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Preliminary
RT9174
Triple Linear Regulator Controllers
General Description
The RT9174 is a triple linear regulator controller designed for motherboard application. The regulators are intended to regulate the
Features
Integrated Three Linear Controllers in a SOP-8 Package Driving NPN or NMOSFET Sourcing ( > 100mA) and Sinking ( > 5mA) Driver Tri-State Output Driver Low Internal 0.8V Reference Adjustable Output Voltage Setting High Output Stability VDDQ 1.5/3.3V Automatic Changing for AGP Wide 3V ~ 8V Input Voltage Range Current Limiting and Thermal Protection
computer system AGP (2X/4X) power, the 2.5V clock power, and the 1.8V power for North/South Bridge core voltage and/or cache memory circuits. All controllers can drive NPN or NMOSFET pass transistor. A special scheme empoly driver voltage could be higher than VDD when driving NMOSFET through the 12V power. The RT9174 future a small SOP-8 package for saving board area. It also builds in current limiting and thermal shutdown protection function.
Applications
Mother Boards Power Supply Graphic Cards
Ordering Information
RT9174C S Package type S : SOP-8 Operating temperature range C: Commercial standard
Pin Configurations
Part Number RT9174CS (Plastic SOP-8)
VDD 1 DRI 1 2 FB1 3 GND 4
Pin Configurations
TOP VIEW
8 DRI 3 7 FB3 6 DRI 2 5 FB2
Function Block Diagram
Thermal Limit OC + DRI1 _ _ + + FB1 _ OC + DRI2
VDD
GND
0.8V
1.3V
Reference
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_
_ _ + FB2 OC DRI3 + FB3
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RT9174
Pin Description
Pin Name VDD DRI1 FB1 GND DRI2 FB2 DRI3 FB3 Pin Function Power Supply Input Regulator 1 Driver Output
Preliminary
Regulator 1 Feedback Non-inverting Input Ground Regulator 2 Driver Output Regulator 2 Feedback Non-inverting Input Regulator 3 Driver Output Regulator 3 Feedback Non-inverting Input
Typical Application Circuit
5V 12V C5 0.1F 3.3V Q1 PHD45N03LT VDDQ 1.5/ 3.3V R2 4.3K R3 4.99K R1 5K C1 1F 3.3V 1 2 VDD DRI1 DRI3 FB3 DRI2 FB2 8 7 6 5 Q2 2SD1802 R4 250 R5 200 #TYPEDET V O2 1.8V C3 470F Q3 2SD1802 R6 424 R7 200
V O3 2.5V
3 FB1 C6 10nF 4 GND D1 1N4148 3.3V R8 1K
+
C4 470F
C2 + 1000F
RT9174
+
VDDQ = 3.3V if FB1 >1.3V #TYPEDET = 0V VDDQ = 1.5V #TYPEDET = Open VDDQ = 3.3V
Fig 1. Triple LDOs with VDDQ for M/B Application
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Preliminary
RT9174
5V 12V C5 0.1F 3.3V Q1 PHD45N03LT V DDQ 1.5/ 3.3V R2 4.3K R3 4.99K C6 10nF R1 5K C1 1F R10 1K 1 2 8 7 6 5
VTTPG
R9 1K Q3 MMBT3904
VDD DRI1
DRI3 FB3 DRI2 FB2
C8 0.01F
3 FB1 4 GND
Q2 R4 113 R11 374 R5 200
3.3V VTT
2SD1802 R6 3K C7 1F
+
D1 1N4148
RT9174
+
C3 470F
3.3V
R8 1K
#TYPEDET V TTSEL Q4 2N7002
R12 8.2K
VDDQ = 3.3V if FB1 >1.3V #TYPEDET = 0V VDDQ = 1.5V #TYPEDET = Open VDDQ = 3.3V VTTSEL = 0V VTT = 1.25V VTTSEL = 5V VTT = 1.5V
Fig 2. Dual LDOs with VTTPG for VRM8.5 Application
12V C5 0.1F R1 5K R8 3K R9 1.2K
7.5V C1 1F
3.3V Q3 PHD45N03LT 8 7 6 5 Q2 PHD45N03LT V O2 R4 250 R5 200 1.8V + C3 470F V O3 2.5V C4 470F
5V Q1 PHD45N03LT VO1 3.3V C2 + 1000F R2 624 R3 200
1 2
VDD DRI1
DRI3 FB3 DRI2 FB2
R6 424 + R7 200
3 FB1 4 GND
RT9174
Fig 3. Triple LDOs Driving MOS Application
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RT9174
Absolute Maximum Ratings
Input Voltage VDD Feedback FB1/FB2/FB3 Driver DRI1/DRI2/DRI3 Power Dissipation, PD @ TA = 25C SOP-8 Package Thermal Resistance SOP-8, JA Operating Junction Temperature Range Storage Temperature Range
Preliminary
8V -0.3 ~ 8V -0.3 ~ 12V 0.625W 160C/W -40C ~ 125C 65C ~ 150C
Electrical Characteristics
(VDD = 5V, CIN = 1F, TA = 25C, unless otherwise specified) Parameter Supply Current Line Regulation Load Regulation Driving Capability Driver Current Limiting Driver Tri-State Threshold Thermal Limit Power On Reset Voltage POR Symbol IDD VLINE VLOAD IO ICL VTS No Load No Load VDD = 4V~7V Source 100mA, DRI1/DRI2/DRI3 = 2.5V Sink 5mA, DRI1/DRI2/DRI3 = 2.5V Sourcing, DRI1/DRI2/DRI3 = 2.5V Sink DRI1/DRI2/DRI3 = 2.5V Sourcing, DRI1/DRI2/DRI3 = 2.5V Sink DRI1/DRI2/DRI3 = 2.5V Sweep FB1/FB2/FB3 to Driver Output Off 1.0 100 5 300 40 1.35 150 2.4 700 150 2.0 0.78 Test Conditions Min Typ 0.8 0.8 2 5 10 Max 2 0.82 10 10 15 Units mA V mV mV mA mA V C V
Feedback Reference Voltage VREF
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Preliminary Typical Operating Charateristics
0.82
RT9174
Driver Sourcing vs Drop Out
Reference vs Tempature
300
VDD = 5V
250 0.81
VDD = 5V
-20C 25C 85C
Reference (Volt)
0.80
Sourcing(mA)
200 150 100 50
0.79
0.78 -50 -10 30 70 110 150
0 0 1 2 3 4 5
Temperature ( C)
VDD - VDRI1,2,3 (Volt)
Supply Current vs Temperature
1.4
50
Driver Sinking vs VOUT
VDD = 5V
-20C 25C
30
85C
1.2
40
IQ(mA)
1
25C
Sinking (mA)
85C
0.8
-20C
0.6
20
0.4 3 4 5 6 7 8
10 0 1 2 3 4 5
VDD (Volt)
VOUT (Volt)
Tri-Sate Vth vs Temperature
1.6 400
Short Current vs Temperature
VDD = 5V
350
VDD = 5V
1.4
Short Current (mA)
-50 -10 30 70 110 150
300 250 200 150
Vth(Volt)
1.2
1.0
0.8
100
Temperature( C)
-50
-20
10
40
70
100
130
Temperature ( C)
DS9174-00 April 2001
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RT9174
Applications Information
Capacitors Selection A 0.1F minimum capacitor is
Preliminary
Layout Considerations recommended There are two critical layout considerations. One is the divider resistors should be located to RT9174 as possible to avoid inducing any noise. The second is COUT should be put at near the pass transistor to avoid oscillation.
V IN V DD 1F DRI1 VDD RT9174 DRI2 DRI3 FB1 FB2 FB3 V OUT R1 R2 + COUT
between VDD and ground to increase stability. The linear controllers use dominant pole compensation integrated into the error amplifier and are sensitive to output capacitor selection. When driving external pass transistor, normally a minimum 470F capacitor must be placed at output for stability and good transient response. When using internal pass transistor, just need 10F capacitor for stable. Pass Transistor Selection The RT9174 are designed specifically to driver external NPN or NMOSFET pass transistor for up to 5A output current. The driver could deliver more 100mA when driving NPN transistor and sinking for a pull up resistor load when driving a NMOSFET. Typically pass transistor with NPN hfe > 50 at Imax or NMOSFET Rds-on 100m are suitable in most application. Output Voltage Setting The RT9174 develop a 0.8V reference voltage, especially suit for low voltage application. As shown in Fig. 4, the output voltage could be easy set by R1 & R2 resistor. The divided resistor must keep below 1K for quick response and stability. Tri-state Operation A special Tri-state design is empolyed in the RT9174 for AGP 2X/4X power supply. Typical application shown the detail circuit. In AGP 2X SELECT = open, FB1 will be pulled up over 1.3V through R8 to trip the Tri-state threshold. R8 has to meet the following relationship: R8 < 0.75 (V33 - 1.3) xR2, if
As close as to RT9174 Fig 4
R3 + R2 x 0.8 = 1.5 . R3
When in AGP 4X SELECT = GND, VDDQ will work in normal 1.5V setting.
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Preliminary Package Information
H A M
RT9174
JB
F
C D I
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
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RT9174
Preliminary
RICHTEK TECHNOLOGY CORP.
Headquarter
6F, No. 35, Hsintai Road, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5510047 Fax: (8863)5537749
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-ic.com.tw
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