CDH2D09 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
MFG CO.
'CDH2D09' PDF : 44 Pages View PDF
PMIC with Integrated Charger and
Smart Power Selector for Handheld Devices
Table 5. Ideal Charge Currents vs.
Charge Setting Resistor
RCISET (kΩ)
3.01
4.02
4.99
6.04
6.98
8.06
9.09
10.0
11.0
12.1
13.0
14.0
15.0
ICHGMAX (mA)
1000
746
601
497
430
372
330
300
273
248
231
214
200
IPQ (mA)
100
75
60
50
43
37
33
30
27
25
23
21
20
ITO (mA)
40
30
24
20
17
15
13
12
11
10
9
9
8
Determine ICHGMAX by considering the characteristics
of the battery. It is not necessary to limit the charge cur-
rent based on the capabilities of the expected AC-to-
DC adapter or USB charging input, the system load, or
thermal limitations of the PCB. The MAX8671X automat-
ically lowers the charging current as necessary to
accommodate these factors.
For the selected value of RCISET, calculate ICHGMAX,
IPQ, and ITO as follows:
ICHGMAX
=
2000 ×
1.5V
RCISET
IPQ = 10% × ICHGMAX
ITO = 4% × ICHGMAX
In addition to setting the charge current, CISET also pro-
vides a means to monitor battery charge current. The
CISET output voltage tracks the charge current delivered
to the battery, and can be used to monitor the charge
rate, as shown in Figure 9. A 1.5V output indicates the
battery is being charged at the maximum set fast-charge
current, and 0V indicates no charging. This voltage is
also used by the charger control circuitry to set and
monitor the battery current. Avoid adding capacitance
MONITORING THE BATTERY CHARGE
CURRENT WITH VCISET
VCISET =
RCISET
2000
x IBAT
1.5
0
DISCHARGING
0
2000 x
1.5V
RCISET
BATTERY CHARGING CURRENT (A)
Figure 9. Monitoring the Battery Charge Current with the
Voltage from CISET to AGND
directly to the CISET pin that exceeds 10pF. If filtering of
the charge current monitor is necessary, include a resis-
tor of 100kΩ or more between CISET and the filter
capacitor to preserve charger stability.
Step-Down Converters
(REG1, REG2, REG3)
REG1, REG2, and REG3 are high-efficiency 2MHz cur-
rent-mode, step-down converters with adjustable out-
puts. Each REG1, REG2, and REG3 step-down
converter delivers at least 425mA.
The step-down regulator power inputs (PV_) must be
connected to SYS. The step-down regulators operate
with VSYS from 2.6V to 5.5V. Undervoltage lockout
ensures that the step-down regulators do not operate
with SYS below 2.6V (typ).
See the Enable/Disable (EN) and Sequencing section
for how to enable and disable the step-down convert-
ers. When enabled, the MAX8671X gradually ramps
each output up during a soft-start time. Soft-start elimi-
nates input current surges when regulators are
enabled.
See the PWM section for information about the step-
down converters control scheme.
32 ______________________________________________________________________________________
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