UNITRODE UC3173A Technical data

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Full Bridge Power Amplifier

UC3173A

FEATURES

• Precision Current Control

•±500mA Load Current

• 1.3V Typical Total V

• Controlled Velocity Head Parking

• Precision Dual Supply Monitor with

Indicator

• Range Control for 4:1 Gain Change

• Compensation Adjust Pin for

Bandwidth Control

• Inhibit Input and UVLO

• 5V or 12V Operation

• 12mA Quiescent Supply Current

• PLCC, SOIC, and Low Profile Quad

Flat Pack Packages

SAT

at 550mA

DESCRIPTION

This full bridge power amplifier, rated for continuous output current of

0.55A, is intended for use in demanding servo applications such as head
positioning for high density disk drives. This device includes a precision cur­rent sense amplifier that senses load current with a single resistor in series
with the load. The UC3173A is optimized to consume a minimum of supply
current, and is designed to operate in both 5V and 12V systems. The power
output stages have a low saturation voltage and are protected with current
limiting and thermal shutdown. When inhibited the device will draw less
than 1.5mA of total supply current.

Auxiliary functions on this device include a dual input undervoltage com­parator, which can monitor two independent supply voltages and activate
the built in head park function when either is below minimum. The park cir­cuitry allows a programmable retract voltage to be applied to the load for
limiting maximum head velocity. A separate low side parking drive pin per­mits a series impedance to be inserted to control maximum retract current.
The parking drive function can be configured to operate with supply volt­ages as low as 1.2V.

The closed loop transconductance of the configured power amplifier can be
switched between a high and low range with a logic input. The 4:1 change
in gain can be used to extend the dynamic range of the servo loop. Band­width variations that would otherwise result with the gain change can be
controlled with a compensation adjust pin.

BLOCK DIAGRAM

04/99

UDG-94039

UC3173A

ABSOLUTE MAXIMUM RATINGS (Note 1)

Input Supply Voltage, (VIN, VC, VL) . . . . . . . . . . . . . . . . . . 20V

UV Comparator

Maximum Forced Voltage . . . . . . . . . . . . . . . . −0.3V to 10V

Maximum Forced Current. . . . . . . . . . . . . . . . . . . . .±10mA

B Amplifier Inverting Input . . . . . . . . . . . . . . −0.3V to VIN + 1.0

A Amplifier Inverting Inputs,

(Aux. and Normal) . . . . . . . . . . . . . . . . . −0.3V to VC + 1.0V

Open Collector Output Voltages . . . . . . . . . . . . . . . . . . . . . 20V

A and B Output Currents (Continuous)

Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internally Limited

Sink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.6A

Parking Drive Output Current

Continuous . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150mA

Pulsed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1A

Output Diode Current (Pulsed). . . . . . . . . . . . . . . . . . . . . . 0.6A

Power OK Output Current (Continuous). . . . . . . . . . . . . . 30mA

Operating Junction Temperature . . . . . . . . . . −55°C to +150°C

Storage Temperature . . . . . . . . . . . . . . . . . . . −65°C to +150°C

Lead Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +300°C

Note 1: Unless otherwise indicated, voltages are referenced to
ground and currents are positive into, negative out of, the speci­fied terminals, “Pulsed” is defined as a less than 10% duty cycle
pulse with a maximum duration of 500

µ

s.

CONNECTION DIAGRAMS

THERMAL DATA

DW Package:

Thermal Resistance Junction to Leads, θjl . . . . . . . . 35°C/W

Thermal Resistance Junction to Ambient, θja . . . . 60-70°C/W

FQ Package:

Thermal Resistance Junction to Leads, θjl. . . . . . . . . 60°C/W

Thermal Resistance Junction to Ambient, θja . . 110-120°C/W

QP Package:

Thermal Resistance Junction to Leads, θjl. . . . . . . . . 15°C/W

Thermal Resistance Junction to Ambient, θja . . . . 30-40°C/W

Note 2: The above numbers forθjl are maximums for the limiting
thermal resistance of the package in a standard mounting con­figuration. Theθja numbers are meant to be guide lines for the
thermal performance of the device/pc-board system. All of the
above numbers assume no ambient airflow.

Note 3: Consult Packaging Section of Unitrode Integrated Cir­cuits databook for thermal specifications and limitations of pack­ages.

SOIC-24 (Top View)
DW Package

TQFP-48 (Top View)
FQ Package

N/C
N/C

REFIN

CS–

PWROK

PRKDRV

48

46

N/C

VL

CSOUT

GND

N/C
N/C
N/C
N/C

INH
UV2
UV1

PARK

RANGE

CS+

COMP

VP ARK

N/C

47

1
2
3
4

5
6
7

8

9
10
11
12

13

15

14

N/C
N/C
BIN
VIN
N/C
N/C

42

44

43

45

17

18

16

40

393837

41

19

20

23

21

22

N/C

36
35

BOUT
BOUT

34

N/C

33

N/C

32

PGND

31

PGND

30

N/C

29

N/C

28

AOUT

27
26

AOUT

25

N/C

24

N/C
N/C
VC
AIN
N/C
N/CN/C

PLCC-28 (Top View)
QP Package

2

UC3173A

ELECTRICAL CHARACTERISTICS:

Unless otherwise stated, these specifications apply for TA= 0 to +70°C, VIN = 5V,

VC = VIN = VL, REFIN = VIN/2, RANGE, PARK, and INH = 0V, and TA=TJ.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Input Supply

VIN Supply Current 10 13 mA
VC Supply Current I

= 0A 1.2 2.0 mA

OUT

VL Supply Current 0.65 1.0 mA
Total Supply Current Supplies = 5V, I

Supplies = 12V, I

= 0A 12 16 mA

OUT

= 0A 13 18 mA

OUT

VL UVLO Threshold Low to High 2.6 2.8 V
UVLO Threshold Hysteresis 300 mV

Under Voltage (UV) Comparator

Input Bias Current Max at Either UV Input −0.25 −1.0 µA
UV Thresholds Low to High, Other Input = 5V 1.28 1.3 1.32 V
UV Threshold Hysteresis 19 24 29 mV
PWROK Vsat I
PWROK Leakage V

= 5mA, UV Input Low 0.15 0.45 V

OUT

= 20V 5 µA

OUT

Power Amplifiers A and B

Input Offset Voltage A Amplifier, VCM= 2.5V 4 mV

B Amplifier, V

Input Bias Current V

= 2.5V, Inverting Inputs Only −150 −500 nA

CM

Input Bias Current at Ref. Input (REFIN − CS+)/48kΩ,T
CMRR V

= 1V to 10V, Supplies = 12V 70 90 dB

CM

PSRR VIN = 4V to 15V, V
Large Signal Voltage Gain Supplies = 12V, V

V

= 11V, I

OUT

= 2.5V 12 mV

CM

= 25°C 152127µA/V

J

= 1.5V 70 90 dB

CM

OUT

= 1V, I

OUT

= −300mA

= 300mA to

OUT

3.0 15.0 V/mV

Gain Bandwidth Product A Amplifier (Note 4) 2.0 MHz

B Amplifier (Note 4) 1.0 MHz
Slew Rate (Note 4) 1.0 V/µs
High-Side Current Limit Low Range Mode 0.6 0.8 A

High Range Mode 1.1 1.6 A

Output Saturation Voltage High-Side, I

High-Side, I
High-Side, I
Low-Side, I
Low-Side, I
Low-Side, I
Total V

SAT,IOUT

Total V

SAT,IOUT

Total V

SAT,IOUT

VC to VIN Headroom Volts below VIN, delta High-Side, V

= −100mA (Note 5) 0.7 V

OUT

= −300mA (Note 5) 0.8 V

OUT

= −550mA (Note 5) 0.95 V

OUT

= 100mA 0.2 V

OUT

= 300mA 0.25 V

OUT

= 550mA 0.35 V

OUT

= 100mA 0.9 1.2 V
= 300mA 1.05 1.4 V
= 550mA 1.3 1.7 V

= 100mV, I

SAT

0.23 0.4 V

OUT

= −550mA (Note 5)
High-Side Diode, V
Low-Side Diode, V

F

F

ID= 550mA 1.0 V

ID= 550mA, INH Activated, B Amplifer Only 1.0 V

3

UC3173A

ELECTRICAL CHARACTERISTICS:

Unless otherwise stated, these specifications apply for TA= 0 to +70°C, VIN = 5V,

VC = VIN = VL, REFIN = VIN/2, RANGE, PARK, and INH = 0V, and TA=TJ.

PARAMETER TEST CONDITIONS MIN TYP MAX UNITS

Current Sense Amplifier

Input Offset Voltage V

Input Offset Change with Common
Mode Input

Voltage Gain V

Saturation Voltage Low-Side, I

= 2.5V, Low range mode 2.0 mV

CM

= 2.5V, High range mode 4.0 mV

V

CM

= –1V to 13V, Supplies = 12V, Low Range Mode 2000 µV/V

V

CM

= –1V to 13V, Supplies = 12V, High Range Mode 4000 µV/V

V

CM

= +1.0 to −1.0V, VCM= 2.5V, High Range Mode 0.485 0.50 0.515 V/V

DIFF

= +1.0 to −1.0V, VCM= 2.5V, Low Range Mode 1.95 2.0 2.05 V/V

V

DIFF

= 1mA 0.1 0.3 V

OUT

High-Side, I

= −1mA, Referenced to VIN 0.1 0.3 V

OUT

Parking Function

Park Input Threshold Voltage 0.6 1.1 1.7 V
Park Input Threshold Current Internal Pull-Up, VIN = 0.6V 50 75 µA
Park Drive Saturation Voltage I
Park Drive Leakage V

= 50mA 0.15 0.35 V

OUT

= 20V 50 µA

OUT

Regulating Voltage at Park Volts Input 1.275 1.30 1.325 V
Amplifier A Auxiliary Input Bias Current −300 −750 nA
Amplifier A Parking High-Side

Saturation Voltage

= −50mA, VIN = 0V, VC = VL = 5V, PARK Open,

I

OUT

VC to V

OUT

Minimum Parking Supply At VC and VL, VIN = 0V,

A Amplifier Out - V

SAT

PRKDRV > 0.5V, I

PARK

=

0.8 0.95 V

1.4 1.7 V

50mA
Minimum Supply for Parking Drive and

Power OK Operation

At VL, VC = VIN = 0V, V

I

PRKDRV = 50mA, Rl = 30Ω to 2V

OUT

PWROK = 5mA, Rl = 300Ω to 2V 1.2 1.6 V

I

OUT

SAT

< 0.5V,

VL Parking Supply Current PARK Open, VL = 5V, VC = 1.6V, VIN = 0V,

PWROK I

= 5mA, PRKDRV I

OUT

OUT

= 50mA

1.1 1.4 V

1.6 3.0 mA

Auxiliary Functions

Inhibit Input Threshold 0.6 1.1 1.7 V
Inhibit Input Current INH = 1.7V −0.5 −1.0 µA
Range Input Threshold 0.6 1.1 1.7 V
Range Input Current RANGE = 1.7V 50 100 µA
Comp Adjust Pin Saturation Voltage RANGE = 0V, Pin Current = ±500µA,

Referenced to A

OUT

Comp Adjust Leakage Current RANGE = 1.7V, Supplies = 12V,

A

OUT-VCOMP

= ±6V

0.02 0.1 V

5 µA

Total Supply Current when Inhibited VIN, VC, and VL currents 1.0 1.5 mA
Thermal Shutdown Temperature (Note 4) 165 °C

Note 4: Guaranteed by design. Not 100% tested in production.
Note 5: The high-side saturation performance of the UC3173A is referenced to the VIN supply pin.
The VC supply pin can operate about 400mV below the VIN supply input without affecting the performance.

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