Datasheet MAX4626, MAX4627, MAX4628 (Maxim) - 6

link to page 4 MAX4626/MAX4627/ 0.5Ω, Low-Voltage, Single-Supply MAX4628 SPST Analog Switches
Detailed Description Applications Information
The MAX4626/MAX4627/MAX4628 are low-on-resistance
Logic Inputs
(RON), low-voltage, single-pole/single-throw (SPST) analog switches that operate from a +1.8V to +5.5V The MAX4626/MAX4627/MAX4628 logic inputs can be single supply. The MAX4626 is normally open (NO), and driven up to +5.5V regardless of the supply voltage. For the MAX4627 is normally closed (NC). The MAX4628 is example, with a +3.3V supply, IN or IN may be driven normally open (NO) and has two control inputs. low to 0V and high to 5.5V. Driving IN or IN Rail-to-Rail® minimizes power consumption. When powered from a +5V supply, their 0.5Ω RON allows high continuous currents to be switched in a variety of
Analog Signal Levels
applications. In the event of an overcurrent condition, Analog signals that range over the entire supply voltage these switches provide both current-limit and thermal- (V+ to GND) can be passed with very little change in on- shutdown protection. resistance (see Typical Operating Characteristics). The
Current-Limit Protection
switches are bidirectional, so the NO, NC, and COM pins can be used as either inputs or outputs. The MAX4626/MAX4627/MAX4628 feature current-limit protection circuitry. When the voltage drop across the on
Power-Supply Sequencing and
switch reaches 0.6V (typ), the internal circuitry activates.
Overvoltage Protection
The current limit is not instantaneous, but rather
Caution: Do not exceed the absolute maximum rat-
integrates over time so that current limiting will not activate
ings; stresses beyond the listed ratings may cause
under momentary short-circuit conditions encountered
permanent damage to the devices.
when the switch output charges a small 0.1μF capacitor. Proper power-supply sequencing is recommended for For sustained overcurrent conditions, the switch turns off all CMOS devices. Always apply V+ before applying (opens). The switch turns on after 5ms and, if the over- analog signals, especially if the analog signal is not cur- load condition persists, the switch will cycle off and on rent limited. If this sequencing is not possible, and if the to produce a pulsed output. A direct short circuit will be analog inputs are not current limited to <20mA, add a detected immediately, and the switch will pulse on for 1μs, small-signal diode (D1) as shown in Figure 1. If the ana- then remain off for 5ms. log signal can dip below GND, add D2. Adding protection diodes reduces the analog range to a diode drop (about 0.7V) below V+ (for D1), and a diode drop above ground (for D2). On-resistance increases by a small amount at low supply voltages. Maximum supply voltage (V+) must POSITIVE SUPPLY not exceed +6V. D1
MAX4626
Adding protection diode D2 causes the logic thresholds to V+
MAX4627
be shifted relative to GND. TTL compatibility is not guar-
MAX4628
anteed when protection diode D2 is added. Protection diodes D1 and D2 also protect against some NO COM overvoltage situations. With Figure 1’s circuit, if the supply voltage is below the absolute maximum rating, and if a Vg fault voltage up to the absolute maximum rating is applied to an analog signal pin, no damage will result. GND D2 Figure 1. Overvoltage Protection Using Two External Blocking Diodes Rail-to-Rail is a registered trademark of Nippon Motorola, Ltd. www.maximintegrated.com Maxim Integrated │ 6