A new commercial-off-the-shelf (COTS) gate driver designed to drive both the high-side and the low-side enhancement-mode GaN FETs, National Semiconductor's type LM5113, was evaluated for operation at temperatures beyond its recommended specified limits of -40 C to +125 C. The effects of limited thermal cycling under the extended test temperature, which ranged from -194 C to +150 C, on the operation of this chip as well as restart capability at the extreme cryogenic and hot temperatures were also investigated. The driver circuit was able to maintain good operation throughout the entire test regime between -194 C and +150 C without undergoing any major changes in its outputs signals and characteristics. The limited thermal cycling performed on the device also had no effect on its performance, and the driver chip was able to successfully restart at each of the extreme temperatures of -194 C and +150 C. The plastic packaging of this device was also not affected by either the short extreme temperature exposure or the limited thermal cycling. These preliminary results indicate that this new commercial-off-the-shelf (COTS) halfbridge eGaN FET driver integrated circuit has the potential for use in space exploration missions under extreme temperature environments. Further testing is planned under long-term cycling to assess the reliability of these parts and to determine their suitability for extended use in the harsh environments of space

Hammoud, Ahmad

Patterson, Richard

NASA Technical Reports Server

 1
December 2011 
 
NASA Electronic Parts and Packaging Program 
 
Operation of a New Half-Bridge Gate Driver for Enhancement-
Mode GaN FETs, Type LM5113, Over a Wide Temperature Range 
 
Richard Patterson, NASA Glenn Research Center 
Ahmad Hammoud, ASRC Corporation / NASA GRC 
 
Scope 
 
Semiconductor devices based on wide-bandgap materials, such as gallium nitride (GaN), 
are becoming more readily available as this enabling technology begins to mature, largely 
due to advancement in the manufacturing process by maximizing yield and reducing 
defects at the wafer level, ability to grow GaN structures on silicon substrates, and 
reduced production cost.  The low on-resistance of wide-bandgap materials allows the 
development of a new generation of transistor devices that switch faster and with much 
reduced losses [1].  The combined higher switching speed and efficiency of GaN 
transistors, for example, allows the operation of DC/DC converters at very high 
frequencies, thereby reducing weight, saving board space, and conserving power.  
Because of the high switching frequencies, circuits populated with GaN switches, 
particularly the enhancement-mode field-effect transistor (eGaN FET), are sensitive to 
layout [1].  In addition, the gate construction of the normally-off eGaN device limits the 
range of the gate voltage that can be applied without damaging the device.  While a 
typical gate voltage for eGaN FET is around 4.5 to 5.5 V, it is not recommended to 
exceed a 6-V level [2]. 
 
A new commercial-off-the-shelf (COTS) gate driver designed to drive both the high-side 
and the low-side enhancement-mode GaN FETs in a synchronous buck or a half bridge 
configuration was released by National Semiconductor Corporation.  This 5A, 100V, 
LM5113 device can operate up to several MHz with low power consumption [3].  The 
high-side bias voltage is generated using a bootstrap technique and is internally clamped 
at 5V, which prevents the gate voltage from exceeding the maximum gate-source voltage 
rating of eGaN FETs [3].  The device is offered in a standard LLP-10 pin package, which 
contains an exposed pad to aid power dissipation, and is rated for -40 °C to +125 °C 
junction temperature range.  Table I shows some of the device manufacturer’s 
specifications [3]. 
 
The operation of the half-bridge LM5113 driver was investigated over a wide 
temperature regime that extended beyond its specified range.  The driver was evaluated 
using the circuit configuration shown in Figure 1 with some modifications.  These 
included the omission of the pull-up and pull-down resistors, which are optional for 
elimination of undesired spikes and reducing ringing and over-shoot, no load was 
applied, and VHS was tied to VSS at 0V.  These were similar to the test conditions reported 
in the datasheet of the device.  A switching frequency of 200 kHz was used.  
 
https://ntrs.nasa.gov/search.jsp?R=20120002771 2019-08-30T19:12:19+00:00Z
 2
Table I.  Specifications of LM5113 half-bridge driver chip [1]. 
 
Parameter Symbol 
   
Digital Supply Voltage (V) VDD +4.5 to +5.5 
Operating Current (mA) IDDO 1 
High Side Floating Voltage (V) VHS 0 to 100 
Source/Sink Current (A) IO 1 to 3 
Operating Temperature (°C) T(oper) -40 to +125 
Low Side Turn-On Propagation Delay (ns) tLPLH 30 
High Side Turn-On Propagation Delay (ns) tHPLH 30 
Output Rise Time (ns) tr 4 
Output Fall Time (ns) tf 4 
Part #  LM5113SDE 
Package  LLP-10 (4mmx4mm)
Lot Number  M1118 
 
The driver chip was characterized in terms of its high-side gate drive output (HO), low-
side gate drive output (LO), outputs rise time, fall time, and turn-on delay time at specific 
test temperatures.  The propagation delay times included tLPLH (LI Rising to LO Rising) 
and tHPLH (HI Rising to HO Rising).  The rise and fall times of the driver output signals as 
well as the supply current were also recorded.  The operational characteristics of the drive 
circuit were obtained over the test temperature range between -194 °C and +150 C using 
a liquid nitrogen-cooled environmental chamber.  Re-restart capability of the circuit at 
extreme temperatures, i.e. power switched on while the driver chip was soaking at 
extreme (hot or cold) temperature, was also investigated.  In addition, the effects of 
limited thermal cycling on the operation of the driver were determined by exposing it to a 
total of 12 cycles between -194 C and +150 C at a temperature rate of 10 C/minute.  
Following the thermal cycling, circuit measurements were then performed at the test 
temperatures of +23, -194, and +150C using a soak time of at least 30 minutes at these 
test temperatures.  Figure 2 shows the half-bridge driver chip mounted on a circuit board 
along with the ceramic bootstrap and decoupling capacitors. 
 
 
 
Figure 1.  Schematic of test circuit of the LM5113 half-bridge driver [3]. 
-
 3
 
 
Figure 2.  LM5113 half-bridge driver and ceramic capacitors mounted on test board. 
 
Test Results 
 
Temperature Effects 
 
Waveforms of the LM5113 low-side driver (LO) and the high-side driver (HO) output 
signals along with the input signals for the low-side (LI) and high-side (HI) drives 
recorded at room temperature are shown in Figure 3.  The operation of the circuit was 
examined, as mentioned earlier, over a wide temperature range and signal waveforms 
were also obtained at the test points of +50, +75, +100, +125, +130, +140, +145, +150, 0, 
-25, -50, -75, -100, -125, -150, -175, -190, and -194 °C.  The circuit maintained proper 
operation and no major change was observed in the shape or magnitude of these 
waveforms as test temperature was changed throughout the range of -194 °C to +150 °C.  
For illustrative purposes, therefore, only waveforms obtained at the extreme temperatures 
of -194 °C and +150 °C are also presented here as shown in Figures 4 and 5, respectively. 
 
 
 
Figure 3.  HI (trace 1), HO (trace 2), LI (trace 3), and LO (trace 4) signals at +23°C. 
(Scale: Vertical 5V/div; Horizontal 2μs/div, for all signals) 
 
 4
 
 
Figure 4.  HI (trace 1), HO (trace 2), LI (trace 3), and LO (trace 4) signals at -194°C. 
(Scale: Vertical 5V/div; Horizontal 2μs/div, for all signals) 
 
 
 
Figure 5.  HI (trace 1), HO (trace 2), LI (trace 3), and LO (trace 4) signals at +150°C. 
(Scale: Vertical 5V/div; Horizontal 2μs/div, for all signals) 
 
Figure 6 shows the turn-on propagation delay time tLPLH for the low-side drive (LI rising 
to LO rising) and the turn-on propagation delay time tHPLH for the high-side drive (HI 
rising to HO rising) of the half-bridge driver as a function of temperature.  It can be seen 
that both drives, at any given test temperature, displayed comparable values in their turn-
on propagation delay time.  Similar trend was also observed in the these attributes with 
change in temperature as the propagation delay time, for either drive, exhibited gradual 
but slight increase as the test conditions varied from cryogenic to high temperature, as 
depicted in Figure 6.  This increase amounted to little over doubling-up in the turn-on 
propagation delay time values as temperature was raised from -194 °C to + 150 °C. 
 
 5
Temperature (°C)
-200 -150 -100 -50 0 50 100 150 200
Pr
op
ag
at
io
n 
D
el
ay
 T
im
e,
 t L
PL
H
 (n
s)
Pr
op
ag
at
io
n 
D
el
ay
 T
im
e,
 t L
PL
H
 (n
s)
0
20
40
60
80
100
Pr
op
ag
at
io
n 
D
el
ay
 T
im
e,
 t H
PL
H
 (n
s)
Pr
op
ag
at
io
n 
D
el
ay
 T
im
e,
 t H
PL
H
 (n
s)
0
20
40
60
80
100
 
Figure 6. Turn-on propagation delay times, tLPLH and tHPLH, as a function of temperature. 
 
The rise and fall time times of the output signal of the low-side driver are shown in 
Figure 7 as a function of temperature.  Little effect of temperature was found on these 
characteristics of the driver as their values held almost a steady value throughout the test 
temperature range.  Similar behavior was observed for these properties of the other drive, 
i.e. high-side, as shown in Figure 8. 
 
Temperature (ºC)
-200 -150 -100 -50 0 50 100 150 200
R
ise
 &
 F
al
l T
im
e 
(n
s)
0
2
4
6
8
10
Rise Time
Fall Time
LO signal
 
 
Figure 7. Rise and fall times of low-side driver output signal (LO) versus temperature. 
 6
Temperature (ºC)
-200 -150 -100 -50 0 50 100 150 200
R
is
e 
&
 F
al
l T
im
e 
(n
s)
0
2
4
6
8
10
Rise Time
Fall Time
HO signal
 
 
Figure 8.  Rise and fall times of high-side driver output signal (HO) versus temperature. 
 
The input current of the driver chip showed some modest dependency on temperature 
mostly in the cryogenic region, as shown in Figure 9.  While the current did not undergo 
any significant change when test temperature increased from room to +150 °C, it 
exhibited gradual decrease as temperature was decreased below 23 °C.  As illustrated in 
Figure 9, the current dropped from 0.72 mA at 23 °C to 0.5 mA at -194 °C. 
 
Temperature (°C)
-200 -150 -100 -50 0 50 100 150 200
Su
pp
ly
 C
ur
re
nt
 (m
A
)
Su
pp
ly
 C
ur
re
nt
 (m
A
)
0.0
0.2
0.4
0.6
0.8
1.0
 
 
Figure 9. Supply current of the LM5113 driver as a function of temperature. 
 7
Restart at Extreme Temperatures 
 
Restart capability of the LM5113 half-bridge driver chip at extreme temperatures was 
also investigated by allowing the device to soak for at least 30 minutes at each of the test 
temperatures of -194 °C and +150 °C without electrical bias.  Power was then applied to 
the driver circuit, and measurements were taken on the output characteristics.  The driver 
chip was able to successfully restart at both extreme temperatures and the results obtained 
were the same as those attained earlier for both temperatures. 
 
Effects of Limited Thermal Cycling 
 
The effects of limited thermal cycling under a wide temperature range on the operation of 
the LM5113 eGaN FET half-bridge driver IC chip were investigated by subjecting it to a 
total of 12 cycles between -194 °C and +150 °C at a temperature rate of 10 °C/minute.  A 
dwell time of 15 minutes was applied at the extreme temperatures.  Following cycling, 
measurements of the investigated parameters were taken again as a function of 
temperature.  A comparison of the input and output signals of both the low-side and high-
side drivers at the selected test temperatures of +23, -194, and +150 °C for pre - and post-
cycling conditions are shown in Figure 10.  It can be clearly seen that the post-cycling 
signal waveforms at any given test temperature were the same as those obtained prior to 
cycling.  Similarly, no significant changes were registered between the pre- and post-
cycling values of the circuit’s propagation delay times, switching characteristics, and the 
current, as depicted in Table II at the selected three test temperatures.  Based on this 
preliminary investigation it, therefore, can be concluded that the extreme temperature 
exposure and the limited thermal cycling did not induce much change in the behavior of 
this half-bridge driver integrated circuit chip.  This limited thermal cycling also appeared 
to have no effect on the structural integrity of this device as no structural deterioration or 
packaging damage was observed. 
 
Table II.  Pre- & post-cycling propagation delays, switching times, & input current. 
 
 Delay Time 
tLPLH  (ns) 
Delay Time 
tHPLH (ns) 
LO Signal HO Signal Input Current 
(mA) tr (ns) tf (ns) tr (ns) tf (ns) 
Temp (°C) Prior Post Prior Post Prior Post Prior Post Prior Post 
+23 33 34 35 36 2.67 2.89 2.86 2.81 0.72 0.73 
-194 21 20 22 22 2.40 2.83 2.59 2.63 0.50 0.50 
+150 47 47 48 48 2.61 3.08 2.76 2.72 0.76 0.76 
 
Long-Term Thermal Cycling 
 
Although this work provided some insight on the capability of this driver chip to operate 
in temperature zones that extended beyond its specified low and high temperature limits 
without impact on its performance as well as surviving exposure to limited cycling under 
a very wide temperature range, these preliminary results are not sufficient to address its 
reliability for inclusion in systems designed for space use.  Extensive long-term thermal 
cycling and other test criteria need to be carried out so that the reliability of such a device 
can be determined.  A test plan is currently underway to perform long-term thermal 
cycling that adheres to NASA and/or military standards. 
 8
 
 
 
Pre-cycling @ 23 °C 
 
 
 
 
Pre-cycling @ -194 °C 
 
 
 
 
Pre-cycling @ +150 °C
 
 
Post-cycling @ 23 °C 
 
 
 
 
Post-cycling -194 °C 
 
 
 
 
Post-cycling @ +150 °C
Figure 10.  Pre- & post-cycling waveforms of HI (trace 1), HO (trace 2), LI (trace 3), and 
LO (trace 4) signals of LM5113 half-bridge driver at selected temperatures. 
 9
Conclusions 
 
A new commercial-off-the-shelf (COTS) gate driver designed to drive both the high-side 
and the low-side enhancement-mode GaN FETs, National Semiconductor’s type 
LM5113, was evaluated for operation at temperatures beyond its recommended specified 
limits of -40 °C to +125 °C.  The effects of limited thermal cycling under the extended 
test temperature, which ranged from -194 °C to +150 °C, on the operation of this chip as 
well as restart capability at the extreme cryogenic and hot temperatures were also 
investigated.  The driver circuit was able to maintain good operation throughout the entire 
test regime between -194 °C and +150 °C without undergoing any major changes in its 
outputs signals and characteristics.  The limited thermal cycling performed on the device 
also had no effect on its performance, and the driver chip was able to successfully restart 
at each of the extreme temperatures of -194 °C and +150 °C.  The plastic packaging of 
this device was also not affected by either the short extreme temperature exposure or the 
limited thermal cycling. 
 
These preliminary results indicate that this new commercial-off-the-shelf (COTS) half-
bridge eGaN FET driver integrated circuit has the potential for use in space exploration 
missions under extreme temperature environments.  Further testing is planned under 
long-term cycling to assess the reliability of these parts and to determine their suitability 
for extended use in the harsh environments of space. 
 
References 
 
[1]. Paul O’Shea, “Enhancement-Mode GaN Aims at the Future, Now – Product of 
the Year; the Story Behind the Story,” Electronic Products Magazine, p8, 
November 2011.  http://www2.electronicproducts.com/ 
 
[2]. Margery Conner, “GaN and SiC: On Track for Speed and Efficiency,” EDN 
Magazine, pp 33-39, August 25, 2011.  http://www.edn.com 
 
[3]. National Semiconductor “LM5113 5A, 100V Half-Bridge Gate Driver for 
Enhancement Mode GaN FETs” Data Sheet, Preliminary 301629, June 29, 2011. 
http://www.national.com 
 
Acknowledgements 
 
This work was performed at the NASA Glenn Research Center under GESS-2 Contract # 
NNC06BA07B.  Funding was provided from the NASA Electronic Parts and Packaging 
(NEPP) Program Task “Reliability of SiGe, SOI, and Advanced Mixed Signal Devices 
for Cryogenic Power Electronics”. 


Operation of a New Half-Bridge Gate Driver for Enhancement - Mode GaN FETs, Type LM5113, Over a Wide Temperature Range

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