MAX847EEI Maxim Integrated Products, MAX847EEI Datasheet

Page 1

... Idle Mode™ (coast) Current Selectable Low-Noise PWM or Low-Current Operation PWM Operating Frequency Synchronized to Seven Times an External Clock Source Operates at 270kHz with No External Clock Automatic Backup-Battery Switchover PART TEMP. RANGE MAX847EEI ________________________Applications Two-Way Pagers GPS Receivers 1-Cell Powered Hand-Held Equipment BATT LBI LX1 LBO ...

Page 2

Step-Up Two-Way Pager System IC ABSOLUTE MAXIMUM RATINGS BATT, OUT, NICD, LBO, RSO to AGND...................-0.3V to +6V REG1, OFS, REG2, REF, R2IN to AGND ...-0.3V to (OUT + 0.3V SYNC, FILT, DR2IN, SCL, SDO, SDI, CH0, LBI, ...

Page 3

ELECTRICAL CHARACTERISTICS (continued) (OUT = 3.0V, BATT = 1.2V, NICD = 3.6V, T PARAMETER SCL to SDO Output Valid SDO Output Valid SDO Disable SCL Setup Time, t ...

Page 4

Step-Up Two-Way Pager System IC ELECTRICAL CHARACTERISTICS (continued) (OUT = 3.0V, BATT = 1.2V, NICD = 3.6V, T PARAMETER LINEAR REGULATORS REG1 PMOS On-Resistance OUT = 3.0V, I REG1 Supply Rejection (Note 15 268.8kHz, C REG1 Clamp ...

Page 5

ELECTRICAL CHARACTERISTICS (continued) (OUT = 3.0V, BATT = 1.2V, NICD = 3.6V, T PARAMETER CH2 Input Hysteresis (Note 15) CH0 Input Current CH0 = 0.2V to 1.27V CH Comparator Response Time 10mV overdrive (Note 15) Note 1: Specifications to -40°C ...

Page 6

Step-Up Two-Way Pager System IC (Circuit of Figure +25°C, unless otherwise noted.) A NO-LOAD BATTERY CURRENT vs. BATTERY VOLTAGE 100 3.0V OUT COAST MODE 0 0.5 1 1.5 BATTERY VOLTAGE ...

Page 7

Description PIN NAME Connect LX1 to the inductor. LX1 is internally connected to an NFET that switches to PGND and a PFET 1 LX1 that switches to OUT. 2 SDI Serial Data Input for SPI Interface 3 SDO Serial ...

Page 8

Step-Up Two-Way Pager System IC N LBO 6 – LBI CH0 9 CP0 FROM – NICD S1 + CP1 – FROM + BATTERY CP2 – 7-BIT CH DAC REF 1.28V ...

Page 9

Detailed Description The MAX847 contains several functional blocks that simplify the integration of power-supply and monitoring functions within a 1-cell powered system. They are described in the following subsections. Voltage Regulators Regulator outputs include the following: • OUT: Main ...

Page 10

Step-Up Two-Way Pager System IC OUT can be set as low as 1.8V; however, some run mode functions are limited when V OUT • The allowed serial-interface clock rate is reduced. • Internal LX FET and DR1 and DR2 ...

Page 11

Table 1. Run and Coast Mode Start-Up Requirements SYNC OPERATION No SYNC clock is used. On initial power-up, system can supply SYNC clock to MAX847 when REG1 is greater than 1.5V. On initial power-up, system can supply SYNC clock to ...

Page 12

Step-Up Two-Way Pager System IC pulse width modulation (PWM), as well as synchroniza- tion, to minimize noise. Some MAX847 functions are confined to Run Mode while others remain active in both Run and Coast. These are outlined as follows. ...

Page 13

Backup Linear Regulator The BACKUP serial input bit turns on the backup regu- lator, which sources current from NICD to OUT. This regulator backs up OUT by using the rechargeable bat- tery (at NICD) when the main battery (at BATT) ...

Page 14

Step-Up Two-Way Pager System CSS t CSH SCLK DIN t DV DOUT Figure 5. Detailed Serial-Interface Timing CS SCL SDO D7 SDI CS, SCL, SDO, and SDI Serial Timing Figure 6. Serial ...

Page 15

Table 5. Serial Output Data D7 (MSB) D6 CH2_OUT CH1_OUT CH0_OUT Table 6. V Output Voltage OUT SERIAL-DATA BIT OV4 OV3 OV2 OV1 ...

Page 16

Step-Up Two-Way Pager System IC Table 7. External Components SUPPLIER PART NO. INDUCTORS (22µH) 0.16 , 3.18mm high, Coilcraft DT1608C-223 shielded 0.94 , 2.6mm high, LQH4N220K low current, low cost Murata 0.71 , 2mm high, low LQH3C221 current, low ...

Page 17

Step-Up Two-Way Pager System IC Package Information 17 ...

Page 18

Step-Up Two-Way Pager System IC 18 ______________________________________________________________________________________ NOTES ...