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Preliminary
RT9188
Dual, Ultra-Low Quiescent, 100mA CMOS LDO Regulator
General Description
The RT9188 series are an efficient, precise dual-channel CMOS LDO regulator optimized for ultra-low-quiescent applications. Both regulator outputs are capable of sourcing 100mA of output current. The RT9188's performance is optimized for batterypowered systems to deliver extremely low dropout voltage and ultra-low quiescent current. Regulator ground current increases only slightly in dropout, further prolonging the battery life. The RT9188 also works with low-ESR ceramic capacitors, reducing the amount of board space necessary for power applications, critical in hand-held wireless devices. Key features include current limit, thermal shutdown, faster transient response, ultra-low quiescent current (typically 8A), low dropout voltage, high output accuracy, current limiting protection, and high ripple rejection ratio. Available in the SOT-23-5 package, the RT9188 also offers a range of 1.2V to 5V with 0.1V per step.
Features
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Ultra-Low Quiescent Current (Typically 8A) Low Dropout : 450mV at 100mA Wide Operating Voltage Ranges : 2V to 6V Faster Transient Response Tight Load and Line Regulation Current Limiting Protection Thermal Shutdown Protection Only 1F Output Capacitor Required for Stability High Power Supply Rejection Ratio Custom Voltages Available RoHS Compliant and 100% Lead (Pb)-Free
Applications
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Cellular Phones and Pages Battery-Powered Equipment Laptop, Palmtops, Notebook Computers Hand-Held Instruments PCMCIA Card Wireless LAN Card/Keyboard/Mouse
Ordering Information
RT9188Package Type B : SOT-23-5 Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard Output Voltage 2 8 : 1.8V Output Voltage 1 K : 3.0V Other Voltage versions please contact RichTek for detail Note : RichTek Pb-free and Green products are : }RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. }Suitable for use in SnPb or Pb-free soldering processes. }100%matte tin (Sn) plating.
Marking Information
For marking information, contact our sales representative directly or through a RichTek distributor located in your area, otherwise visit our website for detail.
Pin Configurations
(TOP VIEW)
VOUT1 VDD NC 1 2 3 4 VOUT2 5 GND
SOT-23-5
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RT9188
Typical Application Circuit
VIN
Preliminary
VDD
VOUT1
CIN 1uF
RT9188
VOUT2 GND
VOUT1 COUT1 1uF VOUT2 COUT2 1uF
Function Block Diagram
VDD
Current Limit 2
Thermal Protector 2
Thermal Protector 1
Current Limit 1
+ VOUT2 VREF2 VREF1
+ VOUT1
GND
Functional Pin Description
Pin Name VDD VOUT1 VOUT2 GND NC Pin Function Supply Input Channel 1 Output Voltage Channel 2 Output Voltage Common Ground No Internal Connection
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Preliminary Absolute Maximum Ratings
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RT9188
(Note 1)
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Supply Input Voltage ------------------------------------------------------------------------------------------------ 7V Power Dissipation, PD @ TA = 25C SOT-23-5 --------------------------------------------------------------------------------------------------------------- 0.4W Package Thermal Resistance (Note 7) SOT-23-5, JA --------------------------------------------------------------------------------------------------------- 250C/W Junction Temperature ----------------------------------------------------------------------------------------------- 150C Lead Temperature (Soldering, 10 sec.)-------------------------------------------------------------------------- 260C Storage Temperature Range --------------------------------------------------------------------------------------- -65C to 150C ESD Susceptibility (Note 2) HBM (Human Body Mode) ----------------------------------------------------------------------------------------- 2kV MM (Machine Mode) ------------------------------------------------------------------------------------------------ 200V (Note 3)
Recommended Operating Conditions
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Supply Input Voltage ------------------------------------------------------------------------------------------------ 2V to 6V Junction Temperature Range -------------------------------------------------------------------------------------- -40C to 125C
Electrical Characteristics
(VDD = 5V, CIN = 1F, COUT = 1F, TA = 25 C, for each LDO unless otherwise specified)
Parameter Output Voltage Accuracy Current Limit Quiescent Current (both LDOs) (Note 6) Dropout Voltage (Note 4)
Symbol VOUT ILIM IQ
Test Conditions IOUT = 1mA RLOAD = 1 IOUT = 0mA IOUT = 50mA, VDD 3.6V IOUT = 100mA, VDD 3.6V VDD = (VOUT (MAX) + 0.3V) to 6V, IOUT = 1mA IOUT = 1mA to 100mA BW = 100Hz to 50kHz COUT = 10F f = 1kHz, C OUT = 1F
Min -2 150 ----0.2 ---125
Typ -450 8 200 380 -0.01 250 -30 --
Max +2 -14 300 600 +0.2 0.04 ----
Units % mA A
V DROP VLINE
mV
Line Regulation Load Regulation (Note 5)
%/V %/mA Vrms dB C
VLOAD e NO PSRR T SD
Output Noise Voltage Power Supply Rejection Rate Thermal Shutdown Protection
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RT9188
Preliminary
Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. 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 remain possibility to affect device reliability. Note 2. Devices are ESD sensitive. Handling precaution recommended. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) - 100mV. Note 5. Regulation is measured at constant junction temperature by using a 20ms current pulse. Devices are tested for load regulation in the load range from 1mA to 100mA. Note 6. Quiescent, or ground current, is the difference between input and output currents. It is defined by IQ = IIN - IOUT under no load condition (IOUT = 0mA). The total current drawn from the supply is the sum of the load current plus the ground pin current. Note 7. JA is measured in the natural convection at T A = 25C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard.
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Preliminary Typical Operating Characteristics
0.8 0.7
RT9188
Short Circuit Current
500 TJ = 25C
Dropout Voltage (VDD - VOUT Dropout Voltage (VDD - VOUT))
Short Circuit Current (mA)
TJJ =125C T = 125C
400 TJ = 125C 300
Dropout Voltage (V)
0.6 0.5 0.4 0.3 0.2 0.1 0 0 20 40 60 VOUT = 3.0V VOUT = 3.0V 80 100 TJ J= 25C T =25C
200
100 0 0 1 2 3 4 5
ILOAD (mA)
Input/Output Differential (V)
Temperature Stability
3.4 3.2 3 VOUT1
10 9
Quisecent Current vs. Temperature
Quiescent Current (uA)
8 7 6 5 4 3 2 1 0
Output Voltage (V)
2.8 2.6 2.4 2.2 2 1.8 1.6 -35 -15 5 25 45 65 85 105 125 VOUT2
-35
-15
5
25
45
65
85
105
125
Temperature (C)
Temperature (C)
PSRR
CIN = 1uF COUT2 = 1uF Electrolytic Capacitor -10 VDD = 5V VOUT2 = 1.8V -20 TA = 25C
0 0 -10 -20
PSRR
CIN = 1uF COUT1 = 1uF Electrolytic VDD = 5V VOUT1 = 3.0V TA = 25C
50mA
50mA
PSRR (dB)
PSRR (dB)
-30
-30 -40 -50 -60 -70
10mA
-40 -50 -60 -70
10mA
10
100
1k
10k
100k
1M
10
100
1k
10k
100k
1M
Frequency (Hz)
Frequency (Hz)
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RT9188
Line Transient Response
300
Preliminary
Line Transient Response
300
Output Voltage Deviation (mV)
100 0> 2
T T
Output Voltage Deviation (mV)
VOUT2 = 1.8V 200 TA = 25C
COUT2 = 1uF Electrolytic IOUT = 50mA
VOUT1 = 3V 200 TA = 25C 100 0> 2
T T
COUT1 = 1uF Electrolytic IOUT = 50mA
Input Voltage Deviation (V)
6 5
1>
T
Input Voltage Deviation (V)
6 5
1>
T
4 3 0 1 2 3 4 5 6 7 8 9 10
4 3 0 1 2 3 4 5 6 7 8 9 10
Time (ms)
Time (ms)
Load Transient Response
100
Load Transient Response
100
Output Voltage Deviation (mV)
0 -50
Output Voltage Deviation (mV)
VDD = 5V, VOUT2 = 1.8V 50 TA = 25C
CIN = 1uF Ceramic COUT2 = 1uF Ceramic
VDD = 5V, VOUT1 = 3V 50 TA = 25C 0
CIN = 1uF Ceramic COUT1 = 1uF Ceramic
-50
200 100 10 -100
200 100 10 -100
Load Current (mA)
Time (500us/Div)
Load Current (mA)
Time (500us/Div)
Current Limit vs. Input Voltage
500 TJ = 25C 400
Current Limit (mA)
TJ = 125C 300
200
100
0 1 2 3 4 5 6
Input Voltage (V)
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Preliminary Application Information
Like any low-dropout regulator, the RT9188 requires input and output decoupling capacitors. The device is specifically designed for portable applications requiring minimum board space and smallest components. These capacitors must be correctly selected for good performance (see Capacitor Characteristics Section). Please note that linear regulators with a low dropout voltage have high internal loop gains which require care in guarding against oscillation caused by insufficient decoupling capacitance. Input Capacitor An input capacitance of 1F is required between the device input pin and ground directly (the amount of the capacitance may be increased without limit). The input capacitor MUST be located less than 1 cm from the device to assure input stability (see PCB Layout Section). A lower ESR capacitor allows the use of less capacitance, while higher ESR type (like aluminum electrolytic) require more capacitance. Capacitor types (aluminum, ceramic and tantalum) can be mixed in parallel, but the total equivalent input capacitance/ESR must be defined as above to stable operation. There are no requirements for the ESR on the input capacitor, but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the capacitance will be 1F over the entire operating temperature range. Output Capacitor The RT9188 is designed specifically to work with very small ceramic output capacitors. The recommended minimum capacitance (temperature characteristics X7R or X5R) in 1F to 4.7F range with 10m to 50m range ceramic capacitor between LDO output and GND for transient stability, but it may be increased without limit. Higher capacitance values help to improve transient. The output capacitor's ESR is critical because it forms a zero to provide phase lead which is required for loop stability. No Load Stability
RT9188
The device will remain stable and in regulation with no external load. This is specially important in CMOS RAM keep-alive applications. Input-Output (Dropout) Voltage A regulator's minimum input-to-output voltage differential (dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the device uses a PMOS, its dropout voltage is a function of drainto-source on-resistance, RDS(ON), multiplied by the load current: VDROPOUT = VDD - VOUT = RDS(ON) x IOUT Current Limit The RT9188 monitors and controls the PMOS' gate voltage, limiting the output current to 450mA (typ). The output can be shorted to ground for an indefinite period of time without damaging the part. Short-Circuit Protection The device is short circuit protected and in the event of a peak over-current condition, the short-circuit control loop will rapidly drive the output PMOS pass element off. Once the power pass element shuts down, the control loop will rapidly cycle the output on and off until the average power dissipation causes the thermal shutdown circuit to respond to servo the on/off cycling to a lower frequency. Please refer to the section on thermal information for power dissipation calculations. Capacitor Characteristics It is important to note that capacitance tolerance and v ariation wit h tem perat ure must be taken i nto consideration when selecting a capacitor so that the minimum required amount of capacitance is provided over the full operating temperature range. In general, a good tantalum capacitor will show very little capacitance variation with temperature, but a ceramic may not be as good (depending on dielectric type).
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RT9188
Preliminary
Tantalums also have good temperature stability: a good quality tantalum will typically show a capacitance value that varies less than 10~15% across the full temperature range of 125C to -40C. ESR will vary only about 2X going from the high to low temperature limits. The increasing ESR at lower temperatures can cause oscillations when marginal quality capacitors are used (if the ESR of the capacitor is near the upper limit of the stability range at room temperature). Aluminum: This capacitor type offers the most capacitance for the money. The disadvantages are that they are larger in physical size, not widely available in surface mount, and hav e poor AC performance (especially at higher frequencies) due to higher ESR and ESL. Compared by size, the ESR of an aluminum electrolytic is higher than either Tantalum or ceramic, and it also varies greatly with temperature. A typical aluminum electrolytic can exhibit an ESR increase of as much as 50X when going from 25C down to -40C. It should also be noted that many aluminum electrolytics only specify impedance at a frequency of 120Hz, which indicates they have poor high frequency performance. Only aluminum electrolytics that have an impedance specified at a higher frequency (between 20kHz and 100kHz) should be used for the device. Derating must be applied to the manufacturer's ESR specification, since it is typically only valid at room temperature. Any applications using aluminum electrolytics should be thoroughly tested at the lowest ambient operating temperature where ESR is maximum.
Aluminum electrolytics also typically hav e large temperature variation of capacitance value. Equally important to consider is a capacitor's ESR change with temperature: this is not an issue with ceramics, as their ESR is extremely low. However, it is very important in Tantalum and aluminum electrolytic capacitors. Both show increasing ESR at colder temperatures, but the increase in aluminum electrolytic capacitors is so severe they may not be feasible for some applications. Ceramic: For values of capacitance in the 10F to 100F range, ceramics are usually larger and more costly than tantalums but give superior AC performance for bypassing high frequency noise because of very low ESR (typically less than 10m). However, some dielectric types do not have good capacitance characteristics as a function of voltage and temperature. Z5U and Y5V dielectric ceramics have capacitance that drops severely with applied voltage. A typical Z5U or Y5V capacitor can lose 60% of its rated capacitance with half of the rated voltage applied to it. The Z5U and Y5V also exhibit a severe temperature effect, losing more than 50% of nominal capacitance at high and low limits of the temperature range. X7R and X5R dielectric ceramic capacitors are strongly recommended if ceramics are used, as they typically maintain a capacitance range within 20% of nominal over full operating ratings of temperature and voltage. Of course, they are typically larger and more costly than Z5U/Y5U types for a given voltage and capacitance. Tantalum: Solid tantalum capacitors are recommended for use on the output because their typical ESR is very close to the ideal value required for loop compensation. They also work well as input capacitors if selected to meet the ESR requirements previously listed.
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Preliminary
Thermal Considerations The RT9188 is a dual channel CMOS regulator designed to provide two output voltage from one package. Each output pin the RT9188 can deliver a current of up to 100mA over the full operating junction temperature range. However, the maximum output current must be derated at higher ambient temperature to ensure the junction temperature does not exceed 125C. With all possible conditions, the junction temperature must be within the range specified under operating conditions. Each regulator contributes power dissipation to the overall power dissipation of the package. Power dissipation can be calculated based on the output current and the voltage drop across each regulator. PD = (VDD - VOUT1) IOUT1 + (VDD - VOUT2) IOUT2 + VIN IGND Each output is rated for 100mA 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 (125C) and T A is the maximum ambient temperature. The junction to ambient thermal resistance (JA) for SOT-23-5 package at recomm-ended minimum footprint is 250C/W (JA is layout dependent). Visit our website in which "Recommended Footprints for Soldering Surface Mount Packages" for detail. PCB Layout Good board layout practices must be used or instability can be induced because of ground loops and voltage drops. The input and output capacitors MUST be directly connected to the input, output, and ground pins of the device using traces which have no other currents flowing through them. The best way to do this is to layout CIN and COUT near the device with short traces to the VDD, VOUT , and ground pins.
RT9188
The regulator ground pin should be connected to the external circuit ground so that the regulator and its capacitors have a "single point ground". It should be noted that stability problems have been seen in applications where vias to an internal ground plane were used at the ground points of the device and the input and output capacitors. This was caused by varying ground potentials at these nodes resulting from current flowing through the ground plane. Using a single point ground technique for the regulator and it's capacitors fixed the problem. Since high current flows through the traces going into VIN and coming from VOUT , Kelvin connect the capacitor leads to these pins so there is no voltage drop in series with the input and output capacitors. Optimum performance can only be achieved when the device is mounted on a PC board according to the diagram below:
VOUT2
GND
VOUT1
VDD
SOT-23-5 Board Layout
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RT9188
Outline Dimension
Preliminary
H D L C B
b A A1 e
Symbol A A1 B b C D e H L
Dimensions In Millimeters Min 0.889 0.000 1.397 0.356 2.591 2.692 0.838 0.080 0.300 Max 1.295 0.152 1.803 0.559 2.997 3.099 1.041 0.254 0.610
Dimensions In Inches Min 0.035 0.000 0.055 0.014 0.102 0.106 0.033 0.003 0.012 Max 0.051 0.006 0.071 0.022 0.118 0.122 0.041 0.010 0.024
SOT-23-5 Surface Mount Package
Richtek Technology Corporation
Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
Richtek Technology Corporation
Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com
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