Datasheet

Meter # 2
- +
Meter # 1
+ -
Meter # 3
+
- +
P/S # 1
Load # 1
_
Meter # 4
+
Jumper
Meter # 2
- +
Meter # 1
Meter # 3
-
- +
P/S # 1
Load # 1
_
Meter # 4
+
Jumper
www.ti.com Test Summary
Figure 1. Test Setup for HPA674A (bq25504 EVM)
3.3 Test procedures
3.3.1 Power-up With No Battery and 10kΩ Load on STOR
1. Connect a 20Ω resistor to J1-1, 10k resistor between J6-1 and J6-3 and place shunt on JP1-DIV.
Connect meters and scope probes to monitor CH1→CH4: V
PHASE
(TP16), V
STOR
, V
P/S #1
, V
BAT
. Set scope
to 1V per division for each channel and 20ms/div, single sequence trigger on V
P/S#1
, see Figure 2.
2. Set PS#1 to 1VDC and hot plug to input with 20Ω series resistor.
This is an example of cold startup (V
STOR
< 1.8V). The input power is harvested by the boost converter and
charges up to the initial OV setting, which is below the actual setting (pseudo softstart), the converter
stops switching and the load discharges the STOR capacitor. Note that if the load is too great with no
battery or a discharge battery the cold start may not be able to charge the battery. Therefore, it is
important to manage the load with a discharged or missing battery, using BAT_OK. The converter
continues to switch until V
STOR
charges up to the OV threshold at 3.1V, the converter shuts off until V
STOR
drops 35 mV (hysteresis) below OV and then the converter switches on periodically to maintain the output
voltage. This is a similar operation to a hysteretic boost converter.
V
PHASE
is the inductor switching node.
5
SLUU654A–October 2011–Revised October 2011 bq25504 EVM – Ultra Low Power Boost Converter with Battery Management for
Energy Harvester Applications
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