
supported with the slew rate controlled by a single capacitor on the SLEW pin. The converter automatically runs
in discontinuous conduction mode (DCM) to optimize light-load efficiency. Two switching frequency selections
are provided, (700 kHz and 1 MHz) to enable optimization of the power chain for the cost, size and efficiency
requirements of the design.
In adaptive on-time converters, the controller varies the on-time as a function of input and output voltage to
maintain a nearly constant frequency during steady-state conditions. In conventional constant on-time converters,
each cycle begins when the output voltage crosses to a fixed reference level. However, in the TPS51462, the
cycle begins when the current feedback reaches an error voltage level which is the amplified difference between
the reference voltage and the feedback voltage.
PWM Operation
Referring to Figure 2, in steady state, continuous conduction mode, the converter operates in the following way.
Starting with the condition that the top FET is off and the bottom FET is on, the current feedback (VCS) is higher
than the error amplifier output (VCOMP). VCS falls until it hits VCOMP, which contains a component of the output
ripple voltage. VCS is not directly accessible by measuring signals on pins of TPS51462. The PWM comparator
senses where the two waveforms cross and triggers the on-time generator.
Current
Feedback
Voltage (V)
VCS
VCOMP
VREF
tON
t
Time (ms)
UDG-10187
Figure 2. D-CAP+™ Mode Basic Waveforms
The current feedback is an amplified and filtered version of the voltage between PGND and SW during low-side
FET on-time. The TPS51462 also provides a single-ended differential voltage (VOUT) feedback to increase the
system accuracy and reduce the dependence of circuit performance on layout.
Copyright © 2011, Texas Instruments Incorporated
9
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
PWM Frequency and Adaptive on Time Control
In general, the on-time (at the SW node) can be estimated by Equation 1.
V
1
tON = OUT ´
VIN
fSW
where
•
fSW is the frequency selected by the connection of the MODE pin
(1)
The on-time pulse is sent to the top FET. The inductor current and the current feedback rises to peak value.
Each ON pulse is latched to prevent double pulsing. Switching frequency settings are shown in Table 3.
Non-Droop Configuration
The TPS51462 offers a non-droop solution only. The benefit of a non-droop approach is that load regulation is
flat, therefore, in a system where tight DC tolerance is desired, the non-droop approach is recommended. For the
Intel system agent application, non-droop is recommended as the standard configuration.
The non-droop approach can be implemented by connecting a resistor and a capacitor between the COMP and
the VREF pins. The purpose of the type II compensation is to obtain high DC feedback gain while minimizing the
phase delay at unity gain cross over frequency of the converter.
The value of the resistor (RC) can be calculated using the desired unity gain bandwidth of the converter, and the
value of the capacitor (CC) can be calculated by knowing where the zero location is desired. An application tool
that calculates these values is available from your local TI Field Application Engineer.
Figure 3 shows the basic implementation of the non-droop mode using the TPS51462.
GMV = 1 mS
VSLEW
RC
CC
+
+
–
RDS(on)
LOUT
+
GMC= 1 mS
+
PWM
Comparator
Driver
ESR
ROUT
RLOAD
COUT
4 kW
+
–
VREF
UDG-11208
Figure 3. Non-Droop Mode Basic Implementation
10
Copyright © 2011, Texas Instruments Incorporated
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
Figure 4 shows the load regulation of the system agent rail using non-droop configuration.
Figure 5 shows the transient response of TPS51462 using non-droop configuration where COUT = 4 × 22 µF. The
applied step load is from 0 A to 2 A.
0.90
Output Voltage (V)
TA = 25°C
VIN = 5 V
0.85
0.80
Mode 3
Mode 4
Mode 7
Mode 8
0.75
0.1
1
Output Current (A)
10
G008
Figure 4. 0.8 V/0.85 V Load Regulation (VIN = 5 V)
Non-Droop Configuration
Figure 5. Non-Droop Configuration Transient
Response
Table 3. Mode Parameter Table
MODE
MODE CONNECTION
SWITCHING
FREQUENCY (fSW)
VID1 = 1
VID0 = 0
(V)
3
22 kΩ
700 kHz
0.80
4
33 kΩ
1 MHz
0.85
7
100 kΩ
700 kHz
0.85
8
Open
1 MHz
0.80
Copyright © 2011, Texas Instruments Incorporated
11
TPS51462
ZHCS623 – DECEMBER 2011
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Light Load Power Saving Features
The TPS51462 has an automatic pulse-skipping mode to provide excellent efficiency over a wide load range.
The converter senses inductor current and prevents negative flow by shutting off the low-side gate driver. This
saves power by eliminating re-circulation of the inductor current. Further, when the bottom FET shuts off, the
converter enters discontinuous mode, and the switching frequency decreases, thus reducing switching losses as
well.
Voltage Slewing
The TPS51462 ramps the SLEW voltage up and down to perform the output voltage transitioning. The timing is
independent of switching frequency, as well as output resistive and capacitive loading. It is set by a capacitor
from SLEW pin to GND, called CSLEW, together with an internal current source of 10 µA. The slew rate is used to
set the startup and voltage transition rate.
I
CSLEW = SLEW
SR
(2)
CSLEW ´ 0.9 V
tSS =
ISLEW
where
•
•
ISLEW = 10 µA (nom)
SR is the target output voltage slew rate, per Intel specification between 0.5 mV/µs and 10 mV/µs
(3)
For the current reference design, an SR of 1 mV/µs is targeted. The CSLEW is calculated to be 10 nF. The slower
slew rate is desired to minimize large inductor current perturbation during startup and voltage transitioning thus
reducing the possibility of acoustic noise.
After the power up, when VID1 is transitioning from 0 to 1, TPS51462 follows the SLEW voltage entering the
forced PWM mode to actively discharge the output voltage from 0.9 V to 0.8 V. The actual output voltage slew
rate is approximately the same as the set slew rate while the bandwidth of the converter supports it and there is
no overcurrent triggered by additional charging current flowing into the output capacitors. After SLEW transition is
completed, PWM mode is maintained for 64 µs (16 clock cycles when the frequency is 1 MHz) to ensure voltage
regulation.
Protection Features
The TPS51462 offers many features to protect the converter power chain as well as the system electronics.
5-V Undervoltage Protection (UVLO)
The TPS51462 continuously monitors the voltage on the V5FILT pin to ensure that the voltage level is high
enough to bias the device properly and to provide sufficient gate drive potential to maintain high efficiency. The
converter starts with approximately 4.3 V and has a nominal of 440 mV of hysteresis. If the 5-V UVLO limit is
reached, the converter transitions the phase node into a 3-state function. And the converter remains in the off
state until the device is reset by cycling 5 V until the 5-V POR is reached (2.3-V nominal). The power input does
not have an UVLO function
Power Good Signals
The TPS51462 has one open-drain power good (PGOOD) pin. During startup, there is a 3 ms power good delay
starting from the output voltage reaching the regulation point (excluding soft-start ramp-up time). And there is
also a 1 ms power good high propagation delay. The PGOOD pin de-asserts as soon as the EN pin is pulled low
or an undervoltage condition on V5FILT is detected. The PGOOD signal is blanked during VID voltage transitions
to prevent false triggering during voltage slewing.
12
Copyright © 2011, Texas Instruments Incorporated
TPS51462
www.ti.com.cn
ZHCS623 – DECEMBER 2011
Output Overvoltage Protection (OVP)
In addition to the power good function described above, the TPS51462 has additional OVP and UVP thresholds
and protection circuits.
An OVP condition is detected when the output voltage is approximately 120% × VSLEW. In this case, the
converter de-asserts the PGOOD signals and performs the overvoltage protection function. The converter
remains in this state until the device is reset by cycling 5 V until the 5-V POR threshold (2.3 V nominal) is
reached.
Output Undervoltage Protection (UVP)
Output undervoltage protection works in conjunction with the current protection described in the Overcurrent
Protection and Overcurrent Limit sections. If the output voltage drops below 70% of VSLEW, after an 8-µs delay,
the device latches OFF. Undervoltage protection can be reset only by EN or a 5-V POR.
Overcurrent Protection
Both positive and negative overcurrent protection are provided in the TPS51462:
• Overcurrent Limit (OCL)
• Negative OCL (level same as positive OCL)
Overcurrent Limit
If the sensed current value is above the OCL setting, the converter delays the next ON pulse until the current
drops below the OCL limit. Current limiting occurs on a pulse-by-pulse basis. The TPS51462 uses a valley
current limiting scheme where the DC OCL trip point is the OCL limit plus half of the inductor ripple current. The
minimum valley OCL is 6 A over process and temperature.
During the overcurrent protection event, the output voltage likely droops until the UVP limit is reached. Then, the
converter de-asserts the PGOOD pin, and then latches OFF after an 8-µs delay. The converter remains in this
state until the device is reset by EN or a 5VFILT POR.
1
IOCL(dc ) = IOCL(valley ) + ´ IP-P
2
(4)
Negative OCL
The negative OCL circuit acts when the converter is sinking current from the output capacitor(s). The converter
continues to act in a valley mode, the absolute value of the negative OCL set point is typically -6.5 A.
Thermal Protection
Thermal Shutdown
The TPS51462 has an internal temperature sensor. When the temperature reaches a nominal 125°C, the device
shuts down until the temperature cools by approximately 10°C. Then the converter restarts.
Copyright © 2011, Texas Instruments Incorporated
13
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
Startup and VID Transition Timing Diagrams
1.05-V Rail
0.95 V
VCCP
EN
Internal Enable
VID1 (3)
VID0 (3)
SLEW (1 mV/ms)
VOUT
VCCSA_PGOOD
Reset Time (2)
UNCORE_PWRGD (1)
260 ms
900 ms
4 ms
2.5 ms
UDG-10191
Figure 6. Fixed VID/Fixed Step Startup and VID Toggle Timing Diagram for 2011 Intel Platform
For Figure 6:
(1) Includes VCCA, VCCAXG, and VDDQ power rails.
(2) Processor reset: VID transition must be completed by this time.
(3) 1-kΩ pull-down resistor required.
14
Copyright © 2011, Texas Instruments Incorporated
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
1.05-V Rail
0.95 V
VCCP
EN
100ms
Internal Enable
VID1 (3)
VID0 (3)
SLEW (1 mV/ms)
VOUT
VCCSA_PGOOD
Reset Time (2)
UNCORE_PWRGD (1)
260 ms
900 ms
4 ms
2.5 ms
UDG-10192
Figure 7. Fixed VID/Fixed Step Startup and VID Toggle Timing Diagram for 2012 Intel Platform
For Figure 7:
(1) Includes VCCA, VCCAXG, and VDDQ power rails.
(2) Processor reset: VID transition must be completed by this time.
(3) 1-kΩ pull-down resistor required.
Copyright © 2011, Texas Instruments Incorporated
15
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
TYPICAL CHARACTERISTICS
90
90
TA = 25°C
VIN = 3.3 V
TA = 25°C
VIN = 5 V
80
Efficiency (%)
Efficiency (%)
80
70
60
Mode 3
Mode 4
Mode 7
Mode 8
50
40
0.01
0.1
1
Output Current (A)
70
60
Mode 3
Mode 4
Mode 7
Mode 8
50
40
0.01
10
Figure 8. Efficiency vs. Output Current
Mode 3
Mode 4
Mode 7
Mode 8
2.00
1.75
Power Loss (W)
Power Loss (W)
1.75
1.50
1.25
1.00
0.75
0.50
1.50
1.25
1.00
0.75
0.50
TA = 25°C
VIN = 3.3 V
0.25
0.00
0.1
1
Output Current (A)
TA = 25°C
VIN = 5 V
0.25
0.00
0.1
10
140
310
120
30
260
20
210
160
Phase
-10
110
-20
60
-40
-50
1000
25°C
-10°C
85°C
10 k
10
100 k
1M
-40
10 M
Phase (°)
Gain (dB)
360
Gain
10
16
G004
100
80
60
40
OTP Boundary
Direct Current SOA
Pulse Current (50 µs) SOA
20
0
1
2
3
4
5
Output Current (A)
Frequency (Hz)
Figure 12. Bode Plot, Non-Droop Mode
10
Figure 11. Power Loss vs. Output Current
Ambient Temperature (°C)
60
50
1
Output Current (A)
G003
Figure 10. Power Loss vs. Output Current
-30
G002
2.25
Mode 3
Mode 4
Mode 7
Mode 8
2.00
0
10
Figure 9. Efficiency vs. Output Current
2.25
40
0.1
1
Output Current (A)
G001
6
7
G000
Figure 13. Safe Operating Area
Copyright © 2011, Texas Instruments Incorporated
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
TYPICAL CHARACTERISTICS (continued)
Figure 14. Mode=8, IOUT = 0 A, VID Transitioning
Figure 15. Mode=8, IOUT = 3 A, VID Transitioning
Figure 16. Mode = 8, OCL
Figure 17. Mode=4, OCL
Figure 18. Mode= 8, IOUT = 3 A, Soft-Start
Figure 19. Mode= 4, IOUT = 3 A, Soft-Start
Copyright © 2011, Texas Instruments Incorporated
17
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
DESIGN PROCEDURE
The simplified design procedure is done for a non-droop application using the TPS51462 converter.
Step One
Determine the specifications.
The System Agent Rail requirements provide the following key parameters:
1. V00 = 0.90 V
2. V10 = 0.80 V
3. ICC(max) = 6 A
4. IDYN(max) = 2 A
5. ICC(tdc) = 3 A
Step Two
Determine system parameters.
The input voltage range and operating frequency are of primary interest. For example:
1. VIN = 5 V
2. fSW = 1 MHz
Step Three
Determine inductor value and choose inductor.
Smaller values of inductor have better transient performance but higher ripple and lower efficiency. Higher values
have the opposite characteristics. It is common practice to limit the ripple current to 25% to 50% of the maximum
current. In this case, use 25%:
IP-P = 6 A ´ 0.25 = 1.5 A
(5)
At fSW = 1 MHz, with a 5-V input and a 0.80-V output:
ö
V10
÷÷
è (fSW ´ VIN ) ø
æ
L=
V ´ dT
=
IP-P
(VIN - V10 )´ çç
IP-P
æ 0.8 ö
÷÷
è (1´ 5 ) ø
(5 - 0.8 )´ çç
=
1.5 A
= 0.45 mH
(6)
For this application, a 0.42-µH, 1.55-mΩ inductor from NEC-TOKIN with part number MPCG0740LR42C is
chosen.
Step Four
Set the output voltage.
The output voltage is determined by the VID settings. The actual voltage set point for each VID setting is listed in
Table 1. No external resistor dividers are needed for this design.
Step Five
Calculate CSLEW.
VID pin transition and soft-start time is determined by CSLEW and 10 µA of internal current source.
I
10 mA
= 10nF
CSLEW = SLEW =
SRDAC 1 mV
ms
(7)
The slower slew rate is desired to minimize large inductor current perturbation during startup and voltage
transition, thus reducing the possibility of acoustic noise.
18
Copyright © 2011, Texas Instruments Incorporated
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
Given the CSLEW, use Equation 8 to calculate the soft start time.
´ 0.9 V 10nF ´ 0.9 V
C
=
= 900 ms
tSS = SLEW
ISLEW
10 mA
(8)
Step Six
Calculate OCL.
The DC OCL level of TPS51462 design is determined by Equation 9,
1
1
IOCL(dc ) = IOCL(valley ) + ´ IP-P = 6 A + ´ 1.5 A = 6.75 A
2
2
(9)
The minimum valley OCL is 6 A over process and temperature, and IP-P = 1.5 A, the minimum DC OCL is
calculated to be 6.75A.
Step Seven
Determine the output capacitance.
To determine COUT based on transient and stability requirement, first calculate the the minimum output
capacitance for a given transient.
Equation 11 and Equation 10 can be used to estimate the amount of capacitance needed for a given dynamic
load step/release. Please note that there are other factors that may impact the amount of output capacitance for
a specific design, such as ripple and stability. Equation 11 and Equation 10 are used only to estimate the
transient requirement, the result should be used in conjunction with other factors of the design to determine the
necessary output capacitance for the application.
æV
ö
´t
L ´ DILOAD(max )2 ´ ç VOUT SW + tMIN(off ) ÷
ç VIN(min )
÷
è
ø
COUT(min_ under ) =
ææ V
ö
ö
IN(min ) - VVOUT
÷
÷ ´ tSW - t
2 ´ DVLOAD(insert ) ´ ç ç
MIN(off ) ÷ ´ VVOUT
çç
÷
VIN(min )
ø
èè
ø
(10)
2
COUT(min_ over ) =
(
LOUT ´ DILOAD(max )
)
2 ´ DVLOAD(release ) ´ VVOUT
(11)
Equation 10 and Equation 11 calculate the minimum COUT for meeting the transient requirement, which is
72.9 µF assuming the following:
• ±3% voltage allowance for load step and release
• MLCC capacitance derating of 60% due to DC and AC bias effect
In this reference design, 4, 22-µF capacitors are used in order to provide this amount of capacitance.
Copyright © 2011, Texas Instruments Incorporated
19
TPS51462
ZHCS623 – DECEMBER 2011
www.ti.com.cn
Step Eight
Determine the stability based on the output capacitance COUT.
In order to achieve stable operation. The 0-dB frequency, f0 should be kept less than 1/5 of the switching
frequency (1 MHz). (See Figure 3)
R
GM
1
´
´ C = 150kHz
f0 =
2p COUT RS
where
•
RS = RDS(on) × GMC × RLOAD
(12)
.
f ´ RS ´ 2p ´ COUT 150kHz ´ 53mW ´ 2p ´ 88 mF
=
» 5kW
RC = 0
GM
1mS
(13)
Using 4, 22-µF capacitors, the compensation resistance, RC can be calculated to be approximately 5 kΩ.
The purpose of the comparator capacitor (CC) is to reduce the DC component to obtain high DC feedback gain.
However, as it causes phase delay, another zero to cancel this effect at f0 is needed. This zero can be
determined by values of CC and the compensation resistor, RC.
f
1
= 0
fZ =
2p ´ RC ´ CC 10
(14)
And since RC has previously been derived, the value of CC is calculated to be 2.2 nF. In order to further boost
phase margin, a value of 3.3-nF is chosen for this reference design.
Step Nine
Select decoupling and peripheral components.
For TPS51462 peripheral capacitors use the following minimum values of ceramic capacitance. X5R or better
temperature coefficient is recommended. Tighter tolerances and higher voltage ratings are always appropriate.
• V5DRV decoupling ≥ 2.2 µF, ≥ 10 V
• V5FILT decoupling ≥ 1 µF, ≥10 V
• VREF decoupling 0.22 µF to 1 µF, ≥ 4 V
• Bootstrap capacitors ≥ 0.1 µF, ≥ 10 V
• Pull-up resistors on PGOOD, 100 kΩ
Layout Considerations
Good layout is essential for stable power supply operation. Follow these guidelines for an efficient PCB layout.
• Connect PGND pins (or at least one of the pins) to the thermal PAD underneath the device. Also connect
GND pin to the thermal PAD underneath the device. Use four vias to connect the thermal pad to internal
ground planes.
• Place VIN, V5DRV, V5FILT and 2VREF decoupling capacitors as close to the device as possible.
• Use wide traces for the VIN, VOUT, PGND and SW pins. These nodes carry high current and also serve as
heat sinks.
• Place feedback and compensation components as close to the device as possible.
• Keep analog signals (SLEW, COMP) away from noisy signals (SW, VBST).
20
Copyright © 2011, Texas Instruments Incorporated
PACKAGE OPTION ADDENDUM
www.ti.com
10-Dec-2020
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
FX006
ACTIVE
VQFN
RGE
24
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
TPS
51462
TPS51462RGER
ACTIVE
VQFN
RGE
24
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
TPS
51462
TPS51462RGET
ACTIVE
VQFN
RGE
24
250
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 85
TPS
51462
(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
