Motorola MC34166TV, MC34166D2TR4, MC34166T, MC34166TH, MC33166D2T Datasheet

  

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 D

2

PAK Package

Order this document by MC34166/D




POWER SWITCHING

REGULATORS

SEMICONDUCTOR

TECHNICAL DATA

TH SUFFIX

PLASTIC PACKAGE

CASE 314A

1

5

Heatsink surface connected to Pin 3.

T SUFFIX

PLASTIC PACKAGE

CASE 314D

1

5

1

5

TV SUFFIX

PLASTIC PACKAGE

CASE 314B

3

Oscillator

PWM

Simplified Block Diagram

(Step Down Application)

I

LIMIT

S

Q

R

UVLO

Thermal

Reference

EA

5

This device contains 143 active transistors.

Pin 1. V oltage Feedback Input

2. Switch Output

3. Ground

4. Input V oltage/V

5. Compensation/Standby

V

in

4

1

5

Heatsink surface (shown as terminal 6

2

in case outline drawing) is connected to Pin 3.

CC

D2T SUFFIX

PLASTIC PACKAGE

CASE 936A

(D2PAK)

ORDERING INFORMATION

L

1

V

O

5.05 V/3.0 A

Device

MC33166D2T
MC33166T
MC33166TH
MC33166TV
MC34166D2T
MC34166T
MC34166TH
MC34166TV

Operating

Temperature Range

TA = – 40° to + 85°C

TA = 0° to + 70°C

Package

Surface Mount
Straight Lead
Horiz. Mount
Vertical Mount
Surface Mount
Straight Lead
Horiz. Mount
Vertical Mount

MOTOROLA ANALOG IC DEVICE DATA

 Motorola, Inc. 1996 Rev 4

1

MAXIMUM RATINGS

Rating Symbol Value Unit

Power Supply Input Voltage V
Switch Output Voltage Range V
Voltage Feedback and Compensation Input

Voltage Range

Power Dissipation

Case 314A, 314B and 314D (TA = +25°C) P

Thermal Resistance, Junction–to–Ambient θ
Thermal Resistance, Junction–to–Case θ

Case 936A (D2PAK) (TA = +25°C) P

Thermal Resistance, Junction–to–Ambient θ

Thermal Resistance, Junction–to–Case θ
Operating Junction Temperature T
Operating Ambient Temperature (Note 3)

MC34166
MC33166

Storage Temperature Range T

V

FB, VComp

MC34166 MC33166

CC

O(switch)

D
JA
JC

D
JA
JC

J

T

A

stg

40 V

–1.5 to + V

in

–1.0 to + 7.0 V

Internally Limited W

65 °C/W

5.0 °C/W

Internally Limited W

70 °C/W

5.0 °C/W

+150 °C

0 to + 70

– 40 to + 85

– 65 to +150 °C

V

°C

ELECTRICAL CHARACTERISTICS (V

= 12 V, for typical values TA = +25°C, for min/max values TA is the operating ambient

CC

temperature range that applies [Notes 2, 3], unless otherwise noted.)

Characteristic

Symbol Min Typ Max Unit

OSCILLAT OR

Frequency (VCC = 7.5 V to 40 V) TA = +25°C

TA = T

low

to T

high

f

OSC

65
62

72

–

81

79

ERROR AMPLIFIER

Voltage Feedback Input Threshold TA = +25°C

TA = T

low

to T

high

Line Regulation (VCC = 7.5 V to 40 V, TA = +25°C) Reg
Input Bias Current (VFB = V

+ 0.15 V) I

FB(th)

V

FB(th)

IB

line

4.95

4.85

5.05
–

5.15

5.2
– 0.03 0.078 %/V
– 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 (I
Low State (I

= 75 µA, VFB = 4.5 V)

Source

= 0.4 mA, VFB = 5.5 V)

Sink

V

OH

V

OL

4.2
–

4.9

1.6

–

1.9

PWM COMPARATOR

Duty Cycle

Maximum (VFB = 0 V)
Minimum (V

Comp

= 1.9 V)

DC

DC

(max)

(min)

92

0

0

95

100

0

SWITCH OUTPUT

Output Voltage Source Saturation (VCC = 7.5 V, I

Off–State Leakage (VCC = 40 V, Pin 2 = Gnd) I
Current Limit Threshold I

= 3.0 A) V

Source

sat

sw(off)

pk(switch)

– (V

CC

–1.5)

(V

CC

–1.8)

– 0 100 µA

3.3 4.3 6.0 A

Switching Times (VCC = 40 V, Ipk = 3.0 A, L = 375 µH, TA = +25°C)

Output Voltage Rise T ime
Output Voltage Fall T ime

t

r

t

f

–
–

100

50

200
100

UNDERVOLTAGE LOCKOUT

Startup Threshold (VCC Increasing, TA = +25°C) V
Hysteresis (VCC Decreasing, TA = +25°C) V

th(UVLO)
H(UVLO)

5.5 5.9 6.3 V

0.6 0.9 1.2 V

TOTAL DEVICE

Power Supply Current (TA = +25°C )

Standby (VCC = 12 V, V
Operating (VCC = 40 V, Pin 1 = Gnd for maximum duty cycle)

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.T

=0°C for MC34166 T

low

=–40°C for MC33166 = + 85°C for MC33166

Comp

< 0.15 V)

high

= + 70°C for MC34166

I

CC

–
–

36
31

100

55

kHz

V

V

%

V

ns

µA

mA

2

MOTOROLA ANALOG IC DEVICE DATA

MC34166 MC33166

Figure 1. V oltage Feedback Input Threshold

versus T emperature

5.25
VCC = 12 V

5.17

5.09

5.01

4.93

, VOLTAGE FEEDBACK INPUT THRESHOLD (V)

4.85

– 55 – 25 0 25 50 75 100 125

FB(th)

V

TA, AMBIENT TEMPERATURE (°C)

V

FB(th)

V

FB(th)

V

FB(th)

Max = 5.15 V

Typ = 5.05 V

Min = 4.95 V

Figure 3. Error Amp Open Loop Gain and

Phase versus Frequency

100

80

60

40

20

, OPEN LOOP VOL TAGE GAIN (dB)

0

VOL

A

–20

Gain

100 1.0 k 10 k 100 k 1.0 M

f, FREQUENCY (Hz)

VCC = 12 V

V

= 3.25 V

Comp

RL = 100 k
TA = +25

°

C

Phase

100

80

60

40

, INPUT BIAS CURRENT (nA)

20

IB

I

0

– 55 – 25 0 25 50 75 100 125

0

30

60

90

120

150

180

10 M10

2.0

1.6

1.2

0.8

0.4

, EXCESS PHASE (DEGREES)

φ

, OUTPUT SA TURATION VOLTAGE (V)

sat

V

0

Figure 2. V oltage Feedback Input Bias

Current versus Temperature

VCC = 12 V
VFB = V

FB(th)

TA, AMBIENT TEMPERATURE (°C)

Figure 4. Error Amp Output Saturation

versus Sink Current

VCC = 12 V
VFB = 5.5 V

°

C

TA = +25

0.4 0.8 1.2 1.6
I

, OUTPUT SINK CURRENT (mA)

Sink

2.00

Figure 5. Oscillator Frequency Change

versus T emperature

4.0

0

– 4.0

– 8.0

, OSCILLAT OR FREQUENCY CHANGE (%)

OSC

–12

f

–55

∆

– 25 0 25 50 75 100 125

TA, AMBIENT TEMPERATURE (

MOTOROLA ANALOG IC DEVICE DATA

VCC = 12 V

°

C)

100

80

60

40

20

DC, SWITCH OUTPUT DUTY CYCLE (%)

0

1.5

Figure 6. Switch Output Duty Cycle

versus Compensation V oltage

VCC = 12 V

°

C

TA = +25

2.0 2.5 3.0 3.5 4.0
V

, COMPENSATION VOLTAGE (V)

Comp

4.5

3

MC34166 MC33166

Figure 7. Switch Output Source Saturation

versus Source Current

0

V

– 0.5

–1.0

–1.5

– 2.0

– 2.5

, SWITCH OUTPUT SOURCE SA TURATION (V)

– 3.0

sat

0 2.0 3.0 4.0 5.0

V

1.0

I

, SWITCH OUTPUT SOURCE CURRENT (A)

Source

CC

TA = +25°C

Figure 9. Switch Output Current Limit

Threshold versus T emperature

4.7
VCC = 12 V

Pins 1, 2, 3 = Gnd

4.5

Figure 8. Negative Switch Output Voltage

versus T emperature

0

VCC = 12 V

– 0.2

Pin 5 = 2.0 V
Pins 1, 3 = Gnd

– 0.4

Pin 2 Driven Negative

– 0.6

– 0.8

–1.0

, SWITCH OUTPUT VOL TAGE (V)

sw

V

–1.2

– 55 – 25 0 25 50 75 100 125

Isw = 10 mA

TA, AMBIENT TEMPERATURE (°C)

Gnd

Isw = 100 µA

Figure 10. Standby Supply Current

versus Supply V oltage

160

Pin 4 = V

CC

Pins 1, 3, 5 = Gnd

A)

µ

120

Pin 2 Open

°

C

TA = +25

4.3

4.1

, CURRENT LIMIT THRESHOLD (A)

pk(switch)

3.9

I

– 55 – 25 0 25 50 75 100 125

TA, AMBIENT TEMPERATURE (°C)

Figure 11. Undervoltage Lockout

Threshold versus T emperature

6.5

6.0

5.5

5.0

4.5

, UNDERVOL TAGE LOCKOUT THRESHOLD (V)

4.0

–55

th(UVLO)

V

– 25 0 25 50 75 100 125

TA, AMBIENT TEMPERATURE (

Startup Threshold

VCC Increasing

Turn–Off Threshold

VCC Decreasing

°

C)

, SUPPLY CURRENT (

CC

I

, SUPPLY CURRENT (mA)

CC

I

40

30

20

10

80

40

0

0

10 20 30 40

VCC, SUPPLY VOLTAGE (V)

Figure 12. Operating Supply Current

versus Supply V oltage

0

0

10 20 30

VCC, SUPPLY VOLTAGE (V)

Pin 4 = V

CC

Pins 1, 3 = Gnd
Pins 2, 5 Open

°

C

TA = +25

40

4

MOTOROLA ANALOG IC DEVICE DATA

MC34166 MC33166

Figure 13. MC34166 Representative Block Diagram

V

in

+

C

T

Oscillator

Pulse Width

Modulator

PWM Latch

Current

Sense

S

Q

R

Undervoltage

Lockout

4

Switch
Output

2

Input Voltage/V

C

in

CC

Timing Capacitor C

4.1 V
T

Compensation

2.3 V

Thermal

Shutdown

µ

A

100

Gnd Compensation

3

Sink Only

=

Positive True Logic

Figure 14. Timing Diagram

+

120

5

5.05 V

Reference

Error

Amp

C

F

R

F

Voltage

+

Feedback
Input

L

V

1

R

2

R

1

O

C

O

ON

Switch Output

OFF

MOTOROLA ANALOG IC DEVICE DATA

5

MC34166 MC33166

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. T o 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:

R

2

V

+

out

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.

5.05

ǒ

Ǔ

)

1

R

1

6

MOTOROLA ANALOG IC DEVICE DATA

MC34166 MC33166

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

DESIGN CONSIDERATIONS

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.

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

Figure 15. Low Power Standby Circuit

100

Compensation

I = Standby Mode

+ +

µ

A

120

5

Error
Amp

1

R

1

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 16. Over Voltage Shutdown Circuit

120

5

+ 0.7

Error

Amp

1

R

1

µ

A

100

Compensation

V

Shutdown

= V

Zener

V

in

Figure 17. Soft–Start Circuit

µ

A

100

Compensation

D

2

1.0 M
t

Soft–Start

+

≈ 35,000 C

120

5

D

C

Error
Amp

1

ss

ss

1

R

1

MOTOROLA ANALOG IC DEVICE DATA

7

MC34166 MC33166

Figure 18. Step–Down Converter

V

in

12 V

+

Oscillator

PWM

Thermal

3

Test Conditions Results

Line Regulation Vin = 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 mV
Short Circuit Current Vin = 12 V, RL = 0.1 Ω 4.3 A
Efficiency Vin = 12 V, IO = 3.0 A 82.8%

L = Coilcraft M1496–A or General Magnetics T echnology GMT–0223, 42 turns of #16 AWG on
Magnetics Inc. 58350–A2 core. Heatsink = AAVID Engineering Inc. 5903B, or 5930B.

S

R

ILIMIT

Q

UVLO

Reference

+

EA

C

5

F

4

Q

1

2

+

1

R

F

68 k0.1

+

pp

C

in

330

D

1

1N5822

R

2

6.8 k

R

1

C

O

2200

L

190

µ

+

5.05 V/3.0 A

H

V

O

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 V
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.

by controlling the percent conduction

ref

Figure 19. Step–Down Converter Printed Circuit Board and Component Layout

3.0

″

V

″

1.9

MC34166 STEP–DOWN

V

in

+–

in

C

RF

O

+–

R2

R1

O

C

+

C

F

D1

L

+

(Bottom View) (Top View)

8

MOTOROLA ANALOG IC DEVICE DATA

MC34166 MC33166

Figure 20. Step–Up/Down Converter

+

Oscillator

PWM

Thermal

3

*Gate resistor RG, zener diode D3, and diode D4 are required only when Vin is greater than 20 V.

S

R

ILIMIT

Q

UVLO

Reference

+

EA

5

C

F

Q

1

+

R

F

4.7 k0.47

4

2

1

V

in

12 V

+

C

in

330

D

1

1N5822

D

4

1N4148

D

1N967A

R

6.8 k

R

1

1.5 k

L

µ

H

190

*R

G

620

Q

2

MTP3055EL

3

D

2

C

O

1000

1N5822

+

28 V/0.6 A

V

O

2

Test Conditions Results

Line Regulation Vin = 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 mV
Short Circuit Current Vin = 12 V, RL = 0.1 Ω 4.0 A
Efficiency Vin = 12 V, IO = 0.6 A 82.8%

L = Coilcraft M1496–A or General Magnetics T echnology GMT–0223, 42 turns of #16 AWG on
Magnetics Inc. 58350–A2 core.
Heatsink = AAVID 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 Vin. 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 Vin. When operating with V
greater than 20 V, a gate protection network is required for the MOSFET. The network consists of components RG, D3, and D4.

pp

in

Figure 21. Step–Up/Down Converter Printed Circuit Board and Component Layout

3.45

″

D3

V

V

in

+–

″

1.9

in

MC34166 STEP–UP/DOWN

C

+

RF

O

+–

R2

R1

O

C

D2

+

C

F

D1

L

R

G

Q2

MOTOROLA ANALOG IC DEVICE DATA

(Top View)(Bottom View)

9

MC34166 MC33166

Figure 22. V oltage–Inverting Converter

V

in

12 V

+

Oscillator

PWM

Thermal

3

Test Conditions Results

Line Regulation Vin = 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 mV
Short Circuit Current Vin = 12 V, RL = 0.1 Ω 3.74 A
Efficiency Vin = 12 V, IO = 1.0 A 81.2%

L = Coilcraft M1496–A or General Magnetics T echnology 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.

S

R

ILIMIT

Q

UVLO

Reference

+

EA

5

C

F

4

+

C

in

330

Q

1

2

+

1

R

F

4.7 k0.47

R

2

3.3 k

pp

190

R

1

2.4 k

C

0.047

L

µ

H

1

D

1

1N5822

–12 V/1.0 A

+

C

O

2200

V

O

10

Figure 23. V oltage–Inverting Converter Printed Circuit Board and Component Layout

3.0

″

+

+

+

V

O

″

1.9

MC34166

VOLTAGE-INVERTING

V

in

+–

in

C

+–

R2

RF

C

C1

R1

C

F

+

+

+

+

(Bottom View) (Top View)

MOTOROLA ANALOG IC DEVICE DATA

+

O

D1

+

+

+

L

+

+

+

MC34166 MC33166

Figure 24. Triple Output Converter

V

in

24 V

+

Oscillator

PWM

Thermal

3

Tests Conditions Results

Line Regulation 5.0 V

12 V

–12 V

Load Regulation 5.0 V

12 V

–12 V

Output Ripple 5.0 V

12 V

–12 V

Short Circuit Current 5.0 V

12 V

–12 V

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 AWG on Magnetics Inc. 58350-A2 core.

T1 = Secondary: VO2 — 65 turns of #26 AWG
T1 = Secondary: VO3 — 96 turns of #28 AWG

Heatsink = AAVID 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/Turn ratio. The number of turns for any given secondary voltage can be calculated by the following equation:

Vin = 15 V to 30 V, IO1 = 2.0 A, IO2 = 300 mA, IO3 = 100 mA 4.0 mV = ± 0.04%

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

Vin = 24 V, IO1 = 2.0 A, IO2 = 300 mA, IO3 = 100 mA 50 mV

Vin = 24 V, RL = 0.1 Ω 4.3 A

S

R

ILIMIT

Q

UVLO

Reference

+

EA

5

4

+

1000

2

1N5822

MUR1 10

1000

+

T1

MUR1 10

+

6.8 k

1

68 k0.1

1000

+

5.05 V/2.0 A

+

1000

V

O1

450 mV = ±1.9%
350 mV = ±1.5%

2.0 mV = ± 0.02%
420 mV = ±1.7%
310 mV = ±1.3%

pp

25 mV

pp

10 mV

pp

1.83 A

1.47 A

V

O3

–12 V/100 mA

V

O2

12 V/300 mA

V

# TURNS

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.

(SEC)

+

O(SEC)

V

ǒ

MOTOROLA ANALOG IC DEVICE DATA

O(PRI)

#TURNS

)
)

V

F(SEC)

V

F(PRI)

(PRI)

Ǔ

11

MC34166 MC33166

Figure 25. Negative Input/Positive Output Regulator

+

Oscillator

PWM

Thermal

3

V

in

–12 V

Line Regulation Vin = –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 mV
Efficiency Vin = –12 V, IO = 0.25 A 79.2%

L = Coilcraft M1496–A or ELMACO CHK1050, 42 turns of #16 AWG on Magnetics Inc. 58350–A2 core.
Heatsink = AAVID Engineering Inc. 5903B or 5930B

1000

+

*Gate resistor RG, zener diode D3, and diode D4 are required only when Vin is greater than 20 V.

Test Conditions Results

S

R

ILIMIT

Q

UVLO

Reference

+

EA

5

0.22 470 k

0.002

4

22

2

1

0.01

1N5822

D

1

Q

1

+

Figure 26. Variable Motor Speed Control with EMF Feedback Sensing

R

1

ǒ

VO+

L

MUR415

R

1

MTP

3055E

Z

1

pp

Ǔ

R

2

36 k

5.1 k

)

+

R

1

R

2

5.05 0.7

2N3906

V

O

+ 36 V/0.25 A

1000

+

Oscillator

PWM

Thermal

3

Test Conditions Results

Low Speed Line Regulation Vin = 12 V to 24 V 1760 RPM ±1%
High Speed Line Regulation Vin = 12 V to 24 V 3260 RPM ± 6%

S

R

ILIMIT

Q

UVLO

Reference

+

EA

5

+

56 k0.1

V

in

4

18 V

+

1000

2

1N5822

Brush
Motor

1

5.6 k

1.0 k

+

47

50 k

Faster

12

MOTOROLA ANALOG IC DEVICE DATA

MC34166 MC33166

Figure 27. Off–Line Preconverter

T1

0.001

MBR20100CT

115 VAC

1N5404

RFI

Filter

T1 = Core and Bobbin – Coilcraft PT3595

T1 = Primary – 104 turns #26 AWG
T1 = Base Drive – 3 turns #26 AWG
T1 = Secondaries – 16 turns #16 AWG
T1 = Total Gap – 0.002

100k

+

220

50

″

MJE13005

0.047

1N4937

3.3

1N4003

+ +

1000

0.001

0.001

MBR20100CT

T

2

0.01

0.001

0.001

100

+

MBR20100CT

0.001

T2 = Core – TDK T6 x 1.5 x 3 H5C2

T2 = 14 turns center tapped #30 AWG

T2 = Heatsink = AAVID Engineering Inc.

T2 = MC34166 and MJE13005 – 5903B
T2 = MBR20100CT – 5925B

+ +

1000

+ +

1000

MC34166

Step–Down

Converter

MC34166

Step–Down

Converter

MC34166

Step–Down

Converter

Output 1

Output 2

Output 3

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 T
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.

Figure 28. D2P AK Thermal Resistance and Maximum

Power Dissipation versus P.C.B. Copper Length

80

70

°

60

50

JA

JUNCTION-TO-AIR ( C/W)

θ

40

R , THERMAL RESISTANCE

30

010203025155.0

Free Air

Mounted

Vertically

P

for TA = +50°C

D(max)

2.0 oz. Copper

Minimum
Size Pad

R

θ

JA

L, LENGTH OF COPPER (mm)

L

L

3.5

3.0

2.5

2.0

1.5

1.0

, MAXIMUM POWER DISSIPATION (W)

D

P

1

MOTOROLA ANALOG IC DEVICE DATA

13

MC34166 MC33166

T able 1. Design Equations

Calculation Step–Down Step–Up/Down Voltage–Inverting

t

on

t

off

(Notes 1, 2)

t

on

Duty Cycle

(Note 3)

IL

avg

I

pk(switch)

L

V

ripple(pp)

V

out

NOTES: 1. V

– Switch Output source saturation voltage, refer to Figure 7.

sat

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

D

V

)

V

out

V

ǒ

ton f

I

sat

D

1

ǒ

sat

t
t

t

on

t

off

out

I

L

R
R

on
off

osc

)

*

2
1

F

*

V

out

Ǔ

)

1

D

I

L

2

V

out

Ǔ

t

on

2

Ǔ

)

)

1

(ESR)

Ǔ

2

Vin*

f

osc

I

Lavg

Vin*

V

ǒ

Ǹ ǒ

ǒ

I

L

8f

oscCo

V

ref

ǒ

t

on

t

off

Vin*

Vin*

)

V

)

out

V

f

osc

I

out

I

Lavg

V

satQ1

Ǹ

Ǔǒ

1

V

ref

VF1)

satQ1

t

on

t

off

t

on

ǒ

t

off

ton f

t

on

ǒ

t

off

D

I

L

f

oscCo

R

ǒ

R

osc

)

*

1

2
1

*

)

)

)

V

V

1

Ǔ

1

D

I

L

2

V

satQ2

2

Ǔ

Ǔ

1

F2

satQ2

Ǔ

)

Ǔ

t

on

(ESR)

|V

Vin*

f

osc

I

out

I

Lavg

Vin*

ǒ

t

2

on

ǒ

t

off

Ǹ

Ǔǒ

)

1

V

ref

specification of 0.92.

(max)

out

t
t

t

ǒ

t

ton f

t

ǒ

t

D

I

f

oscCo

R

ǒ

R

|)V

on

off
on
off

osc

on
off

)

V

L

1

2
1

V

sat

)

)

)

sat

D

Ǔ

F

Ǔ

1

Ǔ

1

I

L

2

t

on

2

Ǔ

)

Ǔ

1

(ESR)

2

The following converter characteristics must be chosen:

V

–

Desired output voltage.

out

I

–

Desired output current.

out
∆IL –

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

minimum current limit threshold of 3.3 A. If the design goal is to use a minimum inductance value, let ∆IL = 2 (IL
reduce the converter’s output current capability.

V

ripple(pp)

Desired peak–to–peak output ripple voltage. For best performance, the ripple voltage should be kept to less than 2% of V

–

should be a low equivalent series resistance (ESR) electrolytic designed for switching regulator applications.

. This will help prevent I

avg

pk(switch)

from reaching the guaranteed

). This will proportionally

avg

. Capacitor C

out

O

14

MOTOROLA ANALOG IC DEVICE DATA

MC34166 MC33166

OUTLINE DIMENSIONS

TH SUFFIX

PLASTIC PACKAGE

CASE 314A–03

K

Q

D 5 PL

Q

F

D 5 PL

U

U

–P

–

B

12345

M M

B

–P

–

12345

M M

TP0.10 (0.254)

SEATING

–T

PLANE

–

C

OPTIONAL
CHAMFER

A

G

E

L

F

K

J 5 PL

S

TP0.014 (0.356)

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.

INCHES

DIMAMIN MAX MIN MAX

0.572 0.613 14.529 15.570

B 0.390 0.415 9.906 10.541
C 0.170 0.180 4.318 4.572
D 0.025 0.038 0.635 0.965
E 0.048 0.055 1.219 1.397
F 0.570 0.585 14.478 14.859
G 0.067 BSC 1.702 BSC
J 0.015 0.025 0.381 0.635
K 0.730 0.745 18.542 18.923
L 0.320 0.365 8.128 9.271
Q 0.140 0.153 3.556 3.886
S 0.210 0.260 5.334 6.604
U 0.468 0.505 11.888 12.827

MILLIMETERS

TV SUFFIX

PLASTIC PACKAGE

CASE 314B–05

NOTES:

C

OPTIONAL
CHAMFER

E

A

L

S

V

W

J 5 PL

G

0.24 (0.610)

M

T

H

N

SEATING

–T

PLANE

–

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.

INCHES MILLIMETERS

MIN MINMAX MAX

DIM

A
B
C
D
E
F
G
H
J
K
L
N
Q
S
U
V

W

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

14.529

9.906

4.318

0.635

1.219

21.590

1.702 BSC0.067 BSC

4.216 BSC0.166 BSC

0.381

22.860

8.128

8.128 BSC0.320 BSC

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

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. “T ypical” 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/Affirmative Action Employer.

MOTOROLA ANALOG IC DEVICE DATA

15

–Q

–

U

K

D

12345

5 PL

0.356 (0.014) T Q

B

M M

MC34166 MC33166

OUTLINE DIMENSIONS

T SUFFIX

PLASTIC PACKAGE

CASE 314D–03

SEATING

–T

PLANE

–

C

E

A

L

S

G

J

H

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.

INCHES MILLIMETERS

MIN MINMAX MAX

DIM

A
B
C
D
E

G

H
J
K
L

Q

U
S

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

14.529

9.906

4.318

0.635

1.219

1.702 BSC0.067 BSC

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

K

B

D

0.010 (0.254) T

M

C

A

123

G

45

S

H

OPTIONA

L

CHAMFE

E

R

N

D2T SUFFIX

PLASTIC PACKAGE

CASE 936A–02

(D2PAK)

–T

–

V

M

L

P

R

TERMINAL 6

NOTES:

1 DIMENSIONING AND TOLERANCING PER ANSI

U

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.

INCHES

DIMAMIN MAX MIN MAX

0.386 0.403 9.804 10.236

B 0.356 0.368 9.042 9.347
C 0.170 0.180 4.318 4.572
D 0.026 0.036 0.660 0.914
E 0.045 0.055 1.143 1.397
G 0.067 BSC 1.702 BSC
H 0.539 0.579 13.691 14.707
K 0.050 REF 1.270 REF
L 0.000 0.010 0.000 0.254
M 0.088 0.102 2.235 2.591
N 0.018 0.026 0.457 0.660
P 0.058 0.078 1.473 1.981

__

R 5 REF
S 0.116 REF 2.946 REF
U 0.200 MIN 5.080 MIN
V 0.250 MIN 6.350 MIN

MILLIMETERS

5 REF

How to reach us:

Mfax is a trademark of Motorola, Inc.

USA/EUROPE /Locations Not Listed: Motorola Literature Distribution; JAPAN: Nippon Motorola Ltd.: SPD, Strategic Planning Office, 4–32–1,
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INTERNET: http://motorola.com/sps

16

◊

MOTOROLA ANALOG IC DEVICE DATA

MC34166/D