DRV101

8

SBVS008B

www.ti.com

BASIC OPERATION

The DRV101 is a low-side, bipolar power switch employing

a pulse-width modulated (PWM) output for driving electro-

mechanical and thermal devices. Its design is optimized for

two types of applications; a two-state driver (open/close) for

loads such as solenoids and actuators, and a linear driver for

valves, positioners, heaters, and lamps. Its wide supply

range, adjustable delay to PWM mode, and adjustable duty

cycle make it suitable for a wide range of applications.

Figure 1 shows the basic circuit connections to operate the

DRV101. A 0.1

µF bypass capacitor is shown connected to

the power supply pin.

The Input (pin 1) is compatible with standard TTL levels.

Input voltages between +2.2V and +5.5V turn the device

output on, while pulling the pin low (0V to +1.2V), shuts the

DRV101 output off. Input current is typically 80

µA.

Delay Adjust (pin 2) and Duty Cycle Adjust (pin 3) allow

external adjustment of the PWM output signal. The Delay

Adjust pin can be left floating for minimum delay to PWM

mode (typically 15

µs) or a capacitor can be used to set the

delay time. Duty cycle of the PWM output can be controlled

FIGURE 1. Basic Circuit Connections and Timing Diagram.

by a resistor, analog voltage, or D/A converter. Figure 1b

provides an example timing diagram with the Delay Adjust

pin connected to 0.1

µF and duty cycle set for 25%. See the

“Delay Adjust” and “Duty Cycle Adjust” text for equations

and further explanation.

Ground (pin 4) is electrically connected to the package tab.

This pin must be connected to system ground for the

DRV101 to function. This serves as the load current path to

ground, as well as the DRV101 reference ground.

The load (solenoid, valve, etc.) is connected between the

supply (pin 5) and output (pin 6). For an inductive load, an

external diode across the output is required as shown in

Figure 1a. The diode serves to maintain the hold force during

PWM operation. For remotely located loads, the external

diode should be placed close to the DRV101 (Figure 1a). The

internal clamp diode between the output and ground should

not be used to carry load current.

The Flag (pin 7) provides fault status for under-current,

over-current, and thermal shutdown conditions. This pin is

active low with pin voltage typically +0.3V during a fault

condition. A small value capacitor may be needed between

Flag and ground for noisy applications.

R

PWM

C

D

Delay

Adjust

Input

(TTL-Compatible)

On

Off

Thermal Shutdown

Over/Under Current

Flag

Load

Duty Cycle Adjust

V

S

24kHz

Oscillator

PWM

23

1

75

6

4

Gnd

Out

(electrically

connected to

tab)

Delay

0.1

µF

(a)

(b)

t

P

t

ON

OUTPUT

V

S

0

INPUT

+2.2V to +5.5V

0V to +1.2V

Duty Cycle =

= 25%

t

ON

t

P

R

t

t

Basic Circuit Connections

Simplified Timing Diagram

C

R

(1)

NOTE: (1) External flyback diode required for inductive loads to conduct load current during the off cycle.

For remotely located loads, diode should be placed close to the DRV101.

Motorola MSRS1100T3 (1A, 100V), MBRS360T3 (3A, 60V)

C

95ms

• • •

• • •

Initial dc Output

(set by value

of C

PWM Mode

(resistor or voltage

controlled)