Manual

MAX847
1-Cell, Step-Up
Two-Way Pager System IC
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(OUT = 3.0V, BATT = 1.2V, NICD = 3.6V, T
A
= -40°C to +85°C, unless otherwise noted. Typical values are at T
A
= +25°C.) (Note 1)
%-3.5 3.5
OUT Error, Coast Mode
(Note 11)
I
OUT
= 1mA to 80mA, Run Mode mV25OUT Load Regulation
Coast Mode, OUT = 1.8V to 4.9V
Circuit of Figure 2, OUT = 3.0V, BATT = 1.1V
Circuit of Figure 2, OUT = 3.0V, BATT = 1.0V
CONDITIONS
BATT = 0.8V to 1.5V mV25OUT Line Regulation
LX1
Ω
0.45 0.9
LX1 On-Resistance
ns100
CS Pulse Width High, t
CSW
ns70SCL to SDO Output Valid, t
DO
ns50
SCL Pulse Width High or Low,
t
CH
, t
CL
mA80 115
Output Current, Run Mode
(Note 10)
mA15 40
Output Current, Coast Mode
(Note 10)
UNITSMIN TYP MAXPARAMETER
NMOS
PMOS 0.65 1.3
T
A
= +25°C, FILT connected to REF kHz210 270 325Frequency, Free-Run
f
SYNC
= 38.4kHz kHz268.8Frequency, Locked
f
SYNC
= 38.4kHz, FILT network = 1nF

(22nF + 10kΩ)
kHz±15Jitter (Note 14)
f
SYNC
= 38.4kHz, FILT network = 1nF

(22nF + 10kΩ)
ms1 25Capture Time (Note 14)
0.2V < (OUT - NICD) < 2V, 15mA_CHG = 1 mA7 25Current High
0.2V < (OUT - NICD) < 2V, 1mA_CHG = 1 mA0.45 1.5Current Low
OUT = 2.8V, I
OUT
= 20mA, NICD = 3.3V %-3.5 3.5OUT Error, Backup Regulator
Backup Mode, NICD = 3.3V
Ω
5 10
Backup-Regulator
On-Resistance (Note 15)
ns70
CS to SDO Disable, t
TR
%-3.5 3.5
OUT Error, Run Mode
(Note 12)
Run Mode, OUT = 1.8V to 4.9V
mV30 100 170
OUT DAC Step Size
(Note 13)
Coast or Run Mode,
OUT = 1.8V to 4.9V
ns50
ns50
CS to SCL Hold Time, t
CSH
CS to SCL Setup Time, t
CSS
ns70
CS to SDO Output Valid, t
DV
OUT = 3.0V %76 83Maximum LX1 Duty Cycle
I
OUT
= 80mA, C
OUT
= 47µF with ESR < 0.25Ω
mVp-p70OUT Voltage Ripple
During the inductor charge cycle mA480 600 720LX1 Switch Current Limit
DC-DC CONVERTER
PHASE-LOCKED LOOP (PLL)
NICD CHARGER