TI DRV593VFP

DRV593
DRV594
www.ti.com
SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
±3−A HIGH−EFFICIENCY PWM POWER DRIVER
FEATURES
DESCRIPTION
D Operation Reduces Output Filter Size and
The DRV593 and DRV594 are high-efficiency,
high-current power amplifiers ideal for driving a wide
variety of thermoelectric cooler elements in systems
powered from 2.8 V to 5.5 V. The operation of the device
requires only one inductor and capacitor for the output
filter, saving significant printed-circuit board area.
Pulse-width modulation (PWM) operation and low output
stage on-resistance significantly decrease power
dissipation in the amplifier.
Cost by 50% Compared to DRV591
D
D
D
D
D
±3-A Maximum Output Current
D
D
D
D
Two Selectable Switching Frequencies
Low Supply Voltage Operation: 2.8 V to 5.5 V
High Efficiency Generates Less Heat
Overcurrent and Thermal Protection
Fault Indicators for Overcurrent, Thermal and
Undervoltage Conditions
The DRV593 and DRV594 are internally protected against
thermal and current overloads. Logic-level fault indicators
signal when the junction temperature has reached
approximately 115°C to allow for system-level shutdown
before the amplifier’s internal thermal shutdown circuitry
activates. The fault indicators also signal when an
overcurrent event has occurred. If the overcurrent circuitry
is tripped, the devices automatically reset (see application
information section for more details).
Internal or External Clock Sync
PWM Scheme Optimized for EMI
9×9 mm PowerPAD Quad Flatpack Package
APPLICATIONS
The PWM switching frequency may be set to 500 kHz or
100 kHz depending on system requirements. To eliminate
external components, the gain is fixed at 2.3 V/V for the
DRV593. For the DRV594, the gain is fixed at 14.5 V/V.
D Thermoelectric Cooler (TEC) Driver
D Laser Diode Biasing
VDD
PWM
PWM
PVDD
PVDD
PVDD
FREQ
INT/EXT
PGND
IN-
PGND
SHUTDOWN
H/C
FAULT1
FAULT0
10 µF
H/C
Shutdown Control
PGND
IN+
H/C
1 kΩ
To TEC or Laser
Diode Anode
PGND
DRV593
DRV594
AREF
H/C
1 kΩ
PGND
COSC
PVDD
1 µF
ROSC
PVDD
220 pF
PGND
PVDD
DC Control
Voltage
10 µH
PWM
AGND (Connect to PowerPAD)
FAULT0
120 kΩ
AVDD
FAULT1
1 µF
PWM
1 µF
10 µF
To TEC or Laser
Diode Cathode
1 µF
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
PowerPAD is a trademark of Texas Instruments.
PRODUCTION DATA information is current as of publication date. Products
conform to specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all parameters.
Copyright  2002, Texas Instruments Incorporated
DRV593
DRV594
www.ti.com
SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
This integrated circuit can be damaged by ESD. Texas
Instruments recommends that all integrated circuits be
handled with appropriate precautions. Failure to observe
proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to
complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could
cause the device not to meet its published specifications.
ORDERING INFORMATION
TA
PowerPAD QUAD FLATPACK
(VFP)
DRV593VFP(1)
-40°C
40°C to 85°C
(1)
DRV594VFP(1)
This package is available taped and reeled. To order this
packaging option, add an R suffix to the part number (e.g.,
DRV593VFPR or DRV594VFPR).
ABSOLUTE MAXIMUM RATINGS
over operating free-air temperature range unless otherwise noted(1)
DRV593, DRV594
Supply voltage, AVDD, PVDD
-0.3 V to 5.5 V
Input voltage, VI
-0.3 V to VDD + 0.3 V
Output current, IO (FAULT0, FAULT1)
1 mA
Continuous total power dissipation
See Dissipation Rating Table
Operating free-air temperature range, TA
-40°C to 85°C
Operating junction temperature range, TJ
-40°C to 150°C
Storage temperature range, Tstg
-65°C to 165°C
(1)
Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
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ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ
ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ
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ÑÑ
Ñ
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ÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑÑ
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MIN
Supply voltage, AVDD, PVDD
2.8
High-level input voltage, VIH
FREQ, INT/EXT, SHUTDOWN, COSC
Low-level input voltage, VIL
FREQ, INT/EXT, SHUTDOWN, COSC
Operating free-air temperature, TA
PACKAGE
ΘJA(1)
(°C/W)
ΘJC
(°C/W)
TA = 25°C
POWER RATING
VFP
29.4
1.2
4.1 W
(1)
2
This data was taken using 2 oz trace and copper pad that is
soldered directly to a JEDEC standard 4-layer 3 in × 3 in PCB.
5.5
2
- 40
PACKAGE DISSIPATION RATINGS
MAX UNIT
V
V
0.8
V
85
°C
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
ELECTRICAL CHARACTERISTICS
over operating free-air temperature range unless otherwise noted
PARAMETER
TEST CONDITIONS
TYP
MAX
UNIT
14
100
mV
VI = VDD
1
µA
VI = 0 V
1
µA
|VOO|
Output offset voltage (measured differentially)
VI = VDD/2,
IO = 0 A
|IIH|
High-level input current
VDD = 5.5V,
|IIL|
Low-level input current
VDD = 5.5V,
Vn
Integrated output noise voltage
f = <1 Hz to 10 kHz
VICM
Common mode voltage range
Common-mode
Av
Closed loop voltage gain
Closed-loop
MIN
VDD = 5 V
1.2
3.8
VDD = 3.3 V
1.2
2.1
DRV593
2.1
2.3
2.6
DRV594
13.7
14.5
15.3
Full power bandwidth
VO
rDS(on)
Voltage output (measured differentially)
60
IO = ±1 A, rds(on) = 65 mΩ, VDD = 5 V
4.87
IO = ±3 A, rds(on) = 65 mΩ, VDD = 5 V
4.61
25
60
95
Low side
25
65
95
VDD = 3.3 V, IO = 4 A,
TA = 25°C
High side
25
80
140
Low side
25
90
140
E t al clock
External
l k frequency
f
range
a
3
Sinking 200 µA
250
300
For 100 kHz operation
45
50
55
VDD = 5 V, No load or filter
Iq(SD)
Quiescent current in shutdown mode
VDD = 5 V, SHUTDOWN = 0.8 V
Output resistance in shutdown
SHUTDOWN = 0.8 V
4
12
2.5
8
0
40
80
1
2
VDD = 3.3 V, No load or filter
Power-on threshold
1.7
Power-off threshold
ZI
0.1
225
Q i
Quiescent
t currentt
mΩ
mΩ
V
kH
kHz
mA
A
µA
kΩ
2.8
1.6
V/V
A
For 500 kHz operation
Iq
V/V
V
High side
Maximum continuous current output
V
kHz
VDD = 5 V, IO = 4 A,
TA = 25°C
Drain source on-state
Drain-source
on state resistance
Status flag output pins (FAULT0, FAULT1)
Fault active (open drain output)
µV
40
2.6
V
V
°C
Thermal trip point
FAULT0 active
115
Thermal shutdown
Power off
150
°C
100
kΩ
Input impedance (IN+, IN-)
3
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
PIN ASSIGNMENTS
FREQ
INT/EXT
PVDD
PVDD
PVDD
PWM
PWM
PWM
VFP PACKAGE
(TOP VIEW)
32 31 30 29 28 27 26 25
AVDD
AGND
ROSC
COSC
AREF
IN+
INSHUTDOWN
1
24
2
23
22
3
4
PowerPAD
5
6
21
20
19
18
7
17
8
PWM
PGND
PGND
PGND
PGND
PGND
PGND
H/C
FAULT1
FAULT0
PVDD
PVDD
PVDD
H/C
H/C
H/C
9 10 11 12 13 14 15 16
Terminal Functions
TERMINAL
I/O
DESCRIPTION
NAME
NO.
AGND
2
AREF
5
O
Connect 1 µF capacitor to ground for AREF voltage filtering
AVDD
1
I
Analog power supply
COSC
4
I
Connect capacitor to ground to set oscillation frequency (220 pF for 500 kHz, 1 nF for 100 kHz) when the internal
oscillator is selected; connect clock signal when an external oscillator is used
FAULT0
10
O
Fault flag 0, low when active open drain output (see application information)
FAULT1
9
O
Fault flag 1, low when active open drain output (see application information)
FREQ
32
I
Selects 500 kHz switching frequency when a TTL logic low is applied to this terminal; selects 100 kHz switching
frequency when a TTL logic high is applied
IN-
7
I
Negative differential input
IN+
6
I
Positive differential input
INT/EXT
31
I
Selects the internal oscillator when a TTL logic high is applied to this terminal; selects the use of an external oscillator when a TTL logic low is applied to this terminal
H/C
14, 15,
16, 17
O
Direction control output for heat and cool modes (4 pins)
PWM
24, 25,
26, 27
O
PWM output for voltage magnitude (4 pins)
PGND
18, 19,
20, 21,
22, 23
PVDD
11, 12,
13, 28,
29, 30
I
High-current power supply (6 pins)
ROSC
3
I
Connect 120-kΩ resistor to AGND to set oscillation frequency (either 500 kHz or 100 kHz). Not needed if an
external clock is used.
SHUTDOWN
8
I
Places the amplifier in shutdown mode when a TTL logic low is applied to this terminal; places the amplifier
in normal operation when a TTL logic high is applied
4
Analog ground
High-current ground (6 pins)
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
FUNCTIONAL BLOCK DIAGRAM
AVDD
AGND
AVDD
R
2.3 × R (DRV593)
14.5 x R (DRV594)
PVDD
+
_
IN_
+
Gate
Drive
H/C
_
+
_
+
+
_
PGND
PVDD
IN+
R
+
_
2.3 × R (DRV593)
14.5 x R (DRV594)
PWM
Gate
Drive
PGND
SHUTDOWN
INT/EXT
FREQ
COSC
ROSC
AREF
TTL
Input
Buffer
Biases
and
References
Ramp
Generator
Start-Up
Protection
Logic
Thermal
OC
Detect
VDDok
FAULT0
FAULT1
5
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
TYPICAL CHARACTERISTICS
TABLE OF GRAPHS
FIGURE
Efficiency
rDS(on)
Drain-source
Drain
source on
on-state
state resistance
vs Load resistance
2, 3
vs Supply voltage
4
vs Free-air temperature
5
vs Free-air temperature
6
7
Iq
Supply current
vs Supply voltage
PSRR
Power supply rejection ratio
vs Frequency
8, 9
Closed loop response
12, 13
vs Output voltage
IO
Maximum output current
VIO
Input offset voltage
vs Ambient temperature
Common-mode input voltage
TEST SETUP FOR GRAPHS
The LC output filter used in Figures 2, 3, 8, and 9 is shown below.
L1
PWM
C1
RL
H/C
L1 = 10 µH (part number: CDRH104R, manufacturer: Sumida)
C1 = 10 µF (part number: ECJ-4YB1C106K, manufacturer: Panasonic)
Figure 1. LC Output Filter
6
14
15
16, 17
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
TYPICAL CHARACTERISTICS
EFFICIENCY
vs
LOAD RESISTANCE
EFFICIENCY
vs
LOAD RESISTANCE
100
100
90
90
PO = 2 W
80
80
PO = 0.5 W
PO = 1 W
70
PO = 0.5 W
Efficiency - %
Efficiency - %
70
60
50
40
PO = 0.25 W
60
50
40
30
30
20
20
VDD = 5 V
fS = 500 kHz
10
VDD = 3.3 V
fS = 500 kHz
10
0
0
1
2
3
4
5
6
7
8
RL - Load Resistance - Ω
9
1
10
Figure 2
IO = 1 A
TA = 25°C
250
Total
150
Low Side
100
High Side
50
0
2.7
3.1
3.5
3.9
4.3
4.7
VDD - Supply Voltage - V
Figure 4
3
4
5
6
7
8
RL - Load Resistance - Ω
9
10
DRAIN-SOURCE ON-STATE RESISTANCE
vs
FREE-AIR TEMPERATURE
rDS(on) - Drain-Source On-State Resistance - mΩ
300
200
2
Figure 3
DRAIN-SOURCE ON-STATE RESISTANCE
vs
SUPPLY VOLTAGE
rDS(on) - Drain-Source On-State Resistance - mΩ
PO = 1 W
5.1
5.5
300
250
VDD = 5 V
IO = 1 A
VFP Package
200
Total
150
Low Side
100
High Side
50
0
-40
-15
10
35
60
TA - Free-Air Temperature - °C
85
Figure 5
7
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
TYPICAL CHARACTERISTICS
SUPPLY CURRENT
vs
SUPPLY VOLTAGE
300
10
VDD = 3.3 V
IO = 1 A
VFP Package
250
No Load
9
8
Total
Iq - Supply Current - mA
rDS(on) - Drain-Source On-State Resistance - mΩ
DRAIN-SOURCE ON-STATE RESISTANCE
vs
FREE-AIR TEMPERATURE
200
150
Low Side
100
High Side
7
6
5
4
3
2
50
1
0
-40
-15
10
35
60
0
2.7
85
TA - Free-Air Temperature - °C
3.1
3.5
5.5
-20
VDD = 5 V
fS = 500 kHz
RL = 1 Ω
Vripple = 100 mVpp
PSRR - Power Supply Rejection Ratio - dB
PSRR - Power Supply Rejection Ratio - dB
5.1
POWER SUPPLY REJECTION RATIO
vs
FREQUENCY
-20
-40
-50
-60
-70
100
1k
10k
f - Frequency - Hz
Figure 8
8
4.7
Figure 7
POWER SUPPLY REJECTION RATIO
vs
FREQUENCY
-80
10
4.3
VDD - Supply Voltage - V
Figure 6
-30
3.9
100k
VDD = 3.3 V
fS = 500 kHz
RL = 1 Ω
Vripple = 100 mVpp
-30
-40
-50
-60
-70
-80
10
100
1k
10k
f - Frequency - Hz
Figure 9
100k
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
TYPICAL CHARACTERISTICS
DRV593
DRV594
CLOSED LOOP RESPONSE
CLOSED LOOP RESPONSE
4
10
16
10
Gain
0
14
-10
3
0
12
-10
Phase
2
-40
Phase - °
-30
Gain - V/V
Gain - V/V
-20
Gain
10
-20
8
-30
6
-40
4
-50
Phase - °
Phase
-50
1
-60
VDD = 5 V
No Load
0
10
100
2
-70
1k
f - Frequency - Hz
10k
-80
100k
0
10
VDD = 5 V
No Load
100
-60
1k
10 k
f - Frequency - Hz
Figure 10
Figure 11
DRV593
DRV594
CLOSED LOOP RESPONSE
CLOSED LOOP RESPONSE
10
4
-70
100 k
16
10
Gain
0
14
Phase
-10
12
-10
Phase
°
-30
2
-40
Phase -
Gain
Gain - V/V
Gain - V/V
-20
10
-20
8
-30
6
-40
4
-50
Phase - °
3
0
-50
1
-60
VDD = 3.3 V
No Load
0
10
100
-70
1k
10k
f - Frequency - Hz
Figure 12
-80
100k
2
0
10
VDD = 3.3 V
No Load
100
-60
1k
10 k
-70
100 k
f - Frequency - Hz
Figure 13
9
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
TYPICAL CHARACTERISTICS
MAXIMUM OUTPUT CURRENT
vs
OUTPUT VOLTAGE
MAXIMUM OUTPUT CURRENT
vs
AMBIENT TEMPERATURE
3.5
3.5
I O - Maximum Output Current - A
I O - Maximum Output Current - A
3
TJ = 100°C
2.5
TJ = 85°C
2
TJ = 125°C
1.5
1
VDD = 5 V
TA = 25°C
VFP Package
0.5
0
0
1
2
3
VO - Output Voltage - V
4
3
2.5
2
1.5
1
0.5
TJ ≤ 125°C
VFP Package
0
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80
TA - Ambient Temperature - °C
5
Figure 14
Figure 15
INPUT OFFSET VOLTAGE
vs
COMMON-MODE INPUT VOLTAGE
INPUT OFFSET VOLTAGE
vs
COMMON-MODE INPUT VOLTAGE
10
19
8
VIO - Input Offset Voltage - mV
VIO - Input Offset Voltage - mV
9
20
VDD = 5 V
No Load
7
6
5
4
3
2
1
0
1.2
18
17
16
15
14
13
12
11
1.6
2.0
2.4
2.8
3.2
VIC - Common-Mode Input Voltage - V
Figure 16
10
VDD = 3.3 V
No Load
3.6 3.8
10
1.2
1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0
VIC - Common-Mode Input Voltage - V
Figure 17
2.1
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
APPLICATION INFORMATION
PULSE-WIDTH MODULATION SCHEME FOR DRV593 AND DRV594
The pulse-width modulation scheme implemented in the DRV593 and DRV594 eliminates one-half of the full output
filter previously required for PWM drivers. The DRV593 and DRV594 require only one inductor and capacitor for the
output filter. The H/C outputs determine the direction of the current and do not switch back and forth. The PWM outputs
switch to produce a voltage across the load that is proportional to the input control voltage.
COOLING MODE
Figure 18 shows the DRV593 and DRV594 in cooling mode. The H/C outputs (pins 14 -17) are at ground and the
PWM outputs (pins 24 -27) create a voltage across the load that is proportional to the input voltage.
The differential voltage across the load is determined using equation (1) and the duty cycle using equation (2). The
differential voltage is defined as the voltage measured after the filter on the PWM output relative to the H/C output.
V Load + D
D+
where
D
Av
VIN+
VINVDD
ǒ
V DD
(1)
Ǔ
A v VIN)–V IN–
V DD
(2)
duty cycle of the PWM signal
Gain of DRV593/594 (DRV593: 2.3 V/V, DRV594: 14.5 V/V)
Positive input terminal of the DRV593/594
Negative input terminal of the DRV593/594
Power supply voltage
For example, a 50% duty cycle, shown in Figure 18, results in 2.5 V across the load for VDD = 5 V.
VDD
PWM
0
VDD
H/C
0
VDD
VDD/2
Load
Voltage
0
Figure 18. Cooling Mode
11
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
HEATING MODE
Figure 19 shows the DRV593 and DRV594 in heating mode. The H/C output is at VDD and the PWM output is
proportional to the voltage across the load.
The differential voltage across the load is determined using equation (3). The variables are the same as used
previously for equations (1) and (2).
V Load + –(1–D)
V DD
(3)
For example, a 50% duty cycle, shown in Figure 19, results in -2.5 V across the load for VDD = 5 V. The differential
voltage across the load is defined as the voltage measured after the filter on the PWM output relative to the H/C output.
VDD
PWM
0
VDD
H/C
0
Load
Voltage
0
-VDD/2
-VDD
Figure 19. Heating Mode
12
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
HEAT/COOL TRANSITION
As the device transitions from cooling to heating, the duty cycle of the PWM outputs decrease to a small value and
the H/C outputs remains at ground. When the device transitions to heating mode, the H/C outputs change from zero
volts to VDD and the PWM outputs change to a high duty cycle. The direction of the current flow is reversed, but a
low voltage is maintained across the load. The duty cycle decreases as the part is put further into heating mode to
drive more current through the load. Figure 20 illustrates the transition from cooling to heating.
ZERO-CROSSING REGION
When the differential output voltage is near zero, the control logic in the DRV593 and DRV594 causes the outputs
to change between heating and cooling modes. There are two possible states for the PWM and H/C outputs to obtain
zero volts differentially: both outputs can be at VDD or both outputs can be at ground. Therefore, random noise causes
the outputs to change between the two states when the two input voltages are equal. The outputs switch from zero
to VDD, although not at a fixed frequency rate. Some of the pulses may be wider than others, but the two outputs
(PWM and H/C) track each other to provide zero differential voltage. These uneven pulse widths can increase the
switching noise during the zero-crossing condition.
To avoid this phenomenon, hysteresis should be implemented in the control loop to prevent the device from operating
within this region. Although planning for operation during the zero-crossing is important, the normal operating points
for the DRV593 and DRV594 are outside of this region. For laser temperature/wavelength regulation, the zero volts
output condition is only a concern when the laser temperature or wavelength, relative to the ambient temperature,
requires no heating or cooling from the TEC element.
VDD
IN +
IN -
0
VDD
PWM
0
VDD
H/C
0
Figure 20. Transition From Cooling to Heating
13
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
VDD
To TEC or Laser
Diode Anode
PWM
PWM
PGND
DRV593
DRV594
PGND
IN+
PGND
IN-
PGND
SHUTDOWN
10 µF
H/C
H/C
H/C
H/C
PVDD
FAULT0
Shutdown Control
PVDD
PGND
COSC
FAULT1
1 µF
PVDD
PGND
ROSC
AREF
1 kΩ
1 kΩ
AGND (Connect to PowerPAD)
PVDD
220 pF
DC Control
Voltage
10 µH
PWM
PVDD
120 kΩ
PVDD
FREQ
AVDD
INT/EXT
1 µF
PWM
1 µF
10 µF
FAULT1
To TEC or Laser
Diode Cathode
FAULT0
1 µF
Figure 21. Typical Application Circuit
OUTPUT FILTER CONSIDERATIONS
TEC element manufacturers provide electrical specifications for maximum dc current and maximum output
voltage for each particular element. The maximum ripple current, however, is typically only recommended to
be less than 10% with no reference to the frequency components of the current. The maximum temperature
differential across the element, which decreases as ripple current increases, may be calculated with the
following equation:
DT +
1
ǒ1 ) N2Ǔ
(4)
DT max
where
∆T = actual temperature differential
∆Tmax = maximum temperature differential (specified by manufacturer)
N = ratio of ripple current to dc current
According to this relationship, a 10% ripple current reduces the maximum temperature differential by 1%. An
LC network may be used to filter the current flowing to the TEC to reduce the amount of ripple and, more
importantly, protect the rest of the system from any electromagnetic interference (EMI).
FILTER COMPONENT SELECTION
The LC filter, which may be designed from two different perspectives, both described below, helps estimate the
overall performance of the system. The filter should be designed for the worst-case conditions during operation,
which is typically when the differential output is at 50% duty cycle. The following section serves as a starting
point for the design, and any calculations should be confirmed with a prototype circuit in the lab.
Any filter should always be placed as close as possible to the DRV593 and DRV594 to reduce EMI.
L
PWM
C
TEC
H/C
Figure 22. LC Output Filter
14
R
DRV593
DRV594
www.ti.com
SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
LC FILTER IN THE FREQUENCY DOMAIN
The transfer function for a second-order low-pass filter (Figures 17 and 18) is shown in equation (5):
H LP(jw) +
(5)
1
ǒ Ǔ
– ww
0
2
jw
) 1 w )1
Q 0
w0 + 1
ǸLC
Q + quality factor
w + DRV593 or DRV594 switching frequency
For the DRV593 and DRV594, the differential output switching frequency is typically selected to be 500 kHz.
The resonant frequency for the filter is typically chosen to be at least one order of magnitude lower than the
switching frequency. equation (5) may then be simplified to give the following magnitude equation (6). These
equations assume the use of the filter in Figure 22.
ŤH LPŤdB
fo +
+ –40 log
ǒǓ
(6)
fs
fo
1
2p ǸLC
f s + 500 kHz (DRV593 or DRV594 switching frequency)
If L=10 µH and C=10 µF, the cutoff frequency is 15.9 kHz, which corresponds to –60 dB of attenuation at the
500 kHz switching frequency. For VDD = 5 V, the amount of ripple voltage at the TEC element is approximately
5 mV.
The average TEC element has a resistance of 1.5 Ω, so the ripple current through the TEC is approximately
3.4 mA. At the 3-A maximum output current of the DRV593 and DRV594, this 5.4 mA corresponds to 0.11%
ripple current, causing less than 0.0001% reduction of the maximum temperature differential of the TEC
element (see equation 4).
LC FILTER IN THE TIME DOMAIN
The ripple current of an inductor may be calculated using equation (7):
DI +
L
ǒVO–V TECǓDTs
(7)
L
D + duty cycle (0.5 worst case)
T s + 1ńfs + 1ń500 kHz
For VO = 5 V, VTEC = 2.5 V, and L = 10 µH, the inductor ripple current is 250 mA. To calculate how much of that
ripple current flows through the TEC element, however, the properties of the filter capacitor must be considered.
For relatively small capacitors (less than 22 µF) with very low equivalent series resistance (ESR, less than
10 mΩ), such as ceramic capacitors, the following equation (8) may be used to estimate the ripple voltage on
the capacitor due to the change in charge:
ǒǓ
f
2
DV + p ǒ1–DǓ o
C
2
fs
(8)
2
V
TEC
D + duty cycle
f s + 500 kHz
fo +
1
2p ǸLC
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DRV593
DRV594
www.ti.com
SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
For L = 10 µH and C = 10 µF, the cutoff frequency, fo, is 15.9 kHz. For worst case duty cycle of 0.5 and
VTEC=2.5 V, the ripple voltage on the capacitors is 6.2 mV. The ripple current may be calculated by dividing the
ripple voltage by the TEC resistance of 1.5 Ω, resulting in a ripple current through the TEC element of 4.1 mA.
Note that this is similar to the value calculated using the frequency domain approach.
For larger capacitors (greater than 22 µF) with relatively high ESR (greater than 100 mΩ), such as electrolytic
capacitors, the ESR dominates over the charging/discharging of the capacitor. The following simple
equation (9) may be used to estimate the ripple voltage:
DV
C
+ DIL
R
(9)
ESR
DI + inductor ripple current
L
R
+ filter capacitor ESR
ESR
For a 100 µF electrolytic capacitor, an ESR of 0.1 Ω is common. If the 10 µH inductor is used, delivering 250 mA
of ripple current to the capacitor (as calculated above), then the ripple voltage is 25 mV. This is over ten times
that of the 10 µF ceramic capacitor, as ceramic capacitors typically have negligible ESR.
SWITCHING FREQUENCY CONFIGURATION: OSCILLATOR COMPONENTS ROSC AND COSC
AND FREQ OPERATION
The onboard ramp generator requires an external resistor and capacitor to set the oscillation frequency. The
frequency may be either 500 kHz or 100 kHz by selecting the proper capacitor value and by holding the FREQ
pin either low (500 kHz) or high (100 kHz). Table 1 shows the values required and FREQ pin configuration for
each switching frequency.
Table 1. Frequency Configuration Options
SWITCHING FREQUENCY
ROSC
COSC
FREQ
500 kHz
120 kΩ
220 pF
LOW (GND)
100 kHz
120 kΩ
1 nF
HIGH (VDD)
For proper operation, the resistor ROSC should have 1% tolerance while capacitor COSC should be a ceramic
type with 10% tolerance. Both components should be grounded to AGND, which should be connected to PGND
at a single point, typically where power and ground are physically connected to the printed-circuit board.
EXTERNAL CLOCKING OPERATION
To synchronize the switching to an external clock signal, pull the INT/EXT terminal low, and drive the clock signal
into the COSC terminal. This clock signal must be from 10% to 90% duty cycle and meet the voltage
requirements specified in the electrical specifications table. Since the DRV593 and DRV594 include an internal
frequency doubler, the external clock signal must be approximately 250 kHz. Deviations from the 250 kHz clock
frequency are allowed and are specified in the electrical characteristic table. The resistor connected from ROSC
to ground may be omitted from the circuit in this mode of operation—the source is disconnected internally.
INPUT CONFIGURATION: DIFFERENTIAL AND SINGLE-ENDED
If a differential input is used, it should be biased around the midrail of the DRV593 or DRV594 and must not
exceed the common-mode input range of the input stage (see the operating characteristics at the beginning
of the data sheet).
The most common configuration employs a single-ended input. The unused input should be tied to VDD/2, which
may be simply accomplished with a resistive voltage divider. For the best performance, the resistor values
chosen should be at least 100 times lower than the input resistance of the DRV593 or DRV594. This prevents
the bias voltage at the unused input from shifting when the signal input is applied. A small ceramic capacitor
should also be placed from the input to ground to filter noise and keep the voltage stable. An op amp configured
as a buffer may also be used to set the voltage at the unused input.
16
DRV593
DRV594
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
FIXED INTERNAL GAIN
The differential output voltage may be calculated using equation (10):
V
O
+V
ǒ
Ǔ
(10)
–V
+ A v V IN)–V IN–
OUT) OUT–
AV is the voltage gain, which is fixed internally at 2.3 V/V for DRV593 and 14.5 V/V for DRV594. The maximum
and minimum ratings are provided in the electrical specification table at the beginning of the data sheet.
POWER SUPPLY DECOUPLING
To reduce the effects of high-frequency transients or spikes, a small ceramic capacitor, typically 0.1 µF to 1 µF,
should be placed as close to each set of PVDD pins of the DRV593 and DRV594 as possible. For bulk
decoupling, a 10 µF to 100 µF tantalum or aluminum electrolytic capacitor should be placed relatively close to
the DRV593 and DRV594.
AREF CAPACITOR
The AREF terminal is the output of an internal mid-rail voltage regulator used for the onboard oscillator and ramp
generator. The regulator may not be used to provide power to any additional circuitry. A 1 µF ceramic capacitor
must be connected from AREF to AGND for stability (see oscillator components above for AGND connection
information).
SHUTDOWN OPERATION
The DRV593 and DRV594 include a shutdown mode that disables the outputs and places the device in a low
supply current state. The SHUTDOWN pin may be controlled with a TTL logic signal. When SHUTDOWN is
held high, the device operates normally. When SHUTDOWN is held low, the device is placed in shutdown. The
SHUTDOWN pin must not be left floating. If the shutdown feature is unused, the pin may be connected to VDD.
FAULT REPORTING
The DRV593 and DRV594 include circuitry to sense three faults:
D Overcurrent
D Undervoltage
D Overtemperature
These three fault conditions are decoded via the FAULT1 and FAULT0 terminals. Internally, these are
open-drain outputs, so an external pullup resistor of 5 kΩ or greater is required.
Table 2. Fault Indicators
FAULT1
FAULT0
0
0
Overcurrent
1
0
Undervoltage
0
1
Overtemperature
1
1
Normal operation
The overcurrent fault is reported when the output current exceeds four amps. As soon as the condition is
sensed, the overcurrent fault is set and the outputs go into a high-impedance state for approximately 3 µs to
5 µs (500 kHz operation). After 3 µs to 5 µs, the outputs are re-enabled. If the overcurrent condition has ended,
the fault is cleared and the device resumes normal operation. If the overcurrent condition still exists, the above
sequence repeats.
The undervoltage fault is reported when the operating voltage is reduced below 2.8 V. This fault is not latched,
so as soon as the power supply recovers, the fault is cleared and normal operation resumes. During the
undervoltage condition, the outputs go into a high-impedance state to prevent overdissipation due to increased
rDS(on).
17
DRV593
DRV594
www.ti.com
SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
The overtemperature fault is reported when the junction temperature exceeds 115°C. The device continues
operating normally until the junction temperature reaches 150°C, at which point the IC is disabled to prevent
permanent damage from occurring. The system’s controller must reduce the power demanded from the
DRV593 or DRV594 once the overtemperature flag is set, or else the device switches off when it reaches 150°C.
This fault is not latched; once the junction temperature drops below 115°C, the fault is cleared, and normal
operation resumes.
POWER DISSIPATION AND MAXIMUM AMBIENT TEMPERATURE
Though the DRV593 and DRV594 are much more efficient than traditional linear solutions, the power drop
across the on-resistance of the output transistors does generate some heat in the package, which may be
calculated as shown in equation (11):
P
DISS
ǒ OUTǓ
+ I
(11)
2
r
DS(on), total
For example, at the maximum output current of 3 A through a total on-resistance of 130 mΩ (at TJ = 25°C),
the power dissipated in the package is 1.17 W.
Calculate the maximum ambient temperature using equation (12):
ǒ
T A + TJ * θ JA
P
DISS
Ǔ
(12)
PRINTED-CIRCUIT BOARD (PCB) LAYOUT CONSIDERATIONS
Since the DRV593 and DRV594 are high-current switching devices, a few guidelines for the layout of the
printed-circuit board (PCB) must be considered:
1. Grounding. Analog ground (AGND) and power ground (PGND) must be kept separated, ideally back to
where the power supply physically connects to the PCB, minimally back to the bulk decoupling capacitor
(10 µF ceramic minimum). Furthermore, the PowerPAD ground connection should be made to AGND, not
PGND. Ground planes are not recommended for AGND or PGND, traces should be used to route the
currents. Wide traces (100 mils) should be used for PGND while narrow traces (15 mils) should be used
for AGND.
2. Power supply decoupling. A small 0.1 µF to 1 µF ceramic capacitor should be placed as close to each
set of PVDD pins as possible, connecting from PVDD to PGND. A 0.1 µF to 1 µF ceramic capacitor should
also be placed close to the AVDD pin, connecting from AVDD to AGND. A bulk decoupling capacitor of at
least 10 µF, preferably ceramic, should be placed close to the DRV593 or DRV594, from PVDD to PGND.
If power supply lines are long, additional decoupling may be required.
3. Power and output traces. The power and output traces should be sized to handle the desired maximum
output current. The output traces should be kept as short as possible to reduce EMI, i.e., the output filter
should be placed as close to the DRV593 or DRV594 outputs as possible.
4. PowerPAD. The DRV593 and DRV594 in the Quad Flatpack package use TI’s PowerPAD technology to
enhance the thermal performance. The PowerPAD is physically connected to the substrate of the DRV593
and DRV594 silicon, which is connected to AGND. The PowerPAD ground connection should therefore be
kept separate from PGND as described above. The pad underneath the AGND pin may be connected
underneath the device to the PowerPAD ground connection for ease of routing. For additional information
on PowerPAD PCB layout, refer to the PowerPAD Thermally Enhanced Package application note,
SLMA002.
5. Thermal performance. For proper thermal performance, the PowerPAD must be soldered down to a
thermal land, as described in the PowerPAD Thermally Enhanced Package application note, SLMA002.
In addition, at high current levels (greater than 2 A) or high ambient temperatures (greater than 25°C), an
internal plane may be used for heat sinking. The vias under the PowerPAD should make a solid connection,
and the plane should not be tied to ground except through the PowerPAD connection, as described above.
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DRV593
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SLOS401A - SEPTEMBER 2002 REVISED - OCTOBER 2002
MECHANICAL DATA
VFP (S-PQFP-G32)
PowerPAD PLASTIC QUAD FLATPACK
0,45
0,30
0,80
24
0,22 M
17
25
16
Thermal Pad
(See Note D)
32
9
0,13 NOM
1
8
5,60 TYP
7,20
SQ
6,80
9,20
SQ
8,80
Gage Plane
0,25
1,45
1,35
0,05 MIN
Seating Plane
1,60 MAX
0°-7°
0,75
0,45
0,10
4200791/A 04/00
NOTES: A.
B.
C.
D.
All linear dimensions are in millimeters.
This drawing is subject to change without notice.
Body dimensions do not include mold flash or protrusion.
The package thermal performance may be enhanced by bonding the thermal pad to an external thermal plane.
This pad is electrically and thermally connected to the backside of the die and possibly selected leads.
E. Falls within JEDEC MS-026
PowerPAD is a trademark of Texas Instruments.
19
PACKAGE OPTION ADDENDUM
www.ti.com
4-Mar-2005
PACKAGING INFORMATION
Orderable Device
Status (1)
Package
Type
Package
Drawing
Pins Package Eco Plan (2)
Qty
Lead/Ball Finish
MSL Peak Temp (3)
DRV593VFP
ACTIVE
HLQFP
VFP
32
250
None
CU NIPDAU
Level-1-235C-UNLIM
DRV593VFPR
ACTIVE
HLQFP
VFP
32
1000
None
CU NIPDAU
Level-1-235C-UNLIM
DRV594VFP
ACTIVE
HLQFP
VFP
32
250
None
CU NIPDAU
Level-1-235C-UNLIM
DRV594VFPR
ACTIVE
HLQFP
VFP
32
1000
None
CU NIPDAU
Level-1-235C-UNLIM
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in
a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
Eco Plan - May not be currently available - please check http://www.ti.com/productcontent for the latest availability information and additional
product content details.
None: Not yet available Lead (Pb-Free).
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements
for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered
at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Green (RoHS & no Sb/Br): TI defines "Green" to mean "Pb-Free" and in addition, uses package materials that do not contain halogens,
including bromine (Br) or antimony (Sb) above 0.1% of total product weight.
(3)
MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDECindustry standard classifications, and peak solder
temperature.
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Addendum-Page 1
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