Max1870a step-up/step-down li+ battery charger – Rainbow Electronics MAX1870A User Manual
Page 4
MAX1870A
Step-Up/Step-Down
Li+ Battery Charger
4
_______________________________________________________________________________________
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
REFERENCE
REF Output Voltage
I
REF
= 0µA
4.076
4.096
4.116
V
REF Load Regulation
0 < I
REF
< 500µA
5
10
mV
REF Undervoltage-Lockout Trip
Point
V
REF
falling
3.1
3.9
V
REFIN Input Range
2.5
3.6
V
REFIN UVLO Rising
1.9
2.2
V
REFIN UVLO Hysteresis
50
mV
V
DCIN
= 18V
50
100
REFIN Input Bias Current
DCIN = 0, V
REFIN
= 3.6V
-1
+1
µA
SWITCHING REGULATOR
C ycl e- b y- C ycl e S tep - U p M axi m um
C ur r ent- Li m i t S ense V ol tag e
V
DCIN
= 12V, V
BATT
= 16.8V
135
150
165
mV
C ycl e- b y- C ycl e S tep - D ow n
M axi m um C ur r ent- Li m i t S ense
V ol tag e
V
DCIN
= 19V, V
BATT
= 16.8V
135
150
165
mV
Step-Down On-Time
V
DCIN
= 18V, V
BATT
= 16.8V
2.2
2.4
2.6
µs
Minimum Step-Down Off-Time
V
DCIN
= 18V, V
BATT
= 16.8V
0.15
0.4
0.50
µs
Step-Up Off-Time
V
DCIN
= 12V, V
BATT
= 16.8V
1.6
1.8
2.0
µs
Minimum Step-Up On-Time
V
DCIN
= 12V, V
BATT
= 16.8V
0.15
0.3
0.40
µs
MOSFET DRIVERS
VHP - VHN Output Voltage
8V < V
VHP
< 28V, no load
4.5
5
5.5
V
VHN Load Regulation
0 < I
VHN
< 10mA
70
150
mV
DHI On-Resistance High
I
SOURCE
= 10mA
2
5
Ω
DHI On-Resistance Low
I
SINK
= 10mA
1
3
Ω
DCIN = 0
0.1
1
µA
VHP Input Bias Current
V
DCIN
= 18V
1.3
2
mA
ICTL = 0
0.1
2
BLKP Input Bias Current
V
ICTL
= V
REFIN
= 3.3V
100
400
µA
DLOV Supply Current
DBST low
5
10
µA
DBST On-Resistance High
I
SOURCE
= 10mA
2
5
Ω
DBST On-Resistance Low
I
SINK
= 10mA
1
3
Ω
ERROR AMPLIFIERS
GMV Amplifier Loop
Transconductance
V C TL = RE FIN , V
BAT T
= 16.8V
0.05
0.1
0.20
µA/mV
GMI Amplifier Loop
Transconductance
ICTL = REFIN, V
CSIP
- V
CSIN
= 72mV
1.8
2.4
3.0
µA/mV
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 2, V
DCIN
= V
CSSP
= V
CSSN
= V
CSSS
= V
VHP
= 18V, V
BATT
= V
CSIP
= V
CSIN
= V
BLKP
= 12V, V
REFIN
= 3.0V, V
ICTL
=
0.75 x V
REFIN
, VCTL = LDO, CELLS = FLOAT, GND = PGND = 0, V
DLOV
= 5.4V,
T
A
= 0°C to +85°C, unless otherwise noted. Typical
values are at T
A
= +25°C.)