DRV120_15 Datasheet, PDF (7/23 Pages) Texas Instruments – Power-Saving Current Controlled Solenoid Driver

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7 Detailed Description
DRV120
SLVSBG3B – JUNE 2012 – REVISED JULY 2015
7.1 Overview
The DRV120 device provides a PWM current converter for use with solenoids. The device provides a quick ramp
to a high peak current value in order to ensure opening of the valve or relay. The peak current is held for a
programmable time and then released to a lower value to maintain the open state of the valve or relay while
reducing the total current consumption. Peak current duration, peak current amount, hold current amount (in the
14-pin package), and PWM frequency can all be controlled by external components or used at default levels by
omitting these components (except peak current duration). Enable and disable of the switch is controlled by the
EN pin which has an internal pullup to V_IN. The DRV120 also features a wide V_IN range from 6 V to 28 V. Finally,
the 14-pin package features an open-drain pulldown path on the STATUS pin which is enabled as long as
undervoltage lockout or thermal shutdown has not triggered.
7.2 Functional Block Diagram
R_OSC
OSC
VIN
V_S
EN
1 uA
LDO
500 kW
<STATUS>¹
V_S
UVLO
Thermal
Shutdown
OSC
PWM_CLK
PWM
Control
OUT
L_S
D₁
75 mV
REF
V_PEAK
V_HOLD
V_REF
1_{Available only in the 14-pin package}
7.3 Feature Description
The DRV120 controls the current through the solenoid as shown in Figure 2. Activation starts when EN pin
voltage is pulled high either by an external driver or internal pullup. In the beginning of activation, DRV120 allows
the load current to ramp up to the peak value I_PEAK and it regulates it at the peak value for the time, t_KEEP, before
reducing it to I_HOLD. The load current is regulated at the hold value as long as the EN pin is kept high. The initial
current ramp-up time depends on the inductance and resistance of the solenoid. Once EN pin is driven to GND,
DRV120 allows the solenoid current to decay to zero.
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