BQ24650 Datasheet, PDF (10/33 Pages) Texas Instruments – Synchronous Switch-Mode Battery Charge Controller for Solar Power With Maximum Power Point Tracking

bq24650
SLUSA75 – JULY 2010
www.ti.com
PIN
NO.
NAME
1
VCC
2
MPPSET
3
STAT1
4
TS
5
STAT2
6
VREF
7
TERM_EN
8
VFB
9
SRN
10 SRP
11 GND
12 REGN
13 LODRV
14 PH
15 HIDRV
16 BTST
Thermal
Pad
TYPE
P
I
O
I
O
P
I
I
I
P/I
P
P
O
P
O
P
PIN FUNCTIONS
DESCRIPTION
IC power positive supply. Place a 1-mF ceramic capacitor from VCC to GND and place it as close as
possible to IC. Place a 10-Ω resistor from input side to VCC pin to filter the noise.
Input voltage set point. Use a voltage divider from input source to GND to set voltage on MPPSET to
1.2V. To disable charge, pull MPPSET below 75mV.
Open drain charge status output to indicate various charger operation. Connect to the cathode of LED
with 10kΩ to the pull-up rail. LOW or LED light up indicates charge in progress. Otherwise stays HI or
LED stays off. When any fault condition occurs, both STAT1 and STAT2 are HI, or both LEDs are off.
Temperature qualification voltage input. Connect to a negative temperature coefficient thermistor.
Program the hot and cold temperature window with a resistor divider from VREF to TS to GND. A
103AT-2 thermister is recommended.
Open drain charge status output to indicate various charger operation. Connect to the cathode of LED
with 10kΩ to the pull-up rail. LOW or LED light up indicates charge is complete. Otherwise, stays HI or
LED stays off. When any fault condition occurs, both STAT1 and STAT2 are HI, or both LEDs are off.
3.3V reference voltage output. Place a 1-mF ceramic capacitor from VREF to GND pin close to the IC.
This voltage could be used for programming voltage on TS and the pull-up rail of STAT1 and STAT2.
Charge termination enable. Pull TERM_EN to GND to disable charge termination. Pull TERM_EN to
VREF to allow charge termination. TERM_EN must be terminated and cannot be left floating.
Charge voltage analog feedback adjustment. Connect the output of a resistor divider powered from the
battery terminals to this node to adjust the output battery voltage regulation.
Charge current sense resistor, negative input. A 0.1-mF ceramic capacitor is placed from SRN to SRP to
provide differential-mode filtering. An optional 0.1-mF ceramic capacitor is placed from SRN to GND for
common-mode filtering.
Charge current sense resistor, positive input. A 0.1-mF ceramic capacitor is placed from SRN to SRP to
provide differential-mode filtering. A 0.1-mF ceramic capacitor is placed from SRP to GND for
common-mode filtering.
Power ground. Ground connection for high-current power converter node. On PCB layout, connect
directly to source of low-side power MOSFET, to ground connection of input and output capacitors of the
charger. Only connect to GND through the thermal pad underneath the IC.
PWM low-side driver positive 6V supply output. Connect a 1-mF ceramic capacitor from REGN to GND,
close to the IC. Use to drive low-side driver and high-side driver bootstrap Schottky diode from REGN to
BTST.
PWM low-side driver output. Connect to the gate of the low-side N-channel power MOSFET with a short
trace.
Switching node, charge current output inductor connection. Connect the 0.1-mF bootstrap capacitor from
PH to BTST.
PWM high-side driver output. Connect to the gate of the high-side N-channel power MOSFET with a short
trace.
PWM high-side driver positive supply. Connect the 0.1-uF bootstrap capacitor from PH to BTST.
Exposed pad beneath the IC. The thermal pad must always be soldered to the board and have the vias
on the thermal pad plane star-connecting to GND and ground plane for high-current power converter. It
also serves as a thermal pad to dissipate heat.
10
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