Datasheet MAX882, MAX883, MAX884 (Maxim) - 9

5V/3.3V or Adjustable, Low-Dropout, Low IQ, 200mA Linear Regulators MAX882/MAX883/MAX884
INPUT OUTPUT VOLTAGE VOLTAGE IN OUT INPUT IN OUT OUTPUT LBI VOLTAGE LBI VOLTAGE R1 R1 MAX882 MAX882 OFF LOAD SET STBY MAX883 (STBY) MAX884 COUT CIN CIN R2 2.2µF O.1µF C R2 OUT O.1µF GND GND SET 2.2µF ( ) ARE FOR MAX882. R1+ R2 VSTBY TRIP = VSTBY , VSTBY = 1.20V R1 + R2 R2 VOUT = VSET , V R2 SET = 1.20V Figure 2. Adjustable Output Using External Feedback Figure 3. Setting an Undervoltage Lockout Threshold Using Resistors STBY
Foldback Current Limiting Power Dissipation and Operating Region
The MAX882/MAX883/MAX884 also include a foldback Maximum power dissipation of the MAX882/MAX883/ current limiter. It monitors and controls the pass transis- MAX884 depends on the thermal resistance of the case tor’s gate voltage, estimating the output current and and PC board, the temperature difference between the limiting it to 430mA for output voltages above 0.8V and die junction and ambient air, and the rate of (VIN - VOUT) > 0.7V. If the output voltage drops below air flow. The power dissipation across the device is 0.8V, implying a short-circuit condition, the output cur- P = IOUT (VIN - VOUT). The resulting power dissipation rent is limited to 170mA. The output can be shorted to is as follows: ground for 1min without damaging the device if the (T − T ) J A package can dissipate (VIN x 170mA) without exceed- P = (θ + θ ) ing TJ = +150°C. When the output is greater than 0.8V JB BA and (VIN - VOUT) < 0.7V (dropout operation), no current where (TJ - TA) is the temperature difference between limiting is allowed, to provide maximum load drive. the MAX882/MAX883/MAX884 die junction and the sur-
Thermal Overload Protection
rounding air, θJB (or θJC) is the thermal resistance of Thermal overload protection limits total power dissipa- the package chosen, and θBA is the thermal resistance tion in the MAX882/MAX883/MAX884. When the junc- through the PC board, copper traces, and other materi- tion temperature exceeds T als to the surrounding air. J = +160°C, the thermal sensor sends a signal to the shutdown logic, turning off The 8-pin small-outline package for the MAX882/ the pass transistor and allowing the IC to cool. The MAX883/MAX884 features a special lead frame with a thermal sensor turns the pass transistor on again after lower thermal resistance and higher allowable power the IC’s junction temperature cools by 10°C, resulting in dissipation. This package’s thermal resistance package a pulsed output during thermal overload conditions. is θJB = 53°C/W, compared with θJB = 110°C/W for an Thermal overload protection is designed to protect the 8-pin plastic DIP package and θJB = 125°C/W for an 8- MAX882/MAX883/MAX884 if fault conditions occur. It is pin ceramic DIP package. not intended to be used as an operating mode. Prolonged operation in thermal-shutdown mode may reduce the IC’s reliability. For continual operation, do not exceed the absolute maximum junction temperature rating of TJ = +150°C.
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