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Preliminary
RT9703
80m, 3A Smart Universal Power Switch with Flag
General Description
The RT9703 is a low voltage, high performance single N-Channel MOSFET power switch, designed for power rail on/off control with low R DS(ON) 80m and full dd protection functions. The RT9703 equipped with a charge pump circuitry to drive the internal MOSFET switch and a flag output is available to indicate fault conditions against large di/dt which may cause the supply to fall out of regulation. In order to fit different application, an IP pin is offered for current limit point setting, a resistor from IP to ground sets the current limit for the switch. Additional features include soft-start to limit inrush current during plug-in, thermal shutdown to prevent catastrophic switch failure from high-current loads, under-voltage lockout (UVLO) to ensure that the device remains off unless there is a valid input voltage present, a precision resistor-programmable output current limit up to 3.5A. Besides, the lower quiescent current as 30A making this device ideal for portable battery-operated equipment. The RT9703 is available in SOP-8 package requiring minimum board space and smallest components.
Features
Adjustable Current Limiting Up To 3.5A Built-In (Typically 80m) N-Channel MOSFET Reverse Current Flow Blocking (no body diode) i.e. Output Can Be Forced Higher Than Input (Off-State) Low Supply Current: 30A Typical at Switch On State Less Than 1A Typical at Switch Off State Guaranteed 3A Continuous Load Current Wide Input Voltage Ranges: 2V to 5.5V Open-Drain Fault Flag Output Hot Plug-In Application (Soft-Start) 1.7V Typical Under-Voltage Lockout (UVLO) Thermal Shutdown Protection Smallest SOP-8 Package Minimizes Board Space
Applications
LCD Monitor, LCD-TV USB Power Module for ADSL Information Appliance and Set-Top Box Battery-Powered Equipment Hot-Plug Power Supplies ACPI Power Distribution PCI Bus Power Switching Motherboard & Notebook PCs PC Card Hot Swap Application
Ordering Information
RT9703 Package Type S : SOP-8 Operating Temperature Range C : Commercial Standard
Pin Configurations
(TOP VIEW)
FLG VOUT VOUT GND 2 3 4 8 7 6 5 IP VIN VIN CE
SOP-8
DS9703-00 September 2003 1
RT9703
Typical Application Circuit
Preliminary
Pull-Up Resistor (10K to 100K) Supply Voltage
VIN
+
FLG RT9703 IP RSET
Fault Flag
10uF
ON OFF
CE
VOUT GND 33uF
+
Peripheral
Functional Pin Description
Pin Name VIN VOUT GND CE FLG IP Pin Function Supply Input Switch Output Common Ground Chip Enable Control Input Open-Drain Fault Flag Output Current Limit Programming Input
Function Block Diagram
VIN
+
-
CE
Bias
UVLO
+
IP VREF
Oscillator
Charge Pump
Gate Control Output Voltage Detection
Thermal Protection
VOUT
FLG Delay
2
Preliminary Test Circuits
1
ISUPPLY VIN RFG
RT9703
ISUPPLY
2
+
A
VIN
FLG ILEAKAGE
A
CIN
VIN
FLG
RT9703 VOUT
S1 IOUT
VFLG VOUT
VIN
CIN
RT9703 VOUT
ON OFF
+
ON OFF
A
RL RSET
CE
CE GND
A
COUT RSET
GND IP
+
IP
RL
IL
3
VRDS(ON)
4
RFG
V
IOUT VIN VOUT
+
VIN
VIN
CIN
RT9703 FLG CE GND IP
COUT
VIN
CIN
FLG VOUT COUT IP
VFLG
+
VOUT IL
Note: Above test circuits reflected the graphs shown on "Typical Operating Characteristics" are as follows: 1-Turn-On Rising & Turn-Off Falling Time vs. Temperature, Turn-On & Off Response, Flag Response at Chip Enable, Flag Response (Enable into Current Limit) 2-On-State & Off-State Supply Current vs. Input Voltage/Temperature, Turn-Off Leakage Current vs. Temperature 3-On-Resistance vs. Input Voltage/Temperature 4-CE Threshold Voltage vs. Input Voltage/Temperature, Flag Delay Time vs. Input Voltage/Temperature, UVLO Threshold vs. Temperature, UVLO at Rising & Falling 5-Current Limit vs. Input Voltage/Temperature/RSET, Current Limit Factor vs. RSET, Short Circuit Current vs. Input Voltage, Inrush Current Response, Soft-Start Response, Current-Limit & Short Circuit with Thermal Shutdown, Short-Circuit Response
+
+
RT9703 CE
RL
RSET
VCE
GND
RSET
5
S2 CIN VIN FLG RT9703 VOUT CE GND IP RSET COUT
+ +
IOUT
VOUT
VIN
A
S3 RL IL
3
RT9703
Absolute Maximum Ratings
Preliminary
(Note 1)
Supply Voltage --------------------------------------------------------------------------------------------------------- 6.5V Chip Enable Input Voltage ------------------------------------------------------------------------------------------ -0.3V to 6.5V Flag Voltage ------------------------------------------------------------------------------------------------------------ 6.5V Power Dissipation, PD @ TA = 25C SOP-8 -------------------------------------------------------------------------------------------------------------------- 0.95W Package Thermal Resistance SOP-8, JA -------------------------------------------------------------------------------------------------------------- 104 C/W Junction Temperature ------------------------------------------------------------------------------------------------ 125C Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260C Storage Temperature Range --------------------------------------------------------------------------------------- -65C to 150C ESD Susceptibility (Note 2) HBM (Human Body Mode) ----------------------------------------------------------------------------------------- 8kV MM (Machine Mode) ------------------------------------------------------------------------------------------------- 800V
Recommended Operating Conditions
(Note 3)
Supply Input Voltage ------------------------------------------------------------------------------------------------- 2V to 5.5V Chip Enable Input Voltage ------------------------------------------------------------------------------------------ 0V to 5.5V Junction Temperature Range -------------------------------------------------------------------------------------- -20C to 100C
Electrical Characteristics
(VIN = 5V, CIN = COUT = 1F, TA = 25C, unless otherwise specified)
Parameter Switch On Resistance Supply Current
Symbol RDS(ON) ISW_ON ISW_OFF
Test Conditions IOUT = 3A (Note 8) Switch On, VOUT = Open Switch Off, VOUT = Open Switch Off Switch On VCE = 0V to 5.5V VCE = 0V, RLOAD = 0 10% to 90% of VOUT rising ILIM x RSET VIN = 3.3V to 5.5V, RSET = 51.4k ILIMSET = 0.5A to 3A (RSET = 360k to 60k) ISINK = 1mA Form fault condition to FLG assertion VIN increasing VIN decreasing
Min ----2.0 ------20 --2 1.3 --
Typ 80 30 0.1 --0 0.5 1.5 180k --15 0.01 4.6 1.7 0.1
Max 100 50 1 0.8 --10 --3.5 +20 400 1 8 ---
Units m A V V A A mS A A % A ms V V
CE Threshold Logic-Low Voltage VIL (Note 7) Logic-High Voltage VIH CE Input Current Output Leakage Current Output Turn-On Rise Time Current Limit Factor (Note 5) Max. Current Limit Setting (Note 6) ILIMSET Current Limit Setting Accuracy FLAG Output Resistance FLAG Off Current FLAG Delay Time (Note 4) Under-Voltage Lockout Under-Voltage Hysteresis ILIMSET RFLG tD VUVLO VUVLO ICE ILEAKAGE TON_RISE
IFLG_OFF VFLG = 5V
4
Preliminary
Parameter Thermal Shutdown Protection Thermal Shutdown Hysteresis Symbol TSD TSD Test Conditions Min --Typ 130 10
RT9703
Max --Units C C
Note 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 in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Note 2. Devices are ESD sensitive. Handling precaution recommended. The human body model is a 100pF capacitor discharged through a 1.5k resistor into input and output pins. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. The FLAG delay time is input voltage dependent, see "Typical Operating Characteristics" graph for further details. Note 5. Current limit is determined by: ILIMIT = 180k/RSET, where RSET is in ohms. Note 6. It is important to note that the maximum current limit value shall be set properly in accordance with its supply voltage otherwise which it may result in the failure occurrence. See "Maximum Current Limit vs. Supply Voltage" graph shown on the applications information section for further details. Note 7. For input voltage lower than 5V, the threshold level will subject to 0.6V deviation throughout the operating junction temperature range. Refer to the "Typical Operating Characteristics" graph for further details. Note 8. RDS(ON) is measured at constant junction temperature by using a 1ms current pulse.
5
RT9703
2
Preliminary
Typical Operating Characteristics
On-State Supply Current vs. Input Voltage
50 45 40 35 30 25 20 15 10 1.5 2 2.5 3 3.5 4 4.5 5 5.5
2
Off-State Supply Current vs. Input Voltage
2 1.5 1 0.5 0 -0.5 -1 -1.5 -2 1.5 2 2.5 3 3.5 4 4.5 5 5.5
VCE = 5V CIN = 10uF RL = Open RSET = 100k
VCE = 5V CIN = 10uF COUT = 33uF RL = Open RSET = 100k
Input Voltage (V)
Input Voltage (V)
2
On-State Supply Current vs. Temperature
50 45 40 35 30 25 20 15 10 -40 -20 0 20 40 60 80 100 120
2
Off-State Supply Current vs. Temperature
2 1.5 1 0.5 0 -0.5 -1 -1.5 -2
VIN = VCE = 5V CIN = 10uF COUT = 33uF RL = Open RSET = 100k
VIN = 5V, VCE = 0V CIN = 10uF COUT = 33uF RL = Open RSET = 100k
Temperature (C)
-40
-20
0
20
40
60
80
100
120
Temperature (C)
5
2.1
Current Limit vs. Input Voltage
CIN = 10uF, COUT = 33uF RL = 0.5, RSET = 100k
2
5
2.1
Current Limit vs. Temperature
VIN = 5V CIN = 10uF, COUT = 33uF RL = 0.5 , RSET = 100k S2 = ON, S3 = OFF
S2 = ON, S3 = OFF
2
1.9
1.9
1.8
1.8
1.7
1.7
1.6 2 2.5 3 3.5 4 4.5 5 5.5
1.6 -40 -20 0 20 40 60 80 100 120
Input Voltage (V)
Temperature (C)
6
Preliminary
5
4
RT9703
Current Limit Factor vs. RSET
12 10 8 6 4 2 0 -2 -4 -6 -8 -10
Current Limit vs. RSET
VIN = 5V, RL = 0.5
3.5 3 2.5 2 1.5 1 0.5 0 50 100 150 200 250 300 350 400 450 500
5
CIN = 10uF, COUT = 33uF S2 = ON, S3 = OFF
VIN = 5V, RL = 0.5 CIN = 10uF, COUT = 33uF S2 = ON, S3 = OFF
50 100 150 200 250 300 350 400
RSET (k )
3
70 69 68 67 66 65 64 63 62 2 2.5 3 3.5 4 4.5 5 5.5 48 -40 -20 0 58 68
RSET (K)
3
88
On-Resistance vs. Input Voltage
IOUT = 0.5A, RSET = 50k CIN = 10uF, COUT = 33uF
On-Resistance vs. Temperature
IOUT = 0.5A, RSET = 50k CIN = 10uF, COUT = 33uF
78
VIN = 5V
20
40
60
80
100
120
Input Voltage (V)
Temperature (C)
5
5
Short Circuit Current Response
VIN = 5V, CIN = 10uF, COUT = 0.1uF RSET = 150k, S2 = S3 = ON
Inrush Current Response
COUT = 1000uF VOUT COUT = 470uF
COUT = 1uF IOUT VIN = 5V, CIN = 10uF RL = 0.5, RSET = 150k, S2 = ON, S3 = OFF
Time (10ms/Div)
Time (5ms/Div)
7
RT9703
4
2.4 2 1.6 1.2 0.8 0.4 0 2 2.5 3 3.5 4 4.5 5
Preliminary
4
CE Threshold Voltage vs. Input Voltage
CIN = 10uF, COUT = 33uF IL = 100mA, RSET = 100k
CE Threshold Voltage vs. Temperature
2.4 2 1.6 1.2 0.8 0.4 0
VIN = 5V, IL = 100mV CIN = 10uF, COUT = 33uF RSET = 100k
5.5
-40
-20
0
20
40
60
80
100
120
Input Voltage (V)
Temperature (C)
1
4 3.5 3 2.5 2 1.5 1 0.5 0 -40
Turn-On Rising Time vs. Temperature
VIN = VCE = 5V CIN = 10uF, COUT = 1uF RL = 30, RSET = 200k S1 = ON
1
Turn-Off Falling Time vs. Temperature
6 5 4 3 2 1 0
VIN = 5V, VCE = 0V CIN = 10uF, COUT = 1uF RL = 30, RSET = 200k S1 = ON
-20
0
20
40
60
80
100
120
-40
-20
0
20
40
60
80
100
120
Temperature (C)
2
Temperature( C)
4
10
Turn-Off Leakage Current vs. Temperature
0.3 0.2 0.1
Flag Dealy Time vs. Input Voltage
VCE = 5V CIN = 10uF, COUT = 33uF
8
VIN = 5V, VCE = 0V CIN = 10uF, COUT = 33uF RL = 0, RSET = 100k
RL = 0.5, RSET = 100k RFG = 1k
6
0
4
-0.1 -0.2 -0.3 -40 -20 0 20 40 60 80 100 120
2
0 2 2.5 3 3.5 4 4.5 5 5.5
Temperature(C)
Input Voltage (V)
8
Preliminary
4
9
RT9703
UVLO Threshold vs. Temperature
3.5 3 2.5 2 1.5 1
Flag Delay Time vs. Temperature
VIN = VCE = 5V CIN = 10uF, COUT = 33uF
8
4
CIN = 10uF, COUT = 33uF RL = 1k, RSET = 100k
RL = 0.5, RSET = 100k RFG = 1k
7
6
5
0.5
4 -40 -20 0 20 40 60 80 100 120
0 -40 -20 0 20 40 60 80 100 120
Temperature (C)
Temperature( C)
1
Turn-On Response
1
VCE
Turn-Off Response
VCE VOUT
IL VIN = 5V VOUT CIN = 10uF, COUT = 1uF RL = 33, RSET = 200k S1 = ON
VIN = 5V CIN = 10uF, COUT = 1uF RL = 30, RSET = 200k S1 = OFF
Time (250us/Div)
Time (100us/Div)
4
UVLO at Rising
4
VIN VOUT
UVLO at Falling
VIN = VCE = 5V CIN = 1000uF, COUT = 1uF RL = 30, RSET = 200k
VIN VOUT VIN = VCE = 5V CIN = 1000uF, COUT = 1uF RL = 30, RSET = 200k
Time (1ms/Div)
Time (25ms/Div)
9
RT9703
1
Preliminary
1
FLAG Response (Enable into Current Limit)
FLAG Response at Chip Enable
VCE
VCE VFLG VFLG VOUT IL (1A/Div) VIN = 5V CIN = 1uF, COUT = 33uF RL = 0.5, RSET = 150k RFG = 1k, S1 = OFF IL (0.5A/Div) VIN = 5V CIN = 1uF, COUT = 33uF RL = 0.5, RSET = 350k RFG = 1k, S1 = OFF
Time (1ms/Div)
Time (10ms/Div)
5
Current Limit with Thermal Shutdown
VIN = 5V CIN = 10uF COUT = 33uF VCE RL = 0.5, RSET = 100k S2 = ON, S3 = OFF
5
Short- Circuit with Thermal Shutdown
VIN = 5V, CIN = 10uF, COUT = 33uF RSET = 100k, S2 = ON, S3 = ON
VTRIGGER
IL (1A/Div)
IL (0.5A/Div)
Time (50ms/Div)
Time (10ms/Div)
5
Soft-Start Response
VCE
VOUT
IL VIN = 5V, RL = 0.5, CIN = 10uF, COUT = 1uF S2 = OFF ON, S3 = OFF
Time (2ms/Div)
10
Preliminary Applications Information
The RT9703 is a high-side, N-Channel, power switch available with active-high enable input. Low RDS(ON)dd 80m and full protection functions make it optimized to replace complex discrete on/off control circuitry. Input and Output VIN (input) is the power source connection to the internal circuitry and the drain of the MOSFET. VOUT (output) is the source of the MOSFET. In a typical application, current flows through the switch from VIN to VOUT toward the load. If VOUT is greater than VIN, current will flow from VOUT to VIN since the MOSFET is bidirectional when on. Unlike a normal MOSFET, there is no a parasitic body diode between drain and source of the MOSFET, the RT9703 prevents reverse current flow if VOUT being externally forced to a higher voltage than VIN when the output disabled (VCE < 0.8V). Fault Flag
RT9703
The RT9703 provides a FLG signal pin which is an N-Channel open drain MOSFET output. This open drain output goes low when VOUT < VIN -1V, current limit or the die temperature exceeds 130C approximately. The FLG output is capable of sinking a 10mA load to typically 150mV above ground. The FLG pin requires a pull-up resistor, this resistor should be large in value to reduce energy drain. A 100k pull-up resistor works well for most applications. In the case of an over-current condition, FLG will be asserted only after the flag response delay time, tD, has elapsed. This ensures that FLG is asserted only upon valid over-current conditions and that erroneous error reporting is eliminated. For example, false over-current conditions may occur during hot-plug events when a highly large capacitive load is connected and causes a high transient inrush current that exceeds the current limit threshold. The FLG response delay time tD is typically 4.6ms. Under-Voltage Lockout
D
S
D
S
G Normal MOSFE T
G RT9704
Chip Enable Input The switch will be disabled when the CE pin is in a logic low condition. During this condition, the internal circuitry and MOSFET are turned off, reducing the supply current to 0.1A typically. The maximum guaranteed voltage for a logic low at the CE pin is 0.8V. A minimum guaranteed voltage of 2V at the CE pin will turn the RT9703 back on. Floating the input may cause unpredictable operation. CE should not be allowed to go negative with respect to GND. The CE pin may be directly tied to VIN to keep the part on. Soft-Start for Hot Plug-In Applications In order to eliminate the upstream voltage droop caused by the large inrush current during hot-plug events, the "soft-start" feature effectively isolates the power source from extremely large capacitive loads.
Under-Voltage lockout (UVLO) prevents the MOSFET switch from turning on until input voltage exceeds approximately 1.7V. If input voltage drops below approximately 1.3V, UVLO turns off the MOSFET switch, FLG will be asserted accordingly. Under- Voltage detection functions only when the chip enable input is enabled. Current Limiting and Short-Circuit Protection The current limit circuitry prevents damage to the MOSFET switch and external load. It is user adjust- able with an external set resistor, RSET, ILIMIT = 180k/RSET in the range of 500mA to 3.5A. The accuracy of current limit set point may vary with operating temperature and supply voltage. See "Typical Operating Characteristics" graph for further details.
11
RT9703
Preliminary
the junction temperature does not exceed 100C. With all possible conditions, the junction temperature must be within the range specified under operating conditions. Power dissipation can be calculated based on the output current and the RDS(ON) of switch as below. PD = RDS(ON) x IOUT2 Although the devices are rated for 3A of output current, but the application may limit the amount of output current based on the total power dissipation and the ambient temperature. The final operating junction temperature for any set of conditions can be estimated by the following thermal equation: PD (MAX) = ( TJ (MAX) - TA ) / JA Where TJ (MAX) is the maximum junction temperature of the die (100 C) and T A is the maximum ambient temperature. The junction to ambient thermal resistance (JA) for SOP-8 package at recommended minimum footprint is 104C/W (JA is layout dependent). Supply Filter/Bypass Capacitor A 10F low-ESR ceramic capacitor from VIN to GND (the amount of the capacitance may be increased without limit), located at the device is strongly recommended to prevent the input voltage drooping during hot-plug events. However, higher capacitor values will further reduce the voltage droop on the input. Furthermore, without the bypass capacitor, an output short may cause sufficient ringing on the input (from source lead inductance) to destroy the internal control circuitry. An important note to be award of is the parasitic inductance of PCB traces can cause over-voltage transients if the PCB trace has even a few tens of nH of inductance. It is recommended to use aluminum electrolytic acted the supply capacitor to prevent the device from being damaged. The input transient must not exceed 6.5V of the absolute maximum supply voltage even for a short duration.
The normal current limit value, ILIMIT, is set with an external resistor between IP (pin 8) and GND (pin 4). When a heavy load or short circuit is applied to an enabled switch, a large transient current may flow until the current limit circuitry responds. Once this current limit threshold is exceeded, the device enters constant current mode until the thermal shutdown occurred or the fault is removed. It is important to note that the maximum current limit value shall be set properly in accordance with its supply voltage otherwise it may result in the failure occurrence. The graph below shows the maximum current limit and supply voltage on the safe operation area.
Maximun Current Limit vs. Supply Voltage
5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 2 2.5 3 3.5 4 4.5 5 5.5
TA = 25C
Supply Voltage (V)
Thermal Shutdown Thermal shutdown is employed to protect the device from damage if the die temperature exceeds approxi- mately 130C. If enabled, the switch automatically restarts when the die temperature falls 10C. The output and FLG signal will continue to cycle on and off until the device is disabled or the fault is removed. Power Dissipation The device's junction temperature depends on several factors such as the load, PCB layout, ambient temperature and package type. The output pin of RT9703 can deliver a current of up to 3A over the full operating junction temperature range. However, the maximum output current must be derated at higher ambient temperature to ensure
12
Preliminary
Fault Flag Filtering (Optional) The transient inrush current to downstream capacitance may cause a short-duration error flag, which may cause erroneous over-current reporting. A simple 1ms RC lowpass filter (10k and 0.1F) in the flag line eliminates short-duration transients.
,3
RT9703
*1'
9,1
&(
PCB Layout In order to meet the voltage drop, droop, and EMI requirements, careful PCB layout is necessary. The following guidelines must be considered: Keep all input and output traces as short as possible and use at least 150-mil, 2 ounce copper for all races. Avoid vias as much as possible. If vias are necessary, make them as large as feasible. Place a ground plane under all circuitry to lower both resistance and inductance and improve DC and transient performance (Use a separate ground and power plans if possible). Locate the bypass capacitors as close as possible to the input and output pin of the RT9703.
Board Layout
*1' )/* 9287
*1'
13
RT9703
Outline Dimension
Preliminary
A
H M
J
B
F
C I D
Symbol A B C D F H I J M
Dimensions In Millimeters Min 4.801 3.810 1.346 0.330 1.194 0.178 0.102 5.791 0.406 Max 5.004 3.988 1.753 0.508 1.346 0.254 0.254 6.198 1.270
Dimensions In Inches Min 0.189 0.150 0.053 0.013 0.047 0.007 0.004 0.228 0.016 Max 0.197 0.157 0.069 0.020 0.053 0.010 0.010 0.244 0.050
8-Lead SOP Plastic Package
RICHTEK TECHNOLOGY CORP.
Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
RICHTEK TECHNOLOGY CORP.
Taipei Office (Marketing) 8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com 14

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