LM74670QDGKRQ1 [TI]
具有 70uA 栅极驱动器的 0.48V 至 42V、零 IQ 汽车理想二极管整流器控制器 | DGK | 8 | -40 to 125;型号: | LM74670QDGKRQ1 |
厂家: | TEXAS INSTRUMENTS |
描述: | 具有 70uA 栅极驱动器的 0.48V 至 42V、零 IQ 汽车理想二极管整流器控制器 | DGK | 8 | -40 to 125 栅极驱动 控制器 光电二极管 驱动器 |
文件: | 总26页 (文件大小:1428K) |
中文: | 中文翻译 | 下载: | 下载PDF数据表文档文件 |
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LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
LM74670-Q1 零 IQ 智能二极管整流器控制器
1 特性
3 说明
1
•
符合 AEC-Q100 标准,其中包括以下内容:
LM74670-Q1 是一种控制器器件,可在交流发电机的
全桥或半桥整流器架构中与 N 通道 MOSFET 搭配使
用。它旨在驱动外部 MOSFET 以模拟理想二极管。此
方案独一无二的优势在于其并无接地基准,因此其具有
零 IQ。采用全桥或半桥整流器和交流发电机的肖特基
二极管可以替换为 LM74670-Q1 解决方案,以避免正
向导电二极管损耗并使交流/直流转换器更加高效。
–
–
–
器件温度 1 级:-40℃ 至 +125℃ 的环境工作温
度范围
超出人体模型 (HBM) 静电放电 (ESD) 分类等级
2
器件充电器件模型 (CDM) ESD 分类等级 C4B
•
•
•
•
•
峰值输入交流电压:42V
零 IQ
LM74670-Q1 控制器为外部 N 通道 MOSFET 提供栅
极驱动,并配有快速响应内部比较器,可使 MOSFET
栅极在反极性情况下放电。此器件支持频率高达
300Hz 的交流信号。
适用于外部 N 通道 MOSFET 的电荷泵栅极驱动器
与肖特基二极管相比,正向压降和功耗更低
能够处理频率高达 300Hz 的交流信号
2 应用
器件信息(1)
•
•
•
•
交流整流器
器件型号
封装
VSSOP (8)
封装尺寸(标称值)
交流发电机
电动工具
LM74670-Q1
3.00mm x 5.00mm
(1) 如需了解所有可用封装,请参阅产品说明书末尾的可订购产品
附录。
反极性保护
智能二极管全桥整流器应用
智能二极管配置
Q1
VIN
VOUT
S
D
G
AC Input
GATE DRIVE GATE PULL DOWN
ANODE
CATHODE
LM74670
VCAPH
VCAPL
VCAP
C
OUT
LOAD
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: SNOSD08
LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
www.ti.com.cn
目录
7.3 Feature Description .................................................. 7
7.4 Device Functional Modes........................................ 10
Application and Implementation ........................ 12
8.1 Typical Rectifier Application ................................... 12
8.2 Design Requirements.............................................. 16
Power Supply Recommendations...................... 17
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....................... 4
6.4 Thermal Information ................................................. 4
6.5 Electrical Characteristics........................................... 4
6.6 Typical Characteristics.............................................. 6
Detailed Description .............................................. 7
7.1 Overview ................................................................... 7
7.2 Functional Block Diagram ......................................... 7
8
9
10 Layout................................................................... 17
10.1 Layout Guidelines ................................................. 17
10.2 Layout Example .................................................... 18
11 器件和文档支持 ..................................................... 19
11.1 社区资源................................................................ 19
11.2 商标....................................................................... 19
11.3 静电放电警告......................................................... 19
11.4 Glossary................................................................ 19
12 机械、封装和可订购信息....................................... 19
7
4 修订历史记录
注:之前版本的页码可能与当前版本有所不同。
Changes from Original (September 2015) to Revision A
Page
•
将“产品预览”更改为“生产数据”................................................................................................................................................ 1
2
Copyright © 2015, Texas Instruments Incorporated
LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
5 Pin Configuration and Functions
DGK Package
8-Pin VSSOP
Top View
VCAP
L
1
8
Cathode
Gate Pull Down
NC
2
3
4
7
6
5
VCAPH
LM74670-Q1
Gate Drive
NC
Anode
Pin Functions
PIN NO.
NAME
I/O
DESCRIPTION
1
2
VcapL
Charge Pump Output, connect to an external charge pump capacitor
Gate Pull Down
Connect to the gate of the external MOSFET for fast turn OFF in the case of
reverse polarity
3
4
5
6
7
8
NC
No connect. Leave floating or connect to Anode pin
Anode
NC
Anode of the diode, connect to source of the external MOSFET
No connect. Leave floating or connect to gate drive pin
Gate Drive
VcapH
Cathode
Gate Drive output, Connect to the Gate of the external MOSFET
Charge Pump Output, connect to an external charge pump capacitor
Cathode of the diode, connect to Drain of the external MOSFET
Copyright © 2015, Texas Instruments Incorporated
3
LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
www.ti.com.cn
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)
(1)
MIN
-3
MAX
45
UNIT
V
(2) (3)
Cathode to Anode (For a 2ms time duration)
Cathode to Anode (Continuous)(3)
VcapH to VcapL
,
-3
42
V
-0.3
-0.3
-0.3
-40
-40
-65
7
V
Anode to VcapL
3
V
Gate Drive, Gate Pull Down to VcapL
7
V
(4)
Ambient Temperature (TA-MAX)
125
125
150
°C
°C
°C
Case Temperature (TC-MAX)
Storage temperature range, Tstg
(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) 42V continuous (and 45V transients for 2ms) absmax condition from Cathode to Anode. Suitable to use with TVS SMBJ28A and
SMBJ14A at the anode.
(3) Reverse voltage rating only. There is no positive voltage limitation for the LM74670-Q1 Anode terminal.
(4) The device performance is ensured over this Ambient Temperature range as long the Case Temperature does not exceed the MAX
value.
6.2 ESD Ratings
VALUE
±4000
±750
UNIT
Human body model (HBM), per AEC Q100-002(2)
Charged-device model (CDM), per AEC Q100-011
V(ESD)
Electrostatic discharge(1)
V
(1) AEC Q100-002 indicates that HBM stressing shall be in accordance with the ANSI/ESDA/JEDEC JS-001 specification.
(2) The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
NOM
MAX
42
UNIT
Cathode To Anode
V
Ambient Temperature (TA-MAX)
Case Temperature (TC-MAX)
-40
125
125
°C
°C
6.4 Thermal Information
LM74670-Q1
THERMAL METRIC(1)
DGK (VSSOP)
UNIT
8 PINS
181
73
RθJA
RθJC(top)
RθJB
ψJT
Junction-to-ambient thermal resistance
Junction-to-case (top) thermal resistance
Junction-to-board thermal resistance
102
11
°C/W
Junction-to-top characterization parameter
Junction-to-board characterization parameter
ψJB
100
(1) For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953
6.5 Electrical Characteristics
(1)TA= 25°C unless otherwise noted. Minimum and Maximum limits are specified through test, design, validation or statistical
correlation. Typical values represent the most likely parametric norm at TA= 25°C and are provided for reference purpose
(1) Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which
operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits
and associated test conditions, see the table of Electrical Characteristics.
4
Copyright © 2015, Texas Instruments Incorporated
LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
Electrical Characteristics (continued)
(1)TA= 25°C unless otherwise noted. Minimum and Maximum limits are specified through test, design, validation or statistical
correlation. Typical values represent the most likely parametric norm at TA= 25°C and are provided for reference purpose
only. VAnode-Cathode= 0.55V for all tests.
only. VAnode-Cathode= 0.55V for all tests.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
VAnode to Cathode
VcapThreshold
Minimum Startup Voltage across External MOSFET VGS = 0V
External MOSFET's Body Diode
0.48
V
Charge Pump Capacitor Drive
Thresholds
Vcap Upper Threshold
Vcap Lower Threshold
VGate to Anode = 2V
6.3
5.15
67
V
V
IGate up
Gate Drive Pull up current
60
55
µA
µA
IGate down
Gate Drive pull down current
during forward voltage
VGate to Anode = 4V
62
IGate pull down
ICharge
Gate drive pull down current
when reverse voltage is sensed
VGate Pull Down = VAnode + 2V
VAnode to Cathode = 0.55 V
Vcap = 6.6V
160
46
mA
µA
µA
Charging current for the charge
pump capacitor
40
IDischarge
VCAP Current Consumption to
power the controller when
MOSFET is ON
0.95
TRecovery
Time to shut off MOSFET when
VAnode to Cathode = -20 mV
2.2
5(2)
µs
voltage is reversed (Equivalent to Cgate = 4 nF
diode reverse recovery time)
D
Duty Cycle
Iload = 3 A, TA = 25°C
98%
92%
60
Iload = 3 A, TA = 125°C
VAnode to Cathode = -13.5 V
ILKG
Iq
Reverse Leakage Current
Quiescent Current to GND
Current into Anode pin
110(2)
µA
µA
µA
0
IAnode
Current into Anode pin when VAnode -
Cathode = 0.3V.
30
(2) Limit applies over the full Operating Temperature Range TA = -40°C to +125°C.
30 mV
VANODE > VCATHODE
VCATHODE > VANODE
0 mV
-20 mV
tTRECOVERY
t
VGATE
0 V
Figure 1. Gate Shut Down Timing in the Event of Reverse Polarity
Copyright © 2015, Texas Instruments Incorporated
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LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
www.ti.com.cn
6.6 Typical Characteristics
300
0.465
0.46
V_Reverse = 13.5 V
V_Reverse = 37 V
250
200
150
100
50
0.455
0.45
0.445
0.44
0.435
-40
-20
0
20
40
60
80
100 120 140
-40
-20
0
20
40
60
80
100 120 140
Temperature (èC)
Temperature (èC)
D001
D002
Figure 2. Reverse Leakage at Negative Voltages
Figure 3. Anode to Cathode Startup Voltage
3.25
3
6.5
6.25
6
VCAP H
VCAP L
2.75
2.5
2.25
2
5.75
5.5
5.25
5
-40
-20
0
20
40
60
80
100 120 140
-40
-20
0
20
40
60
80
100 120 140
Temperature (°C)
Temperature (èC)
D009
D003
Figure 4. Reverse Recovery Time (TRecovery
)
Figure 5. VcapH and VcapL Voltage Threshold
100
90
80
70
60
50
40
30
20
10
0
100
80
60
40
20
0
-40èC
25èC
85èC
125èC
-40èC
25èC
85èC
125èC
-20
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
Current (A)
1
0
1
2
3
4
5
6
7
8
9
10
Current (A)
D005
D004
Figure 6. Duty Cycle of the Output Voltage at Startup
Figure 7. Duty Cycle of the Output Voltage
6
Copyright © 2015, Texas Instruments Incorporated
LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
7 Detailed Description
7.1 Overview
Using N-Channel MOSFETs with controller ICs can be highly effective and more efficient substitutes of lossy
diodes in a bridge rectifier application. The LM74670-Q1 is designed to control a single N-Channel MOSFET in a
full or half bridge rectifier as replacement for diode. In a full bridge rectifier, each diode can be replaced by the
LM74670-Q1 and a MOSFET. Diodes used in bridge rectifiers cause high power losses associated with the
forward voltage drop of each diode. In each cycle of sinusoidal AC voltage, two diodes conduct at the same time.
Power losses during diode forward conduction increase as the output current increases. Diode rectification also
increases peak current for applications that require high value output capacitance due to charge and discharge
with the diode drop voltage. The ON state forward voltage loss in a MOSFET depends upon the RDSON of the
MOSFET. The power losses become substantially lower than diodes for the equivalent current. This solution has
a small increase in complexity; however it eliminates the need for diode heatsinks and thermal management for
high power AC bridge rectifier applications.
The LM74670-Q1 is a zero Iq controller that is combined with an external N-channel MOSFET to replace each
diode in a bridge rectifier. The voltage across the MOSFET source and drain is constantly monitored by the
LM74670-Q1 Anode and Cathode pins. An internal charge pump is used to provide the GATE drive for the
external MOSFET. The forward conduction is through the MOSFET 98% of the time. The forward conduction is
through the MOSFET body diode for 2% of time when energy is stored in an external charge pump capacitor
Vcap Figure 9. This stored energy is used to drive the gate of MOSFET. The voltage drop and power losses
depend on the RDSONof MOSFETs used to replace the rectifier diodes. The LM74670-Q1 has no ground
reference which makes it identical to a diode.
7.2 Functional Block Diagram
Input
Output
S
D
G
ANODE
GATE DRIVE GATE PULL DOWN
11.5 V
CATHODE
VCAP
L
LOGIC
Reverse Batt
Shut Off
VCAP
H
Charge
Pump
7.3 Feature Description
7.3.1 During T0
When power is initially applied, the load current (ID) will flow through the body diode of the MOSFET and produce
a voltage drop (Vf) during T0 in Figure 8. This forward voltage drop (Vf) across the body diode of the MOSFET is
used to charge up the charge pump capacitor Vcap. During this time, the charge pump capacitor Vcap is
charged to a higher threshold of 6.3V (typical).
Copyright © 2015, Texas Instruments Incorporated
7
LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
www.ti.com.cn
Feature Description (continued)
VOUT
Body Diode Voltage Drop
T0
tT1t
FET is ON
VGS
FET is OFF
0 V
Figure 8. Output Voltage and VGSOperation at 1A Output Current
7.3.2 During T1
Once the voltage on the capacitor reaches a higher voltage level of 6.3V (typical), the charge pump is disabled
and the MOSFET turns ON. The energy stored in the capacitor is used to provide the gate drive for the MOSFET
(T1 in Figure 8). When the MOSFET is ON, it provides a low resistive path for the drain current to flow and
minimizes the power dissipation associated with forward conduction. The power losses during the MOSFET ON
state depend primarily on the RDSON of the selected MOSFET and load current. At time when the capacitor
voltage reaches its lower threshold VcapL 5.15V (typical), the MOSFET gate turns OFF. The drain current ID will
then begin to flow through the body diode of the MOSFET, causing the MOSFET body diode voltage drop to
appear across Anode and Cathode pins. The charge pump circuitry is re-activated and begins charging the Vcap.
The LM74670-Q1 operation keeps the MOSFET ON at approximately 98% duty cycle (typical) regardless of the
external charge pump capacitor value. This is the key factor to minimizing the power losses. The forward voltage
drop during this time is limited by the RDSON of the MOSFET.
7.3.3 Pin Operation
7.3.3.1 Anode and Cathode Pins
The LM74670-Q1 Anode and Cathode pins are connected to the source and drain of the external MOSFET. The
current into the Anode pin is 30 µA (typical). When power is initially applied, the load current flows through the
body diode of the external MOSFET, the voltage across Anode and Cathode pins is equal to the forward diode
drop . The minimum value of diode voltage drop required to enable the charge pump circuitry is 0.48V. Once the
MOSFET is turned ON, the Anode and Cathode pins constantly sense the voltage difference across the
MOSFET to determine the magnitude and polarity of the voltage across it. When the MOSFET is on, the voltage
difference across Anode and Cathode pins depends on the RDSON and load current. If voltage difference across
source and drain of the external MOSFET becomes negative, this is sensed as a fault condition by Anode and
Cathode pins and gate is turned off by Gate Pull Down pin as shown in Figure 1. The reverse voltage threshold
across Anode and Cathode to detect the fault condition is -20 mV. The consistent sensing of voltage polarity
across the MOSFET enables the LM74670-Q1 to provide a fast response to the power source failure and limit
the amount and duration of the reverse current flow.
7.3.3.2 VcapH and VcapL Pins
VcapH and VcapL are high and low voltage thresholds respectively that the LM74670-Q1 uses to detect when to
turn the charge pump circuitry ON and OFF. The capacitor charging and discharging time can be correlated to
the duty cycle of the MOSFET gate. Figure 9 shows the voltage behavior across the Vcap. During the time
period T0, the capacitor is storing energy from the charge pump. The MOSFET is turned off and current flow is
only through the body diode during this time period. The conduction though body diode of the MOSFET is for a
8
Copyright © 2015, Texas Instruments Incorporated
LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
Feature Description (continued)
very small period of time (2% typical) which rules out the chances of overheating the MOSFET, regardless of the
output current. Once the capacitor voltage reaches its high threshold, the MOSFET is turned off and charge
pump circuity is deactivated until the Vcap reaches its low voltage threshold (T1). The voltage difference between
Vcap high and low threshold is typically 1.15V. The LM74670-Q1 charge pump has 46µA charging capability with
5-8MHz frequency.
VCAP
H
1.1 V
VCAP
L
VOUT
Body Diode Voltage Drop
T0
tT1t
Figure 9. Vcap Charging and Discarding by the Charge Pump
The Vcap current consumption is 0.95µA (typical) to drive the gate. The MOSFET OFF time (T0) and ON time
(T1) can be calculated using the following expression
dV
DT = C
dI
(1)
Where:
•
•
•
•
C = Vcap Capacitance
dV = 1.15V
dI = 46 µA for charging
dI = 0.95 µA for discharging
Note: Temperature dependence of these parameters – The duty cycle is dependent on temperature since the
capacitance variation over temperature has a direct correlation to the MOSFET OFF and ON periods and the
frequency. If the capacitor varies 20% the periods and the frequency will also vary by 20% so it is recommended
to use a quality X7R/COG cap and not to place the cap in close proximity to high temperature devices. The
variation of the capacitor does not have a thermal impact in the application as the duty cycle does not change.
7.3.3.3 Gate Drive Pin
When the charge pump capacitor is charged to the high voltage level of 6.3V (typ), the Gate Drive pin provides a
67µA (typ) of drive current. When the charge pump capacitor reaches its lower voltage threshold of 5.15V (typ),
Gate is pulled down to the Anode voltage (Vin). During the positive cycle of AC sinusoid, the MOSFET gate is
turned ON by the LM74670-Q1 gate drive to ensure the forward conduction through the MOSFET.
7.3.3.4 Gate Pull Down Pin
The Gate Pull Down pin of the LM74670-Q1 is connected to the Gate Drive pin in a bridge rectifier application.
When the controller detects negative polarity during the negative cycle of AC sinusoidal, the Pull-Down quickly
discharges the MOSFET gate through a discharge transistor. This fast pull down reacts regardless of the Vcap
charge level. When the negative voltage across the Anode and Cathode pins due to reverse current reaches
-20mV (typical), the LM74670-Q1 immediately reacts and discharges the MOSFET gate capacitance as shown in
Figure 10 . The Gate voltage is pulled down to Anode voltage with 160mA pull down current when the negative
Copyright © 2015, Texas Instruments Incorporated
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LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
www.ti.com.cn
Feature Description (continued)
cycle of the AC input starts. . A MOSFET with 4nF of effective gate capacitance can be turned off by the
LM74670-Q1 within 2.2µs (typical). The fast turnoff time minimizes the reverse current flow from MOSFET drain
by opening the circuit. The reverse leakage current does not exceed 110µA for a constant 13.5V reverse voltage
across Anode and Cathode pins. The reverse leakage current for a Schottky diode is 15mA under the same
voltage and temperature conditions.
Figure 10. Gate Pull Down in the Event of Reverse Polarity
7.4 Device Functional Modes
The LM74670-Q1 operates in two modes:
•
Body Diode Conduction Mode
The LM74670-Q1 solution works like a conventional diode during this time with higher forward voltage drop.
The power dissipation during this time can be given as:
PDissipation = V
ì I
ForwardDrop Drain Current
(2)
However, the current only flows through the body diode while the MOSFET gate is being charged to VGS(TH)
This conduction is only for 2% duty cycle, therefore it does not cause any thermal issues.
.
Cì(VcapH- VcapL)
Body Diode ON Time =
ICharge Current
(3)
•
The MOSFET Conduction Mode
The MOSFET is turned on during this time and current flow is only through the MOSFET. The forward voltage
drop and power losses are limited by the RDSON of the specific MOSFET used in the solution. The LM74670-
Q1 solution output is comprised of the MOSFET conduction mode for 98% of its duty cycle. This time period
is given by the following expression:
Cì(VcapH - VcapL)
MOSFET ON Time =
IDischarge Current
(4)
10
Copyright © 2015, Texas Instruments Incorporated
LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
Device Functional Modes (continued)
7.4.1 Duty Cycle Calculation
The LM74670-Q1 has an operating duty cycle of 98% at 25 C̊ and >90% at 125 C̊ . The duty cycle doesn’t
depend on the Vcap capacitance value. However, the variation in capacitance value over temperature has direct
correlation to the switching frequency between the MOSFET and body diode. If the capacitance value decreases,
the charging and discharging time will also decrease, causing more frequent switching between body diode and
the MOSFET condition. The following expression can be used to calculate the duty cycle of the LM74670-Q1:
(MOSFET ON Time)
Duty Cycle (%) =
ì100
(MOSFET ON Time + Body Diode ON Time)
(5)
7.4.2 Startup Voltage
The LM74670-Q1 will not initiate the charge pump operation if a closed loop system is in standby mode or the
drain current is smaller than 1mA (typical). This is due to a minimum body diode voltage requirement of the
LM74670-Q1 controller. If the drain current is too small to produce a minimum voltage drop of 0.48V at 25 ͦC, the
charge pump circuitry will remain off and the MOSFET will act just like a diode. It is very important to know the
body diode voltage parameter of a MOSFET before implementing it into the Smart Diode solution. Some N-
channels MOSFETs have very low body diode voltage at higher temperature. This makes their drain current
requirement higher to achieve 0.48V across the body diode in order to initiate the LM74670-Q1 controller at
higher temperatures.
Copyright © 2015, Texas Instruments Incorporated
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LM74670-Q1
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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 Typical Rectifier Application
The LM74670-Q1 can be used with appropriate N-channel MOSFET to replace a diode in a typical rectifier
application. The rectifier could be industrial for a 12/24AC supply or an automotive rectifier for a single phase or
three phase field winding controlled alternator. The schematic for a typical implementation is shown in Figure 11
to implement a full bridge rectifier. The same schematic can also be extended to six legs for a three phase
alternator rectification. Following considerations need to be made when selecting the appropriate MOSFET for
this application:
1. An input voltage of 24V AC can reach a 34V peak. The MOSFET selected should have a VDS greater than
this voltage.
2. The Continuous drain current of the MOSFET should be nearly 2.5X IAVG to cover peak currents during
rectification.
3. The VGS(TH) threshold voltage of the selected MOSFET should be ≤3V to ensure error-free operation.
+OUT
Q2
LM74670-Q1
Q3
LM74670-Q1
VCAP
L
VCAPH
VCAP
L
VCAPH
1 µF
1 µF
IN~
IN~
Q1
LM74670-Q1
Q4
LM74670-Q1
VCAP
L
VCAPH
VCAP
L
VCAPH
1 µF
1 µF
œOUT
Figure 11. Typical Full Bridge Rectifier Application
12
Copyright © 2015, Texas Instruments Incorporated
LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
Typical Rectifier Application (continued)
8.1.1 Design Requirements
For this design example, use the parameters listed in Table 1 as the input parameters
Table 1. Design Parameters
DESIGN PARAMETER
Input Voltage Range
Output Voltage
EXAMPLE VALUE
4 – 42V peak AC
rectified positive amplitude
Maximum Drain current of MOSFET
3V Max
Output current range
Threshold voltage of FET VGS(TH)
Vcap value
1µF
8.1.2 Detailed Design Procedure
To begin the design process, determine the following:
8.1.2.1 Design Considerations
•
•
•
•
Input voltage range
Output current range
Body Diode forward voltage drop for the selected MOSFET
MOSFET Gate threshold voltage
8.1.2.2 Capacitor Selection
A ceramic capacitor should be placed between VcapL and VcapH. The capacitor acts as a holding tank to power
up the control circuitry when the MOSFET is on.
When the MOSFET is off, this capacitor is charged up to higher voltage threshold of ~6.3V. Once this voltage is
reached, the Gate Drive of LM74670-Q1 will provide drive for the external MOSFET. When the MOSFET is ON,
the voltage across its body diode is collapsed because the forward conduction is through the MOSFET. During
this time, the capacitor acts as a supply for the Gate Drive to keep the MOSFET ON.
The capacitor voltage will gradually decay when the MOSFET is ON. Once the capacitor voltage reaches a lower
voltage threshold of 5.15V, the MOSFET is turned off and the capacitor gets recharged again for the next cycle.
A capacitor value of 220nF to 2.2uF with X7R/COG characteristic and 16V rating or higher is recommended for
this application. A higher value capacitor sets longer MOSFET ON time and OFF time; however, the duty cycle
remains at ~98% for MOSFET ON time irrespective of capacitor value.
If the Vcap value is 1µF, the MOSFET ON time and OFF time can be calculated using Equation 1 :
MOSFET ON Time = (1µF x 1.15V)/0.95µA = 1.21 seconds
Body Diode ON Time = (1µF x 1.15V)/46µA = 25 miliseconds
(6)
(7)
The duty cycle can be calculated using Equation 5 :
Duty Cycle % = 1.21 sec / (1.21 sec + 0.025sec) = 98%
(8)
8.1.2.3 MOSFET Selection
The important MOSFET electrical parameters are the maximum continuous Drain current ID, the maximum drain-
to-source voltage VDS(MAX), the gate-to-source threshold voltage VGS(TH) and the drain-to-source On resistance
RDSON. The maximum continuous drain current, ID, rating must exceed the maximum continuous load current.
The rating for the maximum current through the body diode, IS, is typically rated the same as, or slightly higher
than the drain current, but body diode current only flows for a small period while the MOSFET gate is being
charged to VGS(TH).The LM74670-Q1 can provide up to 5V VGS to drive the external MOSFET, therefore the VGS
threshold of the selected MOSFET must be ≤ 3V.
Copyright © 2015, Texas Instruments Incorporated
13
LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
www.ti.com.cn
The voltage across the MOSFET's body diode must be higher than 0.48V at low current. The body diode voltage
for MOFETS typically decreases as the ambient temperature increases. This will increase the source current
requirement to achieve the minimum body diode drain-to-source voltage for the charge pump to initiate. The
maximum drain-to-source voltage, VDS(MAX), must be high enough to withstand the highest differential voltage
seen in the application. This would include any anticipated fault conditions. Although there are no positive VDS
limitation. However, it is recommended to use MOSFETS with voltage rating up to 45V for automotive
applications, since the LM74670-Q1 has a reverse voltage limit of -45V. Table 2 shows the examples of
recommended MOSFETs to be used with the LM74670-Q1.
8.1.3 Application Curves
In the following plots, the input voltage is 20V AC. The output current is 5A for all frequencies.
VIN (5 V/DIV)
VGS of Q1 (5 V/DIV)
VOUT (5 V/DIV)
Time (5 ms/DIV)
Figure 12. Response to 60Hz AC Input
VIN (5 V/DIV)
VGS of Q1 (5 V/DIV)
VOUT (5 V/DIV)
Time (5 ms/DIV)
Figure 13. Response to 100Hz AC Input
14
Copyright © 2015, Texas Instruments Incorporated
LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
VIN (5 V/DIV)
VGS of Q1 (5 V/DIV)
VOUT (5 V/DIV)
Time (2 ms/DIV)
Figure 14. Response to a 300Hz AC Input
Copyright © 2015, Texas Instruments Incorporated
15
LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
www.ti.com.cn
8.2 Design Requirements
NOTE
Startup voltage is the voltage drop is needed for the controller to turn ON. It directly
influences the Minimum output current at which the MOSFET turns ON.
Table 2. Recommended MOSFET Examples(1)
Diode
Voltage
@ 2A at
Voltage Drain
Vgs
Threshold
(V)
Rdson
mΩ @ 4.5V
Part No
(V)
Current
Package; Footprint
Qual
Current at 25C
125C/175C
CSD17313Q2Q1
SQJ886EP
30
40
40
40
40
40
40
60
60
60
40
60
40
5
60
29
23.5
12
30
22
40
12
23
20
45
50
26
5.5
5.6
6
1.8
2.5
2.5
2.5
2.5
2.5
2.3
2.5
2.5
2.2
2.2
3.3
2.2
0.65
0.5
SON; 2 x 2
Auto
PowerPAK SO-8L; 5 x 6
SO-8; 5 x 6
Auto
SQ4184EY
0.5
Auto
Si4122DY
0.5
SO-8; 5 x 6
Auto
RS1G120MN
RS1G300GN
CSD18501Q5A
SQD40N06-14L
SQ4850EY
20.7
2.5
3.3
17
0.6
HSOP8; 5 x 6
Auto
0.5
HSOP8; 5 x 6
Auto
0.53
0.5
SON; 5 x 6
Industrial
Auto
TO-252; 6 x 10
SO-8; 5 x 6
31
0.55
0.53
0.48
0.55
0.50
Auto
CSD18532Q5B
IPG20N04S4L-07A
IPB057N06N
IPD50N04S4L
3.3
7.2
5.7
7.3
SON;5 x 6
Industrial
Auto
PG-TDSON-8-10; 5 x 6
PG-TO263-3; 10 x 15
PG-TO252-3-313; 6 x10
Auto
Auto
LFPAK56; Power-SO8
(SOT669); 5 x 6
BUK9Y3R5-40E
40
100
3.8
2.1
0.48
Auto
IRF7478PbF-1
SQJ422EP
IRL1004
60
40
40
40
7
30
4.3
6.5
2.2
3
2.5
1
0.55
0.50
0.60
0.65
SO-8; 5 x 6
Industrial
Auto
75
PowerPAK SO-8L; 5 x 6
TO-220AB
130
112
Auto
AUIRL7736
3
DirectFET®; 5 x 6
Auto
(1) The LM74670-Q1 solution is not limited to the MOSFETs included in this table. It only shows examples of compatible MOSFETs.
16
Copyright © 2015, Texas Instruments Incorporated
LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
9 Power Supply Recommendations
While testing the LM74670-Q1 solution, it is important to use low impedance power supply which allows current
sinking. If the power supply does not allow current sinking, it would prevent the current flow in the reverse
direction in the event of reverse polarity. The MOSFET gate won't get pulled down immediately due to the
absence of reverse current flow.
10 Layout
10.1 Layout Guidelines
•
The VIN terminal is recommended to have a low-ESR ceramic bypass-capacitor. The typical recommended
bypass capacitance is a 10-μF ceramic capacitor with a X5R or X7R dielectric.
•
•
•
•
The VIN terminal must be tied to the source of the MOSFET using a thick trace or polygon.
The Anode pin of the LM74670-Q1 is connected to the Source of the MOSFET for sensing.
The Cathode pin of the LM74670-Q1 is connected to the drain of the MOSFET for sensing.
The high current path of for this solution is through the MOSFET, therefor it is important to use thick traces for
source and drain of the MOSFET.
•
•
•
The charge pump capacitor Vcap must be kept away from the MOSFET to lower the thermal effects on the
capacitance value.
The Gate Drive and Gate pull down pins of the LM74670-Q1 must be connected to the MOSFET gate without
using vias.
Obtaining acceptable performance with alternate layout schemes is possible, however this layout has been
shown to produce good results and is intended as a guideline.
版权 © 2015, Texas Instruments Incorporated
17
LM74670-Q1
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
www.ti.com.cn
10.2 Layout Example
1. VcapL
2. PullDown
3. NC
8. Cathode
7. VcapH
6. Gate Drive
5. NC
4. Anode
Figure 15. Layout Example
18
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LM74670-Q1
www.ti.com.cn
ZHCSGN3A –SEPTEMBER 2015–REVISED OCTOBER 2015
11 器件和文档支持
11.1 社区资源
下列链接提供到 TI 社区资源的连接。链接的内容由各个分销商“按照原样”提供。这些内容并不构成 TI 技术规范,
并且不一定反映 TI 的观点;请参阅 TI 的 《使用条款》。
TI E2E™ 在线社区 TI 的工程师对工程师 (E2E) 社区。此社区的创建目的在于促进工程师之间的协作。在
e2e.ti.com 中,您可以咨询问题、分享知识、拓展思路并与同行工程师一道帮助解决问题。
设计支持
TI 参考设计支持 可帮助您快速查找有帮助的 E2E 论坛、设计支持工具以及技术支持的联系信息。
11.2 商标
E2E is a trademark 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
以下页面包括机械、封装和可订购信息。这些信息是指定器件的最新可用数据。这些数据发生变化时,我们可能不
会另行通知或修订此文档。如欲获取此产品说明书的浏览器版本,请参阅左侧的导航栏。
版权 © 2015, Texas Instruments Incorporated
19
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
(1)
(2)
(3)
(4/5)
(6)
LM74670QDGKRQ1
LM74670QDGKTQ1
ACTIVE
ACTIVE
VSSOP
VSSOP
DGK
DGK
8
8
2500 RoHS & Green
250 RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
Level-2-260C-1 YEAR
-40 to 125
-40 to 125
ZGPK
ZGPK
NIPDAUAG
(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 MATERIALS INFORMATION
www.ti.com
17-Jul-2020
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
LM74670QDGKRQ1
LM74670QDGKTQ1
VSSOP
VSSOP
DGK
DGK
8
8
2500
250
330.0
330.0
12.4
12.4
5.3
5.3
3.4
3.4
1.4
1.4
8.0
8.0
12.0
12.0
Q1
Q1
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
17-Jul-2020
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
LM74670QDGKRQ1
LM74670QDGKTQ1
VSSOP
VSSOP
DGK
DGK
8
8
2500
250
366.0
366.0
364.0
364.0
50.0
50.0
Pack Materials-Page 2
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