UCD7100
SLUS651E – MARCH 2005 – REVISED NOVEMBER 2021
UCD7100 Digital Control Compatible Single Low-Side
±4-A MOSFET Driver with Current Sense
1 Features
3 Description
•
•
•
•
•
•
•
•
•
•
•
•
The UCD7100 device is part of the UCD7K family of
digital control compatible drivers for applications that
use digital control technology that requires fast local
peak current limit protection.
Adjustable current limit protection
3.3-V, 10-mA internal regulator
DSP/µC compatible inputs
Single ±4-A TrueDrive™ high current driver
10-ns typical rise and fall times with 2.2-nF loads
25-ns input-to-output propagation delay
25-ns current sense to output delay
Programmable current limit threshold
Digital output current limit flag
4.5-V to 15-V supply voltage range
Rated from –40°C to 105°C
Lead(Pb)-free packaging
2 Applications
•
•
•
•
Digitally controlled power supplies
DC/DC converters
Motor controllers
Line drivers
The UCD7100 is a low-side ±4-A high-current
MOSFET gate driver. It allows the digital power
controllers such as UCD9110 or UCD9501 to interface
to the power stage in single ended topologies. It
provides a cycle-by-cycle current limit function with
programmable threshold and a digital output current
limit flag which can be monitored by the host
controller. With a fast 25-ns cycle-by-cycle current
limit protection, the driver can turn off the power stage
in the unlikely event that the digital system can not
respond to a failure situation in time.
Device Information(1)
PART NUMBER
PACKAGE
BODY SIZE (NOM)
UCD7100
HTSSOP (14)
5.00 mm x 4.40 mm
UCD7100A
HTSSOP (14)
5.00 mm x 4.40 mm
(1)
For all available packages, see the orderable addendum at
the end of the data sheet.
VIN
VOUT
Bias
Winding
Digital Controller
AN1
AGND
UCD7100PWP
3
3V3
PWMA
2
IN
INT
5
CLF
VDD
PWMB
VDD 14
OUT 12
6 ILIM
CS 8
4 AGND
Communication
2
AN2
AN3
Isolation
Amplifier
Simplified Schematic
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
UCD7100
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Table of Contents
1 Features............................................................................1
2 Applications..................................................................... 1
3 Description.......................................................................1
4 Revision History.............................................................. 2
5 Description (continued).................................................. 3
6 Device Comparison Table...............................................3
7 Pin Configuration and Functions...................................3
8 Specifications.................................................................. 5
8.1 Absolute Maximum Ratings........................................ 5
8.2 Handling Ratings.........................................................5
8.3 Recommended Operating Conditions.........................5
8.4 Thermal Information....................................................6
8.5 Electrical Characteristics.............................................6
8.6 Typical Characteristics................................................ 8
9 Detailed Description...................................................... 11
9.1 Overview................................................................... 11
9.2 Functional Block Diagram......................................... 11
9.3 Feature Description...................................................11
9.4 Device Functional Modes..........................................14
10 Application and Implementation................................ 15
10.1 Application Information........................................... 15
10.2 Typical Application.................................................. 15
11 Power Supply Recommendations..............................17
11.1 Supply..................................................................... 17
11.2 Reference and External Bias Supply...................... 17
12 Layout...........................................................................18
12.1 Layout Guidelines................................................... 18
12.2 Layout Example...................................................... 18
12.3 Thermal Considerations..........................................19
13 Device and Documentation Support..........................20
13.1 Device Support....................................................... 20
13.2 Third-Party Products Disclaimer............................. 20
13.3 Documentation Support.......................................... 20
13.4 Receiving Notification of Documentation Updates..20
13.5 Support Resources................................................. 20
13.6 Trademarks............................................................. 20
13.7 Glossary..................................................................20
13.8 Electrostatic Discharge Caution..............................20
14 Mechanical, Packaging, and Orderable
Information.................................................................... 21
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision D (October 2014) to Revision E (November 2021)
Page
• Added the UCD7100A device to Device Information .........................................................................................1
• Added the Device Comparison Table................................................................................................................. 3
2
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5 Description (continued)
For fast switching speeds, the UCD7100 output stage uses the TrueDrive™ output architecture, which delivers
rated current of ±4 A into the gate of a MOSFET during the Miller plateau region of the switching transition. It
also includes a 3.3-V, 10-mA linear regulator to provide power to the digital controller.
The UCD7000 driver family is compatible with standard 3.3-V I/O ports of DSPs, Microcontrollers, or ASICs.
UCD7100 is offered in a PowerPAD™ HTSSOP-14.
6 Device Comparison Table
Table 6-1. UCD7100 Device Comparison
PART NUMBER
COMMENTS
UCD7100
Standard manufacturing flow
UCD7100A
Special manufacturing flow
7 Pin Configuration and Functions
VDD
IN
3V3
AGND
CLF
ILIM
NC
1
2
3
4
5
6
7
14
13
12
11
10
9
8
PVDD
PVDD
OUT
OUT
PGND
PGND
CS
NC − No internal connection
Figure 7-1. PWP 14 PINS Top View
Table 7-1. Pin Functions
UCD7100
HTSSOP-14
PIN NO.
DFN-14 PIN
NO.
PIN NAME
TYPE
FUNCTION
1
1
VDD
I
Supply input pin to power the driver. The UCD7K devices accept an input
range of 4.25 V to 15 V. Bypass the pin with at least 4.7 µF of capacitance.
2
2
IN
I
The IN pin is a high impedance digital input capable of accepting 3.3-V logic
level signals up to 2 MHz. There is an internal Schmitt trigger comparator
which isolates the internal circuitry from any external noise.
3
3
3V3
O
Regulated 3.3-V rail. The onboard linear voltage regulator is capable of
sourcing up to 10 mA of current. Place 0.22-µF of ceramic capacitance from
the pin to ground.
4
4
AGND
—
Analog ground return.
5
5
CLF
O
Current limit flag. When the CS level is greater than the ILIM voltage minus 25
mV, the output of the driver is forced low and the current limit flag (CLF) is set
high. The CLF signal is latched high until the UCD7K device receives the next
rising edge on the IN pin.
6
6
ILIM
I
Current limit threshold set pin. The current limit threshold can be set to any
value between 0.25 V and 1.0 V.
7
7
NC
—
8
8
CS
I
9
9
PGND
—
No Connection.
Current sense pin. Fast current limit comparator connected to the CS pin
is used to protect the power stage by implementing cycle-by-cycle current
limiting.
Power ground return. Connect the two PGNDs together. These ground pins
should be connected very closely to the source of the power MOSFET.
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Table 7-1. Pin Functions (continued)
UCD7100
4
HTSSOP-14
PIN NO.
DFN-14 PIN
NO.
PIN NAME
TYPE
FUNCTION
10
10
PGND
—
Power ground return. Connect the two PGNDs together. These ground pins
should be connected very closely to the source of the power MOSFET.
11
11
OUT
O
The high-current TrueDrive™ driver output. Connect the two OUT pins
together.
12
12
OUT
O
The high-current TrueDrive™ driver output. Connect the two OUT pins
together.
13
13
PVDD
I
Supply pin provides power for the output drivers. It is not connected internally
to the VDD supply rail. Connect the two PVDD pins together.
14
14
PVDD
I
Supply pin provides power for the output drivers. It is not connected internally
to the VDD supply rail. Connect the two PVDD pins together.
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8 Specifications
8.1 Absolute Maximum Ratings
MAX(1)
MIN
VDD
Supply Voltage
IDD
Supply Current
VOUT
Output Gate
Drive Voltage
OUT
Output Gate
Drive Current
OUT
IOUT(sink)
IOUT(source)
16
Quiescent
20
Switching, TA = 25°C, TJ = 125°C, VDD = 12 V
200
3.6
3.6
Digital I/O’s
IN, CLF
–0.3
3.6
Power
Dissipation
TA = 25°C, TJ = 125°C, (PWP-14)
Lead Temperature (Soldering, 10 s)
(2)
4.0
–0.3
TSOL
V
A
–4.0
–0.3
Junction Operating Temperature
mA
VDD
ILIM
TJ
(1)
–1 V
ISET, CS
Analog Input
UNIT(2)
-–55
V
2.67
W
150
°C
+300
°C
Operation outside the Absolute Maximum Ratings may cause permanent device damage. Absolute Maximum Ratings do not imply
functional operation of the device at these or any other conditions beyond those listed under Recommended Operating Conditions. If
outside the Recommended Operating Conditions but within the Absolute Maximum Ratings, the device may not be fully functional, and
this may affect device reliability, functionality, performance, and shorten the device lifetime.
All voltages are with respect to GND. Currents are positive into, negative out of the specified terminal.
8.2 Handling Ratings
Tstg
Storage temperature range
V(ESD)
(1)
(2)
Electrostatic discharge
MIN
MAX
UNIT
–65
150
°C
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all
pins(1)
2000
Charged device model (CDM), per JEDEC specification
JESD22-C101, all pins(2)
500
V
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
8.3 Recommended Operating Conditions
Supply Voltage, VDD
Supply bypass capacitance
MIN
TYP
MAX
UNIT
4.25
12
14.5
V
1
Reference bypass capacitance
0.22
Operating junction temperature
-40
µF
105
°C
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8.4 Thermal Information
UCD7100
THERMAL
METRIC(1)
UNIT
HTSSOP
14 PINS
RθJA
Junction-to-ambient thermal resistance
44.3
RθJC(top)
Junction-to-case (top) thermal resistance
35.3
RθJB
Junction-to-board thermal resistance
29.6
ψJT
Junction-to-top characterization parameter
1.5
ψJB
Junction-to-board characterization parameter
29.3
RθJC(bot)
Junction-to-case (bottom) thermal resistance
4.7
(1)
°C/W
For more information about traditional and new thermal metrics, see the application report, IC Package Thermal Metrics Application
Report.
8.5 Electrical Characteristics
VDD = 12 V, 4.7-µF capacitor from VDD to GND, TA = TJ = –40°C to 105°C, (unless otherwise noted).
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
SUPPLY SECTION
Supply current, OFF
VDD = 4.2 V
200
400
µA
Supply current
Outputs not switching IN = LOW
1.5
2.5
mA
LOW VOLTAGE UNDER-VOLTAGE LOCKOUT
VDD UVLO ON
4.25
4.5
4.75
VDD UVLO OFF
4.05
4.25
4.45
VDD UVLO hysteresis
150
250
350
3.267
3.3
3.333
3.234
3.3
3.366
V
mV
REFERENCE / EXTERNAL BIAS SUPPLY
3V3 initial set point
TA = 25°C
3V3 over temperature
3V3 load regulation
ILOAD = 1 mA to 10 mA, VDD = 5 V
1
6.6
3V3 line regulation
VDD = 4.75 V to 12 V, ILOAD = 10 mA
1
6.6
Short circuit current
VDD = 4.75 to 12 V
11
20
35
3V3 OK threshold, ON
3.3 V rising
2.9
3.0
3.1
3V3 OK threshold, OFF
3.3 V falling
2.7
2.8
2.9
V
mV
mA
V
INPUT SIGNAL
HIGH, positive-going input threshold
voltage (VIT+)
1.65
2.08
LOW negative-going input threshold
voltage (VIT-)
1.16
1.5
0.6
0.8
Input voltage hysteresis, (VIT+ – VIT-)
Frequency
2
V
MHz
CURRENT LIMIT (ILIM)
ILIM internal current limit threshold
ILIM = OPEN
0.466
0.50
0.536
ILIM maximum current limit threshold
ILIM = 3.3 V
0.975
1.025
1.075
ILIM current limit threshold
ILIM = 0.75 V
0.700
0.725
0.750
ILIM minimum current limit threshold
ILIM = 0.25 V
0.21
0.23
0.25
CLF output high level
CS > ILIM , ILOAD = -7 mA
2.64
CLF output low level
CS ≤ ILIM, ILOAD = 7 mA
Propagation delay from IN to CLF
IN rising to CLF falling after a current limit event
0.66
10
20
V
V
mV
V
ns
CURRENT SENSE COMPARATOR
6
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8.5 Electrical Characteristics (continued)
VDD = 12 V, 4.7-µF capacitor from VDD to GND, TA = TJ = –40°C to 105°C, (unless otherwise noted).
PARAMETER
Bias voltage
TEST CONDITIONS
Includes CS comp offset
MIN
TYP
MAX
5
25
50
Input bias current
–1
UNIT
mV
uA
Propagation delay from CS to OUTx
ILIM = 0.5 V, measured on OUTx, CS = threshold + 60 mV
25
40
Propagation delay from CS to CLF
ILIM = 0.5 V, measured on CLF, CS = threshold + 60 mV
25
50
35
75
ns
CURRENT SENSE DISCHARGE TRANSISTOR
Discharge resistance
IN = low, resistance from CS to AGND
10
Ω
OUTPUT DRIVERS
Source current(1)
VDD = 12 V, IN = high, OUT = 5 V
4
Sink current(1)
VDD = 12 V, IN = low, OUT = 5 V
4
VDD = 4.75 V, IN = high, OUT = 0
2
VDD = 4.75 V, IN = low, OUT = 4.75 V
3
Source
current(1)
Sink current(1)
Rise time, tR
(1)
A
CLOAD = 2.2 nF, VDD = 12 V
10
20
Fall time, tF (1)
CLOAD = 2.2 nF, VDD = 12 V
10
15
Output with VDD < UVLO
VDD = 1.0 V, ISINK = 10 mA
0.8
1.2
V
20
35
ns
Propagation delay from IN to OUTx, tD1 CLOAD = 2.2 nF, VDD = 12 V, CLK rising
(1)
ns
Ensured by design. Not 100% tested in production.
VIT+
INPUT
VIT−
tF
tF
tD1
90%
tD2
OUTPUT
10%
Figure 8-1. Timing Diagram
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8.6 Typical Characteristics
5.0
3.36
UVLO on
4.5
3.34
UVLO on
3V3 − Reference Voltage − V
VUVLO − UVLO Thresholds − V
4.0
3.5
3.0
2.5
2.0
1.5
1.0
3.32
3.30
3.28
3.26
UVLO on
0.5
0.0
−50
3.24
−25
0
25
50
75
100
125
−50
−25
0
t − Temperature − °C
Figure 8-2. UVLO Thresholds vs Temperature
125
2.5
Input Rising
22.5
2.0
VINPUT − Input Voltage − V
ISHORT_CKT − Short Circuit Current − mA
100
Figure 8-3. 3V3 Reference Voltage vs Temperature
23.0
22.0
VDD = 4.75 V
21.5
VDD = 12 V
21.0
1.5
Input Falling
1.0
0.5
20.5
20.0
0.0
−50
−25
0
25
50
75
t − Temperature − °C
100
125
Figure 8-4. 3V3 Short Circuit Current vs
Temperature
−50
−25
0
25
50
75
100
125
TJ − Temperature − °C
Figure 8-5. Input Thresholds vs Temperature
65
18.0
16.0
tR = Rise Time
55
CLOAD = 10 nF
14.0
12.0
10.0
tR − Rise Time − ns
tR, tF − Rise and Fall Times − ns
25
50
75
t − Temperature − °C
tF = Fall Time
8.0
6.0
45
CLOAD = 4.7 nF
35
25
CLOAD = 2.2 nF
4.0
15
2.0
CLOAD = 1 nF
0.0
5
−50
−25
0
25
50
75
100
5
125
10
12.5
15
VDD − Supply Voltage − V
TJ − Temperature − °C
Figure 8-6. Output Rise Time and Fall Time vs
Temperature (VDD = 12 V
8
7.5
Figure 8-7. Rise Time vs Supply Voltage
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20
45
tF − Fall Time − ns
35
tPD − Propagation Delay, Rising − ns
40
CLOAD = 10 nF
30
25
CLOAD = 4.7 nF
20
CLOAD = 2.2 nF
15
CLOAD = 10 nF
15
10
CLOAD = 4.7 nF
5
CLOAD = 2.2 nF
CLOAD = 1 nF
10
CLOAD = 1 nF
0
5
5
7.5
10
12.5
5
15
7.5
Figure 8-8. Fall Time vs Supply Voltage
15
Figure 8-9. Propagation Delay Rising vs Supply
Voltage
25
0.54
0.53
VCS − Current Limit Threshold − V
tPD − Propagation Delay, Falling − ns
12.5
VDD − Supply Voltage − V
VDD − Supply Voltage − V
CLOAD = 10 nF
20
15
CLOAD = 4.7 nF
10
CLOAD = 2.2 nF
0.52
0.51
0.50
0.49
0.48
0.47
CLOAD = 1 nF
5
0.46
5
7.5
10
12.5
15
−50
−25
VDD − Supply Voltage − V
0
25
50
75
100
125
TJ − Temperature − °C
Figure 8-10. Propagation Delay Falling vs Supply
Voltage
Figure 8-11. Default Current Limit Threshold vs
Temperature
40
50
45
35
tPD − CS to CLF Propagation Delay − ns
tPD − CS to OUTx Propagation Delay − ns
10
30
25
20
15
10
5
40
35
30
25
20
15
10
5
0
0
−50
−25
0
25
50
75
100
−50
125
−25
0
25
50
75
100
125
TJ − Temperature − °C
TJ − Temperature − °C
Figure 8-12. CS to OUTx Propagation Delay vs
Temperature
Figure 8-13. CS to CLF Propagation Delay vs
Temperature
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35
VDD (2 V/div)
tPD − Propagation Delay − ns
30
25
20
15
3V3 (2 V/div)
10
5
OUTx (2 V/div)
0
−50
−25
0
25
50
75
100
t − Time − 40 µs/div
125
TJ − Temperature − °C
Figure 8-14. IN to OUT Propagation Delay vs
Temperature
Figure 8-15. Start-up Behavior at VDD = 12 V (Input
Tied to 3V3)
VDD (2 V/div)
VDD (2 V/div)
3V3 (2 V/div)
3V3 (2 V/div)
OUTx (2 V/div)
OUTx (2 V/div)
t − Time − 40 µs/div
t − Time − 40 µs/div
Figure 8-16. Shut Down Behavior at VDD = 12 V
(Input Tied to 3V3)
Figure 8-17. Start-up Behavior at VDD = 12 V (Input
Shortened to GND)
Output Voltage − 2 V/div
VDD (2 V/div)
3V3 (2 V/div)
OUTx (2 V/div)
t − Time − 40 ns/div
t − Time − 40 µs/div
Figure 8-18. Shut Down Behavior at VDD = 12 V
(Input Shortened to GND)
10
Figure 8-19. Output Rise and Fall Time (VDD = 12 V,
CLOAD = 10 NF)
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9 Detailed Description
9.1 Overview
The UCD7100 is a member of the UCD7K family of digital control compatible drivers for applications utilizing
digital control techniques, or applications requiring fast local peak current limit protection.
The UCD7100 is a low-side ±4-A high-current MOSFET gate driver. The UCD7100 allows digital power
controllers such as the UCD9110 or UCD9501 to interface to the power stage in single-ended topologies. It
provides a cycle-by-cycle current limit function with programmable threshold and a digital output current limit
flag, which can be monitored by the host controller. With a fast 25-ns cycle-by-cycle current limit protection,
the driver can turn off the power stage in the unlikely event that the digital system cannot respond to a failure
situation in time.
9.2 Functional Block Diagram
14 PVDD
VDD 1
13 PVDD
3V3 Regulator
&
Reference
UVLO
11 OUT
IN 2
3V3 3
10 PGND
AGND 4
25 mV
Q SD
Q
+
9
PGND
8
CS
+
CLF 5
12 OUT
R
ILIM 6
N/C 7
9.3 Feature Description
9.3.1 Input
The IN pin is a high impedance digital input capable of accepting 3.3-V logic level signals up to 2 MHz. There is
an internal Schmitt Trigger comparator which isolates the internal circuitry from any external noise.
If limiting the rise or fall times to the power device is desired, then an external resistance can be added between
the output of the driver and the load device, which is generally a power MOSFET gate. The external resistor may
also help remove power dissipation from the package.
9.3.2 Current Sensing and Protection
A very fast current limit comparator connected to the CS pin is used to protect the power stage by implementing
cycle-by-cycle current limiting.
The current limit threshold is equal to the lesser of the positive inputs at the current limit comparator. The current
limit threshold can be set to any value between 0.25 V and 1.0 V by applying the desired threshold voltage to the
current limit (ILIM) pin. When the CS level is greater than the ILIM voltage minus 25 mV, the output of the driver
is forced low and the current limit flag (CLF) is set high. The CLF signal is latched high until the UCD7K device
receives the next rising edge on the IN pin.
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When the CS voltage is below ILIM, the driver output will follow the PWM input. The CLF digital output flag
can be monitored by the host controller to determine when a current limit event occurs and to then apply the
appropriate algorithm to obtain the desired current limit profile.
One of the main benefits of this local protection feature is that the UCD7K devices can protect the power stage
if the software code in the digital controller becomes corrupted and hangs up. If the controller’s PWM output
stays high, the local current sense circuit will turn off the driver output when an over-current condition occurs.
The system would likely go into a retry mode because; most DSP and microcontrollers have on-board watchdog,
brown-out, and other supervisory peripherals to restart the device in the event that it is not operating properly.
But these peripherals typically do not react fast enough to save the power stage. The UCD7K’s local current limit
comparator provides the required fast protection for the power stage.
The CS threshold is 25 mV below the ILIM voltage. This way, if the user attempts to command zero current
(ILIM < 25 mV) while the CS pin is at ground, for example at start-up, the CLF flag latches high until the IN
pin receives a pulse. At start-up it is necessary to ensure that the ILIM pin always greater than the CS pin for
the handshaking to work as described below. If for any reason the CS pin comes to within 25 mV of the ILIM
pin during start-up, then the CLF flag is latched high and the digital controller must poll the UCD7K device,
by sending it a narrow IN pulse. If the fault condition is not present the IN pulse resets the CLF signal to low
indicating that the UCD7K device is ready to process power pulses.
9.3.3 Handshaking
The UCD7K family of devices have a built-in handshaking feature to facilitate efficient start-up of the digitally
controlled power supply. At start-up the CLF flag is held high until all the internal and external supply voltages
of the UCD7K device are within their operating range. Once the supply voltages are within acceptable limits, the
CLF goes low and the device will process input drive signals. The micro-controller should monitor the CLF flag at
start-up and wait for the CLF flag to go LOW before sending power pulses to the UCD7K device.
9.3.4 Driver Output
The high-current output stage of the UCD7K device family is capable of supplying ±4-A peak current pulses and
swings to both VDD and GND. The driver outputs follows the state of the IN pin provided that the VDD and 3V3
voltages are above their respective under-voltage lockout threshold.
The drive output utilizes Texas Instruments’ TrueDrive™ architecture, which delivers rated current into the gate
of a MOSFET when it is most needed during the Miller plateau region of the switching transition providing
efficiency gains.
TrueDrive™ consists of pullup/ pulldown circuits using bipolar and MOSFET transistors in parallel. The peak
output current rating is the combined current from the bipolar and MOSFET transistors. The output resistance is
the RDS(on) of the MOSFET transistor when the voltage on the driver output is less than the saturation voltage of
the bipolar transistor. This hybrid output stage also allows efficient current sourcing at low supply voltages.
Each output stage also provides a very low impedance to overshoot and undershoot due to the body diode of
the external MOSFET. This means that in many cases, external-schottky-clamp diodes are not required.
9.3.5 Source/Sink Capabilities During Miller Plateau
Large power MOSFETs present a large load to the control circuitry. Proper drive is required for efficient, reliable
operation. The UCD7K drivers have been optimized to provide maximum drive to a power MOSFET during
the Miller plateau region of the switching transition. This interval occurs while the drain voltage is swinging
between the voltage levels dictated by the power topology, requiring the charging/discharging of the drain-gate
capacitance with current supplied or removed by the driver device. See Reference [1]
9.3.6 Drive Current and Power Requirements
The UCD7K family of drivers can deliver high current into a MOSFET gate for a period of several hundred
nanoseconds. High peak current is required to turn the device ON quickly. Then, to turn the device OFF, the
driver is required to sink a similar amount of current to ground. This repeats at the operating frequency of the
power device. A MOSFET is used in this discussion because it is the most common type of switching device
used in high frequency power conversion equipment.
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Reference [1] discusses the current required to drive a power MOSFET and other capacitive-input switching
devices.
When a driver device is tested with a discrete, capacitive load it is a fairly simple matter to calculate the power
that is required from the bias supply. The energy that must be transferred from the bias supply to charge the
capacitor is given by:
E+1
2
CV2
(1)
where C is the load capacitor and V is the bias voltage feeding the driver.
There is an equal amount of energy transferred to ground when the capacitor is discharged. This leads to a
power loss given by the following:
P+1
2
CV2
f
(2)
where f is the switching frequency.
This power is dissipated in the resistive elements of the circuit. Thus, with no external resistor between the
driver and gate, this power is dissipated inside the driver. Half of the total power is dissipated when the capacitor
is charged, and the other half is dissipated when the capacitor is discharged. An actual example using the
conditions of the previous gate drive waveform should help clarify this.
With VDD = 12 V, CLOAD = 10 nF, and f = 300 kHz, the power loss can be calculated as:
P + 10 nF
122
300 kHz + 0.432 W
(3)
With a 12-V supply, this would equate to a current of:
I + P + 0.432 W + 0.036 A
V
12 V
(4)
The actual current measured from the supply was 0.037 A, and is very close to the predicted value. But, the
IDD current that is due to the device internal consumption should be considered. With no load the device current
drawn is 0.0027 A. Under this condition the output rise and fall times are faster than with a load. This could
lead to an almost insignificant, yet measurable current due to cross-conduction in the output stages of the driver.
However, these small current differences are buried in the high frequency switching spikes, and are beyond
the measurement capabilities of a basic lab setup. The measured current with 10-nF load is close to the value
expected.
The switching load presented by a power MOSFET can be converted to an equivalent capacitance by examining
the gate charge required to switch the device. This gate charge includes the effects of the input capacitance plus
the added charge needed to swing the drain of the device between the ON and OFF states. Most manufacturers
provide specifications that provide the typical and maximum gate charge, in nC, to switch the device under
specified conditions. Using the gate charge QG, one can determine the power that must be dissipated when
charging a capacitor. This is done by using the equivalence QG = CEFF x V to provide the following equation for
power:
P+C
V2
f + QG
V
f
(5)
This equation allows a power designer to calculate the bias power required to drive a specific MOSFET gate at a
specific bias voltage.
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Note
The 10% and 90% thresholds depict the dynamics of the bipolar output devices that dominate the
power MOSFET transition through the Miller regions of operation.
9.4 Device Functional Modes
9.4.1 Operation with VDD < 4.25 V (minimum VDD)
The devices operate with VDD voltages above 4.75 V. The maximum UVLO voltage is 4.75 V, and operates at
VDD voltages above 4.75 V. The typical UVLO voltage is 4.5 V. The minimum UVLO voltage is 4.25 V. At VDD
below the actual UVLO voltage, the devices do not operate, and OUT remains low.
9.4.2 Operation with IN Pin Open
If the IN pin is disconnected (open), a 100 kΩ internal resistor connects IN to GND to prevent unpredictable
operation due to a floating IN pin, and OUT remains low.
9.4.3 Operation with ILIM Pin Open
If the ILIM pin is disconnected (open), the current limit threshold is set at 0.5 V.
9.4.4 Operation with ILIM Pin High
If the signal on ILIM pin is higher than 1 V, the current limit threshold is clamped at 1 V.
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10 Application and Implementation
Note
Information in the following applications sections is not part of the TI component specification,
and TI does not warrant its accuracy or completeness. TI’s customers are responsible for
determining suitability of components for their purposes, as well as validating and testing their design
implementation to confirm system functionality.
10.1 Application Information
The UCD7100 is part of a family of digital compatible drivers targeting applications utilizing digital control
techniques or applications that require local fast peak current limit protection.
10.2 Typical Application
VIN
VOUT
Bias
Winding
Digital Controller
AN1
AGND
UCD7100PWP
VDD
3
3V3
PWMA
2
IN
INT
5
CLF
PWMB
VDD 14
OUT 12
6 ILIM
CS 8
4 AGND
Communication
2
AN2
AN3
Isolation
Amplifier
Figure 10-1. Typical Application
10.2.1 Design Requirements
In this design example, the UCD7100 is used to drive a forward converter which is controlled by a digital
controller. The switching frequency is 100 KHz, and the input current cycle-by-cycle protection threshold is set at
5 A.
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10.2.2 Detailed Design Procedure
The cycle-by-cycle current protection is implemented by connecting the current sense signal to the CS pin.
When the CS level is greater than the ILIM voltage minus 25 mV, the output of the driver is forced low and the
current limit flag (CLF) is set high. The CLF signal is latched high until the UCD7K device receives the next rising
edge on the IN pin.
(6)
(7)
The current limit threshold can be set to any value between 0.25 V and 1.0 V, so Rsense must be between 0.045
Ω and 0.195 Ω. For example, if Rsense is 0.15 Ω, then VILIM must be 0.775 V to protect input current at 5 A. If
the digital controller has an internal digital-to-analog converter, then it can generate 0.775 V and connect to ILIM
directly. For a digital controller without an internal digital-to-analog converter, it can generate a PWM signal, send
the PWM signal through a low pass filter, then connect to the ILIM pin. Assuming the magnitude of the PWM
pulse is 3.3 V, then the duty cycle is:
(8)
Output Voltage − 2 V/div
10.2.3 Application Curve
t − Time − 40 ns/div
Figure 10-2. Output Rise and Fall Time (VDD = 12 V, CLOAD = 10 NF)
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11 Power Supply Recommendations
11.1 Supply
The UCD7K devices accept an input range of 4.5 V to 15 V. The device has an internal precision linear regulator
that produces the 3V3 output from this VDD input. A separate pin, PVDD, not connected internally to the VDD
supply rail provides power for the output drivers. In all applications the same bus voltage supplies the two pins. It
is recommended that a low value of resistance be placed between the two pins so that the local capacitance on
each pin forms low pass filters to attenuate any switching noise that may be on the bus.
Although quiescent VDD current is low, total supply current will be higher, depending on the gate drive output
current required by the switching frequency. Total VDD current is the sum of quiescent VDD current and the
average OUT current. Knowing the operating frequency and the MOSFET gate charge (QG), average OUT
current can be calculated from:
IOUT = QG x f, where f is frequency.
For high-speed circuit performance, a VDD bypass capacitor is recommended to prevent noise problems. A
4.7-µF ceramic capacitor should be located close to the VDD to ground connection. A larger capacitor with
relatively low ESR should be connected to the PVDD pin, to help deliver the high current peaks to the load. The
capacitors should present a low impedance characteristic for the expected current levels in the driver application.
The use of surface mount components for all bypass capacitors is highly recommended.
11.2 Reference and External Bias Supply
All devices in the UCD7K family are capable of supplying a regulated 3.3-V rail to power various types of
external loads such as a microcontroller or an ASIC. The onboard linear voltage regulator is capable of sourcing
up to 10 mA of current. For normal operation, place a minimum of 0.22 µF of ceramic capacitance from the
reference pin to ground.
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12 Layout
12.1 Layout Guidelines
In a power driver operating at high frequency, it is a significant challenge to get clean waveforms without much
overshoot/undershoot and ringing. The low output impedance of these drivers produces waveforms with high
di/dt. This tends to induce ringing in the parasitic inductances. Utmost care must be used in the circuit layout.
It is advantageous to connect the driver IC as close as possible to the leads. The driver device layout has the
analog ground on the opposite side of the output, so the ground should be connected to the bypass capacitors
and the load with copper trace as wide as possible. These connections should also be made with a small
enclosed loop area to minimize the inductance.
12.2 Layout Example
VIN
VOUT
Bias Supply
Bias
Winding
UCD7100PWP
1 VDD
3 3V3
1
VDS
2
UCD91xx
with
CLA
Peripheral
PVDD 14
VDS
PVDD 13
IN
2
4 AGND
5 CLF
CS
OUT 12
OUT 11
6 ILIM
FB
7
NC
PGND 10
PGND 9
2
CS 8
CS
COMMUNICATION
(Programming & Status Reporting)
2
Isolation
Amplifier
Figure 12-1. Isolated Forward Converter
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~
VAC
−
+
~
Bias
Supply
VOUT
UCD7100PWP
1
VDD
3 3V3
Signal
Conditioning
Amplifier
UCD9501
Digital
Controller
PFC_ISENSE
VDS
PVDD 14
VDS
PVDD 13
2 IN
4 AGND
OUT 12
OUT 11
CS
5 CLF
FB
6 ILIM
PGND 10
PGND 9
7 NC
CS 8
CS
COMMUNICATION
(Programming & Status Reporting)
Signal
Conditioning
Amplifier
Figure 12-2. PFC Boost Front-End Power Supply
12.3 Thermal Considerations
The useful range of a driver is greatly affected by the drive power requirements of the load and the thermal
characteristics of the device package. In order for a power driver to be useful over a particular temperature range
the package must allow for the efficient removal of the heat produced while keeping the junction temperature
within rated limits. The UCD7K family of drivers is available in PowerPAD™ TSSOP package to cover a range
of application requirements. Both have the exposed pads to relieve thermal dissipation from the semiconductor
junction.
As illustrated in Reference [2], the PowerPAD™ packages offer a leadframe die pad that is exposed at the
base of the package. This pad is soldered to the copper on the PC board (PCB) directly underneath the device
package, reducing the ΘJC down to 4.7°C/W. The PC board must be designed with thermal lands and thermal
vias to complete the heat removal subsystem, as summarized in Reference [3].
Note that the PowerPAD™ is not directly connected to any leads of the package. However, it is electrically and
thermally connected to the substrate which is the ground of the device.
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13 Device and Documentation Support
13.1 Device Support
13.1.1 Development Support
PRODUCT
(1)
(2)
DESCRIPTION
FEATURES
UCD7201
Dual Low Side ±4-A Drivers with Common CS
3V3, CS(1) (2)
UCD7230
±4A Synchronous Buck Driver with CS
3V3, CS(1) (2)
3V3 = 3.3V linear regulator.
CS = current sense and current limit function.
13.2 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
13.3 Documentation Support
13.3.1 Related Documentation
1. Texas Instruments, Power Supply Seminar SEM−1400 Topic 2: Design And Application Guide For High
Speed MOSFET Gate Drive Circuits, by Laszlo Balogh
2. Texas Instruments, Technical Brief, PowerPad Thermally Enhanced Package
3. Texas Instruments, Application Brief, PowerPAD Made Easy
13.4 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. Click on
Subscribe to updates to register and receive a weekly digest of any product information that has changed. For
change details, review the revision history included in any revised document.
13.5 Support Resources
TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight
from the experts. Search existing answers or ask your own question to get the quick design help you need.
Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do
not necessarily reflect TI's views; see TI's Terms of Use.
13.6 Trademarks
TrueDrive™ and PowerPAD™ are trademarks of Texas Instruments.
TI E2E™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
13.7 Glossary
TI Glossary
This glossary lists and explains terms, acronyms, and definitions.
13.8 Electrostatic Discharge Caution
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.
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14 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
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PACKAGE OPTION ADDENDUM
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9-Dec-2021
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
UCD7100APWP
ACTIVE
HTSSOP
PWP
14
90
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 105
UCD7100
UCD7100APWPR
ACTIVE
HTSSOP
PWP
14
2000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 105
UCD7100
UCD7100PWP
ACTIVE
HTSSOP
PWP
14
90
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 105
UCD7100
UCD7100PWPR
ACTIVE
HTSSOP
PWP
14
2000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 105
UCD7100
UCD7100PWPRG4
ACTIVE
HTSSOP
PWP
14
2000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 105
UCD7100
(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)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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