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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
3.0V to 40V input Adjustable Output Voltage Current Limiting Output Switch Current to 1.5A Low Standby Current Operating Frequency to 100kHz Precision 2% Reference The GM34063 has all the functions required for DC-to-DC converters: an internal temperaturecompensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver, and high-current output switch. The 34063 designed for step-down, step-up and voltage-inverting applications using a minimum number of external components.
PIN CONNECTIONS
Switch Collector Switch Emitter Timing Capacitor GND
1 2 3 4
8 7 6 5
Driver Collector Ipk Sense VCC Comparator Inverting unit
(Top View)
Applications:
CD-ROM Motherboards SMPS Power Supply Battery Chargers
SCHEMATIC DIAGRAM
Driver Collector
8
S Q Q2 Q1 100
Ipk Oscillator
1
Switch Collector
Ipk Sense
7
R
2 3
Switch Emitter
CT Timing Capacitor
VCC
6
Comparator
+ Comparator Inverting unit
1.25V Reference Regulator
5
4
GND
(Bottom View) * The GM34063 has 51 active transistors on-chip.
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
Absolute Maximum Ratings
Rating
Power Supply Voltage Comparator Input Voltage Range Switch Collector Voltage Switch Emitter Voltage (VPin 1 = 40 V) Switch Collector to Emitter Voltage Driver Collector Voltage Driver Collector Current (Note 1) Switch Current Power Dissipation and Thermal Characteristics Plastic Package, P, P1 Suffix TA = 25C Thermal Resistance SOIC Package, D Suffix TA = 25C Thermal Resistance Operating Junction Temperature Operating Ambient Temperature Range Storage Temperature Range
Symbol
V CC VIR VC(switch) VE(switch) VCE(switch) VC(driver) IC(driver) ISW
Value
40 -0.3 to +40 40 40 40 40 100 1.5
Unit
V dc V dc V dc Vc V dc V dc mA A
PD R2JA PD R2JA TJ TA Tstg
1.25 100 625 160 +150 0 to +70 -65 to +150
W C/W mW C/W C C C
Note 1. Maximum package power dissipation limits must be observed.
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
ELECTRICAL CHARACTERISTICS
(VCC = 5.0 V, TA = Tlow to Thigh unless otherwise specified)
Characteristics
OSCILLATOR Frequency (VPin 5 = 0 V, CT = 1.0 nF, TA = 25C) Charge Current (VCC = 5.0 V to 40 V, TA = 25C) Discharge Current (VCC = 5.0 V to 40 V, TA = 25C) Discharge to Charge Current Ratio (Pin 7 to VCC, TA = 25C) Current Limit Sense Voltage (I chg = I dischg, TA = 25C) OUTPUT SWITCH (Note 2) Saturation Voltage, Darlington Connection ( ISW = 1.0 A, Pins 1, 8 connected) Saturation Voltage (Note 3) (ISW = 1.0 A, RPin 8 = 82 S to VCC, Forced $ .20) DC Current Gain (ISW = 1.0 A, VCE = 5.0 V, TA = 25C) Collector Off-State Current (VCE = 40 V) COMPARATOR Threshold Voltage TA = 25C TA = Tlow to Thigh Threshold Voltage Line Regulation (V Input Bias Current (Vin = 0 V)
CC
Symbol
Min
Typ
Max
Unit
fosc Ichg Idischg Idischg/Ichg Vipk(sense)
24 24 140 5.2 250
33 35 220 6.5 300
42 42 260 7.5 350
kHz :A :A - mV
VCE(sat) VCE(sat) hFE IC(off)
- - 50 -
1.0 0.45 75 0.01
1.3 0.7 - 100
V V - :A
Vth 1.225 1.210 = 3.0 V to 40 V) Reg line IIB 1.25 1.4 -20 1.275 1.29 5.0 -400
V
mV nA
TOTAL DEVICE Supply Current (VCC = 5.0 V to 40 V, CT = 1.0 nF, Pin 7 = VCC, VPin 5 > Vth, Pin 2 = Gnd, remaining pins open) ICC 4.0 mA
Note 2. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible. Note 3. If the output switch is driven into hard saturation (non-Darlington configuration) at low switch currents (#300 mA) and high driver currents ($30 mA), it may take up to 2.0 s for it to come out of saturation. This condition will shorten the off time at frequencies $30 kHz, and is magnified at high temperatures. 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: Forced of output switch : IC output
$10
IC driver - 7.0 mA * * The 100 resistor in the emitter of the driver device requires about 7.0 mA before the output switch conducts.
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
Test
Li ne Regulati on Load Regulati on Output Ri pple
C onditions
Vin = 8.0 V to 16 V, IO = 175 mA Vin = 12 V, IO = 75 mA to 175 mA Vin = 12 V, IO = 175 mA
R esults
30 mV = 0.05% 10 mV = 0.017% 400 mVpp
Effi ci ency Output Ri pple Wi th Opti onal Fi lter
Vin = 12 V, IO = 175 mA Vin = 12 V, IO = 175 mA
87.7% 40 mVpp
Step-Up Converter
170 H L 8 180 1
SQ
7 Rsc 0.22 Vin 12 V 6 +
Ipk Osc.
Q2 Q1
2
R
CT
3
1N5819
VCC
100 5 R2 47k 2.2k R1
+ -
Comp.
1.25V Reference Regulator
CT
1500 pF
4 Vout 330 +
28 V / 175 mA
1.0 H Vout + Optional Filter 100
CO
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
Figure 9. External Current Boost Connections for IC Peak Greater than 1.5 A
8
1
Vout
SQ R
7 Rsc Vin 6 Comparator
Ipk Oscillator
Q2 Q1 100
2
CT
+ -
1.25V Reference Regulator
External NPN Switch
If the output switch is driven into hard saturation (non - Darlington configuration) at low switch currents (#300 mA) and high driver currents ($30 mA), it may take up to 2.0 s to come out of saturation. This condition will shorten the off time at frequencies $30 kHz, and is magnified at high temperatures. This condition does not occure with a Darlington configuration, since the output switch cannot saturate. If a non-Darlington configuration is used, the following output drive condition is recommended.
8
1
Vout
SQ R
7 Rsc Vin 6 Comparator
Ipk Oscillator
Q2 Q1 100
2
CT
+ -
1.25V Reference Regulator
R 6 0 for const. Vin
External NPN Saturated Switch
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
Test
Line Regulation Load Regulation Output Ripple Short Circuit Current Efficiency Output Ripple With Optional Filter
Conditions
Vin = 15 V to 25 V, IO = 500 mA Vin = 25 V, IO = 75 mA to 500 mA Vin = 25 V, IO = 500 mA Vin = 25 V, RL = 0.1 S Vin = 25 V, IO = 500 mA Vin = 25 V, IO = 500 mA
Results
12 mV = 0.12% 3.0 mV = 0.03% 120 mVpp 1.1 A 83.7% 40 mVpp
Step - Down Converter
8
1
SQ
7 Rsc 0.33 Vin 25 V 6 + 100 5 R2 R1 1.2k 3.6k
Ipk Osc.
Q2 Q1
2
R
CT
1N5819
VCC
+ -
220 H
Comp.
1.25V Reference Regulator
3 4
CT
470 pF
Vout 470 +
5.0 V / 500 mA
1.0 H Vout 100 Optional Filter
CO
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
Figure 11. External Current Boost Connections for IC Peak Greater than 1.5 A
8
1
S
7 Rsc Vin 6 Comparator
Ipk Oscillator
Q
Q2 Q1
2
R
CT
Vout
+ -
1.25V Reference Regulator
External NPN Switch
8
1
SQ R
7 Rsc Vin 6
Ipk Oscillator
Q2 Q1
2
Vout
CT
Comparator
+ -
1.25V Reference Regulator
External PNP Saturated Switch
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
Test
Line Regulation Load Regulation Output Ripple Short Circuit Current Efficiency Output Ripple With Optional Filter
Conditions
Vin = 4.5 V to 6.0 V, IO = 100 mA Vin = 5.0 V, IO = 10 mA to 100 mA Vin = 5.0 V, IO = 100 mA Vin = 5.0 V, RL = 0.1 S Vin = 5.0 V, IO = 100 mA Vin = 5.0 V, IO = 100 mA
Results
3.0 mV = 0.012% 0.022 V = 0.09% 500 mVpp 910 mA 62.2% 70 mVpp
Voltage Inverting Converter
8
1
SQ
7 Rsc 0.24 Vin 4.5 V to 6V 6 + 100 5
Ipk Osc.
Q2 Q1
2
R
CT
88 H
L
1N5819
VCC
+ -
Comp.
1.25V Reference Regulator
3+ 4
1500 pF
R1 R2 8.2k 953 1000 f CO +
Vout
-12 V / 100 mA
1.0 H Vout + 100 Optional Filter
Revision 1, May 2002
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
Figure 13. External Current Boost Connections for IC Peak Greater than 1.5 A
8
1
S
7 Rsc Vin 6 Comparator
Ipk Oscillator
Q
Q2 Q1
2
R
CT
Vout
+ -
1.25V Reference Regulator
External NPN Switch
8
1
SQ R
7 Rsc Vin 6
Ipk Oscillator
Q2 Q1
2
Vout
CT
Comparator
+ -
1.25V Reference Regulator
External PNP Saturated Switch
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PRELIMINARY
GM34063
1.5A DC-to-DC CONVERTER CONTROL CIRCUIT
DESIGN FORMULAS
Calculation
ton/toff V
Step-Up
out F in(min) __________________________
Step-Dow n
out F __________________________
Voltage-Inverting
out F __________________________
+V -V
V
+V
|V | + V V i n - V sa t 1 f
Vin(min) - Vsat 1 f
on off _______________
Vin(min) - Vsat - Vout 1 f
on off _______________
(ton + toff)
t +t
t +t
on off _______________
t +t
toff
t_ _on_ +1 toff (ton + toff) - toff 4.0 x 10
-5
t_ _on_ +1 toff (ton + toff) - toff 4.0 x 10
-5
t_ _on_ +1 toff (ton + toff) - toff 4.0 x 10
-5
ton CT Ipk(switch) Rsc L(min) CO
ton
ton
ton
t_ 2lout(max) _on_ + 1 toff
(
)
(
2lout(max) 0.3/lpk(switch)
(Vin_i_______u__ __ (m n) - Vsat - Vo t )
t_ 2lout(max) _on_ + 1 toff
(
)
0.3/lpk(switch)
0.3/lpk(switch)
(___I_______)
pk(switch)
(Vin(min) - Vsat)
ton(max)
Ipk(switch)
)
ton(max)
(___I_______)
pk(switch)
(Vin(min) - Vsat)
ton(max)
9
out on _____________________
It
pk(switch) on off __________________________
I
(t + t )
Vripple(pp)
8Vripple(pp)
9
out on _____________________
It
Vripple(pp)
Vsat = Saturation voltage of the output switch. VF = Forward voltage drop of the output rectifier. Vin - Nominal input voltage. Vout - Desired output voltage, Iout - Desired output current. fmin - Minimum desired output switching frequency at the selected values of Vin and IO. Vripple(pp) - Desired peak-to-peak output ripple voltage. In practice, the calculated capacitor value will need to be increased due to its equivalent series resistance and board layout. The ripple voltage should be kept to a low value since it will directly affect the line and load regulation.
ORDERING INFORMATION
PACKAGE . GM34063 SOP-8 DIP-8 PART No. GM34063S8 GM34063D8
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