Document
DESCRIPTION
The RM34063 by Analog Integrations Corporation, an improved second source over the industrial standard RM34063, is a monolithic control circuit containing the primary functions required for DC/DC converters.The device consists of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This device is specifically designed to be incorporated in stepdown, step-up and voltage-inverting applications with a minimum number of external components. The ±1.8% internal reference and low quiescent current of 2.4mA are among the improvements of the device over the competition.
RM34063
DC/DC CONVERTER CONTROLLOR
FEATURES
•3V to 40V Input Voltage Operation •Internal 1.2A Peak Current Switch •Internal ±1.8% Reference •Low Quiescent Current at 2.4mA •Frequency Operation from 100Hz to 100KHz. •Current limit
Applications
•Saver for Cellular phones •DC-DC Converter Module
TYPICAL APPLICATION
+5V_800mA
L1 220uH_1.5A
+ C2
D1
470uF_10V IN5819
CT 470pF
U1 1 SC
2 SE
3 TC
4 GND
DRI 8 IPK 7 Vcc 6 FB 5
RM34063
RS 0.33_1%
+Vin
+ C1 470uF
RA 4.5K_1%
C1 22nF
RB 1.5K_1%
Note: VOUT = VFB x (1+RA/RB) . VFB=1.25V
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RM34063
PACKAGE INFORMATION
TOP VIEW
U1
6 Vcc
SE 2
1 SC 8 DRI
TC 3 FB 5
7 IPK
GND 4
RM34063
SOP-8L
PIN FUNCTIONS
Pin Symbol
Function Description
1 SC 1.5A switch collector
2 SE Darlington switch emitter
3 TC Oscillator timing capacitor
4 GND Power GND 5 FB Feedback comparator inverting input 6 VCC VCC - Power supply input 7 IPK IPK -High-side current sense input,VCC -VIPK=300mV 8 DRI Drive collector
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ABSOLUTE MAXIMUM RATINGS
Supply Voltage ......................................................…………............... ...................... 40V Comparator Input Voltage Range ..................................………….................... -0.3V~40V Switch Collector Voltage .......................................…………….....................................40V Switch Emitter Voltage ..................................……………............................................40V Switch Collector to Emitter Voltage .....................…………..........................................40V Driver Collector Voltage .................................……………............................................40V Switch Current ............................................……………..............................................1.2A Power Dissipation and Thermal Characteristics
DIP Package Ta= 25℃ ...............................…………............... ……................. ……......................1.0W Thermal Resistance .................……….................... ……................. ……...........100℃ /W
SO Package Ta= 25℃.................................……………......... ……................. ……...................625mW Thermal Resistance .................……………................. ……................................160℃/W Operating Junction Temperature ................................………..….............................125℃ Operating Ambient Temperature Range .................……...….............................0℃~70℃ Storage Temperature Range .....................……………....…........................ - 65℃~150℃
ELECTRICAL CHARACTERISTICS
(VCC= 5V, Ta=25℃, unless otherwise specified.)
PARAMETER
SYMBOL TEST CONDITIONS
MIN. TYP. MAX. UNIT
Oscillator
Charging Current
ICHG
VPIN7=VCC ,VCC=40V
23 32.0 41.0 μA
Discharge Current
Discharge To Charge Current Ratio
Frequency of Oscillation
Current Limit Sense Voltage
Output Switch
IDISCHG K
Fosc VIPK
VPIN7=VCC,VCC=40V VPIN7=VCC,VCC=40V CT=0.001uf,VCC=5V ICHG=IDISCHG,VCC=5V
140 190 260 μA 5.4 6.3 7.4 26 33 44 kHz 250 300 350 mV
Saturation Voltage, Darlington Connection
Saturation Voltage
DC Current Gain
Collector Off-State Current
Comparator
VCES1 VCES2
hFE IC(off)
ICT1=1.0A,VCT1=VCT2 ICT1=1.0A,
RPIN8=82Ω, VCT1=+5V, ICT1=1.0A,VCET1=5V
VCET1=40V
0.10 0.90 1.20 0.10 0.45 0.70 50 120 260
0.01 10.0
V V
μA
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RM34063
Threshold Voltage Threshold Voltage Line
Regulation Input Bias Current
Overall
Voltage Source Current
VTH ΔVTH
IIB
ICC
BLOCK DIAGRAM
VCC=40V,VCC=5V VCC=40V,VCC=5V VI=0V
VCC=5~40V,CT=0.001μF, VPIN7=VCC ,VPIN5>VTH, PIN to GND
1.228 1.250 1.272 1.5 5.0 0.01 0.4
V mV μA
1.0 2.4 4.0 mA
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■APPLICATION INFORMATION
•DESIGN FORMULA TABLE
Calculation
Step-down
Step-up
Voltage-inverting
ton
t off
( )ton + toff MAX
VOUT + VF VIN − VSAT − VOUT
1 FMIN
VOUT + VF − VIN (MIN ) VIN (MIN ) − VSAT 1 FMIN
VOUT + VF VIN − VSAT
1 FMIN
CT 4 ×10−5 ton
4 ×10−5 ton
4 ×10−5 ton
IC (SWITCH )
2IOUT (MAX )
2
I
out
(
MAX
)
(
ton
+ toff toff
)
2
I
out
(
MAX
)
(
ton
+ toff toff
)
RS 0.33
0.33 0.33
IC (SWITCH )
IC (SWITCH )
IC (SWITCH )
L(MIN )
⎜⎛ VIN (MIN ) − VSAT − VOUT ⎜⎝ IC (SWITCH )
⎟⎟⎠⎞ton ( MA
⎜⎛ VIN (MIN ) − VSAT ⎜⎝ IC(.