DATASHEET ISL91108 FN8448 Rev 1.00 High Efficiency Buck-Boost Regulator with 4.2A Switches November 12, 2014 The ISL91108 is a highly-integrated buck-boost switching Features regulator that accepts input voltages either above or below the Accepts input voltages above or below regulated output regulated output voltage. Unlike other buck-boost regulators, voltage this regulator automatically transitions between operating modes without significant output disturbance. Automatic and seamless transitions between buck and boost modes This device is capable of delivering up to 2.7A of burst current (PVIN = 3V, V = 3.3V), and provides excellent efficiency due Input voltage range: 1.8V to 5.5V OUT to its fully synchronous 4-switch architecture. No load Output current: up to 1.6A DC (PVIN = 2.8V, V = 3.3V) OUT quiescent current of only 27.5A also optimizes efficiency Burst current: up to 2.7A (PVIN = 3V, V = 3.3V, t OUT ON under light-load conditions. Forced PWM and/or <600s, t = 4.6ms) synchronization to an external clock may also be selected for noise sensitive applications. High efficiency: up to 95% 27.5A quiescent current maximizes light load efficiency The ISL91108 is designed for standalone applications and supports a 3.3V fixed output voltage or variable output 2.6MHz switching frequency minimizes external component voltages with an external resistor divider. Output voltages as size low as 1V or as high as 5.2V are supported using an external Selectable forced PWM mode and external synchronization resistor divider. Fully protected for short-circuit, over-temperature, and The ISL91108 requires only a single inductor and very few undervoltage external components. Power supply solution size is minimized Small 2.34mm x 1.72mm WLCSP by a 2.34mmx1.72mm WLCSP and a 2.6MHz switching frequency, which further reduces the size of external Applications components. Smartphones and tablets Related Literature Wireless communication devices AN1903 ISL91108IIA-EVZ/ISL91108IIN-EVZ Evaluation 2G/3G/4G power amplifiers Board User Guide 100 4.5VIN 95 V = IN 90 ISL91108IINZ 1.8V TO 5.5V 85 3.5VIN PVIN LX1 C 1 L1 80 2x10F 1H 3.0VIN VIN LX2 75 2.7VIN MODE VOUT V = 3.3V OUT 70 EN 2.5VIN C2 FB 65 2x22F 60 55 50 0.001 0.01 0.1 1 I (A) OUT FIGURE 1. TYPICAL FIXED OUTPUT APPLICATION FIGURE 2. ISL91108IINZ EFFICIENCY vs OUTPUT CURRENT FN8448 Rev 1.00 Page 1 of 9 November 12, 2014 GND PGND EFFICIENCY (%)ISL91108 Block Diagram LX1 LX2 A2 B2 C2 A4 B4 C4 A1 A5 PVIN B1 B5 VOUT C1 C5 SOFT GATE EN DISCHARGE DRIVERS & ANTI- EN SHOOT THRU EN D2 A3 EN B3 PGND VIN D1 V REF C3 PVIN MONITOR VOUT CLAMP THERMAL SHUTDOWN PWM CURRENT CONTROL MODE D3 DETECT EN VOUT EN MONITOR EN FB D5 OSC EN REF ERROR AMP VOLTAGE PROG. D4 GND Pin Descriptions Pin Configuration ISL91108 PIN PIN NAMES DESCRIPTION (20 BUMP WLCSP) TOP VIEW A5, B5, C5 VOUT Buck-boost output. Connect 2x22F capacitor to PGND. A1 B1 C1 D1 A4, B4, C4 LX2 Inductor connection, output side. A3, B3, C3 PGND Power ground for high switching current. A2 B2 C2 D2 A2, B2, C2 LX1 Inductor connection, input side. A3 B3 C3 D3 A1, B1, C1 PVIN Power input. Range: 1.8V to 5.5V. Connect A4 B4 C4 D4 2x 10F capacitor to PGND. A5 B5 C5 D5 D1 VIN Supply input. Range: 1.8V to 5.5V. D2 EN Logic input, drive HIGH to enable device. D3 MODE/ Logic input, HIGH for auto PFM mode. LOW SYNC for forced PWM operation. Also, this pin can be used with an external clock sync input. Range: 2.75MHz to 3.25MHz. D4 GND Analog ground pin. D5 FB Voltage feedback pin. FN8448 Rev 1.00 Page 2 of 9 November 12, 2014 REVERSE CURRENT