Datasheet MIC38HC43BN, MIC38HC43BM, MIC38HC42BM, MIC38HC42BN, MIC38HC43-1BM Datasheet (MICREL)

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MIC38HC42/3/4/5 Micrel

MIC38HC42/3/4/5

BiCMOS 1A Current-Mode PWM Controllers

General Description

The MIC38HC4x family are fixed frequency current-mode PWM controllers with 1A drive current capability. Micrel’s BiCMOS devices are pin-compatible with 384x bipolar devices. Their high output drive, with fast rise and fall times, combined with low startup current make it an ideal PWM controller where high efficiency is required.

Undervoltage lockout circuitry allows the ’42 and ’44 versions to start up at 14.5V and operate down to 9V, and the ’43 and ’45 versions start at 8.4V with operation down to 7.6V. All versions operate up to 20V.

When compared to bipolar UC384x devices operating from a 15V supply, start-up current has been reduced to 50µA typical and operating current has been reduced to 4.0 mA typical. Decreased output rise and fall times drive larger MOSFETs, and rail-to-rail output capability increases efficiency, especially at lower supply voltages. The MIC38HC4x also features a trimmed oscillator discharge current and bandgap reference.

MIC38HC4x-1 is available in 14-pin plastic DIP and SOIC packages. 8-pin devices feature small size, while 14-pin devices separate the analog and power connections for improved performance and power dissipation.

Features

• Fast 20ns output rise and 15ns output fall times

• –40°C to +85°C temperature range exceeds UC284x specifications

• High-performance, low-power BiCMOS Process

• Ultralow start-up current (50µA typical)

• Low operating current (4mA typical)

• High output drive (1A peak current, HC version)

• CMOS outputs with rail-to-rail swing

• Current-mode operation up to 500kHz

• Trimmed 5V bandgap reference

• Pin-for-pin compatible with UC3842/3843/3844/3845(A)

• Trimmed oscillator discharge current

• UVLO with hysteresis

• Low cross-conduction currents

Applications

• Current-mode, off-line, switched-mode power supplies

• Current-mode, dc-to-dc converters.

• Step-down “buck” regulators

• Step-up “boost” regulators

• Flyback, isolated regulators

• Forward converters

• Synchronous FET converters

Functional Diagram

VDD

7 (12)

VREF

8 (14)

RT/CT

4 (7)

2 (3)

2.5V

( ) pins are on MIC38HC4x-1 (14-lead) versions only * MIC38HC4x (8-lead) versions only

†

MIC38HC42, MIC38HC43 (96% max. duty cycle) versions only

‡

MIC38HC44, MIC38HC45 (50% max. duty cycle) versions only

35V

COMP

1 (1)

Reference

Oscillator

GND*(AGND)

5 (9)

ISNS

3 (5)

UVLO

(VD)

†

‡

(11)

OUT

6 (10)

(PGND)

(8)

Micrel, Inc. • 1849 Fortune Drive • San Jose, CA 95131 • USA • tel + 1 (408) 944-0800 • fax + 1 (408) 944-0970 • http://www.micrel.com

August 2000 1 MIC38HC42/3/4/5

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MIC38HC42/3/4/5 Micrel

Ordering Information

Part Number Temperature Range Package

MIC38HC42BN –40°C to +85°C 8-pin Plastic DIP

MIC38HC43BN –40°C to +85°C 8-pin Plastic DIP

MIC38HC44BN –40°C to +85°C 8-pin Plastic DIP

MIC38HC45BN –40°C to +85°C 8-pin Plastic DIP

MIC38HC42-1BN –40°C to +85°C 14-pin Plastic DIP

MIC38HC43-1BN –40°C to +85°C 14-pin Plastic DIP

MIC38HC44-1BN –40°C to +85°C 14-pin Plastic DIP

MIC38HC45-1BN –40°C to +85°C 14-pin Plastic DIP

MIC38HC42BM –40°C to +85°C 8-pin SOIC

MIC38HC43BM –40°C to +85°C 8-pin SOIC

MIC38HC44BM –40°C to +85°C 8-pin SOIC

MIC38HC45BM –40°C to +85°C 8-pin SOIC

MIC38HC42-1BM –40°C to +85°C 14-pin SOIC

MIC38HC43-1BM –40°C to +85°C 14-pin SOIC

MIC38HC44-1BM –40°C to +85°C 14-pin SOIC

MIC38HC45-1BM –40°C to +85°C 14-pin SOIC

Selection Guide

UVLO Thresholds

Startup 8.4V Startup 14.5V

Duty Cycle Minimum Operating 7.6V Minimum Operating 9V

0% to 96% MIC38HC43 MIC38HC42

0% to 50% MIC38HC45 MIC38HC44

MIC38HC42/3/4/5 2 August 2000

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MIC38HC42/3/4/5 Micrel

Pin Configuration

MIC38HC4x-1

1COMP VREF14

2NC NC13

3FB VDD12

COMP

ISNS

RT/CT

MIC38HC4x

8-Pin DIP (N)

8-Lead SOIC (M)

VREF

VDD

OUT

GND

4NC VD11

5ISNS OUT10

6NC AGND9

7RT/CT PGND8

14-Pin DIP (-1BN)

14-Lead SOIC (-1BM)

Pin Description

Pin Number Pin Number Pin Name Pin Function

N, M, MM -1BN, -1BM

1 1 COMP Compensation: Connect external compensation network to modify the error

amplifier output.

2 NC Not internally connected.

2 3 FB Feedback (Input): Error amplifier input. Feedback is 2.5V at desired output

voltage.

4 NC Not internally connected.

3 5 ISNS Current Sense (Input): Current sense comparator input. Connect to current

sensing resistor or current transformer.

6 NC Not internally connected.

4 7 RT/CT Timing Resistor/Timing Capacitor: Connect external RC network to select

switching frequency.

5 GND Ground: Combined analog and power ground.

8 PGND Power Ground: N-channel driver transistor ground.

9 AGND Analog Ground: Controller circuitry ground.

6 10 OUT Power Output: Totem-pole output.

11 VD Power Supply (Input): P-channel driver transistor supply input. Return to

power ground (PGND).

7 12 VDD Analog Supply (Input): Controller circuitry supply input. Return to analog

ground (AGND).

13 NC Not internally connected.

8 14 VREF 5V Reference (Output): Connect external RC network.

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MIC38HC42/3/4/5 Micrel

Absolute Maximum Ratings

Zener Current (VDD) ...................................................30mA

Operation at

≥18V may require

special precautions (Note 6).

Supply Voltage (V

), Note 6 .......................................20V

Switch Supply Voltage (VD) ..........................................20V

Current Sense Voltage (V Feedback Voltage (V

Output Current, 38HC42/3/4/5 (I

) ..................... –0.3V to 5.5V

ISNS

) ................................ –0.3V to 5.5V

) .............................. 1A

OUT

Operating Junction Temperature (TJ) ....................... 150°C

Package Thermal Resistance

8-Pin Plastic DIP (θ

) ....................................... 125°C/W

8-Pin MM8™ (θJA) ............................................. 250°C/W

8-Pin SOIC (θJA) ...............................................170°C/W

14-Pin Plastic DIP (θJA) ....................................... 90°C/W

14-Pin SOIC (θJA) .............................................145°C/W

Storage Temperature (T

) ....................... –65°C to +150°C

Electrical Characteristics

VDD = 15V, Note 4; RT = 9.09kΩ; CT = 3.3nF; –40°C ≤ TA ≤ 85°C; unless noted

Parameter Test Conditions Min Typ Max Units

Reference Section

Output Voltage TA = 25°C, IO = 1mA 4.90 5.00 5.10 V

Line Regulation 12V ≤ VDD ≤ 18V, IO = 5µA, Note 6 220mV

Load Regulation 1 ≤ IO ≤ 20mA 1 25 mV

Temp. Stability Note 1 0.2 mV/°C

Total Output Variation Line, Load, Temp., Note 1 4.82 5.18 V

Output Noise Voltage 10Hz ≤ f ≤ 10kHz, TA = 25°C, Note 1 50 µV

Long Term Stability TA = 125°C, 1000 hrs., Note 1 525mV

Output Short Circuit –30 –80 –180 mA

Oscillator Section

Initial Accuracy TA = 25°C, Note 5 49 52 55 kHz

Voltage Stability 12 ≤ VDD ≤ 18V, Note 6 0.2 1.0 %

Temp. Stability T

Clock Ramp TA = 25°C, V

Reset Current TA = T

Amplitude V

Error Amp Section

Input Voltage V

Input Bias Current VFB = 5.0V –0.1 –2 µA

VOL

Unity Gain Bandwidth Note 1 0.7 1.0 MHz

≤ TA ≤ T

MIN

to T

MIN

peak to peak 1.9 Vp-p

RT/CT

= 2.5V 2.42 2.50 2.58 V

COMP

2 ≤ VO ≤ 4V 65 90 dB

, Note 1 0.04 %/°C

MAX

= 2V 7.7 8.4 9.0 mA

RT/CT

MAX

7.2 8.4 9.5 mA

PSRR 12 ≤ VDD ≤ 18V 60 dB

Output Sink Current VFB = 2.7V, V

Output Source Current VFB = 2.3V, V

High VFB = 2.3V, RL = 15k to ground 5 6.8 V

OUT

Low VFB = 2.7V, RL = 15k to V

OUT

= 1.1V 2 14 mA

COMP

= 5V –0.5 –1mA

COMP

REF

0.1 1.1 V

MIC38HC42/3/4/5 4 August 2000

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MIC38HC42/3/4/5 Micrel

Parameter Test Conditions Min Typ Max Units

Current Sense

Gain Notes 2, 3 2.85 3.0 3.15 V/V

MaximumThreshold V

= 5V, Note 2 0.9 1 1.1 V

COMP

PSRR 12 ≤ VDD ≤ 18V, Note 2 70 dB

Input Bias Current –0.1 –2 µA

Delay to Output 120 250 ns

Output

‘HC’ High I

DS(ON)

‘HC’ Low I

DS(ON)

SOURCE

SINK

= 200mA 10 Ω

= 200mA 5.5 Ω

Rise Time TA = 25°C, CL = 1nF 20 50 ns

Fall Time TA = 25°C, CL = 1nF 15 40 ns

Undervoltage Lockout

Start Threshold MIC38HC42/4 13.5 14.5 15.5 V

MIC38HC43/5 7.8 8.4 9.0 V

Minimum Operating Voltage MIC38HC42/4 8 9 10 V

MIC38HC43/5 7.0 7.6 8.2 V

Pulse Width Modulator

Maximum Duty Cycle MIC38HC42/3 94 96 %

MIC38HC44/5 46 50 %

Minimum Duty Cycle 0%

Total Standby Current

Start-Up Current VDD = 13V, 38HC42/44 50 200 µA

VDD = 7.5V, 38HC43/45

Operating Supply Current VFB = V

Zener Voltage (VDD)I

= 25mA, Note 6 30 37 V

= 0V 4.0 6.0 mA

ISNS

Note 1: These parameters, although guaranteed, are not 100% tested in production. Note 2: Parameter measured at trip point of latch with VEA = 0. Note 3: Gain defined as:

∆

PIN1

A =

V (I )

; ≤≤

0 V (I ) 0.8V

SNS

Note 4: Adjust VDD above the start threshold before setting at 15V. Note 5: Output frequency equals oscillator frequency for the MIC38HC42 and MIC38HC43. Output frequency for the MIC38HC44, and

MIC38HC45 equals one half the oscillator frequency.

Note 6: On 8-pin version, 20V is maximum input on pin 7, as this is also the supply pin for the output stage. On 14-pin version, 40V is

maximum for pin 12 and 20V maximum for pin 11.

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MIC38HC42/3/4/5 Micrel

Typical Characteristics

Oscillator Frequency

100

RESISTANCE (kΩ) R

1x10

Configuration

200pF

470pF

1nF

1.8nF

4.7nF 10nF

VDD = 15V

OSCILLATOR FREQUENCY (Hz)

1x10

Current Sense Amplifier

vs. Error Amplifier Output

1.2

1.0

0.8

0.6

0.4

0.2

0.0

CURRENT SENSE AMP THRESHOLD (V)

125°C

25°C

-50°C

02468

ERROR AMPLIFIER OUTPUT (V)

MIC38C/HC42/43 Output Dead

Time vs. Oscillator Frequency

100

VDD = 15V

4.7nF

10nF

OUTPUT DEAD TIME (%)

1x10

FREQUENCY (Hz)

1x10

18nF

1nF

200pF

470pF

1x10

Short-Circuit Reference

Current vs. Temperature

120

100

VDD = 15V

SHORT CURCUIT CURRENT (mA)

REF

-60 -30 0 30 60 90 120 150

TEMPERATURE (°C)

Oscillator Discharge

Current vs. Temperature

9.0

8.8

8.6

8.4

8.2

8.0

7.8

7.6

7.4

7.2

7.0

OSC. DISCHARGE CURRENT (mA)

-60 -30 0 30 60 90 120 150 TEMPERATURE (°C)

VDD = 15V V

= 2V

OSC

MIC38C4x

Output Waveform

-5 VD = 15V

OUTPUT VOLTAGE (V)

-10

= 1nF

-15

0.0 0.2 0.4 0.6 0.8 1.0 TIME (µs)

MIC38HC42/3/4/5 6 August 2000

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MIC38HC42/3/4/5 Micrel

Package Information

PIN 1

DIMENSIONS:

INCH (MM)

.235 (5.969) .215 (5.461)

.160 MAX

(4.064)

0.018 (0.57)

0.100 (2.54)

0.380 (9.65)

0.370 (9.40)

8-Pin Plastic DIP (N)

.770 (19.558) MAX

.060 (1.524) .045 (1.143)

0.135 (3.43)

0.125 (3.18)

0.130 (3.30)

0.0375 (0.952)

0.255 (6.48)

0.245 (6.22)

0.300 (7.62)

0.013 (0.330)

0.010 (0.254)

0.380 (9.65)

0.320 (8.13)

PIN 1

.310 (7.874) .280 (7.112)

.080 (1.524) .015 (0.381)

.015 (0.381)

.160 (4.064) .100 (2.540)

.110 (2.794) .090 (2.296)

.060 (1.524) .045 (1.143)

.023 (.5842) .015 (.3810)

.400 (10.180)

.330 (8.362)

.008 (0.2032)

14-Pin Plastic DIP (N)

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MIC38HC42/3/4/5 Micrel

0.026 (0.65) MAX)

PIN 1

0.157 (3.99)

0.150 (3.81)

0.064 (1.63)

0.045 (1.14)

0.154 (3.90)

0.026 (0.65) MAX)

0.050 (1.27) TYP

0.197 (5.0)

0.189 (4.8)

0.050 (1.27) TYP

0.020 (0.51)

0.013 (0.33)

0.0098 (0.249)

0.0040 (0.102)

0°–8°

SEATING

PLANE

8-Pin SOIC (M)

PIN 1

0.016 (0.40) TYP

0.006 (0.15)

DIMENSIONS:

INCHES (MM)

0.050 (1.27)

0.016 (0.40)

0.244 (6.20)

0.228 (5.79)

DIMENSIONS:

INCHES (MM)

45°

0.010 (0.25)

0.007 (0.18)

0.193 (4.90)

45°

3°–6°

0.244 (6.20)

0.228 (5.80)

0.057 (1.45)

0.049 (1.25)

0.344 (8.75)

0.337 (8.55)

SEATING

PLANE

14-Pin SOIC (M)

MICREL INC. 1849 FORTUNE DRIVE SAN JOSE, CA 95131 USA

TEL + 1 (408) 944-0800 FAX + 1 (408) 944-0970 WEB http://www.micrel.com

This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or

other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.

MIC38HC42/3/4/5 8 August 2000