www.apexanalog.com © Apex Microtechnology Inc.All rights reservedAug 2019

MP204U Rev B

4-Channel Power Amplifier

MP204

FEATURES • 4 Channel Power Amplifier for Ricoh GEN4/GEN5 Print Heads• Operate from Single High Current Supply• 7.5A Pulsed Current (C=320nF, R=0.1 Ω @ 15V/μs) • 1.5A Continuous Current• Programmable Current Limit

APPLICATIONS• Ricoh GEN4 and GEN5 Print Heads

DESCRIPTIONThe MP204 is a high output current quad channel amplifier for driving the Ricoh GEN4 and GEN5 print

heads. The MP204 utilizes ICs combined with discrete semiconductors and passive elements on a thermallyconductive insulated metal substrate, delivering very high power from a compact module. The amplifier gainis fixed at 14V/V. Internal compensation provides optimum slew rate and insures stability. The only externalcomponents required are the current limit resistors RLIM, a series isolation resistor RS and power supplybypass capacitors.

Figure 1: Equivalent Schematic (Channel A)

B

-V

CHAN_IN_A

AGND

+

-

INPUTAMPLIFIER

BIAS &OVERCURRENT

LIMIT

+V

PGND

+R

CHAN_A_OUTOUTPUT BUFFER

+V

B

S

LIM

CHANNEL A/B TEMP SENSOR+VS TEMP_A/B_OUT

MP204

2 MP204U Rev B

PINOUT AND DESCRIPTION TABLE Figure 2: External Connections

123456789

10111213141516

3534333231

292827262524232221

36

30

+VS_A+VS_A

PGND_APGND_A -VB_ABOUT_A

N/C+VB_AB

N/COUT_D

-VB_CDTEMP_ABTEMP_CD

+VB_CD

IN_BIN_A

OUT_C+VS_C+VS_CIL_CIL_C

PGND_CPGND_C

PGND_DPGND_D

IL_D

+VS_DIL_D

37

IN_DIN_C

38

IL_A

+VS_DMP204(Viewed from

backplate)

IL_A17181920

404142

SGND_CD

SGND_ABOUT_BPGND_BPGND_BIL_BIL_B+VS_B+VS_B

39

MP204

MP204U Rev B 3

Pin Number Name Description1,2 PGND_C Power GND: Channel C

3,4 IL_CHigh current output pins for channel C. A current

limit resistor must be placed between these pins and the output pin 7

5,6 +VS_C +Supply Voltage: Channel C7 OUT_C Output: Channel C8 SGND_CD Signal GND: Channels C/D9 IN_D Noninverting Input: Channel D

10 IN_C Noninverting Input: Channel C11 IN_A Noninverting Input: Channel A12 IN_B Noninverting Input: Channel B13 SGND_AB Signal GND: Channels A/B14 OUT_B Output: Channel B

15,16 PGND_B Power GND: Channel B

17,18 IL_BHigh current output pins for channel B. A current

limit resistor must be placed between these pins and output pin 14

19,20 +VS_B +Supply Voltage: Channel B

21,22 +VS_A +Supply Voltage: Channel A

23,24IL_A High current output pins for channel A. A current

limit resistor must be placed between these pins and the output pin 28

25,26 PGND_A Power GND: Channel A27 -VB_AB -Boost Supply: Channel A/B28 OUT_A Output: Channel A

29,31 N/C Unused30 +VB_AB + Boost Supply: Channel A/B32 OUT_D Output: Channel D33 -VB_CD -Boost Supply: Channel C/D34 TEMP_AB Channel C Temp Output 35 TEMP_CD Channel D Temp Output 36 +VB_CD + Boost Supply: Channel C/D

37,38 +VS_D +Supply Voltage: Channel D

39, 40 IL_DHigh current output pins for channel D. A current

limit resistor must be placed between these pins and output pin 32

41, 42 PGND_D Power GND: Channel D

MP204

4 MP204U Rev B

SPECIFICATIONSUnless otherwise noted: TC = 25°C, DC input specifications are ± value given. Power supply voltage is typicalrating.

ABSOLUTE MAXIMUM RATINGS

INPUT (EACH CHANNEL)

Parameter Symbol Min Max UnitsSupply Voltage, +VS +VS to PGND 34 V

Positive Boost Supply, +VB +VB to PGND +VS 40 V

Negative Boost Supply, -VB -VB to PGND -12 0.0 V

Overall Supply Voltage, +VB-(-VB) 50 V

Output Current, source, sink, peak, within SOA

IOUT 7.5 A

Power Dissipation, continuous @ TC = 25°C

PD 20 W/per Channel

Input Voltage 1

1. Guaranteed by design.

-0.05 +5 V

Temperature, pin solder, 10s max 260 °C

Temperature, junction 2

2. Long term operation at the maximum junction temperature will result in reduced product life. Derate inter-nal power dissipation to achieve high MTTF.

TJ 150 °C

Temperature Range, storage -55 +125 °C

Operating Temperature Range, case TC -25 +85 °C

Parameter Test Conditions Min Typ Max UnitsOffset Voltage, initial -5 ±1 5 mVOffset Voltage vs. Temperature Full temp range ±7 µV/°CBias Current, initial -100 ±20 pA

Input Impedance, DC 1013 Ω

Input Capacitance 6 pF

Input Voltage Range 1

1. “Min/Max” limited by the common mode range of input amplifier. Typical is that of the input waveform from a DAC to achieve VOUT=24V. Guaranteed by design

-0.5 to 2.4 V

Input Noise f = 1 kHz 14 nV/√Hz

MP204

MP204U Rev B 5

GAIN (EACH CHANNEL)

OUTPUT (EACH CHANNEL)

POWER SUPPLY

Parameter Test Conditions Min Typ Max UnitsFixed Gain 14 V/VGain Bandwidth Product -3db 7.4 MHz

Power Bandwidth+VS=24V, +VB = +VS + 6V,-VB = -5V, VOUT(IOUT) = 2V, VOUT(hi)=22V

370 kHz

Open Loop Gain @ 15 Hz 96 dB

Parameter Test Conditions Min Typ Max Units

Voltage Swing IOUT = 1A, +VB = VS +VS-8 +VS-6 V

Voltage Swing IOUT = -1A, -VB = PGND- 5V PGND+0.4 PGND+1.2 V

Voltage Swing IOUT= 1.5A, +VB = VS + 6V +VS-1 V

Current, Peak 7.5 ACurrent, Continuous 1.5 A

Slew RateLoad CL = 320nF,AV= 14V/V, RLIM = 0

15 V/µs

Parameter Test Conditions Min Typ Max UnitsPositive Supply Voltage, +VS 3 24 34 V

Positive Boost Voltage, +VB 8 40 V

Negative Boost Voltage, -VB -12 -5 V

+VS quiescent current No Load 3.4 mA

+VB quiescent current No Load 26 mA

-VB quiescent current No Load 26 mA

MP204

6 MP204U Rev B

THERMAL

TEMPERATURE SENSOR

Parameter Test Conditions Min Typ Max Units

Resistance, AC, junction to case 1

1. Rating applies if the output current alternates between both output transistors at a rate faster than 60 Hz.

Full temp range, f > 60 Hz 4.5 °C/W

Resistance, DC, junction to case Full temp range, f < 60 Hz 5.8 °C/WResistance, junction to air Full temp range 14.5 °C/W

Temperature Range, case Meets full range specifica-tions -25 +85 °C

Parameter Test Conditions MP204

UnitsMin Typ Max

Temp Sensor Output TC = 25°C 2.98 V

Temp Sensor Gain 10 mV/°C

Temperature Accuracy TC = -40°C to + 85°C + 1 °C

MP204

MP204U Rev B 7

TYPICAL PERFORMANCE GRAPHS

Figure 3: Closed Loop Gain vs. Frequency Figure 4: Closed Loop Phase vs. Frequency

Figure 5: +VB Quiescent Current vs. Supply Voltage

Figure 6: -VB Quiescent Current vs. Supply Voltage

30.0

25.0

15.0

10.0

5.0

0.0

20.0

1K 10K 100K 1M 10M Frequency (Hz) - Channel Average

Gai

n (d

B)

50.0

0.0

-50.0

-100.0

-150.0

-200.0

-250.01K 10K 100K 1M 10M

Frequency (Hz)-Channel Average

Phas

e (°

)

1.05

1.04

1.03

1.02

1.01

1.00

0.99

0.98

0.97

20 22 24 26 28 3230 +VB (V)

I Q N

orm

alize

d

0.96

0.95 34 36 38 40 42

I Q N

orm

alize

d

1.03

1.02

1.01

1.00

0.99

0.98

0.97

0.96

0.95

-VB (V)-15 -13 -11 -9 -7 -5 -3

MP204

8 MP204U Rev B

Figure 7: +VB Quiescent Current vs. Temperature

Figure 8: -VB Quiescent Current vs. Temperature

Figure 9: Typical Source Voltage Drop +VB = +Vs + 6V

Figure 10: Typical Sink Voltage Drop -VB = -5V

32 31 30 29

28 27

262524

-30 -20 -10 0 10 7020

Temperature (°C)

+VB I Q

(mA)

23222120

30 40 50 60 80 90

323130292827262524

20 30 40 50 7060

Temperature (°C)

-VBI Q

(mA)

23222120

-30-20 -10 0 10 80 90

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0.000 1 3 4 52 6

Source Current (A)

V DRO

P (V)

-0.50

-0.45

-0.40

-0.35

-0.30

-0.25

-0.20

-0.15

-0.10

0 -1 -2 -3 -4 -6-5

Sink Current (A)

V DRO

P (V

)

-0.05

0.00

MP204

MP204U Rev B 9

Figure 11: Typical Source Voltage Drop +VB = +VS

Figure 12: Temperature Monitor Output Voltages (typ.)

Figure 13: Channel to Channel Gain Variation Five (5) Units

Figure 14: Single Pulse Output Voltage CLOAD= 320nF

4.00

3.90

3.80

3.70

3.60

3.50

3.40

3.30

3.20

0.0 1.00.2 0.80.4 0.6 1.2

Source Current (A)

V DRO

P (V

)

3.10

3.00

4.00

3.50

2.50

3.00

2.00-30 -10 40 50 7060

Temperature (°C)Te

mp

Mon

itor O

utpu

t (V)

0 10 20 30 80 90-20

14.6

14.4

14.2

14.0

13.8

13.6

13.41 3 5 7

Channel Number

Gai

n (V

/V)

9 11 13 15 17 19

35

30

25

20

15

10

5

050 10 15 20 25 3530

Time (μs)

Chan

nel O

uput

Vol

tage

(V)

40

MP204

10 MP204U Rev B

Figure 15: Single Pulse Output Current CLOAD= 320nF

Figure 16: Multi Waveform Voltage Pattern, CLOAD= 320nF

Figure 17: Multi Waveform Current Pattern, CLOAD = 320nF

6543210-1-2

0 5 10 15 20 3025

Time ( s)

Chan

nel O

utpu

t Cur

rent

(A)

-3-4-5-6

35 40

40

35

30

25

20

15

10

5

0180 200 220 240 260 300280

Time (μs)

Chan

nel O

utpu

t Vol

tage

(Vol

ts)

320

5

4 3

2

1

0

-1

-3

180 200 220 240 260 300280

Time (μs)

Chan

nel O

utpu

t Cur

rent

(Am

ps)

-4

-6-5

-2

320

MP204

MP204U Rev B 11

SAFE OPERATING AREA (SOA) Figure 18: SOA

POWER DERATING CURVE Figure 19: Power Derating

10.00

1.00

0.101 10 100

S O

S

C = 25 0C

C = 85 0CC = 25 0C

C = 25 0C

20

18

16

14

12

10

8

6

4

-40 -20 0 20 40 8060

Case Temperature, TC (°C)

P

er C

hann

el, P

(W)

2

0100

MP204

12 MP204U Rev B

GENERALPlease read Application Note 1 “General Operating Considerations” which covers stability, supplies, heat

sinking, mounting, current limit, SOA interpretation, and specification interpretation. Visit www.apexana-log.com for Apex Microtechnology’s complete Application Notes library, Technical Seminar Workbook, andEvaluation Kits.

TYPICAL APPLICATIONThe MP204 consists of four (4) identical channels specifically designed to drive the high capacitance loads

of industrial print heads. Each channel has a fixed gain of 14 V/V (22.9 dB) and is internally compensated tooperate with capacitive print head loading.

Figure 20: Typical Application (Single Channel)

POWER SUPPLY BYPASSING Bypass capacitors to power supply terminals +VS +VB and -VB must be connected physically close to thepins to prevent local parasitic oscillation in the output stage of the MP204. For +VS use electrolytic capacitorswith at least 10μF per amp out of output current capacity. In turn, bypass the electrolytic capacitors for +VSwith high quality ceramic capacitors (X7R) of 0.1μF or greater. Duplicate the supply bypass elements for thesupply terminals of each amplifier channel.

+VS

100 μF 0.1 - 1 μF

RIN

Print NozzleCommand Voltage

AGND

PGND

AGNDPGND -VB

+VS +VB IL IL

OUT

IL

TMP

+

Read JunctionTemperature

-VB

0.1 – 1 μF

+VB

0.1 - 1μF

RLIM

RSN

CSN

RSMP204

Piezo Printhead

MP204

13 MP204U Rev B

SERIES ISOLATION RESISTOR, RS To ensure stability with all capacitive loads, a series isolation resistor should be included between the out-

put and the load as seen in the typical applications schematic. A 1.5 Ω resistor works well for capacitive loadsof up to 320nF. The resistor will affect the rise and fall times of the output pulse at the load; however, this canbe compensated by the input signal.

BACKPLATE GROUNDING The substrate of the MP204 is an insulated metal substrate. It is required that the substrate be properlyconnected to signal ground but should not be used to carry significant ground current.

TEMPERATURE SENSING The MP204 has two IC temperature sensors, located near the output MOSFETS of each channel pair(TEMP_AB and TEMP_CD). The scale factor of the sensors is 10 mV/°C. The output voltage of each sensor isequal to approximately 2.98V at room temperature (TC = 25°C). The sensors have an uncalibrated tempera-ture error of + 1°C. The scale factor of each sensor can be adjusted by connecting and optional resistor "R"(refer to Fig. 22) to TEMP_AB and TEMP_CD respectively. The scaled output voltage can be determined by thefollowing equation, where T is the case temperature in °C.

R-C SNUBBER CIRCUITS Driving piezoelectric element provides another design challenge since the load is primarily capacitive.

This being said, any inductance in the output connection to the actual printing element can cause outputinstabilities due to the L-C combination.

Usually the frequency of oscillation is greater than the unity gain bandwidth of the amplifier. To compen-sate for this shift, it is necessary to lower the high frequency gain of the amplifier. This is accomplished by theaddition of the R-C snubber circuit to the amplifier output. The individual component values are dependenton the application requirements. This is accomplished by the addition of the RC snubber circuit to the ampli-fier output (Figure 21).

VRR

10000 R+------------------------- 0.01T 2.73 + =

MP204

MP204U Rev B 14

Figure 21: RC Snubber Application

Figure 22: Temperature Sense

CURRENT LIMITFor proper operation, the current limit resistor (RLIM) must be connected as shown in the Typical Applicationconnection diagram. For optimum reliability the resistor value should be set as high as possible. The value iscalculated as follows, with the maximum practical value of 30 Ω.

RI RF

V IN

-

+

V OUT

0.1 to 1μF

10 to 100 Ω

TemperatureSensor IC

VT

Pin #34 and #35

10K

R

To DVM

MP204

RLIM 0.65V ILIM=

MP204

MP204U Rev B 15

INTERNAL POWER DISSIPATION CONSIDERATIONSThe determination of dissipated power in a Drop on Drop print head application is fundamentally diffi-

cult, since it is very dependent on the character “content” being printed. This content is also a function of thespecific print head algorithm being used.

For the sake of this discussion we will assume that all channels are on simultaneously and are operated atthe same frequency.Total power dissipation in the MP204 amplifiers consists two components;

1. Quiescent Power and

2. Output Stage Power

Quiescent power dissipation is caused by the quiescent current draw of the power op amp. This current isused internally to bias the various stages of the amplifier. It also flows when the amplifier is idling. Thequiescent power dissipation can be calculated as:

with IQS and IQB being the quiescent current for VS and VB respectively for all the 4 separate amplifiers.

Output (stage) power dissipation is caused by the conducting output stage transistor, dropping a certainvoltage from the supply rail to produce the required output voltage, and the output current that flowsthrough this transistor.

Output current can be determined by, where C is the piezo print element capacitance:

We can determine the average output stage current on the rising and falling edge of the output pulse be:

This can be written as:

PQS IQS V S=

PQB IQBS +VB VB– – =

PQ,TOTAL PQS PQB+=

IOUT CdVdt------- A =

POUT,R VS VMID– IOUT=

POUT,F VMID VS– IOUT=

PD,SWITCHING TF POUT,F TR POUT,R+ freq=

MP204

16 MP204U Rev B

Where

TF = the duration of the falling edge

TR = the duration of the rising edge

freq = operating frequency

Also note that the total power being dissipated in each the MP204 channels is the sum of the switching lossesand quiescent losses

Where

This is the per channel power dissipation that needs to be managed for all application scenarios. For furtherdetailed information consult the MP204 Applications Note.

POWER SUPPLY PROTECTIONUnidirectional Transient Voltage Suppressor (TVS) diodes are recommended as protection on the supply

pins. The TVS diodes clamp transients to voltages within the power supply rating and also clamp power sup-ply reversals to ground. Whether the TVS diodes are used or not, the system power supply should be evalu-ated for transient performance including power-on overshoot and power-off polarity reversals as well as lineregulation.

Conditions which can cause open circuits or polarity reversals on either power supply rail should beavoided or protected against. Reversals or opens on the negative supply rail is known to induce input stagefailure. Unidirectional TVS diodes prevent this, and it is desirable that they both be electrically and physicallyas close to the amplifier as possible.

POWER SUPPLY SEQUENCINGIf separate boost supplies are not used, then connect +VB to +VS for each of the 4 channels.

If separate boost supplies are used, then use the following sequence:

Turn ON Sequence: -VB, +VB, +VSTurn OFF Sequence: +VS, +VB, -VB

PDISS_TOTAL PD,SWITCHING PQ_1_CH+=

PQ_1_CH PQ_TOTAL 4=

MP204

MP204U Rev B 17

NEED TECHNICAL HELP? CONTACT APEX SUPPORT! For all Apex Microtechnology product questions and inquiries, call toll free 800-546-2739 in North America. Forinquiries via email, please contact apex.support@apexanalog.com. International customers can also requestsupport by contacting their local Apex Microtechnology Sales Representative. To find the one nearest to you,go to www.apexanalog.com

IMPORTANT NOTICE

Apex Microtechnology, Inc. has made every effort to insure the accuracy of the content contained in this document. However, the information issubject to change without notice and is provided "AS IS" without warranty of any kind (expressed or implied). Apex Microtechnology reserves the rightto make changes without further notice to any specifications or products mentioned herein to improve reliability. This document is the property ofApex Microtechnology and by furnishing this information, Apex Microtechnology grants no license, expressed or implied under any patents, maskwork rights, copyrights, trademarks, trade secrets or other intellectual property rights. Apex Microtechnology owns the copyrights associated with theinformation contained herein and gives consent for copies to be made of the information only for use within your organization with respect to ApexMicrotechnology integrated circuits or other products of Apex Microtechnology. This consent does not extend to other copying such as copying forgeneral distribution, advertising or promotional purposes, or for creating any work for resale. APEX MICROTECHNOLOGY PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN PRODUCTS USED FOR LIFESUPPORT, AUTOMOTIVE SAFETY, SECURITY DEVICES, OR OTHER CRITICAL APPLICATIONS. PRODUCTS IN SUCH APPLICATIONS ARE UNDERSTOOD TO BEFULLY AT THE CUSTOMER OR THE CUSTOMER’S RISK. Apex Microtechnology, Apex and Apex Precision Power are trademarks of Apex Microtechnology, Inc. All other corporate names noted herein may betrademarks of their respective holders.

PACKAGE OPTIONS

PACKAGE STYLE KK

Part Number Apex Package Style DescriptionMP204 KK 42-Pin Open Frame

3.150[80.01]

2.860[72.64]

2.710[68.83]

3.000[76.2]

.380[9.65]

1.430[36.32]

.155[3.94]

.155[3.94]

.164[4.17]COMPONENT CLEARANCE

2.400[60.96]

.128[3.26]

.363[9.22]

1.200[30.48]

.025 SQ.[0.64]

.100[2.54]

1.430[36.32]

.145[3.68]

.380[9.65]

1.355[34.42]

.070[1.78]

.129[ 3.28]THRU

4 PLACES

Notes:1. Scale 2.802. Dimensions are in inches; alternate units are [mm].3. Recommended PCB hole diameter for pins: 0.050[1.27].4. Tin over nickel plated phospher bronze pins.5. It is not recommended that mounting of the package rely on the pins for mechanical support.

CL

CLCL

PIN 1

1

20

21

42

MP204FeaturesApplicationsDescriptionFigure 1: Equivalent Schematic (Channel A)

Pinout and Description TableFigure 2: External Connections

SpecificationsAbsolute Maximum RatingsInput (Each Channel)Gain (Each Channel)Output (Each Channel)Power SupplyThermal

Typical Performance GraphsSafe operating area (SOA)Figure 18: SOA

Power Derating CurveFigure 19: Power Derating

GeneralTypical ApplicationFigure 20: Typical Application (Single Channel)

POWER SUPPLY BYPASSINGSERIES ISOLATION RESISTOR, RsBACKPLATE GROUNDINGTEMPERATURE SENSINGR-C snubber circuitsFigure 21: RC Snubber ApplicationFigure 22: Temperature Sense

CURRENT LIMITINTERNAL POWER DISSIPATION ConsiderationsPower Supply ProtectionPower Supply SequencingPackage OptionsPackage Style KK