OSCILLATOR
(Pin 9)
An external RC network is connected to this input to set the fre-
quency of the Sawtooth Schmitt Trigger Oscillator. The Sawtooth
is applied to the PWM Comparator along with the output of the Er-
ror Amplifier. The output of the PWM Comparator is a Pulse
Width Modulated Signal which is used to vary the effective drive
to the motor and, hence, the motor speed.
OVERCURRENT SENSE
(Pins 10, 11)
The input to Pin 10 comes from the high side of a fractional ohm
current sensing resistor. The voltage at this input is compared to
an internal 100mV Reference. When the voltage exceeds the
100mV Reference, an Overcurrent Condition exists and the Out-
put Drivers are switched Off until the end of the sawtooth os-
cillator ramp-up. When the sawtooth switches low, the Over-
current Condition is sampled, and if it no longer exists, the Output
Drivers are switched On again. Otherwise, the Output Drivers re-
main Off until the end of the next sawtooth. The input to Pin 11
comes from the low side (Gnd) of the current sensing resistor and
connects to the low side of the internal 100mV Reference.
PWM CONTROL Input
(Pin 21)
A High on this input causes only the Bottom Drivers to be Pulse
Width Modulated. A Low on this input causes both Top and Bot-
tom Drivers to have PWM.
TACHOMETER Output
(Pin 5)
The output of the Frequency To Pulse Width Converter is tied to
this pin. The Converter uses the three Sensor Inputs and external
RC Network to generate a variable frequency output with a fixed
positive pulse width.
RC Input
(Pin 4)
The external RC network connected to this input programs the
positive pulse width of the Frequency to Pulse Width Converter.
V
SS
(Pin 18) Supply Voltage negative terminal.
ERROR AMPLIFIER Inputs
(Pins 6, 7)
Output
(Pin 8)
For closed loop control, the Tachometer Output is applied through
a resistor to the negative input of the Error Amplifier on Pin 7. A
speed control potentiometer is connected to the positive input of
the Error Amplifier on Pin 6. A parallel RC Network is connected
between the Output of the Error Amplifier on Pin 8 and Pin 7. The
Amplifier, configured this way, enables the variable pulse width to
be converted to a DC voltage which is used to control the motor
speed. The potentiometer is used to set the desired motor speed.
For open loop control, configure the Error Amplifier as a voltage
follower by connecting Pin 7 directly to Pin 8 and do not connect
the Tachometer Output signal to the Error Amplifier.
TOP DRIVER POLARITY SELECT Input
(Pin 20)
A High on this input selects a High Polarity to enable the Top Out-
put Motor Drivers and a Low selects a Low Polarity to enable the
Top Output Motor Drivers.
OUTPUT DRIVERS
(Pins 12, 13, 14, 15, 16, 17)
Each Driver Output provides a CMOS compatible signal for driv-
ing Buffers/Power Transistors. The Outputs are capable of sink-
ing/sourcing 25mA with a 1.5V drop across the IC, at V
DD
= 12V.
FAULT INDICATOR Output
(Pin 3)
Open drain output to provide sinking current for driving an ex-
ternal device, such as a LED, through an emitter follower (see
Figure 3) to indicate a malfunction condition. The output occurs
under any of the following conditions:
1) Overcurrent Sense condition
2) Enable Input below V
R
/ 2.2
3) Invalid Sensor code
4) Chip power supply less than 9V
5) V
R
Output less than 4.1V
V
R
Output
(Pin 19)
6V Reference Voltage Output that can supply 20mA of current at
V
DD
= 12V for powering input Sensors.
V
DD
(Pin 28) Supply Voltage positive terminal.
MAXIMUM RATINGS
(Voltages referenced to Vss)
Power Supply Voltage
Voltage at any input
Operating Temperature
Storage Temperature
Output Drive Sink/Source Current
V
R
Output Source Current
SYMBOL
V
DD
V
IN
T
A
T
STG
Io
I
R
VALUE
20
Vs
S
- 0.5 to V
R
-25 to +85
-65 to +150
75
30
UNIT
V
V
°C
°C
mA
mA
ELECTRICAL CHARACTERISTICS
V
DD
= 12V, R
T
= 47kΩ, C
T
= 0.001µF, R
S
= 10kΩ, C
S
= 0.01µF, R
F
= 5.6kΩ (See Figure 3) T
A
= 25°C, unless otherwise specified
PARAMETER
Reference Voltage
Line Regulation
V
DD
= 10V to 18V, I
REF
= 1.0mA
Temperature Stability
T
A =
0°C to 70°C
T
A =
0°C to 85°C
Error Amplifier:
Input Offset Voltage
Input Current
Input Common Mode Voltage Range
Open Loop Voltage Gain (R
L
= 15kΩ)
Common Mode Rejection Ratio
Power Supply Rejection Ratio
7560N-030906-2
SYMBOL
V
R
∆V
R
∆V
R
∆V
R
V
IO
I
IN
V
ICR
A
VOL
C
MRR
P
SRR
MIN
5.7
-
TYP
6.0
100
MAX
6.35
200
UNIT
V
mV
-
-
+/- 1.0
+/- 1.3
-
-
%
%
-
-
(0 to V
R
)
70
60
60
5
0
80
-
-
15
10
-
-
-
mV
nA
V
dB
dB
dB
LSI [ LSI COMPUTER SYSTEMS ]
