MOTOROLA MC33341D, MC33341DR2 Datasheet

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The MC33341 is a monolithic regulation control circuit that is specifically designed to close the voltage and current feedback loops in power supply and battery charger applications. This device features the unique ability to perform source high–side, load high–side, source low–side and load low–side current sensing, each with either an internally fixed or externally adjustable threshold. The various current sensing modes are accomplished by a means of selectively using the internal differential amplifier, inverting amplifier, or a direct input path. Positive voltage sensing is performed by an internal voltage amplifier. The voltage amplifier threshold is internally fixed and can be externally adjusted in all low–side current sensing applications. An active high drive output is provided to directly interface with economical optoisolators for isolated output power systems. This device is available in 8–lead dual–in–line and surface mount packages.

• Differential Amplifier for High–Side Source and Load Current Sensing

• Inverting Amplifier for Source Return Low–Side Current Sensing

• Non–Inverting Input Path for Load Low–Side Current Sensing

• Fixed or Adjustable Current Threshold in All Current Sensing Modes

• Positive Voltage Sensing in All Current Sensing Modes

• Fixed Voltage Threshold in All Current Sensing Modes

• Adjustable Voltage Threshold in All Low–Side Current Sensing Modes

• Output Driver Directly Interfaces with Economical Optoisolators

• Operating Voltage Range of 2.3 V to 16 V

Representative Block Diagram

Drive

Output

Current Sense Input B/

Voltage Threshold Adjust

Voltage Sense

Input

Order this document by MC33341/D



POWER SUPPLY

BATTERY CHARGER

REGULATION

CONTROL CIRCUIT

SEMICONDUCTOR

TECHNICAL DATA

P SUFFIX

PLASTIC PACKAGE

CASE 626

D SUFFIX

PLASTIC PACKAGE

CASE 751

(SO–8)

PIN CONNECTIONS

Differential

Amp

1.0

1.2 V

1.0

Inverting/

Noninverting Amp

Current Sense

Input A

This device contains 114 active transistors.

0.2 V

Current

Threshold Adjust

MOTOROLA ANALOG IC DEVICE DATA

Voltage and Current

Transconductance

Amp/Driver

Reference

Compensation

Gnd

Current Sense

Input A

Current Threshold

Adjust

Compensation

Gnd

(Top View)

Drive Output

Current Sense Input B/

Voltage Threshold Adjust

Voltage Sense Input

ORDERING INFORMATION

Operating

Device

MC33341D MC33341P

 Motorola, Inc. 1998 Rev 1

Temperature Range

TA = –25° to +85°C

Package

SO–8

Plastic DIP

MAXIMUM RATINGS

ÁÁÁÁ

Rating Symbol Value Unit

Power Supply Voltage (Pin 7) Voltage Range

Current Sense Input A (Pin 1)

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Current Threshold Adjust (Pin 2)

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Compensation (Pin 3) Voltage Sense Input (Pin 5)

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Current Sense Input B/Voltage Threshold Adjust (Pin 6)

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Drive Output (Pin 8) Drive Output Source Current (Pin 8) I Thermal Resistance, Junction–to–Air

P Suffix, DIP Plastic Package, Case 626

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D Suffix, SO–8 Plastic Package, Case 751 Operating Junction Temperature (Note 1) Storage Temperature

NOTE: ESD data available upon request.

MC33341

ÁÁ

Source

θJA

ÁÁ

stg

–1.0 to V

ÁÁÁ

50 mA

100

ÁÁÁ

178 –25 to +150 –55 to +150

V V

°C/W

°C °C

ELECTRICAL CHARACTERISTICS (V

= 6.0 V, TA = 25°C, for min/max values TA is the operating junction

temperature range that applies (Note 1), unless otherwise noted.)

Characteristic

Symbol Min Typ Max Unit

CURRENT SENSING (Pins 1, 2, 6)

High–Side Source and Load Sensing Pin 1 to Pin 6 (Pin 1 >1.6 V)

th(I HS)

Internally Fixed Threshold Voltage (Pin 2 = VCC)

TA = 25°C 187 197 207 TA = T

low

to T

high

183 – 211 Externally Adjusted Threshold Voltage (Pin 2 = 0 V) – 10 – Externally Adjusted Threshold Voltage (Pin 2 = 200 mV) – 180 –

Low–Side Load Sensing Pin 1 to Pin 4 (Pin 1 = 0 V to 0.8 V)

th(I LS+)

Internally Fixed Threshold Voltage (Pin 2 = VCC)

TA = 25°C 194 200 206 TA = T

low

to T

high

192 – 208 Externally Adjusted Threshold Voltage (Pin 2 = 0 V) – 10 – Externally Adjusted Threshold Voltage (Pin 2 = 200 mV) – 180 –

Low–Side Source Return Sensing Pin 1 to 4 (Pin 1 = 0 V to –0.2 V)

th(I LS–)

Internally Fixed Threshold Voltage (Pin 2 = VCC)

TA = 25°C –195 –201 –207 TA = T

low

to T

high

–193 – –209 Externally Adjusted Threshold Voltage (Pin 2 = 0 V) – –10 – Externally Adjusted Threshold Voltage (Pin 2 = 200 mV) – –180 –

Current Sense Input A (Pin 1)

Input Bias Current, High–Side Source and Load Sensing

(Pin 2 = 0 V to V

Pin 6

Input Bias Current, Low–Side Load Sensing

(Pin 2 = 0 V to 0.8 V)

Input Resistance, Low–Side Source Return Sensing

(Pin 2 = –0.6 V to 0 V)

Current Sense Input B/Voltage Threshold Adjust (Pin 6)

IB(A HS)

IB(A LS+)

in(A LS–)

IB(B)

– 40 – µA

– 10 – nA

– 10 – kΩ

Input Bias Current

High–Side Source and Load Current Sensing (Pin 6 > 2.0 V) – 20 – µA Voltage Threshold Adjust (Pin 6 < 1.2 V) – 100 – nA

Current Sense Threshold Adjust (Pin 2)

IB(I th)

–

Input Bias Current

Transconductance, Current Sensing Inputs to Drive Output

NOTE: 1. T ested ambient temperature range for the MC33341: T

= –25°C, T

low

high

m(I)

= +85°C.

–

6.0

–

mhos

MOTOROLA ANALOG IC DEVICE DATA

MC33341

ÁÁÁÁ

ELECTRICAL CHARACTERISTICS (continued) (V

= 6.0 V, TA = 25°C, for min/max values TA is the operating junction

temperature range that applies (Note 1), unless otherwise noted.)

Characteristic UnitMaxTypMinSymbol

DIFFERENTIAL AMPLIFIER DISABLE LOGIC (Pins 1, 6)

Logic Threshold Voltage Pin 1 (Pin 6 = 0 V)

Enabled, High–Side Source and Load Current Sensing V Disabled, Low–Side Load and Source Return Current Sensing V

th(I HS)

th(I LS)

– ≥1.7 – – ≤1.3 –

VOLTAGE SENSING (Pins 5, 6)

Positive Sensing Pin 5 to Pin 4

th(V)

Internally Fixed Threshold Voltage

TA = 25°C 1.186 1.210 1.234 V TA = T

low

to T

high

1.174 – 1.246 V Externally Adjusted Threshold Voltage (Pin 6 = 0 V) – 40 – mV Externally Adjusted Threshold Voltage (Pin 6 = 1.2 V) – 1.175 – V

Voltage Sense, Input Bias Current (Pin 5) Transconductance, Voltage Sensing Inputs to Drive Output

IB(V)

m(V)

– –

7.0

– –

DRIVE OUTPUT (Pin 8)

High State Source Voltage (I High State Source Current (Pin 8 = 0 V)

Source

= 10 mA)

Source

–

VCC – 0.8

– –

TOTAL DEVICE (Pin 7)

Operating Voltage Range Power Supply Current (VCC = 6.0 V)

NOTE: 1. T ested ambient temperature range for the MC33341: T

= –25°C, T

low

high

= +85°C.

2.5 to 15 –

2.3 to 15 300

–

600

mhos

µA

PIN FUNCTION DESCRIPTION

Pin Name Description

Current Sense Input A

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Current Threshold Adjust

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Compensation

ББББББ

Ground

Voltage Sense Input

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Current Sense Input B/

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Voltage Threshold Adjust

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Drive Output

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This multi–mode current sensing input can be used for either source high–side, load high–side, source–return low–side, or load low–side sensing. It is common to a Differential Amplifier, Inverting

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Amplifier, and a Noninverting input path. Each of these sensing paths indirectly connect to the current

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sense input of the Transconductance Amplifier. This input is connected to the high potential side of a current sense resistor when used in source high–side, load high–side, or load low–side current

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sensing modes. In source return low–side current sensing mode, this pin connects to the low potential

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side of a current sense resistor. The current sense threshold can be externally adjusted over a range of 0 V to 200 mV with respect to

Pin 4, or internally fixed at 200 mV by connecting Pin 2 to VCC.

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This pin is connected to a high impedance node within the transconductance amplifier and is made available for loop compensation. It can also be used as an input to directly control the Drive Output.

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An active low at this pin will force the Drive Output into a high state. This pin is the regulation control IC ground. The control threshold voltages are with respect to this pin. This is the voltage sensing input of the Transconductance Amplifier. It is normally connected to the

power supply/battery charger output through a resistor divider. The input threshold is controlled by

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Pin 6. This is a dual function input that is used for either high–side current sensing, or as a voltage threshold

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adjustment for Pin 5. This input is connected to the low potential side of a current sense resistor when used in source high–side or load high–side current sensing modes. In all low–side current sensing

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modes, Pin 6 is available as a voltage threshold adjustment for Pin 5. The threshold can be externally

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adjusted over a range of 0 V to 1.2 V with respect to Pin 4, or internally fixed at 1.2 V by connecting Pin 6 to VCC.

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This is the positive supply voltage for the regulation control IC. The typical operating voltage range is

2.3 V to 15 V with respect to Pin 4. This is a source–only output that normally connects to a linear or switching regulator control circuit.

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This output is capable of 15 mA, allowing it to directly drive an optoisolator in primary side control applications where galvanic isolation is required.

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MOTOROLA ANALOG IC DEVICE DATA

MC33341

Figure 1. V oltage Sensing

Threshold Change versus T emperature

4.0

–4.0

–8.0

, VOLTAGE SENSING THRESHOLD CHANGE (mV)

–12

–50

th(v)

∆

–25 0 25 50 75 100 125

TA, AMBIENT TEMPERATURE (°C)

Figure 3. Closed–Loop V oltage Sensing Input

versus V oltage Threshold Adjust

1.6 VCC = 6.0 V

1.4

VO = 1.0 V IO = 1.0 mA

, VOLTAGE SENSING INPUT (V)

Pin 5

1.2

1.0

0.8

0.6

0.4

0.2

TA = 25

Pin 5

Pin 6–VPin 5

0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 40 80 120 160 200 240 280 V

, VOLTAGE THRESHOLD ADJUST (V)

Pin 6

VCC = 6.0 V

16 14 12 10

8.0

6.0

4.0

2.0 0

Threshold Change versus T emperature

1.0

–1.0

, CURRENT SENSING

–2.0

th(I HS)

THRESHOLD CHANGE (mV)

∆

1 – Source High–Side and Load High–Side 2 – Source Return Low–Side 3 – Load Low–Side

–3.0

–50

–25 0 25 50 75 100 125

Figure 4. Closed–Loop Current Sense Input B

–40

–80 –120 –160 –200

, INPUT DIFFERENCE VOL TAGE (mV)

, CURRENT SENSE INPUT B (mV)

Pin 5

–V

Pin 6

Differential Amplifier is active for source high–side and load high–side current sensing. Both vertical axis are

–240

Pin 6

expressed in millivolts down to VCC.

–280

Figure 2. Current Sensing

VCC = 6.0 V

TA, AMBIENT TEMPERATURE (

versus Current Threshold Adjust

Pin 1–VPin 6

Pin 6

, CURRENT THRESHOLD ADJUST (V)

Pin 2

VCC = 6.0 V VO = 1.0 V IO = 1.0 mA Pin 1 = V TA = 25

2.0

4.0

6.0

8.0 10

, INPUT DIFFERENCE VOL TAGE (mV)

Pin 6

–V

Pin 1

Figure 5. Closed–Loop Current Sensing Input A

versus Current Threshold Adjust

280

Noninverting input path is active

240

for load low–side current sensing. VCC = 6.0 V

200

VO = 1.0 V IO = 1.0 mA

TA = 25

160 120

, CURRENT SENSE INPUT A (mV)

Pin 1

80 40

Pin 5

Pin 2–VPin 1

40 80 120 160 200 240 280 40 80 120 160 200 240 280

, CURRENT THRESHOLD ADJUST (mV)

Pin 2

Gnd

14 12 10

8.0

6.0

4.0

2.0 0

–120 –160 –200

, INPUT DIFFERENCE VOL TAGE (mV)

, CURRENT SENSE INPUT A (mV)

Pin 1

–240

Pin 1

–V

–260

Pin 2

Figure 6. Closed–Loop Current Sensing Input A

versus Current Threshold Adjust

0 –40 –80

Gnd

Pin 5

–|V

Pin 1

Inverting Amplifier is active for source return low–side current sensing.

Pin 2

, CURRENT THRESHOLD ADJUST (mV)

Pin 2

VCC = 6.0 V VO = 1.0 V IO = 1.0 mA TA = 25

MOTOROLA ANALOG IC DEVICE DATA

14 12 10

8.0

6.0

4.0

|, INPUT DIFFERENCE VOL TAGE (mV)

Pin 1

2.0 –|V

Pin 2

MC33341

Figure 7. Bode Plot

V oltage Sensing Inputs to Drive Output

VCC = 6.0 V

VOLTAGE GAIN (dB)

, VOLTAGE SENSING OPEN–LOOP

VOL(V)

VO = 1.0 V RL = 1.0 k

Pin 3 = 1.0 nF TA = 25

1.0 k

Figure 9. Transconductance

V oltage Sensing Inputs to Drive Output

8.0

6.0

Gain

f, FREQUENCY (Hz)

Phase

VCC = 6.0 V VO = 1.0 V TA = 25

Figure 8. Bode Plot

Current Sensing Inputs to Drive Output

)

100

120

140

, EXCESS PHASE (

160

180

VOLTAGE GAIN (dB)

, CURRENT SENSING OPEN–LOOP

VOL(I)

1.0 k

Phase Low–Side Sensing

VCC = 6.0 V VO = 1.0 V RL = 1.0 k Pin 3 = 1.8 nF

TA = 25

Phase High–Side Sensing

Gain

10 k10 k 100 k 1.0 M 100 k 1.0 M

f, FREQUENCY (Hz)

100

120

140

160

180

)

, EXCESS PHASE (

Figure 10. Transconductance

Current Sensing Inputs to Drive Output

8.0

6.0

VCC = 6.0 V VO = 1.0 V

TA = 25

4.0

2.0

, VOLTAGE SENSING TRANSCONDUCTANCE (mhos)

0.1

m(v)

–0.4

–0.8

–1.2

–1.6

4.0

2.0

0.2 0.3 0.5 1.0 2.0 3.0 5.0 10 0.2 0.3 0.5 1.0 2.0 3.0 5.0 10 IO, DRIVE OUTPUT LOAD CURRENT (mA)

Figure 11. Drive Output High State

Source Saturation versus Load Current

VCC = 6.0 V

TA = 25

, CURRENT SENSING TRANSCONDUCT ANCE (mhos)

0.1

m(I)

1.0

0.8

0.6

0.4

0.2

IO, DRIVE OUTPUT LOAD CURRENT (mA)

Figure 12. Supply Current

versus Supply V oltage

Drive Output High State

IO = 0 mA TA = 25

Drive Output Low State

, OUTPUT SOURCE SA TURATION VOLTAGE (V)

–2.0

4.0 8.0 12 16 20 4.0 8.0 12 16 IL, OUTPUT LOAD CURRENT (mA)

MOTOROLA ANALOG IC DEVICE DATA

, SUPPLY CURRENT, DRIVE OUTPUT LOW ST ATE (mA)

VCC, SUPPLY VOLTAGE (V)

MC33341

INTRODUCTION

Power supplies and battery chargers require precise control of output voltage and current in order to prevent catastrophic damage to the system load. Many present day power sources contain a wide assortment of building blocks and glue devices to perform the required sensing for proper regulation. Typical feedback loop circuits may consist of a voltage and current amplifier, level shifting circuitry , summing circuitry and a reference. The MC33341 contains all of these basic functions in a manner that is easily adaptable to many of the various power source–load configurations.

OPERA TING DESCRIPTION

The MC33341 is an analog regulation control circuit that is specifically designed to simultaneously close the voltage and current feedback loops in power supply and battery charger applications. This device can control the feedback loop in either constant–voltage or constant–current mode with automatic crossover. A concise description of the integrated circuit blocks is given below. Refer to the block diagram in Figure 13.

Transconductance Amplifier

A quad input transconductance amplifier is used to control the feedback loop. This amplifier has separate voltage and current channels, each with a sense and a threshold input. Within a given channel, if the sense input level exceeds that of the threshold input, the amplifier output is driven high. The channel with the largest difference between the sense and threshold inputs will set the output source current of the amplifier and thus dominate control of the feedback loop. The amplifier output appears at Pin 8 and is a source–only type that is capable of 15 mA.

A high impedance node within the transconductance amplifier is made available at Pin 3 for loop compensation. This pin can sink and source up to 10 µA of current. System stability is achieved by connecting a capacitor from Pin 3 to ground. The Compensation Pin signal is out of phase with respect to the Drive Output. By actively clamping Pin 3 low, the Drive Output is forced into a high state. This, in effect, will shutdown the power supply or battery charger, by forcing the output voltage and current regulation threshold down towards zero.

V oltage Sensing

The voltage that appears across the load is monitored by the noninverting V This voltage is resistively scaled down and connected to Pin 5. The threshold at which voltage regulation occurs is set by the level present at the inverting Vth input of the transconductance amplifier. This level is controlled by Pin 6. In source high–side and load high–side current sensing modes, Pin 6 must be connected to the low potential side of current sense resistor RS. Under these conditions, the voltage regulation threshold is internally fixed at 1.2 V. In source return low–side and load low–side current sensing modes, Pin 6 is available, and can be used to lower the regulation threshold of Pin 5. This threshold can be externally adjusted over a range of 0 V to 1.2 V with respect to the IC ground at Pin 4.

Current Sensing

Current sensing is accomplished by monitoring the voltage that appears across sense resistor RS, level shifting it with respect to Pin 4 if required, and applying it to the

input of the transconductance amplifier.

sen

noninverting I order to allow for maximum circuit flexibility, there are three methods of current sensing, each with different internal paths.

In source high–side (Figures 13 and 14) and load high–side (Figures 17 and 18) current sensing, the Differential Amplifier is active with a gain of 1.0. Pin 1 connects to the high potential side of current sense resistor RS while Pin 6 connects to the low side. Logic circuitry is provided to disable the Differential Amplifier output whenever low–side current sensing is required. This circuit clamps the Differential Amplifier output high which disconnects it from the I Transconductance Amplifier . This happens if Pin 1 is less than

1.2 V or if Pin 1 is less than Pin 6.

With source return low–side current sensing (Figures 15 and 16), the Inverting Amplifier is active with a gain of –1.0. Pin 1 connects to the low potential side of current sense resistor RS while Pin 4 connects to the high side. Note that a negative voltage appears across RS with respect to Pin 4.

In load low–side current sensing (Figures 19 and 20) a Noninverting input path is active with a gain of 1.0. Pin 1 connects to the high potential side of current sense resistor RS while Pin 4 connects to the low side. The Noninverting input path lies from Pin 1, through the Inverting Amplifier input and feedback resistors R, to the cathode of the output diode. With load low–side current sensing, Pin 1 will be more positive than Pin 4, forcing the Inverting Amplifier output low. This causes the diode to be reverse biased, thus preventing the output stage of the amplifier from loading the input signal that is flowing through the feedback resistors.

The regulation threshold in all of the current sensing modes is internally fixed at 200 mV with Pin 2 connected to VCC. Pin 2 can be used to externally adjust the threshold over a range of 0 to 200 mV with respect to the IC ground at Pin 4.

Reference

An internal band gap reference is used to set the 1.2 V voltage threshold and 200 mV current threshold. The reference is initially trimmed to a ±1.0% tolerance at TA = 25°C and is guaranteed to be within ±2.0% over an ambient operating temperature range of –25° to 85°C.

Applications

Each of the application circuits illustrate the flexibility of this device. The circuits shown in Figures 13 through 20 contain an optoisolator connected from the Drive Output at Pin 8 to ground. This configuration is shown for ease of understanding and would normally be used to provide an isolated control signal to a primary side switching regulator controller. In non–isolated, primary or secondary side applications, a load resistor can be placed from Pin 8 to ground. This resistor will convert the Drive Output current to a voltage for direct control of a regulator.

In applications where excessively high peak currents are possible from the source or load, the load induced voltage drop across RS could exceed 1.6 V. Depending upon the current sensing configuration used, this will result in forward biasing of either the internal VCC clamp diode, Pin 6, or the device substrate, Pin 1. Under these conditions, input series resistor R3 is required. The peak input current should be limited to 20 mA. Excessively large values for R3 will degrade the current sensing accuracy. Figure 21 shows a method of bounding the voltage drop across RS without sacrificing current sensing accuracy.

input of the transconductance amplifier. In

sen

input of the

sen

MOTOROLA ANALOG IC DEVICE DATA

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