DRV103UG4 Datasheet, PDF (8/24 Pages) Burr-Brown (TI) – PWM LOW-SIDE DRIVER (1.5A and 3A) for Solenoids, Coils, Valves, Heaters, and Lamps

APPLICATIONS INFORMATION
POWER SUPPLY
The DRV103 operates from a single +8V to +32V supply
with excellent performance. Most behavior remains un-
changed throughout the full operating voltage range. Param-
eters that vary significantly with operating voltage are shown
in the Typical Performance Curves. The DRV103 supply
voltage should be ≥ the supply voltage on the load.
ADJUSTABLE DELAY TIME (INITIAL 100% DUTY CYCLE)
A unique feature of the DRV103 is its ability to provide an
initial constant DC output (100% duty cycle) and then
switch to PWM mode output to save power. This function is
particularly useful when driving solenoids that have a much
higher pull-in current requirement than continuous hold
requirement.
The duration of this constant DC output (before PWM
output begins) can be externally controlled by a capacitor
connected from Delay Adjust (pin 2) to ground according to
the following equation:
Delay Time ≈ C_D • 10⁶
(time in seconds, C_D in Farads • 1.1)
Leaving the Delay Adjust pin open results in a constant
output time of approximately 18µs. The duration of this
initial output can be reduced to less than 1µs by connecting
the pin to 5V. Table I provides examples of delay times
(constant output before PWM mode) achieved with selected
capacitor values.
INITIAL CONSTANT
OUTPUT DURATION
1µs
18µs
110µs
1.1ms
11ms
110ms
1.1s
11s
TABLE I. Delay Adjust Times.
C_D
Pin 2 Tied to +5V
Pin 2 Open
100pF
1nF
10nF
100nF
1µF
10µF
The internal Delay Adjust circuitry is composed of a 3µA
current source and a 2.6V comparator, as shown in Figure 3.
Thus, when the pin voltage is less than 2.6V, the output
device is 100% ON (DC output mode).
OSCILLATOR FREQUENCY ADJUST
The DRV103 PWM output frequency can be easily pro-
grammed over a wide range by connecting a resistor (R_FREQ)
between the Osc Freq Adj pin (pin 3) and ground. A range of
500Hz to 100kHz can be achieved with practical resistor
values, as shown in Table II. Refer to “PWM Frequency vs
R_FREQ” typical performance curve shown in Figure 4 for
additional information. Although oscillator frequency opera-
tion below 500Hz is possible, resistors higher than 10M will
be required. The pin becomes a very high impedance node and
is, therefore, sensitive to noise pickup and PCB leakage
currents if very high resistor values are used. Refer to Figure
3 for a simplified circuit of the frequency adjust input.
OSCILLATOR FREQUENCY
(Hz)
R_FREQ (nearest 1% values)
(Ω)
100k
50k
25k
10k
5k
500
47.5k
100k
205k
523k
1.07M
11.3M
TABLE II. Oscillator Frequency Resistance.
1000M
PWM FREQUENCY vs R_FREQ
100M
10M
1M
100k
10k
1k
10
100
1k
10k
100k
1M
Frequency (Hz)
FIGURE 4. Using a Resistor to Program Oscillator Frequency.
R_FREQ (kΩ) = 6808417 /F^(1.0288)
+V_S
3µA
C_D
Reset
Input
R_FREQ
V_FREQ
I_REF
+2.6V
V_REF
+1.3V
FIGURE 3. Simplified Delay Adjust and Frequency Adjust Inputs.
8
DRV103
SBVS029A