BQ24721 Datasheet, PDF (9/48 Pages) Texas Instruments – ADVANCED MULTI-CHEMISTRY AND MULTI-CELL SYNCHRONOUS SWITCH-MODE CHARGER AND SYSTEM POWER SELECTOR

bq24721
www.ti.com
SLUS683 – NOVEMBER 2005
ELECTRICAL CHARACTERISTICS
8 Vdc ≤ V_(VCC) ≤ 24 Vdc, 0°C ≤ T_J ≤ 125°C, all voltages with respect to AGND (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
PWM HIGH-SIDE N-Channel MOSFET DRIVER (HIDRV)
R_{(DS_HIDRV) High-side on-state resistance}
HSD switch on, HIDRV = HI, V_(BOOST,PH) = 5.5 V
2.2
Hi
R_{(DS_HIDRV) High-side off-state resistance}
HSD switch off, HIDRV = LO, V_(BOOST,PH) = 5.5 V
1.5
Lo
PWM LOW-SIDE N-Channel MOSFET DRIVER (LODRV)
R_{(DS_LODRV) Low-side on-state resistance}
LSD switch on, LODRV = HI, V_(PVCC) = 7 V
2.2
Hi
R_{(DS_LODRV) Low-side off-state resistance}
LSD switch off, LODRV = LO, V_(PVCC) = 7 V
1.5
Lo
PWM LOW-SIDE DRIVER REGULATOR (REGN)
V_O(HREGN) REGN output voltage
I_{O(REGN_SW)}
REGN output current while
charger switching
V(REGN) at I(REGN) = 10 mA, sourcing,
Adapter detected (V_ACDET > V_(ACD)), V_(PVCC) > 7 V
V(REGN) at I(REGN) = 10 mA, sourcing,
Adapter not detected, (V_ACDET < V_(ACD)), V_(PVCC) > 7 V
2 times 25 nC load, Fs = 300 kHz
2 times 25 nC load, Fs = 500 kHz
5.5
6
4.2
15
25
I_{(REGN_LIM)}
REGN Current limit
Adapter detected
REGN Current limit
Adapter not detected
PWM DRIVERS TIMING
VREGN = 5 V
Adapter detected (V_ACDET > V_(ACD)), V_(PVCC)> 7 V
VREGN = 0 V, shorted
Adapter detected (V_ACDET > V_(ACD)), V_(PVCC)> 7 V
VREGN = 4.2 V
Adapter not detected, (V_ACDET < V_(ACD)), V_(PVCC)> 7 V
100
13.3
15
Dead time when switching
between LSD and HSD, no
30
load at LSD and HSD
PWM OSCILLATOR
V_(RAMPLO)
PWM oscillator ramp voltage ,
low value
0% duty cycle occurs below this threshold
0.35
V_(RAMPHI)
PWM oscillator ramp voltage ,
high value
near 100% duty cycle occurs above this threshold
V_PP(RAMP)
PWM ramp peak-to-peak
amplitude
0.1×VCC
V_(RAMPCL)
PWM oscillator ramp clamp
voltage
3.5
PWM oscillator frequency (300
kHz)
F_S
PWM oscillator frequency (500
kHz)
265
300
425
500
INTERNAL SOFT START (8 steps to Ireg)
SRSET pin voltage number of
steps during soft start.
Eight steps of charge current regulation to get to programmed
value
(SRSET = 1 V).
8
Step Duration.
Eight steps of charge current regulation to get to programmed
value
(SRSET = 1 V).
0.8
1
CHARGER SECTION POWER-UP SEQUENCING
Time delay between power up
of charger block references
1
(first) and start charge (second)
Time delay from adapter
detected until ACDRV enable
500
and charger block enable
MAX UNIT
3
Ω
2.5
Ω
3
Ω
2.5
Ω
6.5
V
V
mA
mA
mA
mA
mA
ns
V
3
V
V
V
345 kHz
575 kHz
step
1.2 ms/step
ms
ms
9