Datasheet MAX1684, MAX1685 (Maxim) - 4

Low-Noise, 14V Input, 1A, PWM Step-Down Converters ELECTRICAL CHARACTERISTICS
(VIN = V SHDN = 6V, STBY = SYNC/PWM = CVL, VBOOT = VOUT, FB = AGND, circuit of Figure 1,
TA = -40°C to +85°C
, unless other- wise noted.) (Note 5)
PARAMETER SYMBOL CONDITIONS MIN MAX UNITS
Input Voltage Range 2.7 14 V Output Feedback Voltage VFB VFB = VOUT, ILOAD = 0 to 1A 1.233 1.269 V Output Voltage (3.3V Mode) VOUT FB = AGND, ILOAD = 0 to 1A 3.280 3.382 V Output Current Capability VIN = 6V to 14V 1 A Output Adjust Range BOOT = AGND (Note 1) VREF VIN V FB Input Current IFB VFB = 1.4V -50 50 nA Current Limit in PWM Mode ILIM 1.2 2.3 A Current Limit in Low-Power I STBY = low Mode LIMLP 285 475 mA Normal mode, SYNC/PWM = low, 2 V
MAX1684/MAX1685
BOOT = 3.3V (Note 2) Quiescent Power Consumption mW Low-power mode, STBY = low, 0.27 VBOOT = 3.3V (Note 2) Shutdown Supply Current SHDN = low 6 µA MAX1684 240 350 Oscillator Frequency fOSC kHz MAX1685 480 700 Reference Output Voltage IREF = 0 1.232 1.268 V V CVL Regulator Output Voltage IN = 3V to 14V, BOOT = AGND, 2.7 3.15 V ICVL = 0 to 5mA CVL Undervoltage Lockout BOOT = AGND, CVL falling edge, 2.4 2.6 V Threshold typical hysteresis is 40mV CVH with Respect to VIN ICVH = -1mA -5.0 -4.1 V BOOT Switchover Threshold BOOT falling edge, typical hysteresis is 0.1V 2.35 2.65 V ILIM/SS Source Current VILIM/SS = 1.4V 3.1 4.7 µA Logic Input High Voltage VIH 2 SHDN, STBY, SYNC/PWM V Logic Input Low Voltage VIL 0.7
Note 1:
The output adjust range with BOOT connected to VOUT is VREF to 5.5V. Connect BOOT to AGND for VOUT > 5.5V.
Note 2:
The quiescent power-consumption specifications include chip supply and gate-drive loss only. Divide these values by VIN (6V) to obtain quiescent currents. In normal and low-power modes, chip supply current dominates and quiescent power is proportional to VBOOT (BOOT connected to OUT). In PWM mode, gate-drive loss dominates and quiescent power is propor- tional to VIN ✕ (VIN - VCVH). In addition, IR losses in power switches and external components typically increase PWM quies- cent power consumption by 5mW to 10mW. Note that if the device is not bootstrapped, additional power is dissipated in the CVL linear regulator.
Note 3:
When the duty factor (VOUT / VIN) is less than this value, the switching frequency decreases in PWM mode to maintain regulation.
Note 4:
Thermal shutdown is disabled in low-power mode (STBY = low) to reduce power consumption.
Note 5:
Specifications to -40°C are guaranteed by design, not production tested.
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