

Order this document by MC34166/D
SEMICONDUCTOR
TECHNICAL DATA
POWER SWITCHING
REGULATORS
T SUFFIX
PLASTIC PACKAGE
CASE 314D
ORDERING INFORMATION
Device Operating
Temperature Range Package
Pin 1. Voltage Feedback Input
2. Switch Output
3. Ground
4. Input Voltage/VCC
5. Compensation/Standby
TH SUFFIX
PLASTIC PACKAGE
CASE 314A
TV SUFFIX
PLASTIC PACKAGE
CASE 314B
Heatsink surface connected to Pin 3.
D2T SUFFIX
PLASTIC PACKAGE
CASE 936A
(D2PAK)
Heatsink surface (shown as terminal 6
in case outline drawing) is connected to Pin 3.
5
1
5
1
5
1
5
1
MC33166D2T
MC33166T
MC33166TH
MC33166TV
TA = – 40° to + 85°C
Surface Mount
Straight Lead
Horiz. Mount
Vertical Mount
MC34166D2T
MC34166T
MC34166TH
MC34166TV
TA = 0
°
to + 70
°
C
Surface Mount
Straight Lead
Horiz. Mount
Vertical Mount
1
MOTOROLA ANALOG IC DEVICE DATA
  
The MC34166, MC33166 series are high performance fixed frequency
power switching regulators that contain the primary functions required for
dc–to–dc converters. This series was specifically designed to be
incorporated in step–down and voltage–inverting configurations with a
minimum number of external components and can also be used cost
effectively in step–up applications.
These devices consist of an internal temperature compensated
reference, fixed frequency oscillator with on–chip timing components,
latching pulse width modulator for single pulse metering, high gain error
amplifier, and a high current output switch.
Protective features consist of cycle–by–cycle current limiting,
undervoltage lockout, and thermal shutdown. Also included is a low power
standby mode that reduces power supply current to 36 µA.
Output Switch Current in Excess of 3.0 A
Fixed Frequency Oscillator (72 kHz) with On–Chip Timing
Provides 5.05 V Output without External Resistor Divider
Precision 2% Reference
0% to 95% Output Duty Cycle
Cycle–by–Cycle Current Limiting
Undervoltage Lockout with Hysteresis
Internal Thermal Shutdown
Operation from 7.5 V to 40 V
Standby Mode Reduces Power Supply Current to 36 µA
Economical 5–Lead TO–220 Package with Two Optional Leadforms
Also Available in Surface Mount D2PAK Package
Simplified Block Diagram
(Step Down Application)
EA VO
ILIMIT
Vin
4
2
SQ
R
UVLO
35
L
5.05 V/3.0 A
Reference
Thermal
PWM
Oscillator
1
This device contains 143 active transistors.
Motorola, Inc. 1996 Rev 4
MC34166 MC33166
2MOTOROLA ANALOG IC DEVICE DATA
MAXIMUM RATINGS
Rating Symbol Value Unit
Power Supply Input Voltage VCC 40 V
Switch Output Voltage Range VO(switch) –1.5 to + Vin V
Voltage Feedback and Compensation Input
V oltage Range VFB, VComp –1.0 to + 7.0 V
Power Dissipation
Case 314A, 314B and 314D (TA = +25°C) PDInternally Limited W
Thermal Resistance, Junction–to–Ambient θJA 65 °C/W
Thermal Resistance, Junction–to–Case θJC 5.0 °C/W
Case 936A (D2PAK) (TA = +25°C) PDInternally Limited W
Thermal Resistance, Junction–to–Ambient θJA 70 °C/W
Thermal Resistance, Junction–to–Case θJC 5.0 °C/W
Operating Junction Temperature TJ+150 °C
Operating Ambient Temperature (Note 3)
MC34166
MC33166
TA0 to + 70
40 to + 85
°C
Storage Temperature Range Tstg 65 to +150 °C
ELECTRICAL CHARACTERISTICS (VCC = 12 V, for typical values TA = +25°C, for min/max values TA is the operating ambient
temperature range that applies [Notes 2, 3], unless otherwise noted.)
Characteristic Symbol Min Typ Max Unit
OSCILLATOR
Frequency (VCC = 7.5 V to 40 V) TA = +25°C
TA = Tlow to Thigh fOSC 65
62 72
79
81 kHz
ERROR AMPLIFIER
Voltage Feedback Input Threshold TA = +25°C
TA = Tlow to Thigh VFB(th) 4.95
4.85 5.05
5.15
5.2 V
Line Regulation (VCC = 7.5 V to 40 V, TA = +25°C) Regline 0.03 0.078 %/V
Input Bias Current (VFB = VFB(th) + 0.15 V) IIB 0.15 1.0 µA
Power Supply Rejection Ratio (VCC = 10 V to 20 V, f = 120 Hz) PSRR 60 80 dB
Output Voltage Swing
High State (ISource = 75 µA, VFB = 4.5 V)
Low State (ISink = 0.4 mA, VFB = 5.5 V) VOH
VOL 4.2
4.9
1.6
1.9
V
PWM COMPARATOR
Duty Cycle
Maximum (VFB = 0 V)
Minimum (VComp = 1.9 V) DC(max)
DC(min) 92
095
0100
0
%
SWITCH OUTPUT
Output Voltage Source Saturation (VCC = 7.5 V, ISource = 3.0 A) Vsat (VCC
–1.5) (VCC
–1.8) V
Off–State Leakage (VCC = 40 V, Pin 2 = Gnd) Isw(off) 0 100 µA
Current Limit Threshold Ipk(switch) 3.3 4.3 6.0 A
Switching T imes (VCC = 40 V, Ipk = 3.0 A, L = 375 µH, TA = +25°C)
Output Voltage Rise Time
Output Voltage Fall Time tr
tf
100
50 200
100
ns
UNDERVOLTAGE LOCKOUT
Startup Threshold (VCC Increasing, TA = +25°C) Vth(UVLO) 5.5 5.9 6.3 V
Hysteresis (VCC Decreasing, TA = +25°C) VH(UVLO) 0.6 0.9 1.2 V
TOTAL DEVICE
Power Supply Current (TA = +25°C )
Standby (VCC = 12 V, VComp < 0.15 V)
Operating (VCC = 40 V, Pin 1 = Gnd for maximum duty cycle)
ICC
36
31 100
55 µA
mA
NOTES: 1.Maximum package power dissipation limits must be observed to prevent thermal shutdown activation.
2.Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
3.Tlow =0°C for MC34166 Thigh = + 70°C for MC34166
=–40°C for MC33166 = + 85°C for MC33166
MC34166 MC33166
3
MOTOROLA ANALOG IC DEVICE DATA
Figure 1. Voltage Feedback Input Threshold
versus Temperature Figure 2. Voltage Feedback Input Bias
Current versus Temperature
Figure 3. Error Amp Open Loop Gain and
Phase versus Frequency Figure 4. Error Amp Output Saturation
versus Sink Current
Figure 5. Oscillator Frequency Change
versus Temperature Figure 6. Switch Output Duty Cycle
versus Compensation Voltage
–20
AVOL, OPEN LOOP VOLT AGE GAIN (dB)
10 M10 f, FREQUENCY (Hz)
0
30
60
90
120
150
180
100 1.0 k 10 k 100 k 1.0 M
0
20
40
60
80
100
, EXCESS PHASE (DEGREES)
φ
Gain
Phase
–12
–55 T
A
, AMBIENT TEMPERATURE (
°
C)
25 0 25 50 75 100 125
8.0
4.0
0
4.0
, OSCILLATOR FREQUENCY CHANGE (%)
OSC
f
4.85
VFB(th), VOLTAGE FEEDBACK INPUT THRESHOLD (V)
TA, AMBIENT TEMPERATURE (
°
C)
4.93
5.01
5.09
5.17
5.25
55 25 0 25 50 75 100 125
VCC = 12 V
0
IIB, INPUT BIAS CURRENT (nA)
TA, AMBIENT TEMPERATURE (
°
C)
20
40
60
80
100
55 25 0 25 50 75 100 125
Vsat, OUTPUT SATURATION VOLTAGE (V)
2.00 ISink, OUTPUT SINK CURRENT (mA)
0.4 0.8 1.2 1.6
0
0.4
0.8
1.2
1.6
2.0
DC, SWITCH OUTPUT DUTY CYCLE (%)
1.5 VComp, COMPENSATION VOLT AGE (V)
2.0 2.5 3.0 3.5 4.0
0
20
40
60
80
100
4.5
VCC = 12 V
VComp = 3.25 V
RL = 100 k
TA = +25
°
C
VFB(th) Max = 5.15 V
VFB(th) Min = 4.95 V
VFB(th) Typ = 5.05 V
VCC = 12 V
VFB = VFB(th)
VCC = 12 V
VFB = 5.5 V
TA = +25
°
C
VCC = 12 V
TA = +25
°
C
VCC = 12 V
MC34166 MC33166
4MOTOROLA ANALOG IC DEVICE DATA
Figure 7. Switch Output Source Saturation
versus Source Current Figure 8. Negative Switch Output Voltage
versus Temperature
Figure 9. Switch Output Current Limit
Threshold versus Temperature Figure 10. Standby Supply Current
versus Supply Voltage
Figure 11. Undervoltage Lockout
Threshold versus Temperature Figure 12. Operating Supply Current
versus Supply Voltage
4.5
–55 T
A
, AMBIENT TEMPERATURE (
°
C)
25 0 25 50 75 100 125
5.0
5.5
6.0
6.5
, UNDERVOLTAGE LOCKOUT THRESHOLD (V)
th(UVLO)
V
2.5
ISource, SWITCH OUTPUT SOURCE CURRENT (A)
2.0
–1.5
–1.0
0.5
0
0 2.0 3.0 4.0 5.0 TA, AMBIENT TEMPERATURE (
°
C)
55 25 0 25 50 75 100 125
3.0
Vsat, SWITCH OUTPUT SOURCE SATURATION (V)
–1.0
0.8
0.6
0.4
0.2
0
–1.2
Vsw, SWITCH OUTPUT VOLTAGE (V)
VCC = 12 V
Pin 5 = 2.0 V
Pins 1, 3 = Gnd
Pin 2 Driven Negative
Gnd
3.9
4.1
4.3
4.5
4.7
, CURRENT LIMIT THRESHOLD (A)
pk(switch)
I
55 25 0 25 50 75 100 125
VCC = 12 V
Pins 1, 2, 3 = Gnd
0
40
80
120
160
, SUPPLY CURRENT (
CC
I
0VCC, SUPPLY VOLTAGE (V)
10 20 30 40
Pin 4 = VCC
Pins 1, 3, 5 = Gnd
Pin 2 Open
TA = +25
°
C
µ
A)
4.0
, SUPPLY CURRENT (mA)
CC
I
00VCC, SUPPLY VOLTAGE (V)
10 20 30 40
10
20
30
40
Pin 4 = VCC
Pins 1, 3 = Gnd
Pins 2, 5 Open
TA = +25
°
C
TA, AMBIENT TEMPERATURE (
°
C)
1.0
TA = +25
°
C
VCC
Isw = 100
µ
A
Isw = 10 mA
Startup Threshold
VCC Increasing
T urn–Off Threshold
VCC Decreasing
MC34166 MC33166
5
MOTOROLA ANALOG IC DEVICE DATA
Figure 13. MC34166 Representative Block Diagram
+
4
2
1
5
3
+
CFRF
R1
COVO
R2
120
Error
Amp
5.05 V
Reference
Thermal
Shutdown
Oscillator S
RQ
Pulse Width
Modulator
CT
PWM Latch
Gnd Compensation
100
µ
A
Undervoltage
Lockout
Voltage
Feedback
Input
L
Switch
Output
Current
Sense
Vin
Cin
Input Voltage/VCC
Sink Only
Positive True Logic
=
Figure 14. Timing Diagram
4.1 V
Timing Capacitor CT
Compensation
2.3 V
ON
OFF
Switch Output
+
MC34166 MC33166
6MOTOROLA ANALOG IC DEVICE DATA
INTRODUCTION
The MC34166, MC33166 series are monolithic power
switching regulators that are optimized for dc–to–dc converter
applications. These devices operate as fixed frequency,
voltage mode regulators containing all the active functions
required to directly implement step–down and
voltage–inverting converters with a minimum number of
external components. They can also be used cost effectively
in step–up converter applications. Potential markets include
automotive, computer , industrial, and cost sensitive consumer
products. A description of each section of the device is given
below with the representative block diagram shown in
Figure 13.
Oscillator
The oscillator frequency is internally programmed to
72 kHz by capacitor CT and a trimmed current source. The
charge to discharge ratio is controlled to yield a 95%
maximum duty cycle at the Switch Output. During the
discharge of CT, the oscillator generates an internal blanking
pulse that holds the inverting input of the AND gate high,
disabling the output switch transistor. The nominal oscillator
peak and valley thresholds are 4.1 V and 2.3 V respectively.
Pulse Width Modulator
The Pulse Width Modulator consists of a comparator with
the oscillator ramp voltage applied to the noninverting input,
while the error amplifier output is applied into the inverting
input. Output switch conduction is initiated when CT is
discharged to the oscillator valley voltage. As CT charges to
a voltage that exceeds the error amplifier output, the latch
resets, terminating output transistor conduction for the
duration of the oscillator ramp–up period. This PWM/Latch
combination prevents multiple output pulses during a given
oscillator clock cycle. Figures 6 and 14 illustrate the switch
output duty cycle versus the compensation voltage.
Current Sense
The MC34166 series utilizes cycle–by–cycle current
limiting as a means of protecting the output switch transistor
from overstress. Each on–cycle is treated as a separate
situation. Current limiting is implemented by monitoring the
output switch transistor current buildup during conduction, and
upon sensing an overcurrent condition, immediately turning off
the switch for the duration of the oscillator ramp–up period.
The collector current is converted to a voltage by an
internal trimmed resistor and compared against a reference
by the Current Sense comparator. When the current limit
threshold is reached, the comparator resets the PWM latch.
The current limit threshold is typically set at 4.3 A. Figure 9
illustrates switch output current limit threshold versus
temperature.
Error Amplifier and Reference
A high gain Error Amplifier is provided with access to the
inverting input and output. This amplifier features a typical dc
voltage gain of 80 dB, and a unity gain bandwidth of
600 kHz with 70 degrees of phase margin (Figure 3). The
noninverting input is biased to the internal 5.05 V reference
and is not pinned out. The reference has an accuracy of
±2.0% at room temperature. To provide 5.0 V at the load, the
reference is programmed 50 mV above 5.0 V to compensate
for a 1.0% voltage drop in the cable and connector from the
converter output. If the converter design requires an output
voltage greater than 5.05 V, resistor R1 must be added to
form a divider network at the feedback input as shown in
Figures 13 and 18. The equation for determining the output
voltage with the divider network is:
Vout
+ǒ
R2
R1
)
1
Ǔ
5.05
External loop compensation is required for converter
stability. A simple low–pass filter is formed by connecting a
resistor (R2) from the regulated output to the inverting input,
and a series resistor–capacitor (RF, CF) between Pins 1 and
5. The compensation network component values shown in
each of the applications circuits were selected to provide
stability over the tested operating conditions. The step–down
converter (Figure 18) is the easiest to compensate for
stability. The step–up (Figure 20) and voltage–inverting
(Figure 22) configurations operate as continuous conduction
flyback converters, and are more difficult to compensate. The
simplest way to optimize the compensation network is to
observe the response of the output voltage to a step load
change, while adjusting RF and CF for critical damping. The
final circuit should be verified for stability under four boundary
conditions. These conditions are minimum and maximum
input voltages, with minimum and maximum loads.
By clamping the voltage on the error amplifier output
(Pin 5) to less than 150 mV, the internal circuitry will be
placed into a low power standby mode, reducing the power
supply current to 36 µA with a 12 V supply voltage. Figure 10
illustrates the standby supply current versus supply voltage.
The Error Amplifier output has a 100 µA current source
pull–up that can be used to implement soft–start. Figure 17
shows the current source charging capacitor CSS through a
series diode. The diode disconnects CSS from the feedback
loop when the 1.0 M resistor charges it above the operating
range of Pin 5.
Switch Output
The output transistor is designed to switch a maximum of
40 V, with a minimum peak collector current of 3.3 A. When
configured for step–down or voltage–inverting applications,
as in Figures 18 and 22, the inductor will forward bias the
output rectifier when the switch turns off. Rectifiers with a
high forward voltage drop or long turn–on delay time should
not be used. If the emitter is allowed to go sufficiently
negative, collector current will flow, causing additional device
heating and reduced conversion efficiency. Figure 8 shows
that by clamping the emitter to 0.5 V, the collector current will
be in the range of 100 µA over temperature. A 1N5822 or
equivalent Schottky barrier rectifier is recommended to fulfill
these requirements.
Undervoltage Lockout
An Undervoltage Lockout comparator has been
incorporated to guarantee that the integrated circuit is fully
functional before the output stage is enabled. The internal
5.05 V reference is monitored by the comparator which
enables the output stage when VCC exceeds 5.9 V. To
prevent erratic output switching as the threshold is crossed,
0.9 V of hysteresis is provided.
MC34166 MC33166
7
MOTOROLA ANALOG IC DEVICE DATA
Thermal Protection
Internal Thermal Shutdown circuitry is provided to protect
the integrated circuit in the event that the maximum junction
temperature is exceeded. When activated, typically at 170°C,
the latch is forced into a ‘reset’ state, disabling the output
switch. This feature is provided to prevent catastrophic failures
from accidental device overheating. It is not intended to be
used as a substitute for proper heatsinking. The MC34166
is contained in a 5–lead TO–220 type package. The tab of the
package is common with the center pin (Pin 3) and is normally
connected to ground.
DESIGN CONSIDERATIONS
Do not attempt to construct a converter on wire–wrap
or plug–in prototype boards. Special care should be taken
to separate ground paths from signal currents and ground
paths from load currents. All high current loops should be
kept as short as possible using heavy copper runs to
minimize ringing and radiated EMI. For best operation, a tight
component layout is recommended. Capacitors CIN, CO, and
all feedback components should be placed as close to the IC
as physically possible. It is also imperative that the Schottky
diode connected to the Switch Output be located as close to
the IC as possible.
Figure 15. Low Power Standby Circuit Figure 16. Over Voltage Shutdown Circuit
Figure 17. Soft–Start Circuit
1
5
R1
120
Error
Amp
Compensation
100
µ
A
I = Standby Mode
VShutdown = VZener + 0.7
tSoft–Start
35,000 Css
Css
D1
D2
1.0 M
Vin
1
5
R1
120
Error
Amp
Compensation
100
µ
A
1
5
R1
120
Error
Amp
Compensation
100
µ
A
+ +
+
MC34166 MC33166
8MOTOROLA ANALOG IC DEVICE DATA
Figure 18. Step–Down Converter
4
2
1
5
3
+
CFRF
R1
CO
2200
VO
5.05 V/3.0 A
R2
EA
Reference
Thermal
Oscillator S
RQ
PWM UVLO
ILIMIT
Vin
12 V
Cin
330
+
6.8 k
68 k0.1
Q1
D1
1N5822
L
190
µ
H
+
+
+
Test Conditions Results
Line Regulation V in = 8.0 V to 36 V, IO = 3.0 A 5.0 mV = ±0.05%
Load Regulation Vin = 12 V, IO = 0.25 A to 3.0 A 2.0 mV = ±0.02%
Output Ripple Vin = 12 V, IO = 3.0 A 10 mVpp
Short Circuit Current Vin = 12 V, RL = 0.1 4.3 A
Efficiency Vin = 12 V, IO = 3.0 A 82.8%
L = Coilcraft M1496–A or General Magnetics Technology GMT–0223, 42 turns of #16 AWG on
Magnetics Inc. 58350–A2 core. Heatsink = AAVID Engineering Inc. 5903B, or 5930B.
The Step–Down Converter application is shown in Figure 18. The output switch transistor Q1 interrupts the input voltage, generating a squarewave at the LCO filter
input. The filter averages the squarewaves, producing a dc output voltage that can be set to any level between Vin and Vref by controlling the percent conduction
time of Q1 to that of the total oscillator cycle time. If the converter design requires an output voltage greater than 5.05 V, resistor R1 must be added to form a divider
network at the feedback input.
ÉÉÉ
ÉÉÉ
ÉÉÉÉÉ
ÉÉÉÉÉ
ÉÉÉÉÉ
ÉÉÉÉÉ
ÉÉÉÉÉ
ÉÉÉÉÉ
Figure 19. Step–Down Converter Printed Circuit Board and Component Layout
(Bottom View) (Top View)
3.0
1.9
MC34166 STEP–DOWN
Vin
VO
CO
Cin
L
CF
RF
R2
R1
D1
+– +
+
+
MC34166 MC33166
9
MOTOROLA ANALOG IC DEVICE DATA
Figure 20. Step–Up/Down Converter
4
2
1
5
3
+
CFRF
R1
1.5 k
CO
1000
VO
28 V/0.6 A
R2
EA
Reference
Thermal
Oscillator S
RQ
PWM UVLO
ILIMIT
Vin
12 V
Cin
330
+
6.8 k
4.7 k0.47
Q1D1
1N5822
+
*Gate resistor RG, zener diode D3, and diode D4 are required only when V in is greater than 20 V.
L
190
µ
H
*RG
620
D3
1N967A D2
1N5822
Q2
MTP3055EL
D4
1N4148
+
+
Test Conditions Results
Line Regulation V in = 8.0 V to 24 V, IO = 0.6 A 23 mV = ±0.41%
Load Regulation Vin = 12 V, IO = 0.1 A to 0.6 A 3.0 mV = ±0.005%
Output Ripple Vin = 12 V, IO = 0.6 A 100 mVpp
Short Circuit Current Vin = 12 V, RL = 0.1 4.0 A
Efficiency Vin = 12 V, IO = 0.6 A 82.8%
L = Coilcraft M1496–A or General Magnetics Technology GMT–0223, 42 turns of #16 AWG on
Magnetics Inc. 58350–A2 core.
Heatsink = AA VID Engineering Inc.
MC34166: 5903B, or 5930B
MTP3055EL: 5925B
Figure 20 shows that the MC34166 can be configured as a step–up/down converter with the addition of an external power MOSFET. Energy is stored in the
inductor during the on–time of transistors Q1 and Q2. During the off–time, the energy is transferred, with respect to ground, to the output filter capacitor and load.
This circuit configuration has two significant advantages over the basic step–up converter circuit. The first advantage is that output short–circuit protection is
provided by the MC34166, since Q1 is directly in series with Vin and the load. Second, the output voltage can be programmed to be less than V in. Notice that during
the off–time, the inductor forward biases diodes D1 and D2, transferring its energy with respect to ground rather than with respect to V in. When operating with V in
greater than 20 V, a gate protection network is required for the MOSFET. The network consists of components RG, D3, and D4.
Î
Î
Î
Î
Î
Î
Î
Î
ÎÎÎÎÎÎ
ÎÎÎÎÎÎ
ÎÎÎÎÎÎ
ÎÎÎÎÎÎ
ÎÎÎÎÎÎ
ÎÎÎÎÎÎ
ÎÎÎ
(Top View)(Bottom View)
3.45
1.9
Figure 21. Step–Up/Down Converter Printed Circuit Board and Component Layout
MC34166 STEP–UP/DOWN
Vin
VO
CO
Cin
L
CF
RF
R2
R1
D1
+– +
+
+
D3
D2
RG
Q2
MC34166 MC33166
10 MOTOROLA ANALOG IC DEVICE DATA
Figure 22. Voltage–Inverting Converter
4
2
1
5
3
+
CFRF
R2
3.3 k
R1
EA
Reference
Thermal
Oscillator S
RQ
PWM UVLO
ILIMIT
Vin
12 V
Cin
330
+
2.4 k
4.7 k0.47
Q1
+
CO
2200
VO
–12 V/1.0 A
D1
1N5822
L
190
µ
H
C1
0.047
+
+
Test Conditions Results
Line Regulation V in = 8.0 V to 24 V, IO = 1.0 A 3.0 mV = ±0.01%
Load Regulation Vin = 12 V, IO = 0.1 A to 1.0 A 4.0 mV = ±0.017%
Output Ripple Vin = 12 V, IO = 1.0 A 80 mVpp
Short Circuit Current Vin = 12 V, RL = 0.1 3.74 A
Efficiency Vin = 12 V, IO = 1.0 A 81.2%
L = Coilcraft M1496–A or General Magnetics Technology GMT–0223, 42 turns of #16 AWG on
Magnetics Inc. 58350–A2 core. Heatsink = AAVID Engineering Inc. 5903B, or 5930B.
Two potential problems arise when designing the standard voltage–inverting converter with the MC34166. First, the Switch Output emitter is limited to –1.5 V with
respect to the ground pin and second, the Error Amplifier’s noninverting input is internally committed to the reference and is not pinned out. Both of these problems
are resolved by connecting the IC ground pin to the converter’s negative output as shown in Figure 22. This keeps the emitter of Q1 positive with respect to the
ground pin and has the effect of reversing the Error Amplifier inputs. Note that the voltage drop across R1 is equal to 5.05 V when the output is in regulation.
+
+
+
+
+
+
+
+
+
+
+
+
ÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
ÎÎÎÎÎ
Figure 23. Voltage–Inverting Converter Printed Circuit Board and Component Layout
(Bottom View) (Top View)
3.0
1.9
MC34166
VOLTAGE-INVERTING
Vin
VO
CO
Cin
L
CF
RF
R2
R1
D1
+–
+
+
+
C1
MC34166 MC33166
11
MOTOROLA ANALOG IC DEVICE DATA
Figure 24. Triple Output Converter
4
2
1
5
3
+
VO1
5.05 V/2.0 A
EA
Reference
Thermal
Oscillator S
RQ
PWM UVLO
ILIMIT
Vin
24 V
1000
+
6.8 k
68 k0.1
1N5822
+
1000
1000
+
1000
+
MUR110
MUR110
VO3
–12 V/100 mA
VO2
12 V/300 mA
T1
+
+
Tests Conditions Results
Line Regulation 5.0 V
12 V
–12 V
Vin = 15 V to 30 V, IO1 = 2.0 A, IO2 = 300 mA, IO3 = 100 mA 4.0 mV = ±0.04%
450 mV = ±1.9%
350 mV = ±1.5%
Load Regulation 5.0 V
12 V
–12 V
Vin = 24 V, IO1 = 500 mA to 2.0 A, IO2 = 300 mA, IO3 = 100 mA
Vin = 24 V, IO1 = 2.0 A, IO2 = 100 mA to 300 mA, IO3 = 100 mA
Vin = 24 V, IO1 = 2.0 A, IO2 = 300 mA, IO3 = 30 mA to 100 mA
2.0 mV = ±0.02%
420 mV = ±1.7%
310 mV = ±1.3%
Output Ripple 5.0 V
12 V
–12 V
Vin = 24 V, IO1 = 2.0 A, IO2 = 300 mA, IO3 = 100 mA 50 mVpp
25 mVpp
10 mVpp
Short Circuit Current 5.0 V
12 V
–12 V
Vin = 24 V, RL = 0.1 4.3 A
1.83 A
1.47 A
Efficiency TOTAL Vin = 24 V, IO1 = 2.0 A, IO2 = 300 mA, IO3 = 100 mA 83.3%
T1 = Primary: Coilcraft M1496-A or General Magnetics Technology GMT–0223, 42 turns of #16 A WG on Magnetics Inc. 58350-A2 core.
T1 = Secondary: VO2 — 65 turns of #26 AWG
T1 = Secondary: VO3 — 96 turns of #28 AWG
Heatsink = AA VID Engineering Inc. 5903B, or 5930B.
Multiple auxiliary outputs can easily be derived by winding secondaries on the main output inductor to form a transformer . The secondaries must be connected so that
the energy is delivered to the auxiliary outputs when the Switch Output turns off. During the OFF time, the voltage across the primary winding is regulated by the feedback
loop, yielding a constant Volts/T urn ratio. The number of turns for any given secondary voltage can be calculated by the following equation:
# TURNS(SEC)
+
VO(SEC)
)
VF(SEC)
ǒ
VO(PRI)
)
VF(PRI)
#TURNS(PRI)
Ǔ
Note that the 12 V winding is stacked on top of the 5.0 V output. This reduces the number of secondary turns and improves lead regulation. For best auxiliary regulation,
the auxiliary outputs should be less than 33% of the total output power.
MC34166 MC33166
12 MOTOROLA ANALOG IC DEVICE DATA
VO
+ 36 V/0.25 A
D1
L
R1MUR415
Z1
22
0.01
1N5822
MTP
3055E
2N3906
R1
36 k
R2
5.1 k
+1000
VO
+ǒ
R1
R2
Ǔ)
Figure 25. Negative Input/Positive Output Regulator
4
2
1
5
3
+
0.22 470 k
EA
Reference
Thermal
Oscillator S
RQ
PWM UVLO
ILIMIT
Q1
*Gate resistor RG, zener diode D3, and diode D4 are required only when V in is greater than 20 V.
Vin
–12 V 1000
+
0.002
5.05 0.7
+
+
Test Conditions Results
Line Regulation V in = –10 V to – 20 V, IO = 0.25 A 250 mV = ±0.35%
Load Regulation Vin = –12 V, IO = 0.025 A to 0.25 A 790 mV = ±1.19%
Output Ripple Vin = –12 V, IO = 0.25 A 80 mVpp
Efficiency Vin = –12 V, IO = 0.25 A 79.2%
L = Coilcraft M1496–A or ELMACO CHK1050, 42 turns of #16 A WG on Magnetics Inc. 58350–A2 core.
Heatsink = AA VID Engineering Inc. 5903B or 5930B
47
+
50 k
Faster
Brush
Motor
Figure 26. Variable Motor Speed Control with EMF Feedback Sensing
4
2
1
5
3
+
EA
Reference
Thermal
Oscillator S
RQ
PWM
UVLO
ILIMIT Vin
18 V
1000
5.6 k
56 k0.1
1N5822
+
1.0 k
+
+
Test Conditions Results
Low Speed Line Regulation Vin = 12 V to 24 V 1760 RPM ±1%
High Speed Line Regulation V in = 12 V to 24 V 3260 RPM ±6%
MC34166 MC33166
13
MOTOROLA ANALOG IC DEVICE DATA
Figure 27. Off–Line Preconverter
1000
T1
+ +
MC34166
Step–Down
Converter
0.001
0.001
Output 1
MBR20100CT
1000+ +
MC34166
Step–Down
Converter
0.001
0.001
Output 2
MBR20100CT
1000+ +
MC34166
Step–Down
Converter
0.001
0.001
Output 3
MBR20100CT
0.01
RFI
Filter
100
3.3
1N4003
MJE13005
220
0.047
1N4937
50
100k T2
1N5404
115 VAC
T1 = Core and Bobbin – Coilcraft PT3595
T1 = Primary – 104 turns #26 A WG
T1 = Base Drive – 3 turns #26 A WG
T1 = Secondaries – 16 turns #16 A WG
T1 = Total Gap – 0.002
T2 = Core – TDK T6 x 1.5 x 3 H5C2
T2 = 14 turns center tapped #30 A WG
T2 = Heatsink = AAVID Engineering Inc.
T2 = MC34166 and MJE13005 – 5903B
T2 = MBR20100CT – 5925B
+
+
The MC34166 can be used cost effectively in off–line applications even though it is limited to a maximum input voltage of 40 V. Figure 27 shows a simple and efficient
method for converting the AC line voltage down to 24 V. This preconverter has a total power rating of 125 W with a conversion efficiency of 90%. Transformer T1
provides output isolation from the AC line and isolation between each of the secondaries. The circuit self–oscillates at 50 kHz and is controlled by the saturation
characteristics of T2. Multiple MC34166 post regulators can be used to provide accurate independently regulated outputs for a distributed power system.
R , THERMAL RESISTANCE
JA
θ
JUNCTION-T O-AIR ( C/W)
°
30
40
50
60
70
80
1.0
1.5
2.0
2.5
3.0
3.5
010203025155.0
L, LENGTH OF COPPER (mm)
PD(max) for TA = +50
°
C
Minimum
Size Pad
2.0 oz. Copper
L
L
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
ÎÎÎÎ
Free Air
Mounted
Vertically
PD, MAXIMUM POWER DISSIPATION (W)
R
θ
JA
Figure 28. D2PAK Thermal Resistance and Maximum
Power Dissipation versus P.C.B. Copper Length
MC34166 MC33166
14 MOTOROLA ANALOG IC DEVICE DATA
Table 1. Design Equations
Calculation Step–Down Step–Up/Down Voltage–Inverting
ton
toff
(Notes 1, 2)
Vout
)
VF
Vin
*
Vsat
*
Vout Vout
)
VF1
)
VF2
Vin
*
VsatQ1
*
VsatQ2 |Vout|
)
VF
Vin
*
Vsat
ton
ton
toff
fosc
ǒ
ton
toff
)
1
Ǔ
ton
toff
fosc
ǒ
ton
toff
)
1
Ǔ
ton
toff
fosc
ǒ
ton
toff
)
1
Ǔ
Duty Cycle
(Note 3) ton fosc ton fosc ton fosc
IL avg Iout Iout
ǒ
ton
toff
)
1
Ǔ
Iout
ǒ
ton
toff
)
1
Ǔ
Ipk(switch) ILavg
)
D
I
L
2I
Lavg
)
D
I
L
2I
Lavg
)
D
I
L
2
L
ǒ
V
in
*
Vsat
*
Vout
D
IL
Ǔ
ton
ǒ
Vin
*
VsatQ1
*
VsatQ2
D
IL
Ǔ
ton
ǒ
Vin
*
Vsat
D
IL
Ǔ
ton
Vripple(pp)
D
IL
ǒ
1
8foscCo
Ǔ
2
)
(ESR)2
Ǹǒ
ton
toff
)
1
Ǔǒ
1
f
oscCo
Ǔ
2
)
(ESR)2
Ǹǒ
ton
toff
)
1
Ǔǒ
1
f
oscCo
Ǔ
2
)
(ESR)2
Ǹ
Vout Vref
ǒ
R2
R1
)
1
Ǔ
Vref
ǒ
R2
R1
)
1
Ǔ
Vref
ǒ
R2
R1
)
1
Ǔ
NOTES: 1.Vsat – Switch Output source saturation voltage, refer to Figure 7.
2.VF – Output rectifier forward voltage drop. Typical value for 1N5822 Schottky barrier rectifier is 0.5 V.
3.Duty cycle is calculated at the minimum operating input voltage and must not exceed the guaranteed minimum DC(max) specification of 0.92.
Vout
Iout
IL
Vripple(pp)
Desired output voltage.
Desired output current.
Desired peak–to–peak inductor ripple current. For maximum output current especially when the duty cycle is greater than 0.5, it is suggested
that IL be chosen to be less than 10% of the average inductor current IL avg. This will help prevent Ipk(switch) from reaching the guaranteed
minimum current limit threshold of 3.3 A. If the design goal is to use a minimum inductance value, let IL = 2 (IL avg). This will proportionally
reduce the converter’s output current capability.
Desired peak–to–peak output ripple voltage. For best performance, the ripple voltage should be kept to less than 2% of V out. Capacitor CO
should be a low equivalent series resistance (ESR) electrolytic designed for switching regulator applications.
The following converter characteristics must be chosen:
MC34166 MC33166
15
MOTOROLA ANALOG IC DEVICE DATA
TH SUFFIX
PLASTIC PACKAGE
CASE 314A–03
OUTLINE DIMENSIONS
TV SUFFIX
PLASTIC PACKAGE
CASE 314B–05
G
E
J 5 PL
D 5 PL
FK
U
B
AL
C
12345
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION D DOES NOT INCLUDE
INTERCONNECT BAR (DAMBAR) PROTRUSION.
DIMENSION D INCLUDING PROTRUSION SHALL
NOT EXCEED 0.043 (1.092) MAXIMUM.
SEATING
PLANE
–T
S
TP0.014 (0.356) M M
OPTIONAL
CHAMFER
Q
DIM
AMIN MAX MIN MAX
MILLIMETERS
0.572 0.613 14.529 15.570
INCHES
B0.390 0.415 9.906 10.541
C0.170 0.180 4.318 4.572
D0.025 0.038 0.635 0.965
E0.048 0.055 1.219 1.397
F0.570 0.585 14.478 14.859
G0.067 BSC 1.702 BSC
J0.015 0.025 0.381 0.635
K0.730 0.745 18.542 18.923
L0.320 0.365 8.128 9.271
Q0.140 0.153 3.556 3.886
S0.210 0.260 5.334 6.604
U0.468 0.505 11.888 12.827
–P
G
W
E
J 5 PL
D 5 PL
F
K
U
B
AL
C
H
12345
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION D DOES NOT INCLUDE
INTERCONNECT BAR (DAMBAR) PROTRUSION.
DIMENSION D INCLUDING PROTRUSION SHALL
NOT EXCEED 0.043 (1.092) MAXIMUM.
1.702 BSC0.067 BSC
MIN MINMAX MAX
INCHES MILLIMETERS
DIM
A
B
C
D
E
F
G
H
J
K
L
N
Q
S
U
V
W
14.529
9.906
4.318
0.635
1.219
21.590
0.381
22.860
8.128
3.556
11.888
2.286
15.570
10.541
4.572
0.965
1.397
23.749
0.635
27.940
9.271
3.886
15.748
12.827
18.669
2.794
0.572
0.390
0.170
0.025
0.048
0.850
0.015
0.900
0.320
0.140
0.468
0.090
0.613
0.415
0.180
0.038
0.055
0.935
0.025
1.100
0.365
0.153
0.620
0.505
0.735
0.110
SEATING
PLANE
–T
N
SV
T
0.24 (0.610) M
–P
Q
TP0.10 (0.254) M M
4.216 BSC0.166 BSC
8.128 BSC0.320 BSC
OPTIONAL
CHAMFER
Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding
the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and
specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be provided in Motorola
data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals”
must be validated for each customer application by customer’s technical experts. Motorola does not convey any license under its patent rights nor the rights of
others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other
applications intended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury
or death may occur. Should Buyer purchase or use Motorola products for any such unintended or unauthorized application, Buyer shall indemnify and hold Motorola
and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees
arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that
Motorola was negligent regarding the design or manufacture of the part. Motorola and are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal
Opportunity/Af firmative Action Employer .
MC34166 MC33166
16 MOTOROLA ANALOG IC DEVICE DATA
T SUFFIX
PLASTIC PACKAGE
CASE 314D–03
OUTLINE DIMENSIONS
D2T SUFFIX
PLASTIC PACKAGE
CASE 936A–02
(D2PAK)
–Q
–T
SEATING
PLANE
C
U
G
E
H
J
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION D DOES NOT INCLUDE
INTERCONNECT BAR (DAMBAR) PROTRUSION.
DIMENSION D INCLUDING PROTRUSION SHALL
NOT EXCEED 10.92 (0.043) MAXIMUM.
MIN MINMAX MAX
INCHES MILLIMETERS
DIM
A
B
C
D
E
G
H
J
K
L
Q
U
S
14.529
9.906
4.318
0.635
1.219
2.210
0.381
25.908
8.128
3.556
2.667
13.792
15.570
10.541
4.572
0.965
1.397
2.845
0.635
27.051
9.271
3.886
2.972
14.783
0.572
0.390
0.170
0.025
0.048
0.087
0.015
1.020
0.320
0.140
0.105
0.543
0.613
0.415
0.180
0.038
0.055
0.112
0.025
1.065
0.365
0.153
0.117
0.582
A
B
L
S
K
D 5 PL
1.702 BSC0.067 BSC
12345
0.356 (0.014) T Q
M M
5 REF
A
123
K
B
S
H
0.010 (0.254) T
M
D
G
C
E
–T
MLP
NR
V
U
TERMINAL 6
NOTES:
1 DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2 CONTROLLING DIMENSION: INCH.
3 TAB CONTOUR OPTIONAL WITHIN DIMENSIONS
A AND K.
4 DIMENSIONS U AND V ESTABLISH A MINIMUM
MOUNTING SURFACE FOR TERMINAL 6.
5 DIMENSIONS A AND B DO NOT INCLUDE MOLD
FLASH OR GATE PROTRUSIONS. MOLD FLASH
AND GATE PROTRUSIONS NOT TO EXCEED
0.025 (0.635) MAXIMUM.
DIM
AMIN MAX MIN MAX
MILLIMETERS
0.386 0.403 9.804 10.236
INCHES
B0.356 0.368 9.042 9.347
C0.170 0.180 4.318 4.572
D0.026 0.036 0.660 0.914
E0.045 0.055 1.143 1.397
G0.067 BSC 1.702 BSC
H0.539 0.579 13.691 14.707
K0.050 REF 1.270 REF
L0.000 0.010 0.000 0.254
M0.088 0.102 2.235 2.591
N0.018 0.026 0.457 0.660
P0.058 0.078 1.473 1.981
R5 REF
S0.116 REF 2.946 REF
U0.200 MIN 5.080 MIN
V0.250 MIN 6.350 MIN
__
45
OPTIONA
L
CHAMFE
R
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MC34166/D