Renesas HIP2103-4DEMO1Z User Manual

USER’S MANUAL

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HIP2103-4DEMO1Z

HIP2103/HIP2104, 3-phase, Full, or Half Bridge Motor Drive

Introduction

The HIP2103-4DEMO1Z is a general purpose motor drive with
a microprocessor controller. Three motor drive topologies are
supported: 3-phase for BLDC motors, and full and half bridge
for conventional brushed DC motors. Hall effect rotor position
sensors are used to control the switching sequence of the
BLDC topology (not required for the brushed DC motors).

The operating bridge voltage can vary between 13V and 50V
and the maximum motor current is 20A (with sufficient air
flow). This motor drive can be used as a design reference for
multiple applications including e-bikes, battery powered tools,
electric power steering, wheel chairs, or any other application
where a brushed or brushless DC motors are utilized. Because
this demonstration board is primarily intended to highlight the
application of the HIP2103 and HIP2104 3-phase MOSFET
drivers with no specific motor targeted, the control features
are limited to simple functions such as start/stop, reverse
rotation, and braking. Open loop speed control is
implemented. More advanced control features such as torque
control, speed regulation and regenerative braking are not
implemented because these methods require close
integration with the characteristics of the motor load
dynamics.

implementation of the HIP2103 and HIP2104 drivers including
recommended support circuits.

Also covered is the design method of the bipolar current
sensing feature. Presently, current sensing on this demo board
is used only for pulse-by-pulse current limiting but an analog
signal proportional to the motor current is available on board
as a design reference.

The microcontroller firmware is also provided as a reference
but the only support offered by Intersil will be for bug
corrections and for adding more switching sequences. Please
refer to Microchip for details on the use of the PIC18F2431.

Physical Layout

The HIP2103-4DEMO1Z board is 90mm by 82.5mm. The
tallest component is a 470µF capacitor. The total height is
32mm with standoffs. The Hall effect rotor position sensor
inputs are miniature terminal blocks. The phase terminal
blocks are high current outputs rated for 20A.

AN1899

Rev 0.00

January 8, 2014

Important

Because Hall sensor switching logic sequences for BLDC
motors are not all the same, this demo board supports most, if
not all, variations of sequence logic. Please refer to the
sequence charts at the end of this application note to verify
that your desired sequence is implemented. If you require a
different sequence for your specific motor application or if you
need help identifying the correct switching sequence for your
specific motor, please contact Intersil prior to ordering this
demo board for possible support for a new switching
sequence.

Specifications

3-phase BLDC motor with Hall sensors
Full bridge for brushed DC motors

Motor topologies

Operating voltage range 13 - 50VDC

Maximum continuous
bridge current

Hall sensor bias voltage 3.3V, 15mA

PWM switching frequency ~20kHz

(bidirectional)
Half bridge for brushed DC motors
(unidirectional)

20A (with sufficient air flow)

Scope

This application note covers the design details of the
HIP2103-4DEMO1Z with a focus on the design

FIGURE 1. HIP2103-4DEMO1Z INPUTS AND OUTPUTS

The controller section is a daughter card which contains push
buttons for reset, brake, reverse, and start/stop functions. Also
on the controller card are dip switches for configuration, LEDs
for status, and a programming port. As an option, a customer
designed controller daughter card can be substituted for the
Intersil supplied controller.

The speed control section includes an on-board potentiometer
for speed control or an optional external potentiometer can be
connected to the signal terminal block.

The current sense section includes current amplifiers,
comparators, and current sense resistors.

AN1899 Rev 0.00 Page 1 of 24
January 8, 2014

HIP2103-4DEMO1Z

FIGURE 2. HIP2103-4DEMO1Z BLOCK DIAGRAM

HIP2103-4DEMO1Z REV. A

HIP2104

CONTROLLER

PUSH

BUTTONS

13-50V

3-PHASE

BRIDGE

ISL28246

CURRENT

LIMIT

AND

MONITOR

3

2

3

VDEN

SWITCH

HIP2103

Vcc
Vdd

6 2

2

2

2

2

4

3.3V

3

2

DIP

SWITCHES

8

LEDs

4

HIP2103

12V

VDen
VCen

VBAT

BLDC

MOTOR

Hall Bias

HALL INPUTS

2

DAUGHTER CARD

PROGRAM

PORT

2

SPEED

CONTROL

Bias supplies
are internal to
the HIP2104

The Hall inputs section is the terminal connections from the
BLDC motor for the hall sensors and the 3.3V bias for the
sensors.

The phase A, B, and C sections include the HIP2103/4 drivers,
bridge FETs, and power terminal connections for the motor.

For those customers who would like to modify the firmware of
the PIC18F2431 microcontroller, an RJ11 connector is provided
for easy connection with Microchip firmware development tools
(not provided or supported by Intersil).

Block Diagram

The HIP2103-4DEMO1Z is composed of seven major circuit
function illustrating the use of several Intersil products. The
following descriptions reference Figure 2.

Bias Supplies

Two bias supplies are required and are provided by one HIP2104
driver with internal linear regulators. The VCC output (3.3V) of the
HIP2104 provides the bias to the controller, Hall sensors, and
LEDs. The VDD output (12V) of the HIP2104 provides its own bias
for its driver portion and also to the other two HIP2103s (which
do not have internal regulators).

HIP2103 and HIP2104 Drivers

The one HIP2104 and the two HIP2103s are the featured Intersil
parts. Each driver’s outputs (HO and LO) are connected to a half

bridge pair of SiR662DP-T1-GE3 power FETS operating with a
PWM frequency of 20kHz. Associated with the HIP2103s and
HIP2104 are the necessary support circuits such as the
decoupling and boot capacitors.

Controller

The microcontroller is located on a daughter card to provide the
customer with the option to incorporate their own controller
design. The features on the controller daughter card are
configuration dip switches, status LEDs, a programming port,
and 4 push-buttons.

The Hall sensor inputs are decoded by the microcontroller to
provide the appropriate switching sequence signals to the 3
HIP2103/4s to drive the six bridge FETs that drive a 3-phase
BLDC motor. The SW5 dip switch is used to select the appropriate
switching sequence for the BLDC motor.

With appropriate setting to the SW6 dip switch, the motor driver
can be configured with a full bridge topology for bidirectional
control of a conventional brushed DC motor. A half bridge option
is also provided to drive a brushed DC motor without bidirectional
control. See Table 1 for more details on configuring SW6.

In addition to decoding the Hall sensors, the microcontroller
reads the push buttons to invoke the various operating functions
of the motor, and controls the status LEDs.

The microcontroller firmware is provided for reference but the
only support offered by Intersil will be for bug corrections and for

AN1899 Rev 0.00 Page 2 of 24
January 8, 2014

HIP2103-4DEMO1Z

adding more switching sequences. Firmware for this demo board
can be found on the Intersil website.

Speed Control

The on-board potentiometer (or an optional external pot) is
monitored by the microcontroller to provide a duty cycle to the
motor that is proportional to the tap voltage of the potentiometer
and varies between 0% and 100% duty cycle. This proportional
duty cycle is open loop and is independent of the bridge voltage.
Consequently, any motor voltage between 13V and 50V can be
used with this demo board.

The Speed push button on the control card is not implemented in
this design.

Current Sensing/Current Limit

Two Intersil low offset, dual op-amps (ISL28246) are used for
current monitoring and current limiting. One op-amp is
configured as a differential amplifier for Kelvin connections
across the current sensing resistor. The diff-amp is biased so that
zero motor current results with an output voltage that is 1/2 of
the +3.3V bias. Consequently, positive bridge currents results
with a current monitor signal that is greater than 1.65V (up to
~3.3V). Negative bridge currents (that occur with regenerative
braking) is less than 1.65V (down to a minimum of ~0V). This
“bipolar” analog signal can be monitored by the microcontroller
for purposes such as torque control and/or regenerative braking.

The output of the analog differential amplifier is also connected
to two op-amps configured as outside window comparators for
pulse-by-pulse current limits for either positive or negative bridge
currents. The OR’ed comparator outputs are sent to the
microcontroller for pulse by pulse current limiting.

3-phase Bridge

The 3-phase bridge is composed of six SiR662DP-T1-GE3 power
MOSFETS (60V, 60A). Each FET is driven by one of the six driver
outputs of the HIP2103/4 MOSFET drivers. The dead time
provided by the controller is 1µs which is sufficient for the default
hardware configuration of the HIP2103-4DEMO1Z.

Related Literature

• FN8276 60V, 1A/2A Peak, 1/2 Bridge Driver with 4V UVLO

• FN6321
Input-Output (RRIO) Op Amps

ISL28246, 5MHz, Single and Dual Rail-to-Rail

Setup and Operating Instructions

Required and Recommended Lab Equipment

• Lab supply or battery, 13V minimum to 50V maximum. The
current rating of the lab supply must have sufficient capacity
for the motor being tested. If a battery is the power source, it is
highly recommended that an appropriate fuse be used.

• Bench fan (likely not needed)

• Test motor (3-phase BLDC or conventional brushed DC motor)

• Multichannel oscilloscope, 100MHz or greater

• Current probe for oscilloscope.

•Multimeter

• Temperature probe (optional)

Caution: Although the HIP2103-4DEMO1Z has large heat
dissipating copper planes on the power FETS, if it is
operated for an extended period at high power levels, it may
be necessary to use a fan to keep the temperature of the
bridge FETs to less than 100°C as measured on the heat
sink plane. The HIP2104 has internal thermal protection
(150°C) but this may not be sufficient to protect the power
FETs from excessive temperature.

BLDC MOTOR SETUP (3-phase)

1. Connect the 3-phase motor leads to the MA, MB, and MC
terminal blocks. For high current applications, it is
recommended that both terminals of each block be used. It is
also recommended that during initial setup the motor not be
mechanically loaded.

2. Connect the HALL sensor leads of the motor to the HA, HB,
and HC terminals. The +V bias (3.3V) and GND leads must all
be connected.

3. Rotate the R13 potentiometer to the left (CCW) until it clicks.
This will set the starting voltage on the motor to a minimum.

4. Eight different 6 step hall logic sequences are supported by
the this demo board. Refer to Figures 14 and 15 to setup SW5
dip switch for the appropriate Hall logic.

5. The motor driver must also be configured for the required
motor topology (3-phase, full or half bridge). For the BLDC
motor, SW6:1 must be on and switches SW6:2, 3, 4 must be
off. Refer to Table 1 for complete configuration details for
SW6.

6. Ensure that the SW1 toggle switch is off. When this switch is
off, the bias supplies (VDD and VCC) of the HIP2104 are off
and consequently, the bridge FETs are also off.

7. With the lab supply turned off, connect the lab supply or the
battery to the BATT terminal block. If a battery is used, the
470µF filter capacitor across the bridge may cause a spark
when connecting to the terminal block.

Caution: Reverse polarity protection is not provided.

8. Ensure that the motor is securely mounted prior to proceeding
with the following steps.

Caution: Do not exceed the maximum rated RPM of your
motor.

AN1899 Rev 0.00 Page 3 of 24
January 8, 2014

HIP2103-4DEMO1Z

led1led3 led2

At initial turn on, leds will turn on and

off one at a time starting with led1

led4

led1led3 led2led4

SW6 is not configured corrrectly

led1led3 led2

While the motor is rotating, the RUN LED is blinking

RUNREVERSEBRAKE

led4

i LIMIT

led1led3 led2

RUNREVERSEBRAKE

led4

i LIMIT

led1led3 led2

RUNREVERSEBRAKE

led4

i LIMIT

led1led3 led2

RUNREVERSEBRAKE

led4

i LIMIT

led1led3 led2

RUNREVERSEBRAKE

led4

i LIMIT

9. Turn on the lab supply. Set SW1 (toggle switch) on. Observe
that the four LEDs turn on and off, one after another.

This initial flash of the LEDs indicates that power has been
applied. After the initial flash, all LEDs will be off. Operation
of the motor is now possible. If all four LEDs are flashing
simultaneously, SW6 is not configured correctly. Reconfigure
SW6 then turn off, then on, the toggle switch to restart.

10. Press the Start/Stop push button once. The RUN LED (led1)
will blink indicating that the motor has been started. The
motor at this point may not be rotating because minimal
voltage is being applied to the motor.

11. Slowly increase the voltage on the motor by rotating the
potentiometer, R13, to the right (CW). At some point the
motor will start to rotate slowly. The actual starting voltage is
dependent on the specific motor being used.

12. If the motor is vibrating back and forth instead of rotating, it
is possible that the Hall sensors or the motor leads were not
connected correctly. If the correct switching sequence has
been selected, all that should be necessary to correct this
misbehavior is to swap two of the motors lead (or to swap two
of the Hall sensor leads).

13. Continue to rotate the pot until the motor is running at a
moderate speed of roughly 25%. Do not run the motor with
maximum voltage until the setup check-out is completed.

14. Press again the START/STOP push button. The motor will free
wheel to a stop and the blinking led1 will turn off.

15. Press again the START/STOP button. The motor will
accelerate to the previous run speed (assuming that the
potentiometer was not rotated). The blinking led0 will also
turn on.

16. While the motor is running, press the REVERSE button. The
RUN LED (led1) will turn off and the REVERSE LED (led2) will
turn on without blinking. After a short pause while the motor
is freewheeling to a stop, the motor will restart rotating in the
opposite direction. The RUN LED will be blinking and the
REVERSE LED will continue to be on.

17. Press again the REVERSE button. As before, the motor will
stop. But this time the REVERSE LED will turn off. After a
pause, the motor will restart but this time rotating in the
forward direction.

18. While the motor is running, the motor can be hard braked by
pressing the BRAKE push button.

The BRAKE LED (led3) will be on without blinking. When the
motor is restarted, the BRAKE LED will turn off.

CAUTION: This braking method turns on simultaneously all of
the low side bridge FETs. This will force the motor to a very
rapid stop. It the motor is loaded, or if the motor is not
designed for a rapid stop, mechanical damage to the motor
or to the load can result. If you are not sure about using this
braking method, only apply the brake when the motor speed
is relatively slow.

19. If, while operating the motor turns off, and all 4 LEDs are
blinking, the current limit shut-down has been activated after
255 consecutive pulse-by-pulse current limits. This may
happen if the motor speed (with load) is accelerated too
quickly, or if there is a fault with the motor or connections, or if
the motor is stalled. The iLimit LED will turn on momentarily by
itself if the overcurrent duration is less than 255 pulse-by-pulse
current limits.

It is now safe to proceed with testing at higher power levels or
speeds.

DC Motor Setup (Full Bridge)

The HIP2103-4DEMO1Z can also be used to drive a conventional
brushed DC motor. The setup procedure is essentially the same
as the BLDC configuration except that Hall sensor inputs are not
used and only two motor connections are used, MB (TB4) and MC
(TB5). When configured in a full bridge topology, phase A (MA) is
disabled by setting the corresponding HIP2103 to sleep.

To setup the motor driver for a full bridge topology, set SW6:2 to
on and sw

itches SW6:0, 3, 4 to off. Refer to Table 1 for complete

configuration details for SW6.

As with the BLDC configuration, the motor rotation direction can
be controlled. But unlike the BLDC configuration, the motor can
be reversed even if it has not yet stopped rotating. Be cautious
when reversing the motor before it has stopped rotating.

The motor can also be braked by grounding both motor leads
similar to the BLDC motor.

DC Motor Setup (Half bridge)

The HIP2103-4DEMO1Z can also be used to drive a conventional
brushed DC motor with a half bridge Topology. The setup
procedure is essentially the same as the BLDC configuration
except that Hall sensor inputs are not used and only two motor
connections are used, MB (TB5) and the negative connection of

January 8, 2014

AN1899 Rev 0.00 Page 4 of 24

HIP2103-4DEMO1Z

BLDC

MOTOR

AHO

ALO BHO

BLO

CHO

CLO

000 100 110 111 011 000 100 110 111 011001 001

Hall Sensor Logic

HC

HB

HA

ZLP PLZ PZL ZPL LPZ LZP ZLP PLZ PZL ZPL LPZ LZP

MB

MA

MC

1 2 3 4 5 6 1 2 3 4 5 6

0060012001800240

0

Bridge State Logic: P=PWM, L=Low, Z=off

006001200180024000

0

Sequence Step numbers

Z

L

P

ZLP PLZ PZL ZPL LPZ LZP ZLP PLZ PZL ZPL LPZ LZP

MB

MA

MC

Bridge State Logic: P=PWM, L=Low, Z=off

idealized motor voltage waveforms

MC

MB

MA

+Vbat

-Vbat

~ ½ Vbat

20KHz PWM freq.

Motor rotation period

per pole

BATT (TB7). When configured in a half bridge topology, phase A
(MA) and phase B (MC) are disabled by configuring the
corresponding HIP2103s to sleep.

The half bridge topology cannot reverse the direction of the
motor.

To setup the motor driver for a half bridge topology, set SW6:1 to
on and SW6:2 to on. Refer to Table 1 for complete configuration
details for SW6.

TABLE 1. SW6 SETUP

SWITCH POSITION

4321

Motor

TOPOLOGY

Other settings (error) - - - -

3 PHASE off off off on

FULL BRIDGE off off on off

HALF BRIDGE off on off off

Factory test on off off off

Theory of Operation (3-Phase)

The HIP2103-4DEMO1Z demonstration board is a general
purpose 3-phase BLDC motor controller. Three half bridge power
circuits drive the motor as shown in Figure 3.

Three 6 step bridge state logic diagrams, illustrated in Figure 4,
are used to drive the motor. The bridge state logic diagrams
represents the logic status of the each half bridge but the actual
voltage applied to the motor appears much differently. Figure 5
illustrates the bridge status logic vs the actual voltage waveforms
applied to each motor lead.

FIGURE 3. BASIC BLDC MOTOR POWER TOPOLOGY

FIGURE 4. HALL SENSOR LOGIC vs BRIDGE STATE LOGIC

FIGURE 5. BRIDGE STATE LOGIC vs MOTOR VOLTAGE

AN1899 Rev 0.00 Page 5 of 24
January 8, 2014

HIP2103-4DEMO1Z

FIGURE 6. SEQUENCE STEPS 1 TO 3

N

N

S

S

N

S

N

S

N

S

N

S

N

S

N

S

S

S

N

N

2

P

Z

L

3

P

L

Z

N

S

N

S

N

S

N

S

N

S

N

S

N

S

N

S

HC
HB
HA

MB

MA

MC

1

2 3

HC
HB
HA

MB

MA

MC

HC
HB
HA

MB

MA

MC

L

L

L

P

P

P

Z

Z

Z

Z

ZPP L

L

1

Z L

neutral

P

Z

P

L

neutral neutral

neutralneutralneutral

neutralneutral neutral

neutral neutral neutral

The HIP2103-4DEMO1Z demo board has 6 gate drive outputs,
two per HIP2103/4 (HO and LO), to control the six bridge FETs
individually. If the gate drives for both FETs of one half bridge are
low, current will not flow in the corresponding motor lead (high
impedance or Hi-Z). If the gate drive for the low FET is high and
the gate drive for the high FET is low, then the phase node of that
half bridge, and the corresponding motor lead, is connected to
ground (Low). If the low and high gate drives are complementary
driven, the phase node is pulse width modulated (Pwm) to
control the average voltage on that motor lead.

The motor rotation period and the amplitude of the bridge
voltage waveforms are modified by the microcontroller to control
the speed of the motor. Pulse width modulation is used to modify
the amplitude of the voltage waveforms and the motor rotation
period is established by the rotor position hall sensors that signal
the controller to change the switching sequence. Typical hall
sensor logic is illustrated in Figure 4. Each hall logic diagram, HA,
HB, and HC, correspond respectively to the bridge state logic
diagrams, MA, MB, and MC. For example, the transition of the
hall sensor logic, from step 1 to 2, results with the drive
waveform transition of ZLP to PLZ where P, L, and Z define the
state of each half bridge.

Switching Sequence Phase Currents

The following motor winding diagrams illustrate how currents
flow in a 3-phase BLDC motor during each switching period of the
6 step voltage waveform. These diagrams are for a very simple
motor with only 6 stator poles. Most 3-phase motors have more
stator poles (multiples of 6) to reduce torque modulation
(cogging) but the principles of operation are the same.

Each phase winding is color coded and black arrows indicate the
direction of positive current in that winding for each step. As
described in Figure 6, the half bridge state of each motor lead,
MA, MB, or MC, is labeled with P, L, or Z. Observe that the active
coils are highlighted. The inactive coils (those with no current) are
white.

The dark gray structures are the permanent magnets that are
mounted on the light gray rotor. The bold black arrow is the flux
vector of the permanent magnets. The bold dark blue arrow is
the magnetic flux vector generated by the active coils for each
waveform step. The switching step occurs when these two
vectors are perpendicular for maximum torque. Notice how the
flux vectors are rotating counter clockwise, 60 degrees for each
step.

This tutorial for BLDC motors is very fundamental. For more
information about a specific motor, please contact the motor
manufacturer.

AN1899 Rev 0.00 Page 6 of 24
January 8, 2014

HIP2103-4DEMO1Z

FIGURE 7. SEQUENCE STEPS 4 TO 6

S

N

S

N

S

N

S

N

S

N

S

N

4

Z

L

P

5

L

Z

P

6

L

P

Z

S

S

N

N

N

N

S

S

S

N

S

N

N

S

N

S

N

S

N

S

N

S

N

S

64 5

HC
HB
HA

MB

MA

MC

HC
HB
HA

MB

MA

MC

HC
HB
HA

MB

MA

MC

L Z

P

LL

PP Z

Z

Z

Z

Z

P

PP

L

L

L

neutral neutral neutral

neutralneutralneutral

neutral neutral neutral

neutral neutral

neutral

HB

HO
LO

HS

VSS

Vdd
HI
LI

motor

Vbat

current

sense

HB

HO
LO

HS

Vbat

VSS

VCen
VDen
Vcc
Vdd
HI
LI

HB

HO
LO

HS

VSS

Vdd

HI
LI

HIP2103

HIP2104

HIP2103

A

B

C

Controller

U2

R14 R17

R15 R18

R4

R3

R11

R12

3.3V

ISL28246FUZ

32.4K

32.4K

32.4K

32.4K

511

511

1.15K

1.15K

filter capacitors
are not shown.

R21 R22

from

bridge

.015.015

I

motor

+

-

HIP2103_4 Circuit Description

The simplified schematic of Figure 8 illustrates the three power
phases of the motor driver. Each phase has identical components
(except for the one HIP2104 and two HIP2103s). For specific
component values and complete circuit details, please refer to

customer may change the resistor values or even remove the
diodes to suit the customer’s application needs.

The HIP2103/4 drivers do not have internal dead time features.
A dead time is provided by the controller and can be adjusted by
the SW6 dip switch settings.

the BOM and schematic found at the end of this application note.

Current Monitor and Current Limit

There are two current control features in the HIP2103-4DEMO1Z.
A linear current monitor op amp, U2, amplifies the voltage across
R21 and R22. This op amp is configured as a true differential
amplifier to allow Kelvin connections across the current sensing
resistors (see Figure 9). R3 and R4, each 32.4kΩ, have a
Thevenin equivalent value that is the parallel value of R3 and R4
(or 1/2 of 32.4kΩ). The Thevenin equivalent voltage also is 1/2
of the bias voltage of 3.3V. Consequently, the output of the
differential amplifier is offset by +1.65V (see Figure 10).

The HIP2104 (red) provides the Vcc (3.3V) bias for the controller
and the Vdd bias (12V) for itself and for the two HIP2103s (green
and blue).

Series connected gate resistors on each bridge FET are used to
reduce the switching speed to help minimize EMI radiating from
the power leads to the motor. The diodes in parallel with the FET
gate resistors are used to provide rapid turn off of the FETs. The

AN1899 Rev 0.00 Page 7 of 24
January 8, 2014

FIGURE 8. SIMPLIFIED 3-PHASE BRIDGE

FIGURE 9. DIFFERENTIAL CURRENT MONITOR AMPLIFIER

HIP2103-4DEMO1Z

U2

R14+R17

R15+R18

R3||R4

R11||R12

1.65V

thev

ISL28246FUZ

16.2K

16.2K

1.611K

1.611K

Note that resistors labeled Rx||Ry
represent a parallel equivalent resistor
of Rx and Ry. Rx+Ry represents the
series combination of Rx and Ry.

R21||R22

from

bridge

.0075

I

motor

+

-

U3

R4

R1

R12A

ISL28246FUZ

10K

604

+

-

R38

3.3V

U3

R11

R39

R12B

ISL28246FUZ

10K

+

-

R11B

3.3V

1M

1M

10K

10K

604

Imotor

to

microcontroller

.188V

3.3V-.188V

FIGURE 10. THEVENIN EQUIVALENT DIFFERENTIAL AMPLIFIER

The current monitor output, I

, digitized by the

motor

microcontroller, can be used to control the torque of the motor or
to limit the battery recharging current during regenerative
braking. Because of the offset voltage on the current monitor
output, signals above 1.65VDC represents positive motor current
and signals less that 1.65VDC represent negative motor current.
(Note that this hardware feature is provided for customer
evaluation but is not implemented in the microcontroller
firmware.)

The output voltage of the differential amplifier is (with
superposition):

= (R3||R4)/(R14+R17) x (R21||R22) x I

Vout

CS

+(R15+R18)/[R11||R12+(R15+R18)] x
[(R3||R4)+(R14+R17)]/(R14+R17) x 1.65V

where I

is the bridge current (motor current),

M

R3||R4 = R11||R12, and (R14+R17) = (R15+R18) (as required
for the diff- amp topology).

Using the defaults values of the HIP2103-4DEMO1Z, Equation 1
simplifies to:

Vout

= [16.2K /1.661K] x (.0075) x I

CS

M

+ 1.661K/(16.K+1.022K) x (16.2K+1.611K)/(1.611K)x 1.65V
or
Vout

= 0.07315 x IM+1.65V

CS

The I

signal is monitored by two comparators. See

motor

Figure 11. The output of the upper U3 comparator is biased to go
low when the positive motor current exceeds ~ 20A. Conversely,
the output of the lower comparator is biased to go low when the
negative motor current exceeds ~-20A.

The OR’ed outputs of these two comparators is monitored by the
microcontroller. Pulse-by-pulse current limiting is provided on
each negative transition. After 256 consecutive pulse limits, all
the bridge FETs are permanently turned off and the current limit
alarm LED (led3) is turned on.

There are two different methods to change the pulse-by pulse
current limit. The easiest method is to change the value of the
current sensing resistors R23 and R24. For example, removing
R24 halves the pulse by pulse current limit to ±10A while not
affecting the full scale I

AN1899 Rev 0.00 Page 8 of 24
January 8, 2014

motor

output signal.

M

(EQ. 1)

(EQ. 2)

FIGURE 11. PULSE-BY-PULSE CURRENT LIMIT COMPARATORS

Equation 3 calculates the value of the current sensing resistors to
set the pulse-by-pulse current limit at a desired level without
changing the full scale output voltage swing of the I

motor

signal.
This equation assumes that the only change made to the
HIP2103-4DEMO1Z is modifying the values of the current
sensing resistors R23 and R24.

R21||R22 = [(1.65-.188)V /(16.2K /1.661K)] / Im)

(EQ. 3)

For example: for Ilimit = ±5A,

R21||R22 = [(1.65-.188)V /(16.2K /1.661K)] / 5)
R21||R22 = 0.030Ω

An alternative method for changing the pulse-by-pulse current is
to change the gain of the diff-amp.

For example, if it is desired to decrease the current limit to 10A
without changing the current sense resistors, R21 and R22, the
gain of the diff-amp can be increased. Equation 4 illustrates this
method that reduces the value of R17 (and consequently R18) to
increase the gain of the diff-amp.

Equation 4 sets the positive current limit bias voltage.

R17 = (R3||R4)/[(1.65-.188)V / (R21||R21 x 10A)] - R14.
or
R17 = 16.2K/[1.462V/(.0075 x 10A)] - 511 = 320

(EQ. 4)

Because the diff-amp topology requires symmetry, R18 must
also be changed to 320.

In the above examples both the positive and negative current
limit value are equal in absolute values. It is acceptable to have
different limits for the positive and negative values.