MAX1686HEUA -40 C to +85 C 8 µmax TOP VIEW IN

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1 9-376; Rev ; 2/98 3V to 5V Regulating General Description The MAX686 provides power for dual-voltage subscriber ID module (SIM) cards in portable applications such as GSM cellular phones. Designed to reside in the portable unit (cellular phone handset), the MHz charge pump converts a 2.7V to 4.2V input to regulated 5V output. The MAX686H has a nominal output voltage of 5., while the MAX686 is set to 4.75V to reduce SIMcard current drain. The charge pump has only 45µA quiescent supply current, which reduces to 3µA when a 3V-capable SIM card is being powered and the charge pump is disabled. An internal input/output shorting switch provides power for 3V SIM cards. The require only three external capacitors around their space-saving, thin (mm) 8-pin µmax packages. GSM Cellular Phones PCS Phones Portable POS Terminals Personal Communicators Applications Features 2.7V to 4.2V Input Range 2mA min Charge-Pump Output Current 45µA Quiescent Supply Current.µA Supply Current in Shutdown Mode 5. Regulated Charge-Pump Output (MAX686H) 4.75V Regulated Charge-Pump Output (MAX686) Input-Output Shorting Switch for 3V Cards Small External Components (Uses a.47µf,.µf, and a 2.2µF Capacitor) Output Driven to Ground in Shutdown Mode Super-Small 8-Pin µmax Package Soft-Start and Short-Circuit Protection Ordering Information PART TEMP. RANGE P-PACKAGE MAX686EUA -4 C to +85 C 8 µmax MAX686HEUA -4 C to +85 C 8 µmax Typical Operating Circuit Pin Configuration C X TOP VIEW PUT 2.7V TO 4.2V CXN CXP PUT V OR 5V/2mA C MAX686 MAX686H C GND MAX686 MAX686H CXP CXN PGND GND PGND µmax Maxim Integrated Products For free samples & the latest literature: or phone For small orders, phone

2 ABSOLUTE MAXIMUM RATGS,,, to GND...-.3V to +6V CXP to GND...-.3V to ( +.3V) CXN to GND...-.3V to (V +.3V) PGND to GND...-.3V to +.3V Short Circuit to GND...Continuous -to- Current...5mA ELECTRICAL CHARACTERISTICS Continuous Power Dissipation (T A = +7 C ) 8-Pin µmax (derate 4.mW/ C above +7 C)...33mW Operating Temperature Range MAX686EUA/MAX686HEUA...-4 C to +85 C Junction Temperature...+5 C Storage Temperature Range C to +65 C Lead Temperature (soldering, sec)...+3 C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. (V = V = 3.3V, = GND, C X =.22µF, C = µf (see Applications Information section to use smaller capacitors), T A = T M to T MAX, unless otherwise noted. Typical values are at T A = +25 C.) (Note ) PARAMETER CONDITIONS M TYP MAX UNITS Input Voltage Range V Input Undervoltage-Lockout Threshold Voltage -to- Switch On-Resistance V Charge pump enabled, T A = +25 C 45 Quiescent Supply Current no load, = GND T A = -4 C to +85 C 5 µa Charge pump disabled, no load, = 3 Shutdown Supply Current V = 3.6V, = GND. 5 µa V = 2.7V to 4.2V, MAX Output Voltage load = to 2mA MAX686H V = V V = V = Ω Discharge Switch On-Resistance = GND or, = GND 8 2 Ω Short-Circuit Current = GND or 2 2 ma Logic Input Low Voltage,.5 V.3 V V Logic Input High Voltage,.7 V.5 V V Logic Input Leakage Current, = GND or. µa Charge-Pump Frequency T A = +25 C 8 2 T A = -4 C to +85 C 7 3 khz Note : Electrical specifications are measured by pulse testing and are guaranteed for a junction temperature within the operating temperature range, unless otherwise noted. Limits are % production tested at T A = +25 C. Limits over the entire operating temperature range are guaranteed through correlation using Statistical Quality Control (SQC) methods and are not production tested. 2

3 Typical Operating Characteristics (See Typical Operating Circuit, C =.47µF, C X =.22µF, C = µf, V = 3.3V, T A = +25 C, unless otherwise noted.) EFFICIENCY (%) PUT CURRENT (µa) , EFFICIENCY vs. LOAD CURRENT (5V MODE) V = 2.7V. LOAD CURRENT (ma) V = 3.3V V = 3.6V NO-LOAD PUT CURRENT vs. PUT VOLTAGE (5V MODE) MAX686- MAX686-4 EFFICIENCY (%) PUT VOLTAGE (V) EFFICIENCY vs. PUT VOLTAGE (5V MODE) I LOAD = ma I LOAD = ma PUT VOLTAGE vs. LOAD CURRENT (3V MODE) LOAD CURRENT (ma) MAX686-TOC2 MAX686-5 PUT CURRENT (µa) PUT VOLTAGE (V) NO-LOAD PUT CURRENT vs. PUT VOLTAGE (3V MODE) MAX686 PUT VOLTAGE vs. LOAD CURRENT (5V MODE). LOAD CURRENT (ma) V = 3.6V V = 3.3V V = 2.7V MAX686-3 MAX PUT VOLTAGE vs. PUT VOLTAGE (3V MODE) NO LOAD MAX PUT VOLTAGE vs. PUT VOLTAGE (5V MODE) NO LOAD MAX686H MAX686-8 PUT WAVEFORM (I LOAD = ma) MAX686-9 PUT VOLTAGE (V) PUT VOLTAGE (V) MAX686 (2mV/div) µs/div 5V MODE, AC COUPLED, C = µf.µf 3

4 Typical Operating Characteristics (continued) (See Typical Operating Circuit, C =.47µF, C X =.22µF, C = µf, V = 3.3V, T A = +25 C, unless otherwise noted.) (2mV/div) PUT WAVEFORM (I LOAD = ma) 25µs/div 5V MODE, AC COUPLED, C = µf.µf MAX686- V (5mV/div) (5mV/div) LE-TRANSIENT RESPONSE 2.5ms/div V = 2.8V to 3.3V, I LOAD = ma, 5V MODE, AC COUPLED MAX686- I LOAD (ma/div) (5mV/div) LOAD-TRANSIENT RESPONSE 2.5ms/div I LOAD = TO ma, 5V MODE, AC COUPLED MAX686-2 START-UP WAVEFORM (3V MODE, R L = 5Ω) START-UP WAVEFORM (5V MODE, R L = 5Ω) 3V MODE TO 5V MODE WAVEFORM (R L = 5Ω) MAX686-3 MAX686-4 MAX µs/div 25µs/div 25µs/div SHUTDOWN WAVEFORM (3V MODE, NO LOAD) SHUTDOWN WAVEFORM (5V MODE, NO LOAD) 5V MODE TO 3V MODE WAVEFORM (NO LOAD) MAX686-6 MAX686-7 MAX686-8 ms/div ms/div 5µs/div R L = 5Ω 4

5 P NAME FUNCTION 3V/5V Select Input. When low, the output is regulated at 4.75V for MAX686, 5. for MAX686H. When high, the output is shorted to the input. 2 Active-Low Shutdown Input. = GND is off. Output is actively pulled low in shutdown. 3 Supply Input Pin. Can range from 2.7V to 4.2V. Bypass to ground with a ceramic capacitor. 4 GND Ground Pin 5 PGND Power Ground. Connect to GND through a short trace. 6 CXN Negative Terminal of the Charge-Pump Transfer Capacitor 7 CXP Positive Terminal of the Charge-Pump Transfer Capacitor 8 Power Output. Bypass to GND with an output filter capacitor. CXN C X CXP Pin Description PGND S S2 OSC EN.23V SS POWER MANAGEMENT PWROK DIS MAX686 MAX686H GND Figure. Functional Diagram Detailed Description The charge pumps provide two modes of operation: 3V mode or 5V mode. The devices consist of an error amplifier, a.23v bandgap reference, an internal resistive feedback network, a MHz oscillator, high-current MOSFET drivers and switches, and a power-management block as shown in the Functional Diagram (Figure ). In 3V mode ( = ), the input is connected to the output through a 2.5Ω switch. In 5V mode ( = GND), the MAX686 s output voltage is regulated at 4.75V (5. for the MAX686H) with a 2.7V to 4.2V input and can deliver more than 2mA of load current. Designed specifically for compact applications, these regulators require only three small external capacitors. The Skip Mode control scheme provides high efficiency over a wide output current range. The devices offer a shutdown feature which actively discharges the output to ground and reduces the supply current to less than 5

6 µa. Other features include soft-start, undervoltage lockout, and short-circuit protection. Charge-Pump Control Figure 2 shows an idealized, unregulated charge-pump voltage doubler. The oscillator runs at a 5% duty cycle. During one half of the period, the transfer capacitor (C X ) charges to the input voltage. During the other half, the doubler stacks the voltage across C X and the input voltage, and transfers the sum of the two voltages to the output filter capacitor (C ). The MAX686 uses Skip Mode control to regulate its output voltage and to achieve good efficiency over a large output current range. When the comparator detects that the output voltage is too low, the MHz oscillator is enabled and C X is switched. When the output voltage is above regulation, the oscillator is disabled and C X is connected at the input. Soft-Start In the 5V mode ( = GND), the start-up current is limited by the soft-start control to typically 2mA, independent of the load. Until the output voltage reaches V / 2, the input is connected to the output through a 5Ω series P-channel MOSFET and the charge pump is disabled. For V / 2 < < 4.75V (5. for MAX686H) and for a maximum of 2ms the charge pump is active, but R ON of the switch S2 is limited to 5Ω. This limits typical current surges associated with charge pumps at start-up. When soft-start is complete, > 4.75V (5. for MAX686H) or 2ms (whichever occurs first), switch S2 s on-resistance is decreased to minimize losses. In 3V mode ( = ), the start-up current is limited by the 5Ω series P-channel MOSFET connected between and until the output voltage reaches V / 2. For > V / 2, R ON is reduced to 2.5Ω. With a 5Ω load the device turns on in less than.5ms (see Typical Operating Characteristics for graphs of start-up waveforms). Shutdown Mode Driving low places the device in shutdown mode, which disables the oscillator, the control logic, and the reference. Placing the device in shutdown mode reduces the no-load supply current to less than µa; the output is actively discharged through the internal N- channel FET and disconnected from the input. In normal operation, is driven high or connected to. Applications Information Capacitor Selection The MAX686 requires only three external capacitors. The capacitor values are closely linked to the output current capability, noise, and switching frequency. The MHz oscillator frequency minimizes capacitor size compared to lower-frequency charge pumps. Generally, the transfer capacitor (C X ) will be the smallest, the input capacitor (C ) will be twice the size of C X, and the output capacitor (C ) can be from to 5 times C X. The suggested capacitor values are C =.µf, C X =.47µF, and C = 2.2µF as shown in Figure 3. For input voltages as low as 2.7V, the following values are recommended: C =.47µF, CX =.22µF, and C = µf. Table lists the perfor- C X C X.47µF C S CXN OSC CXP S2 C GND PUT 2.85V TO 4.2V C.µF 3V 5V CXN CXP MAX686 GND PGND 4 5 PUT V OR 4.75V AT 2mA C 2.2µF (CERAMIC) Figure 2. Unregulated Voltage Doubler Figure 3. Standard Application Circuit 6

7 mance with different input voltages and an additional small.µf capacitor at the output. The extra.µf capacitor improves start-up capability under full load and reduces output ripple for high input voltages. Table 2 lists the recommended capacitor manufacturers. Low-ESR capacitors, such as surface-mount ceramics, decrease noise and give the best efficiency. Capacitance and ESR variation over temperature need to be taken into consideration for best performance in applications with large operating temperature ranges. For applications where the minimum input voltage is 3V or greater, the flying capacitor, C X, can be decreased to.µf. This provides two benefits: the inrush surge current at start-up is reduced, and the output ripple voltage (especially at high input voltages) is also reduced. Table. Ripple and Efficiency vs. Input Voltage and Load Current PUT VOLTAGE (V) LOAD CURRENT (ma) RIPPLE (mv) EFFICIENCY (%) Layout Considerations High switching frequencies and large peak currents make PC board layout an important part of design. All capacitors should be soldered close to the IC. Connect ground and power ground through a short, lowimpedance trace. Keep the extra copper on the board and integrate it into ground as a pseudo-ground plane. On multilayer boards, route the star ground using component-side copper fill, then connect it to the internal ground plane using vias. Ensure that the load is connected directly across the output filter capacitor. Table 2. Recommended Surface-Mount Capacitor Manufacturers VALUE (µf) to to 47 to DESCRIPTION 595D-series tantalum TPS-series tantalum 267 series tantalum.47 to 2.2 X7R ceramic MFR. PHONE NUMBER Sprague (63) AVX (83) Matsuo (74) TDK (847) AVX (83) TRANSISTOR COUNT: 84 Chip Information 7

8 Package Information 8LUMAXD.EPS Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. 8 Maxim Integrated Products, 2 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.