DRV104PWPR Datasheet, PDF (8/25 Pages) Texas Instruments – 1.2A PWM High-Side Driver

APPLICATIONS INFORMATION
POWER SUPPLY
The DRV104 operates from a single +8V to +32V supply with
excellent performance. Most behavior remains unchanged
throughout the full operating voltage range. Parameters that
vary significantly with operating voltage are shown in the
Typical Characteristics.
ADJUSTABLE DELAY TIME
(INITIAL 100% DUTY CYCLE)
A unique feature of the DRV104 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 con-
nected from Delay Adjust (pin 2) to ground according to
Equation 1:
Delay Time ≈ (C_D • 10⁶)/1.24
(1)
(time in seconds, C_D in Farads)
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 3µs by connecting the pin to 5V.
Table I provides examples of delay times (constant output
before PWM mode) achieved with selected capacitor values.
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 DRV104 PWM output frequency can be easily pro-
grammed over a wide range by connecting a resistor (R_FREQ)
between Osc Freq Adj (pin 3) and ground. A range of 500Hz
to 100kHz can be achieved with practical resistor values, as
shown in Table II. Refer to the PWM Frequency vs R_FREQ plot
shown in Figure 4 for additional information. Although oscilla-
tor frequency operation below 500Hz is possible, resistors
higher than 10MΩ will be required. The pin becomes a very
high impedance node and is therefore sensitive to noise
INITIAL CONSTANT
OUTPUT DURATION
3µs
18µs
81µs
0.81ms
8.1ms
81ms
0.81s
8.1s
TABLE I. Delay Adjust Times.
C_D
Pin 2 Tied to +5V
Pin 2 Open
100pF
1nF
10nF
100nF
1µF
10µF
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.
The DRV104’s adjustable PWM output frequency allows it to
be optimized for driving virtually any type of load.
+V_S
3µA
C_D
Reset
Input
R_FREQ
V_REF
I_REF
+2.6V
V_REF
+1.25V
FIGURE 3. Simplified Delay Adjust and Frequency Adjust Inputs.
OSCILLATOR FREQUENCY
(Hz)
R_FREQ (nearest 1% values)
(Ω)
100k
50k
25k
10k
5k
500
47.5k
100k
191k
499k
976M
10M
TABLE II. Oscillator Frequency Resistance.
1000M
PWM FREQUENCY vs R_FREQ
100M
10M
1M
100k
10k
R_FREQ(kΩ )
=
1.4518
×
10^−6
+
1
2.0593
× 10^−7
×
F(Hz)
1k
10
100
1k
10k
100k
1M
Frequency (Hz)
FIGURE 4. Using a Resistor to Program Oscillator Frequency.
When switching a high-load current, 100pF capacitors in
parallel with R_FREQ are recommended to maintain a clean
output switching waveform and duty cycle, see Figure 5.
8
DRV104
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