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RT34063A
DC-to-DC Converter Control Circuits
General Description
The RT34063A Series is a monolithic control circuit containing the primary functions required for DC-to-DC converters. These devices consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This series was specially designed to be incorporated in step-down and step-up and Voltage-inverting applications with a minimum number of external components.
Features
Operation from 3.0V to 30V Input Low Standby Current Current Limiting Internal Switch Current to 1.5A Output Voltage Adjustable Frequency Operation to 100kHz Precision 2% Reference RoHS Compliant and 100% Lead (Pb)-Free
Applications
Saver for Cellular Phones DC-DC Converter Module
Ordering Information
RT34063A Package Type N : DIP-8 S : SOP-8 Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard)
SC SE TC GND 2 3 4
Pin Configurations
(TOP VIEW)
8 7 6 5 DRIVER IPK VCC COMP
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.
DIP-8 / SOP-8
Functional Pin Description
Pin Name SC SE TC GND COMP VCC IPK DRIVER Pin Function 1.5A Switch Collector Darlington Switch Emitter Oscillator Timing Capacitor Power GND Feedback Comparator Inverting Input Power Supply Input Highside Current Sense Input VCC-VIPK = 330mV Driver Collector
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RT34063A
Function Block Diagram
DRIVER 8 SQ R Q1 IPK 7 100 2 SE Q2 1 SC
IPK CT Oscillator VCC 6 Comparator + COMP 5 1.25V Reference Regulator 4 GND 3 TC
Typical Application Circuit
170uH 8 180 S R 7 RSC 0.22 6
+
L 1 Q
2 IPK OSC + COMP
1N5819
CT 1.25V Ref
VIN 12V
CT 3 1500pF 4
Optional Filter
100uF 5
R2
+
1.0uH VOUT
28V/175mA
R1 2.2K
47K 330uF
VOUT 100uF
+
CO
Figure 1. Step-up Converter
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RT34063A
8 1
+
VOUT
7 VIN
2
6
3
5
4
(a) External NPN Switch
8 1
R
+
VOUT
7 VIN
2
R 0 for Constant VIN
6
3
5
4
(b) External NPN Saturated Switch (See Note) Figure 2. External Current Boost Connections for IC Peak Greater than 1.5A
Note: If the output switch is driven into hard saturation (non-Darlington configuration) at low switch currents (
300mA) and
high driver currents ( 30mA), it may take up to 2.0s to come out of saturation. This condition will shorten the off time at frequencies 30kHz, and is magnified at high temperature. This condition does not occur with a Darlington configuration, since the output switch cannot saturate. If a non-Darlington configuration is used, the following output drive condition is recommended.
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RT34063A
8 1 S R Q1 7 RSC 0.33 6
+
Q
Q2
2 1N5819
VIN 25V
IPK CT OSC + COMP
CT 3 1.25V Ref 4 470pF
L 220uH
100uF 5
Optional Filter
R2
+
1.0uH VOUT
5.0V/500mA
VOUT 100uF
+
R1 1.2K
3.6K 470uF
CO
Figure 3. Step-down Converter
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RT34063A
8 1
7 VIN
2 VOUT
+
6
3
5
4
(a) External NPN Switch
8 1
+
VOUT
7 VIN
2
6
3
5
4
(b) External PNP Saturated Switch Figure 4. External Current Boost Connections for IC Peak Greater than 1.5A
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RT34063A
8 180 S R Q1 7 RSC 0.24 6
+
1 Q Q2
2 IPK CT OSC + COMP
88uH 3 1.25V Ref
L 1N5819
VIN 4.5V to 6.0V
100uF 5
1500pF 4
Optional Filter
R2 R1 8.2K 953 1000uF
+
1.0uH VOUT
-12V/100mA
VOUT 100uF
+
CO
Figure 5. Voltage Inverting Converter
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RT34063A
8 1
7
2 VOUT
+
VIN
6
3
5
4
(a) External NPN Switch
8 1 VOUT 7 VIN 2
+
6
3
5
4
(b) External PNP Saturated Switch Figure 6. External Current Boost Connections for Peak Greater than 1.5A
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RT34063A
Design Formula Table
Calculation ton/toff Step-up Step-down Voltage-Inverting
VOUT + VF - VIN (MIN) VIN (MIN) - VSAT
VOUT + VF VIN (MIN) - VSAT - VOUT
1 f
ton + toff ton +1 toff
V OUT + V F V IN - V SAT
1 f
ton + toff ton +1 toff
(ton + toff)
1 f
ton + toff ton +1 toff
toff
ton CT
Ipk (SWITCH)
(ton + toff ) - toff
4.0 x 10-5 ton
(ton + toff ) - toff
4.0 x 10-5 ton
2 IOUT (MAX)
(ton + toff ) - toff
4.0 x 10-5 ton
ton 2 IOUT (MAX) + 1 toff 0.3/Ipk (SWITCH) (VIN(MIN) - VSAT ) Ipk(SWITCH) ton(MAX )
ton 2 IOUT(MAX) + 1 toff 0.3/Ipk (SWITCH) (VIN(MIN) - VSAT ) Ipk(SWITCH ) ton(MAX )
RSC
0.3/Ipk (SWITCH) (VIN(MIN) - VSAT ) Ipk(SWITCH ) ton(MAX )
L (min)
CO
9
IOUT ton Vripple (pp)
Ipk(SWITCH )( ton + toff ) 8 Vripple(pp)
9
IOUT ton Vripple (pp)
VSAT VF
: Saturation voltage of the output switch. : Forward voltage drop of the output rectifier.
The following power supply characteristics must be chosen: VIN VOUT IOUT f Vripple(pp) : Nominal input voltage. : Desired output voltage VOUT = 1.25(1+ : Desired output current. : Minimum desired output switching frequency at the selected values of Vin and IO. : Desired peak-to-peak output ripple voltage. In practice, the calculated capacitor value needs to be increased due to its equivalent series resistance and board layout. The ripple voltage should be kept to a low value since it directly affects the line and load regulation.
R2 R1 )
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RT34063A
Absolute Maximum Ratings
Power Supply Voltage ------------------------------------------------------------------------------------------------ 30V Feedback Input Voltage Range ------------------------------------------------------------------------------------- -0.3 to +30V Switch Collector Voltage --------------------------------------------------------------------------------------------- 30V Switch Emitter Voltage ----------------------------------------------------------------------------------------------- 30V Switch Collector to Emitter Voltage ------------------------------------------------------------------------------- 30V Driver Collector Voltage ---------------------------------------------------------------------------------------------- 30V Driver Collector Current (see Note) -------------------------------------------------------------------------------- 100mA Switch Current --------------------------------------------------------------------------------------------------------- 1.5A Power Dissipation, PD @ TA = 25C DIP-8 --------------------------------------------------------------------------------------------------------------------- 1.25W SOP-8 -------------------------------------------------------------------------------------------------------------------- 0.625W Package Thermal Resistance DIP-8, JA --------------------------------------------------------------------------------------------------------------- 100C/W SOP-8, JA -------------------------------------------------------------------------------------------------------------- 160C/W Operating Junction Temperature ----------------------------------------------------------------------------------- +125C Storage Temperature Range ---------------------------------------------------------------------------------------- 65 to +150C Note:Maximum package power dissipation limits must be observed.
Electrical Characteristics
(VCC = 5V, TA = 25C, unless otherwise specified)
Parameter Oscillator Frequency Charge Current Discharge Current Discharge to Charge Current Ratio Current Limit Sense Voltage Output Switch Saturation Voltage, Darlington Connection Saturation Voltage, Darlington Connection DC Current Gain Collector Off-state Current Comparator Threshold Voltage Threshold Voltage Line Regulation Input Bias Current Total Device Supply Current
Symbol
Test Conditions
Min
Typ
Max Units
VPIN5 = 0V, CT = 1.0nF ICHG 5.0V VCC 30V IDISCHG 5.0V VCC 30V Pin 7 to VCC VLIMIT ICHG = IDISCHG ISW = 1.0A, Pins1, 8 connected ISW = 1.0A, RPIN8 = 82 to VCC, Forced 20 ISW = 1.0A, VCE = 5.0V VCE = 30V
26 25 160 5.5 280 --50 --
38 36 250 6.9 330 1.0 0.45 75 0.01
48 43 290 7.9 380 1.3 0.7 -100
kHz A A -mV V V -A V mV nA
1.225 1.25 1.275 3.0V VCC 30V IBIAS VIN = 0V VCC = 5.0V to 30V, CT = 1.0nF, Pin7 = VCC, VPIN5 > VTH, Pin2 = GND, Remaining pins open --1.4 -20 5.0 -400
ICC
--
3.0
4.5
mA
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RT34063A
Typical Operating Characteristics
Output Switch On-Off Time vs. Oscillator Timing Capacitor
1000
T On-Off , Output Switch On-Off Time (us)
Timing Capacitor Waveform
VCC = 5.0V Pin 7 = VCC Pin 5 = GND TA = 25C
100
10
VOUT = 5.0V Pin 1,8 = Open, Pin 7 = VCC CT = 1.0nF ,Pin 5 = GND TA = 25C
0.1 1 10
1 0.01
Time (10us/Div)
TC, Oscilator Timing Capacitor (nF)
Emitter Follower Configuration Output Saturation Voltage vs. Emiter Current
A VCE, Saturation Voltage (V)
1.6 1.5 1.4 1.3 1.2 1.1 1 0 0.3 0.6 0.9 1.2 1.5
Common Emiter Configuration Output Switch Saturation Voltage vs. Collector Current
A VCE, Saturation Voltage (V)
1.0
1.7
0.8
0.6
0.4
VCC = 5.0V Pin 1,7,8 = VCC Pin 3,5 = GND TA = 25C
0.2
VCC = 5.0V Pin 7 = VCC Pin 2,3,5 = GND TA = 25C
0 0.3 0.6 0.9 1.2 1.5
0.0
IE, Emitter Current (A)
ICC, Collector Current (A)
Standyby Supply Current vs. Supply Voltage
3.5
Current Limit Sense Voltage vs. Temperature
400
Current Limit Sense Voltage (mV) .
ICC, Supply Current (mA) .
3.0 2.5 2.0 1.5 1.0 0.5 0.0 0 5 10 15 20 25 30
380 360 340 320 300 280 260 240 220 200 -40 -20 0 20 40 60 80
VCC = 5.0V Pin 7 = VCC Pin 5 = 2.0V Pin 2 = GND TA = 25C
VCC = 5.0V ICHARGE = IDISCHARGE
Supply Voltage (V)
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Temperature (C)
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RT34063A
IC vs. VCE(Q1) Curve
2000
IC vs. VCE(Q1) Curve
2000
TJ = -20C
Ib = 34mA
1600
TJ = -10C
Ib = 34mA
1600
I C (mA)
I C (mA)
1200
Ib = 15mA
1200
Ib = 15mA
800
Ib = 8mA
800
Ib = 8mA
400
400
Ib = 2.4mA
0 0 160 320 480 640 800
Ib = 2.4mA
0 0 160 320 480 640 800
VCE (mV)
VCE (mV)
IC vs. VCE(Q1) Curve
2000
2000
IC vs. VCE(Q1) Curve
Ib = 34mA
1600
TJ = 0C
1600
TJ = 25C
Ib = 34mA
I C (mA)
I C (mA)
1200
Ib = 15mA
1200
Ib = 15mA Ib = 8mA
800
Ib = 8mA
800
400
400
Ib= 2.4mA Ib = 2.4mA
0
0 0 160 320 480 640 800
0
160
320
480
640
800
VCE (mV)
VCE (mV)
IC vs. VCE(Q1) Curve
1800
TJ = 70C
1500
Ib = 34mA
Ib = 15mA
1200
I C (mA)
Ib = 8mA
900 600 300 0 0 160 320 480 640 800
Ib = 2.4mA
VCE (mV)
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RT34063A
Outline Dimension
A
B
E C L I D F
J
Dimensions In Millimeters Symbol Min A B C D E F I J L 9.068 6.198 3.556 0.356 1.397 2.337 3.048 7.366 0.381 Max 9.627 6.604 4.318 0.559 1.651 2.743 3.556 8.255
Dimensions In Inches Min 0.357 0.244 0.140 0.014 0.055 0.092 0.120 0.290 0.015 Max 0.379 0.260 0.170 0.022 0.065 0.108 0.140 0.325
8-Lead DIP Plastic Package
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RT34063A
A
H M
J
B
F
C I D
Dimensions In Millimeters Symbol Min A B C D F H I J M 4.801 3.810 1.346 0.330 1.194 0.170 0.050 5.791 0.400 Max 5.004 3.988 1.753 0.508 1.346 0.254 0.254 6.200 1.270
Dimensions In Inches Min 0.189 0.150 0.053 0.013 0.047 0.007 0.002 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 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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